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Diffstat (limited to 'contrib/gcc/tree-ssa-loop-ivopts.c')
| -rw-r--r-- | contrib/gcc/tree-ssa-loop-ivopts.c | 5906 |
1 files changed, 5906 insertions, 0 deletions
diff --git a/contrib/gcc/tree-ssa-loop-ivopts.c b/contrib/gcc/tree-ssa-loop-ivopts.c new file mode 100644 index 0000000..0874620 --- /dev/null +++ b/contrib/gcc/tree-ssa-loop-ivopts.c @@ -0,0 +1,5906 @@ +/* Induction variable optimizations. + Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc. + +This file is part of GCC. + +GCC is free software; you can redistribute it and/or modify it +under the terms of the GNU General Public License as published by the +Free Software Foundation; either version 2, or (at your option) any +later version. + +GCC is distributed in the hope that it will be useful, but WITHOUT +ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or +FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +for more details. + +You should have received a copy of the GNU General Public License +along with GCC; see the file COPYING. If not, write to the Free +Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301, USA. */ + +/* This pass tries to find the optimal set of induction variables for the loop. + It optimizes just the basic linear induction variables (although adding + support for other types should not be too hard). It includes the + optimizations commonly known as strength reduction, induction variable + coalescing and induction variable elimination. It does it in the + following steps: + + 1) The interesting uses of induction variables are found. This includes + + -- uses of induction variables in non-linear expressions + -- addresses of arrays + -- comparisons of induction variables + + 2) Candidates for the induction variables are found. This includes + + -- old induction variables + -- the variables defined by expressions derived from the "interesting + uses" above + + 3) The optimal (w.r. to a cost function) set of variables is chosen. The + cost function assigns a cost to sets of induction variables and consists + of three parts: + + -- The use costs. Each of the interesting uses chooses the best induction + variable in the set and adds its cost to the sum. The cost reflects + the time spent on modifying the induction variables value to be usable + for the given purpose (adding base and offset for arrays, etc.). + -- The variable costs. Each of the variables has a cost assigned that + reflects the costs associated with incrementing the value of the + variable. The original variables are somewhat preferred. + -- The set cost. Depending on the size of the set, extra cost may be + added to reflect register pressure. + + All the costs are defined in a machine-specific way, using the target + hooks and machine descriptions to determine them. + + 4) The trees are transformed to use the new variables, the dead code is + removed. + + All of this is done loop by loop. Doing it globally is theoretically + possible, it might give a better performance and it might enable us + to decide costs more precisely, but getting all the interactions right + would be complicated. */ + +#include "config.h" +#include "system.h" +#include "coretypes.h" +#include "tm.h" +#include "tree.h" +#include "rtl.h" +#include "tm_p.h" +#include "hard-reg-set.h" +#include "basic-block.h" +#include "output.h" +#include "diagnostic.h" +#include "tree-flow.h" +#include "tree-dump.h" +#include "timevar.h" +#include "cfgloop.h" +#include "varray.h" +#include "expr.h" +#include "tree-pass.h" +#include "ggc.h" +#include "insn-config.h" +#include "recog.h" +#include "hashtab.h" +#include "tree-chrec.h" +#include "tree-scalar-evolution.h" +#include "cfgloop.h" +#include "params.h" +#include "langhooks.h" + +/* The infinite cost. */ +#define INFTY 10000000 + +/* The expected number of loop iterations. TODO -- use profiling instead of + this. */ +#define AVG_LOOP_NITER(LOOP) 5 + + +/* Representation of the induction variable. */ +struct iv +{ + tree base; /* Initial value of the iv. */ + tree base_object; /* A memory object to that the induction variable points. */ + tree step; /* Step of the iv (constant only). */ + tree ssa_name; /* The ssa name with the value. */ + bool biv_p; /* Is it a biv? */ + bool have_use_for; /* Do we already have a use for it? */ + unsigned use_id; /* The identifier in the use if it is the case. */ +}; + +/* Per-ssa version information (induction variable descriptions, etc.). */ +struct version_info +{ + tree name; /* The ssa name. */ + struct iv *iv; /* Induction variable description. */ + bool has_nonlin_use; /* For a loop-level invariant, whether it is used in + an expression that is not an induction variable. */ + unsigned inv_id; /* Id of an invariant. */ + bool preserve_biv; /* For the original biv, whether to preserve it. */ +}; + +/* Types of uses. */ +enum use_type +{ + USE_NONLINEAR_EXPR, /* Use in a nonlinear expression. */ + USE_ADDRESS, /* Use in an address. */ + USE_COMPARE /* Use is a compare. */ +}; + +/* The candidate - cost pair. */ +struct cost_pair +{ + struct iv_cand *cand; /* The candidate. */ + unsigned cost; /* The cost. */ + bitmap depends_on; /* The list of invariants that have to be + preserved. */ + tree value; /* For final value elimination, the expression for + the final value of the iv. For iv elimination, + the new bound to compare with. */ +}; + +/* Use. */ +struct iv_use +{ + unsigned id; /* The id of the use. */ + enum use_type type; /* Type of the use. */ + struct iv *iv; /* The induction variable it is based on. */ + tree stmt; /* Statement in that it occurs. */ + tree *op_p; /* The place where it occurs. */ + bitmap related_cands; /* The set of "related" iv candidates, plus the common + important ones. */ + + unsigned n_map_members; /* Number of candidates in the cost_map list. */ + struct cost_pair *cost_map; + /* The costs wrto the iv candidates. */ + + struct iv_cand *selected; + /* The selected candidate. */ +}; + +/* The position where the iv is computed. */ +enum iv_position +{ + IP_NORMAL, /* At the end, just before the exit condition. */ + IP_END, /* At the end of the latch block. */ + IP_ORIGINAL /* The original biv. */ +}; + +/* The induction variable candidate. */ +struct iv_cand +{ + unsigned id; /* The number of the candidate. */ + bool important; /* Whether this is an "important" candidate, i.e. such + that it should be considered by all uses. */ + enum iv_position pos; /* Where it is computed. */ + tree incremented_at; /* For original biv, the statement where it is + incremented. */ + tree var_before; /* The variable used for it before increment. */ + tree var_after; /* The variable used for it after increment. */ + struct iv *iv; /* The value of the candidate. NULL for + "pseudocandidate" used to indicate the possibility + to replace the final value of an iv by direct + computation of the value. */ + unsigned cost; /* Cost of the candidate. */ + bitmap depends_on; /* The list of invariants that are used in step of the + biv. */ +}; + +/* The data used by the induction variable optimizations. */ + +typedef struct iv_use *iv_use_p; +DEF_VEC_P(iv_use_p); +DEF_VEC_ALLOC_P(iv_use_p,heap); + +typedef struct iv_cand *iv_cand_p; +DEF_VEC_P(iv_cand_p); +DEF_VEC_ALLOC_P(iv_cand_p,heap); + +struct ivopts_data +{ + /* The currently optimized loop. */ + struct loop *current_loop; + + /* Number of registers used in it. */ + unsigned regs_used; + + /* Numbers of iterations for all exits of the current loop. */ + htab_t niters; + + /* The size of version_info array allocated. */ + unsigned version_info_size; + + /* The array of information for the ssa names. */ + struct version_info *version_info; + + /* The bitmap of indices in version_info whose value was changed. */ + bitmap relevant; + + /* The maximum invariant id. */ + unsigned max_inv_id; + + /* The uses of induction variables. */ + VEC(iv_use_p,heap) *iv_uses; + + /* The candidates. */ + VEC(iv_cand_p,heap) *iv_candidates; + + /* A bitmap of important candidates. */ + bitmap important_candidates; + + /* Whether to consider just related and important candidates when replacing a + use. */ + bool consider_all_candidates; +}; + +/* An assignment of iv candidates to uses. */ + +struct iv_ca +{ + /* The number of uses covered by the assignment. */ + unsigned upto; + + /* Number of uses that cannot be expressed by the candidates in the set. */ + unsigned bad_uses; + + /* Candidate assigned to a use, together with the related costs. */ + struct cost_pair **cand_for_use; + + /* Number of times each candidate is used. */ + unsigned *n_cand_uses; + + /* The candidates used. */ + bitmap cands; + + /* The number of candidates in the set. */ + unsigned n_cands; + + /* Total number of registers needed. */ + unsigned n_regs; + + /* Total cost of expressing uses. */ + unsigned cand_use_cost; + + /* Total cost of candidates. */ + unsigned cand_cost; + + /* Number of times each invariant is used. */ + unsigned *n_invariant_uses; + + /* Total cost of the assignment. */ + unsigned cost; +}; + +/* Difference of two iv candidate assignments. */ + +struct iv_ca_delta +{ + /* Changed use. */ + struct iv_use *use; + + /* An old assignment (for rollback purposes). */ + struct cost_pair *old_cp; + + /* A new assignment. */ + struct cost_pair *new_cp; + + /* Next change in the list. */ + struct iv_ca_delta *next_change; +}; + +/* Bound on number of candidates below that all candidates are considered. */ + +#define CONSIDER_ALL_CANDIDATES_BOUND \ + ((unsigned) PARAM_VALUE (PARAM_IV_CONSIDER_ALL_CANDIDATES_BOUND)) + +/* If there are more iv occurrences, we just give up (it is quite unlikely that + optimizing such a loop would help, and it would take ages). */ + +#define MAX_CONSIDERED_USES \ + ((unsigned) PARAM_VALUE (PARAM_IV_MAX_CONSIDERED_USES)) + +/* If there are at most this number of ivs in the set, try removing unnecessary + ivs from the set always. */ + +#define ALWAYS_PRUNE_CAND_SET_BOUND \ + ((unsigned) PARAM_VALUE (PARAM_IV_ALWAYS_PRUNE_CAND_SET_BOUND)) + +/* The list of trees for that the decl_rtl field must be reset is stored + here. */ + +static VEC(tree,heap) *decl_rtl_to_reset; + +/* Number of uses recorded in DATA. */ + +static inline unsigned +n_iv_uses (struct ivopts_data *data) +{ + return VEC_length (iv_use_p, data->iv_uses); +} + +/* Ith use recorded in DATA. */ + +static inline struct iv_use * +iv_use (struct ivopts_data *data, unsigned i) +{ + return VEC_index (iv_use_p, data->iv_uses, i); +} + +/* Number of candidates recorded in DATA. */ + +static inline unsigned +n_iv_cands (struct ivopts_data *data) +{ + return VEC_length (iv_cand_p, data->iv_candidates); +} + +/* Ith candidate recorded in DATA. */ + +static inline struct iv_cand * +iv_cand (struct ivopts_data *data, unsigned i) +{ + return VEC_index (iv_cand_p, data->iv_candidates, i); +} + +/* The single loop exit if it dominates the latch, NULL otherwise. */ + +edge +single_dom_exit (struct loop *loop) +{ + edge exit = loop->single_exit; + + if (!exit) + return NULL; + + if (!just_once_each_iteration_p (loop, exit->src)) + return NULL; + + return exit; +} + +/* Dumps information about the induction variable IV to FILE. */ + +extern void dump_iv (FILE *, struct iv *); +void +dump_iv (FILE *file, struct iv *iv) +{ + if (iv->ssa_name) + { + fprintf (file, "ssa name "); + print_generic_expr (file, iv->ssa_name, TDF_SLIM); + fprintf (file, "\n"); + } + + fprintf (file, " type "); + print_generic_expr (file, TREE_TYPE (iv->base), TDF_SLIM); + fprintf (file, "\n"); + + if (iv->step) + { + fprintf (file, " base "); + print_generic_expr (file, iv->base, TDF_SLIM); + fprintf (file, "\n"); + + fprintf (file, " step "); + print_generic_expr (file, iv->step, TDF_SLIM); + fprintf (file, "\n"); + } + else + { + fprintf (file, " invariant "); + print_generic_expr (file, iv->base, TDF_SLIM); + fprintf (file, "\n"); + } + + if (iv->base_object) + { + fprintf (file, " base object "); + print_generic_expr (file, iv->base_object, TDF_SLIM); + fprintf (file, "\n"); + } + + if (iv->biv_p) + fprintf (file, " is a biv\n"); +} + +/* Dumps information about the USE to FILE. */ + +extern void dump_use (FILE *, struct iv_use *); +void +dump_use (FILE *file, struct iv_use *use) +{ + fprintf (file, "use %d\n", use->id); + + switch (use->type) + { + case USE_NONLINEAR_EXPR: + fprintf (file, " generic\n"); + break; + + case USE_ADDRESS: + fprintf (file, " address\n"); + break; + + case USE_COMPARE: + fprintf (file, " compare\n"); + break; + + default: + gcc_unreachable (); + } + + fprintf (file, " in statement "); + print_generic_expr (file, use->stmt, TDF_SLIM); + fprintf (file, "\n"); + + fprintf (file, " at position "); + if (use->op_p) + print_generic_expr (file, *use->op_p, TDF_SLIM); + fprintf (file, "\n"); + + dump_iv (file, use->iv); + + if (use->related_cands) + { + fprintf (file, " related candidates "); + dump_bitmap (file, use->related_cands); + } +} + +/* Dumps information about the uses to FILE. */ + +extern void dump_uses (FILE *, struct ivopts_data *); +void +dump_uses (FILE *file, struct ivopts_data *data) +{ + unsigned i; + struct iv_use *use; + + for (i = 0; i < n_iv_uses (data); i++) + { + use = iv_use (data, i); + + dump_use (file, use); + fprintf (file, "\n"); + } +} + +/* Dumps information about induction variable candidate CAND to FILE. */ + +extern void dump_cand (FILE *, struct iv_cand *); +void +dump_cand (FILE *file, struct iv_cand *cand) +{ + struct iv *iv = cand->iv; + + fprintf (file, "candidate %d%s\n", + cand->id, cand->important ? " (important)" : ""); + + if (cand->depends_on) + { + fprintf (file, " depends on "); + dump_bitmap (file, cand->depends_on); + } + + if (!iv) + { + fprintf (file, " final value replacement\n"); + return; + } + + switch (cand->pos) + { + case IP_NORMAL: + fprintf (file, " incremented before exit test\n"); + break; + + case IP_END: + fprintf (file, " incremented at end\n"); + break; + + case IP_ORIGINAL: + fprintf (file, " original biv\n"); + break; + } + + dump_iv (file, iv); +} + +/* Returns the info for ssa version VER. */ + +static inline struct version_info * +ver_info (struct ivopts_data *data, unsigned ver) +{ + return data->version_info + ver; +} + +/* Returns the info for ssa name NAME. */ + +static inline struct version_info * +name_info (struct ivopts_data *data, tree name) +{ + return ver_info (data, SSA_NAME_VERSION (name)); +} + +/* Checks whether there exists number X such that X * B = A, counting modulo + 2^BITS. */ + +static bool +divide (unsigned bits, unsigned HOST_WIDE_INT a, unsigned HOST_WIDE_INT b, + HOST_WIDE_INT *x) +{ + unsigned HOST_WIDE_INT mask = ~(~(unsigned HOST_WIDE_INT) 0 << (bits - 1) << 1); + unsigned HOST_WIDE_INT inv, ex, val; + unsigned i; + + a &= mask; + b &= mask; + + /* First divide the whole equation by 2 as long as possible. */ + while (!(a & 1) && !(b & 1)) + { + a >>= 1; + b >>= 1; + bits--; + mask >>= 1; + } + + if (!(b & 1)) + { + /* If b is still even, a is odd and there is no such x. */ + return false; + } + + /* Find the inverse of b. We compute it as + b^(2^(bits - 1) - 1) (mod 2^bits). */ + inv = 1; + ex = b; + for (i = 0; i < bits - 1; i++) + { + inv = (inv * ex) & mask; + ex = (ex * ex) & mask; + } + + val = (a * inv) & mask; + + gcc_assert (((val * b) & mask) == a); + + if ((val >> (bits - 1)) & 1) + val |= ~mask; + + *x = val; + + return true; +} + +/* Returns true if STMT is after the place where the IP_NORMAL ivs will be + emitted in LOOP. */ + +static bool +stmt_after_ip_normal_pos (struct loop *loop, tree stmt) +{ + basic_block bb = ip_normal_pos (loop), sbb = bb_for_stmt (stmt); + + gcc_assert (bb); + + if (sbb == loop->latch) + return true; + + if (sbb != bb) + return false; + + return stmt == last_stmt (bb); +} + +/* Returns true if STMT if after the place where the original induction + variable CAND is incremented. */ + +static bool +stmt_after_ip_original_pos (struct iv_cand *cand, tree stmt) +{ + basic_block cand_bb = bb_for_stmt (cand->incremented_at); + basic_block stmt_bb = bb_for_stmt (stmt); + block_stmt_iterator bsi; + + if (!dominated_by_p (CDI_DOMINATORS, stmt_bb, cand_bb)) + return false; + + if (stmt_bb != cand_bb) + return true; + + /* Scan the block from the end, since the original ivs are usually + incremented at the end of the loop body. */ + for (bsi = bsi_last (stmt_bb); ; bsi_prev (&bsi)) + { + if (bsi_stmt (bsi) == cand->incremented_at) + return false; + if (bsi_stmt (bsi) == stmt) + return true; + } +} + +/* Returns true if STMT if after the place where the induction variable + CAND is incremented in LOOP. */ + +static bool +stmt_after_increment (struct loop *loop, struct iv_cand *cand, tree stmt) +{ + switch (cand->pos) + { + case IP_END: + return false; + + case IP_NORMAL: + return stmt_after_ip_normal_pos (loop, stmt); + + case IP_ORIGINAL: + return stmt_after_ip_original_pos (cand, stmt); + + default: + gcc_unreachable (); + } +} + +/* Returns true if EXP is a ssa name that occurs in an abnormal phi node. */ + +static bool +abnormal_ssa_name_p (tree exp) +{ + if (!exp) + return false; + + if (TREE_CODE (exp) != SSA_NAME) + return false; + + return SSA_NAME_OCCURS_IN_ABNORMAL_PHI (exp) != 0; +} + +/* Returns false if BASE or INDEX contains a ssa name that occurs in an + abnormal phi node. Callback for for_each_index. */ + +static bool +idx_contains_abnormal_ssa_name_p (tree base, tree *index, + void *data ATTRIBUTE_UNUSED) +{ + if (TREE_CODE (base) == ARRAY_REF) + { + if (abnormal_ssa_name_p (TREE_OPERAND (base, 2))) + return false; + if (abnormal_ssa_name_p (TREE_OPERAND (base, 3))) + return false; + } + + return !abnormal_ssa_name_p (*index); +} + +/* Returns true if EXPR contains a ssa name that occurs in an + abnormal phi node. */ + +bool +contains_abnormal_ssa_name_p (tree expr) +{ + enum tree_code code; + enum tree_code_class class; + + if (!expr) + return false; + + code = TREE_CODE (expr); + class = TREE_CODE_CLASS (code); + + if (code == SSA_NAME) + return SSA_NAME_OCCURS_IN_ABNORMAL_PHI (expr) != 0; + + if (code == INTEGER_CST + || is_gimple_min_invariant (expr)) + return false; + + if (code == ADDR_EXPR) + return !for_each_index (&TREE_OPERAND (expr, 0), + idx_contains_abnormal_ssa_name_p, + NULL); + + switch (class) + { + case tcc_binary: + case tcc_comparison: + if (contains_abnormal_ssa_name_p (TREE_OPERAND (expr, 1))) + return true; + + /* Fallthru. */ + case tcc_unary: + if (contains_abnormal_ssa_name_p (TREE_OPERAND (expr, 0))) + return true; + + break; + + default: + gcc_unreachable (); + } + + return false; +} + +/* Element of the table in that we cache the numbers of iterations obtained + from exits of the loop. */ + +struct nfe_cache_elt +{ + /* The edge for that the number of iterations is cached. */ + edge exit; + + /* Number of iterations corresponding to this exit, or NULL if it cannot be + determined. */ + tree niter; +}; + +/* Hash function for nfe_cache_elt E. */ + +static hashval_t +nfe_hash (const void *e) +{ + const struct nfe_cache_elt *elt = e; + + return htab_hash_pointer (elt->exit); +} + +/* Equality function for nfe_cache_elt E1 and edge E2. */ + +static int +nfe_eq (const void *e1, const void *e2) +{ + const struct nfe_cache_elt *elt1 = e1; + + return elt1->exit == e2; +} + +/* Returns tree describing number of iterations determined from + EXIT of DATA->current_loop, or NULL if something goes wrong. */ + +static tree +niter_for_exit (struct ivopts_data *data, edge exit) +{ + struct nfe_cache_elt *nfe_desc; + struct tree_niter_desc desc; + PTR *slot; + + slot = htab_find_slot_with_hash (data->niters, exit, + htab_hash_pointer (exit), + INSERT); + + if (!*slot) + { + nfe_desc = xmalloc (sizeof (struct nfe_cache_elt)); + nfe_desc->exit = exit; + + /* Try to determine number of iterations. We must know it + unconditionally (i.e., without possibility of # of iterations + being zero). Also, we cannot safely work with ssa names that + appear in phi nodes on abnormal edges, so that we do not create + overlapping life ranges for them (PR 27283). */ + if (number_of_iterations_exit (data->current_loop, + exit, &desc, true) + && zero_p (desc.may_be_zero) + && !contains_abnormal_ssa_name_p (desc.niter)) + nfe_desc->niter = desc.niter; + else + nfe_desc->niter = NULL_TREE; + } + else + nfe_desc = *slot; + + return nfe_desc->niter; +} + +/* Returns tree describing number of iterations determined from + single dominating exit of DATA->current_loop, or NULL if something + goes wrong. */ + +static tree +niter_for_single_dom_exit (struct ivopts_data *data) +{ + edge exit = single_dom_exit (data->current_loop); + + if (!exit) + return NULL; + + return niter_for_exit (data, exit); +} + +/* Initializes data structures used by the iv optimization pass, stored + in DATA. */ + +static void +tree_ssa_iv_optimize_init (struct ivopts_data *data) +{ + data->version_info_size = 2 * num_ssa_names; + data->version_info = XCNEWVEC (struct version_info, data->version_info_size); + data->relevant = BITMAP_ALLOC (NULL); + data->important_candidates = BITMAP_ALLOC (NULL); + data->max_inv_id = 0; + data->niters = htab_create (10, nfe_hash, nfe_eq, free); + data->iv_uses = VEC_alloc (iv_use_p, heap, 20); + data->iv_candidates = VEC_alloc (iv_cand_p, heap, 20); + decl_rtl_to_reset = VEC_alloc (tree, heap, 20); +} + +/* Returns a memory object to that EXPR points. In case we are able to + determine that it does not point to any such object, NULL is returned. */ + +static tree +determine_base_object (tree expr) +{ + enum tree_code code = TREE_CODE (expr); + tree base, obj, op0, op1; + + /* If this is a pointer casted to any type, we need to determine + the base object for the pointer; so handle conversions before + throwing away non-pointer expressions. */ + if (TREE_CODE (expr) == NOP_EXPR + || TREE_CODE (expr) == CONVERT_EXPR) + return determine_base_object (TREE_OPERAND (expr, 0)); + + if (!POINTER_TYPE_P (TREE_TYPE (expr))) + return NULL_TREE; + + switch (code) + { + case INTEGER_CST: + return NULL_TREE; + + case ADDR_EXPR: + obj = TREE_OPERAND (expr, 0); + base = get_base_address (obj); + + if (!base) + return expr; + + if (TREE_CODE (base) == INDIRECT_REF) + return determine_base_object (TREE_OPERAND (base, 0)); + + return fold_convert (ptr_type_node, + build_fold_addr_expr (base)); + + case PLUS_EXPR: + case MINUS_EXPR: + op0 = determine_base_object (TREE_OPERAND (expr, 0)); + op1 = determine_base_object (TREE_OPERAND (expr, 1)); + + if (!op1) + return op0; + + if (!op0) + return (code == PLUS_EXPR + ? op1 + : fold_build1 (NEGATE_EXPR, ptr_type_node, op1)); + + return fold_build2 (code, ptr_type_node, op0, op1); + + default: + return fold_convert (ptr_type_node, expr); + } +} + +/* Allocates an induction variable with given initial value BASE and step STEP + for loop LOOP. */ + +static struct iv * +alloc_iv (tree base, tree step) +{ + struct iv *iv = XCNEW (struct iv); + + if (step && integer_zerop (step)) + step = NULL_TREE; + + iv->base = base; + iv->base_object = determine_base_object (base); + iv->step = step; + iv->biv_p = false; + iv->have_use_for = false; + iv->use_id = 0; + iv->ssa_name = NULL_TREE; + + return iv; +} + +/* Sets STEP and BASE for induction variable IV. */ + +static void +set_iv (struct ivopts_data *data, tree iv, tree base, tree step) +{ + struct version_info *info = name_info (data, iv); + + gcc_assert (!info->iv); + + bitmap_set_bit (data->relevant, SSA_NAME_VERSION (iv)); + info->iv = alloc_iv (base, step); + info->iv->ssa_name = iv; +} + +/* Finds induction variable declaration for VAR. */ + +static struct iv * +get_iv (struct ivopts_data *data, tree var) +{ + basic_block bb; + + if (!name_info (data, var)->iv) + { + bb = bb_for_stmt (SSA_NAME_DEF_STMT (var)); + + if (!bb + || !flow_bb_inside_loop_p (data->current_loop, bb)) + set_iv (data, var, var, NULL_TREE); + } + + return name_info (data, var)->iv; +} + +/* Determines the step of a biv defined in PHI. Returns NULL if PHI does + not define a simple affine biv with nonzero step. */ + +static tree +determine_biv_step (tree phi) +{ + struct loop *loop = bb_for_stmt (phi)->loop_father; + tree name = PHI_RESULT (phi); + affine_iv iv; + + if (!is_gimple_reg (name)) + return NULL_TREE; + + if (!simple_iv (loop, phi, name, &iv, true)) + return NULL_TREE; + + return (zero_p (iv.step) ? NULL_TREE : iv.step); +} + +/* Finds basic ivs. */ + +static bool +find_bivs (struct ivopts_data *data) +{ + tree phi, step, type, base; + bool found = false; + struct loop *loop = data->current_loop; + + for (phi = phi_nodes (loop->header); phi; phi = PHI_CHAIN (phi)) + { + if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (PHI_RESULT (phi))) + continue; + + step = determine_biv_step (phi); + if (!step) + continue; + + base = PHI_ARG_DEF_FROM_EDGE (phi, loop_preheader_edge (loop)); + base = expand_simple_operations (base); + if (contains_abnormal_ssa_name_p (base) + || contains_abnormal_ssa_name_p (step)) + continue; + + type = TREE_TYPE (PHI_RESULT (phi)); + base = fold_convert (type, base); + if (step) + step = fold_convert (type, step); + + set_iv (data, PHI_RESULT (phi), base, step); + found = true; + } + + return found; +} + +/* Marks basic ivs. */ + +static void +mark_bivs (struct ivopts_data *data) +{ + tree phi, var; + struct iv *iv, *incr_iv; + struct loop *loop = data->current_loop; + basic_block incr_bb; + + for (phi = phi_nodes (loop->header); phi; phi = PHI_CHAIN (phi)) + { + iv = get_iv (data, PHI_RESULT (phi)); + if (!iv) + continue; + + var = PHI_ARG_DEF_FROM_EDGE (phi, loop_latch_edge (loop)); + incr_iv = get_iv (data, var); + if (!incr_iv) + continue; + + /* If the increment is in the subloop, ignore it. */ + incr_bb = bb_for_stmt (SSA_NAME_DEF_STMT (var)); + if (incr_bb->loop_father != data->current_loop + || (incr_bb->flags & BB_IRREDUCIBLE_LOOP)) + continue; + + iv->biv_p = true; + incr_iv->biv_p = true; + } +} + +/* Checks whether STMT defines a linear induction variable and stores its + parameters to IV. */ + +static bool +find_givs_in_stmt_scev (struct ivopts_data *data, tree stmt, affine_iv *iv) +{ + tree lhs; + struct loop *loop = data->current_loop; + + iv->base = NULL_TREE; + iv->step = NULL_TREE; + + if (TREE_CODE (stmt) != MODIFY_EXPR) + return false; + + lhs = TREE_OPERAND (stmt, 0); + if (TREE_CODE (lhs) != SSA_NAME) + return false; + + if (!simple_iv (loop, stmt, TREE_OPERAND (stmt, 1), iv, true)) + return false; + iv->base = expand_simple_operations (iv->base); + + if (contains_abnormal_ssa_name_p (iv->base) + || contains_abnormal_ssa_name_p (iv->step)) + return false; + + return true; +} + +/* Finds general ivs in statement STMT. */ + +static void +find_givs_in_stmt (struct ivopts_data *data, tree stmt) +{ + affine_iv iv; + + if (!find_givs_in_stmt_scev (data, stmt, &iv)) + return; + + set_iv (data, TREE_OPERAND (stmt, 0), iv.base, iv.step); +} + +/* Finds general ivs in basic block BB. */ + +static void +find_givs_in_bb (struct ivopts_data *data, basic_block bb) +{ + block_stmt_iterator bsi; + + for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) + find_givs_in_stmt (data, bsi_stmt (bsi)); +} + +/* Finds general ivs. */ + +static void +find_givs (struct ivopts_data *data) +{ + struct loop *loop = data->current_loop; + basic_block *body = get_loop_body_in_dom_order (loop); + unsigned i; + + for (i = 0; i < loop->num_nodes; i++) + find_givs_in_bb (data, body[i]); + free (body); +} + +/* For each ssa name defined in LOOP determines whether it is an induction + variable and if so, its initial value and step. */ + +static bool +find_induction_variables (struct ivopts_data *data) +{ + unsigned i; + bitmap_iterator bi; + + if (!find_bivs (data)) + return false; + + find_givs (data); + mark_bivs (data); + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + tree niter = niter_for_single_dom_exit (data); + + if (niter) + { + fprintf (dump_file, " number of iterations "); + print_generic_expr (dump_file, niter, TDF_SLIM); + fprintf (dump_file, "\n\n"); + }; + + fprintf (dump_file, "Induction variables:\n\n"); + + EXECUTE_IF_SET_IN_BITMAP (data->relevant, 0, i, bi) + { + if (ver_info (data, i)->iv) + dump_iv (dump_file, ver_info (data, i)->iv); + } + } + + return true; +} + +/* Records a use of type USE_TYPE at *USE_P in STMT whose value is IV. */ + +static struct iv_use * +record_use (struct ivopts_data *data, tree *use_p, struct iv *iv, + tree stmt, enum use_type use_type) +{ + struct iv_use *use = XCNEW (struct iv_use); + + use->id = n_iv_uses (data); + use->type = use_type; + use->iv = iv; + use->stmt = stmt; + use->op_p = use_p; + use->related_cands = BITMAP_ALLOC (NULL); + + /* To avoid showing ssa name in the dumps, if it was not reset by the + caller. */ + iv->ssa_name = NULL_TREE; + + if (dump_file && (dump_flags & TDF_DETAILS)) + dump_use (dump_file, use); + + VEC_safe_push (iv_use_p, heap, data->iv_uses, use); + + return use; +} + +/* Checks whether OP is a loop-level invariant and if so, records it. + NONLINEAR_USE is true if the invariant is used in a way we do not + handle specially. */ + +static void +record_invariant (struct ivopts_data *data, tree op, bool nonlinear_use) +{ + basic_block bb; + struct version_info *info; + + if (TREE_CODE (op) != SSA_NAME + || !is_gimple_reg (op)) + return; + + bb = bb_for_stmt (SSA_NAME_DEF_STMT (op)); + if (bb + && flow_bb_inside_loop_p (data->current_loop, bb)) + return; + + info = name_info (data, op); + info->name = op; + info->has_nonlin_use |= nonlinear_use; + if (!info->inv_id) + info->inv_id = ++data->max_inv_id; + bitmap_set_bit (data->relevant, SSA_NAME_VERSION (op)); +} + +/* Checks whether the use OP is interesting and if so, records it. */ + +static struct iv_use * +find_interesting_uses_op (struct ivopts_data *data, tree op) +{ + struct iv *iv; + struct iv *civ; + tree stmt; + struct iv_use *use; + + if (TREE_CODE (op) != SSA_NAME) + return NULL; + + iv = get_iv (data, op); + if (!iv) + return NULL; + + if (iv->have_use_for) + { + use = iv_use (data, iv->use_id); + + gcc_assert (use->type == USE_NONLINEAR_EXPR); + return use; + } + + if (zero_p (iv->step)) + { + record_invariant (data, op, true); + return NULL; + } + iv->have_use_for = true; + + civ = XNEW (struct iv); + *civ = *iv; + + stmt = SSA_NAME_DEF_STMT (op); + gcc_assert (TREE_CODE (stmt) == PHI_NODE + || TREE_CODE (stmt) == MODIFY_EXPR); + + use = record_use (data, NULL, civ, stmt, USE_NONLINEAR_EXPR); + iv->use_id = use->id; + + return use; +} + +/* Checks whether the condition *COND_P in STMT is interesting + and if so, records it. */ + +static void +find_interesting_uses_cond (struct ivopts_data *data, tree stmt, tree *cond_p) +{ + tree *op0_p; + tree *op1_p; + struct iv *iv0 = NULL, *iv1 = NULL, *civ; + struct iv const_iv; + tree zero = integer_zero_node; + + const_iv.step = NULL_TREE; + + if (TREE_CODE (*cond_p) != SSA_NAME + && !COMPARISON_CLASS_P (*cond_p)) + return; + + if (TREE_CODE (*cond_p) == SSA_NAME) + { + op0_p = cond_p; + op1_p = &zero; + } + else + { + op0_p = &TREE_OPERAND (*cond_p, 0); + op1_p = &TREE_OPERAND (*cond_p, 1); + } + + if (TREE_CODE (*op0_p) == SSA_NAME) + iv0 = get_iv (data, *op0_p); + else + iv0 = &const_iv; + + if (TREE_CODE (*op1_p) == SSA_NAME) + iv1 = get_iv (data, *op1_p); + else + iv1 = &const_iv; + + if (/* When comparing with non-invariant value, we may not do any senseful + induction variable elimination. */ + (!iv0 || !iv1) + /* Eliminating condition based on two ivs would be nontrivial. + ??? TODO -- it is not really important to handle this case. */ + || (!zero_p (iv0->step) && !zero_p (iv1->step))) + { + find_interesting_uses_op (data, *op0_p); + find_interesting_uses_op (data, *op1_p); + return; + } + + if (zero_p (iv0->step) && zero_p (iv1->step)) + { + /* If both are invariants, this is a work for unswitching. */ + return; + } + + civ = XNEW (struct iv); + *civ = zero_p (iv0->step) ? *iv1: *iv0; + record_use (data, cond_p, civ, stmt, USE_COMPARE); +} + +/* Returns true if expression EXPR is obviously invariant in LOOP, + i.e. if all its operands are defined outside of the LOOP. */ + +bool +expr_invariant_in_loop_p (struct loop *loop, tree expr) +{ + basic_block def_bb; + unsigned i, len; + + if (is_gimple_min_invariant (expr)) + return true; + + if (TREE_CODE (expr) == SSA_NAME) + { + def_bb = bb_for_stmt (SSA_NAME_DEF_STMT (expr)); + if (def_bb + && flow_bb_inside_loop_p (loop, def_bb)) + return false; + + return true; + } + + if (!EXPR_P (expr)) + return false; + + len = TREE_CODE_LENGTH (TREE_CODE (expr)); + for (i = 0; i < len; i++) + if (!expr_invariant_in_loop_p (loop, TREE_OPERAND (expr, i))) + return false; + + return true; +} + +/* Cumulates the steps of indices into DATA and replaces their values with the + initial ones. Returns false when the value of the index cannot be determined. + Callback for for_each_index. */ + +struct ifs_ivopts_data +{ + struct ivopts_data *ivopts_data; + tree stmt; + tree *step_p; +}; + +static bool +idx_find_step (tree base, tree *idx, void *data) +{ + struct ifs_ivopts_data *dta = data; + struct iv *iv; + tree step, iv_base, iv_step, lbound, off; + struct loop *loop = dta->ivopts_data->current_loop; + + if (TREE_CODE (base) == MISALIGNED_INDIRECT_REF + || TREE_CODE (base) == ALIGN_INDIRECT_REF) + return false; + + /* If base is a component ref, require that the offset of the reference + be invariant. */ + if (TREE_CODE (base) == COMPONENT_REF) + { + off = component_ref_field_offset (base); + return expr_invariant_in_loop_p (loop, off); + } + + /* If base is array, first check whether we will be able to move the + reference out of the loop (in order to take its address in strength + reduction). In order for this to work we need both lower bound + and step to be loop invariants. */ + if (TREE_CODE (base) == ARRAY_REF) + { + step = array_ref_element_size (base); + lbound = array_ref_low_bound (base); + + if (!expr_invariant_in_loop_p (loop, step) + || !expr_invariant_in_loop_p (loop, lbound)) + return false; + } + + if (TREE_CODE (*idx) != SSA_NAME) + return true; + + iv = get_iv (dta->ivopts_data, *idx); + if (!iv) + return false; + + /* XXX We produce for a base of *D42 with iv->base being &x[0] + *&x[0], which is not folded and does not trigger the + ARRAY_REF path below. */ + *idx = iv->base; + + if (!iv->step) + return true; + + if (TREE_CODE (base) == ARRAY_REF) + { + step = array_ref_element_size (base); + + /* We only handle addresses whose step is an integer constant. */ + if (TREE_CODE (step) != INTEGER_CST) + return false; + } + else + /* The step for pointer arithmetics already is 1 byte. */ + step = build_int_cst (sizetype, 1); + + iv_base = iv->base; + iv_step = iv->step; + if (!convert_affine_scev (dta->ivopts_data->current_loop, + sizetype, &iv_base, &iv_step, dta->stmt, + false)) + { + /* The index might wrap. */ + return false; + } + + step = fold_build2 (MULT_EXPR, sizetype, step, iv_step); + + if (!*dta->step_p) + *dta->step_p = step; + else + *dta->step_p = fold_build2 (PLUS_EXPR, sizetype, *dta->step_p, step); + + return true; +} + +/* Records use in index IDX. Callback for for_each_index. Ivopts data + object is passed to it in DATA. */ + +static bool +idx_record_use (tree base, tree *idx, + void *data) +{ + find_interesting_uses_op (data, *idx); + if (TREE_CODE (base) == ARRAY_REF) + { + find_interesting_uses_op (data, array_ref_element_size (base)); + find_interesting_uses_op (data, array_ref_low_bound (base)); + } + return true; +} + +/* Returns true if memory reference REF may be unaligned. */ + +static bool +may_be_unaligned_p (tree ref) +{ + tree base; + tree base_type; + HOST_WIDE_INT bitsize; + HOST_WIDE_INT bitpos; + tree toffset; + enum machine_mode mode; + int unsignedp, volatilep; + unsigned base_align; + + /* TARGET_MEM_REFs are translated directly to valid MEMs on the target, + thus they are not misaligned. */ + if (TREE_CODE (ref) == TARGET_MEM_REF) + return false; + + /* The test below is basically copy of what expr.c:normal_inner_ref + does to check whether the object must be loaded by parts when + STRICT_ALIGNMENT is true. */ + base = get_inner_reference (ref, &bitsize, &bitpos, &toffset, &mode, + &unsignedp, &volatilep, true); + base_type = TREE_TYPE (base); + base_align = TYPE_ALIGN (base_type); + + if (mode != BLKmode + && (base_align < GET_MODE_ALIGNMENT (mode) + || bitpos % GET_MODE_ALIGNMENT (mode) != 0 + || bitpos % BITS_PER_UNIT != 0)) + return true; + + return false; +} + +/* Return true if EXPR may be non-addressable. */ + +static bool +may_be_nonaddressable_p (tree expr) +{ + switch (TREE_CODE (expr)) + { + case COMPONENT_REF: + return DECL_NONADDRESSABLE_P (TREE_OPERAND (expr, 1)) + || may_be_nonaddressable_p (TREE_OPERAND (expr, 0)); + + case ARRAY_REF: + case ARRAY_RANGE_REF: + return may_be_nonaddressable_p (TREE_OPERAND (expr, 0)); + + case VIEW_CONVERT_EXPR: + /* This kind of view-conversions may wrap non-addressable objects + and make them look addressable. After some processing the + non-addressability may be uncovered again, causing ADDR_EXPRs + of inappropriate objects to be built. */ + return AGGREGATE_TYPE_P (TREE_TYPE (expr)) + && !AGGREGATE_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))); + + default: + break; + } + + return false; +} + +/* Finds addresses in *OP_P inside STMT. */ + +static void +find_interesting_uses_address (struct ivopts_data *data, tree stmt, tree *op_p) +{ + tree base = *op_p, step = NULL; + struct iv *civ; + struct ifs_ivopts_data ifs_ivopts_data; + + /* Do not play with volatile memory references. A bit too conservative, + perhaps, but safe. */ + if (stmt_ann (stmt)->has_volatile_ops) + goto fail; + + /* Ignore bitfields for now. Not really something terribly complicated + to handle. TODO. */ + if (TREE_CODE (base) == BIT_FIELD_REF) + goto fail; + + if (may_be_nonaddressable_p (base)) + goto fail; + + if (STRICT_ALIGNMENT + && may_be_unaligned_p (base)) + goto fail; + + base = unshare_expr (base); + + if (TREE_CODE (base) == TARGET_MEM_REF) + { + tree type = build_pointer_type (TREE_TYPE (base)); + tree astep; + + if (TMR_BASE (base) + && TREE_CODE (TMR_BASE (base)) == SSA_NAME) + { + civ = get_iv (data, TMR_BASE (base)); + if (!civ) + goto fail; + + TMR_BASE (base) = civ->base; + step = civ->step; + } + if (TMR_INDEX (base) + && TREE_CODE (TMR_INDEX (base)) == SSA_NAME) + { + civ = get_iv (data, TMR_INDEX (base)); + if (!civ) + goto fail; + + TMR_INDEX (base) = civ->base; + astep = civ->step; + + if (astep) + { + if (TMR_STEP (base)) + astep = fold_build2 (MULT_EXPR, type, TMR_STEP (base), astep); + + if (step) + step = fold_build2 (PLUS_EXPR, type, step, astep); + else + step = astep; + } + } + + if (zero_p (step)) + goto fail; + base = tree_mem_ref_addr (type, base); + } + else + { + ifs_ivopts_data.ivopts_data = data; + ifs_ivopts_data.stmt = stmt; + ifs_ivopts_data.step_p = &step; + if (!for_each_index (&base, idx_find_step, &ifs_ivopts_data) + || zero_p (step)) + goto fail; + + gcc_assert (TREE_CODE (base) != ALIGN_INDIRECT_REF); + gcc_assert (TREE_CODE (base) != MISALIGNED_INDIRECT_REF); + + base = build_fold_addr_expr (base); + + /* Substituting bases of IVs into the base expression might + have caused folding opportunities. */ + if (TREE_CODE (base) == ADDR_EXPR) + { + tree *ref = &TREE_OPERAND (base, 0); + while (handled_component_p (*ref)) + ref = &TREE_OPERAND (*ref, 0); + if (TREE_CODE (*ref) == INDIRECT_REF) + *ref = fold_indirect_ref (*ref); + } + } + + civ = alloc_iv (base, step); + record_use (data, op_p, civ, stmt, USE_ADDRESS); + return; + +fail: + for_each_index (op_p, idx_record_use, data); +} + +/* Finds and records invariants used in STMT. */ + +static void +find_invariants_stmt (struct ivopts_data *data, tree stmt) +{ + ssa_op_iter iter; + use_operand_p use_p; + tree op; + + FOR_EACH_PHI_OR_STMT_USE (use_p, stmt, iter, SSA_OP_USE) + { + op = USE_FROM_PTR (use_p); + record_invariant (data, op, false); + } +} + +/* Finds interesting uses of induction variables in the statement STMT. */ + +static void +find_interesting_uses_stmt (struct ivopts_data *data, tree stmt) +{ + struct iv *iv; + tree op, lhs, rhs; + ssa_op_iter iter; + use_operand_p use_p; + + find_invariants_stmt (data, stmt); + + if (TREE_CODE (stmt) == COND_EXPR) + { + find_interesting_uses_cond (data, stmt, &COND_EXPR_COND (stmt)); + return; + } + + if (TREE_CODE (stmt) == MODIFY_EXPR) + { + lhs = TREE_OPERAND (stmt, 0); + rhs = TREE_OPERAND (stmt, 1); + + if (TREE_CODE (lhs) == SSA_NAME) + { + /* If the statement defines an induction variable, the uses are not + interesting by themselves. */ + + iv = get_iv (data, lhs); + + if (iv && !zero_p (iv->step)) + return; + } + + switch (TREE_CODE_CLASS (TREE_CODE (rhs))) + { + case tcc_comparison: + find_interesting_uses_cond (data, stmt, &TREE_OPERAND (stmt, 1)); + return; + + case tcc_reference: + find_interesting_uses_address (data, stmt, &TREE_OPERAND (stmt, 1)); + if (REFERENCE_CLASS_P (lhs)) + find_interesting_uses_address (data, stmt, &TREE_OPERAND (stmt, 0)); + return; + + default: ; + } + + if (REFERENCE_CLASS_P (lhs) + && is_gimple_val (rhs)) + { + find_interesting_uses_address (data, stmt, &TREE_OPERAND (stmt, 0)); + find_interesting_uses_op (data, rhs); + return; + } + + /* TODO -- we should also handle address uses of type + + memory = call (whatever); + + and + + call (memory). */ + } + + if (TREE_CODE (stmt) == PHI_NODE + && bb_for_stmt (stmt) == data->current_loop->header) + { + lhs = PHI_RESULT (stmt); + iv = get_iv (data, lhs); + + if (iv && !zero_p (iv->step)) + return; + } + + FOR_EACH_PHI_OR_STMT_USE (use_p, stmt, iter, SSA_OP_USE) + { + op = USE_FROM_PTR (use_p); + + if (TREE_CODE (op) != SSA_NAME) + continue; + + iv = get_iv (data, op); + if (!iv) + continue; + + find_interesting_uses_op (data, op); + } +} + +/* Finds interesting uses of induction variables outside of loops + on loop exit edge EXIT. */ + +static void +find_interesting_uses_outside (struct ivopts_data *data, edge exit) +{ + tree phi, def; + + for (phi = phi_nodes (exit->dest); phi; phi = PHI_CHAIN (phi)) + { + def = PHI_ARG_DEF_FROM_EDGE (phi, exit); + find_interesting_uses_op (data, def); + } +} + +/* Finds uses of the induction variables that are interesting. */ + +static void +find_interesting_uses (struct ivopts_data *data) +{ + basic_block bb; + block_stmt_iterator bsi; + tree phi; + basic_block *body = get_loop_body (data->current_loop); + unsigned i; + struct version_info *info; + edge e; + + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Uses:\n\n"); + + for (i = 0; i < data->current_loop->num_nodes; i++) + { + edge_iterator ei; + bb = body[i]; + + FOR_EACH_EDGE (e, ei, bb->succs) + if (e->dest != EXIT_BLOCK_PTR + && !flow_bb_inside_loop_p (data->current_loop, e->dest)) + find_interesting_uses_outside (data, e); + + for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) + find_interesting_uses_stmt (data, phi); + for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) + find_interesting_uses_stmt (data, bsi_stmt (bsi)); + } + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + bitmap_iterator bi; + + fprintf (dump_file, "\n"); + + EXECUTE_IF_SET_IN_BITMAP (data->relevant, 0, i, bi) + { + info = ver_info (data, i); + if (info->inv_id) + { + fprintf (dump_file, " "); + print_generic_expr (dump_file, info->name, TDF_SLIM); + fprintf (dump_file, " is invariant (%d)%s\n", + info->inv_id, info->has_nonlin_use ? "" : ", eliminable"); + } + } + + fprintf (dump_file, "\n"); + } + + free (body); +} + +/* Strips constant offsets from EXPR and stores them to OFFSET. If INSIDE_ADDR + is true, assume we are inside an address. If TOP_COMPREF is true, assume + we are at the top-level of the processed address. */ + +static tree +strip_offset_1 (tree expr, bool inside_addr, bool top_compref, + unsigned HOST_WIDE_INT *offset) +{ + tree op0 = NULL_TREE, op1 = NULL_TREE, tmp, step; + enum tree_code code; + tree type, orig_type = TREE_TYPE (expr); + unsigned HOST_WIDE_INT off0, off1, st; + tree orig_expr = expr; + + STRIP_NOPS (expr); + + type = TREE_TYPE (expr); + code = TREE_CODE (expr); + *offset = 0; + + switch (code) + { + case INTEGER_CST: + if (!cst_and_fits_in_hwi (expr) + || zero_p (expr)) + return orig_expr; + + *offset = int_cst_value (expr); + return build_int_cst (orig_type, 0); + + case PLUS_EXPR: + case MINUS_EXPR: + op0 = TREE_OPERAND (expr, 0); + op1 = TREE_OPERAND (expr, 1); + + op0 = strip_offset_1 (op0, false, false, &off0); + op1 = strip_offset_1 (op1, false, false, &off1); + + *offset = (code == PLUS_EXPR ? off0 + off1 : off0 - off1); + if (op0 == TREE_OPERAND (expr, 0) + && op1 == TREE_OPERAND (expr, 1)) + return orig_expr; + + if (zero_p (op1)) + expr = op0; + else if (zero_p (op0)) + { + if (code == PLUS_EXPR) + expr = op1; + else + expr = fold_build1 (NEGATE_EXPR, type, op1); + } + else + expr = fold_build2 (code, type, op0, op1); + + return fold_convert (orig_type, expr); + + case ARRAY_REF: + if (!inside_addr) + return orig_expr; + + step = array_ref_element_size (expr); + if (!cst_and_fits_in_hwi (step)) + break; + + st = int_cst_value (step); + op1 = TREE_OPERAND (expr, 1); + op1 = strip_offset_1 (op1, false, false, &off1); + *offset = off1 * st; + + if (top_compref + && zero_p (op1)) + { + /* Strip the component reference completely. */ + op0 = TREE_OPERAND (expr, 0); + op0 = strip_offset_1 (op0, inside_addr, top_compref, &off0); + *offset += off0; + return op0; + } + break; + + case COMPONENT_REF: + if (!inside_addr) + return orig_expr; + + tmp = component_ref_field_offset (expr); + if (top_compref + && cst_and_fits_in_hwi (tmp)) + { + /* Strip the component reference completely. */ + op0 = TREE_OPERAND (expr, 0); + op0 = strip_offset_1 (op0, inside_addr, top_compref, &off0); + *offset = off0 + int_cst_value (tmp); + return op0; + } + break; + + case ADDR_EXPR: + op0 = TREE_OPERAND (expr, 0); + op0 = strip_offset_1 (op0, true, true, &off0); + *offset += off0; + + if (op0 == TREE_OPERAND (expr, 0)) + return orig_expr; + + expr = build_fold_addr_expr (op0); + return fold_convert (orig_type, expr); + + case INDIRECT_REF: + inside_addr = false; + break; + + default: + return orig_expr; + } + + /* Default handling of expressions for that we want to recurse into + the first operand. */ + op0 = TREE_OPERAND (expr, 0); + op0 = strip_offset_1 (op0, inside_addr, false, &off0); + *offset += off0; + + if (op0 == TREE_OPERAND (expr, 0) + && (!op1 || op1 == TREE_OPERAND (expr, 1))) + return orig_expr; + + expr = copy_node (expr); + TREE_OPERAND (expr, 0) = op0; + if (op1) + TREE_OPERAND (expr, 1) = op1; + + /* Inside address, we might strip the top level component references, + thus changing type of the expression. Handling of ADDR_EXPR + will fix that. */ + expr = fold_convert (orig_type, expr); + + return expr; +} + +/* Strips constant offsets from EXPR and stores them to OFFSET. */ + +static tree +strip_offset (tree expr, unsigned HOST_WIDE_INT *offset) +{ + return strip_offset_1 (expr, false, false, offset); +} + +/* Returns variant of TYPE that can be used as base for different uses. + We return unsigned type with the same precision, which avoids problems + with overflows. */ + +static tree +generic_type_for (tree type) +{ + if (POINTER_TYPE_P (type)) + return unsigned_type_for (type); + + if (TYPE_UNSIGNED (type)) + return type; + + return unsigned_type_for (type); +} + +/* Records invariants in *EXPR_P. Callback for walk_tree. DATA contains + the bitmap to that we should store it. */ + +static struct ivopts_data *fd_ivopts_data; +static tree +find_depends (tree *expr_p, int *ws ATTRIBUTE_UNUSED, void *data) +{ + bitmap *depends_on = data; + struct version_info *info; + + if (TREE_CODE (*expr_p) != SSA_NAME) + return NULL_TREE; + info = name_info (fd_ivopts_data, *expr_p); + + if (!info->inv_id || info->has_nonlin_use) + return NULL_TREE; + + if (!*depends_on) + *depends_on = BITMAP_ALLOC (NULL); + bitmap_set_bit (*depends_on, info->inv_id); + + return NULL_TREE; +} + +/* Adds a candidate BASE + STEP * i. Important field is set to IMPORTANT and + position to POS. If USE is not NULL, the candidate is set as related to + it. If both BASE and STEP are NULL, we add a pseudocandidate for the + replacement of the final value of the iv by a direct computation. */ + +static struct iv_cand * +add_candidate_1 (struct ivopts_data *data, + tree base, tree step, bool important, enum iv_position pos, + struct iv_use *use, tree incremented_at) +{ + unsigned i; + struct iv_cand *cand = NULL; + tree type, orig_type; + + if (base) + { + orig_type = TREE_TYPE (base); + type = generic_type_for (orig_type); + if (type != orig_type) + { + base = fold_convert (type, base); + if (step) + step = fold_convert (type, step); + } + } + + for (i = 0; i < n_iv_cands (data); i++) + { + cand = iv_cand (data, i); + + if (cand->pos != pos) + continue; + + if (cand->incremented_at != incremented_at) + continue; + + if (!cand->iv) + { + if (!base && !step) + break; + + continue; + } + + if (!base && !step) + continue; + + if (!operand_equal_p (base, cand->iv->base, 0)) + continue; + + if (zero_p (cand->iv->step)) + { + if (zero_p (step)) + break; + } + else + { + if (step && operand_equal_p (step, cand->iv->step, 0)) + break; + } + } + + if (i == n_iv_cands (data)) + { + cand = XCNEW (struct iv_cand); + cand->id = i; + + if (!base && !step) + cand->iv = NULL; + else + cand->iv = alloc_iv (base, step); + + cand->pos = pos; + if (pos != IP_ORIGINAL && cand->iv) + { + cand->var_before = create_tmp_var_raw (TREE_TYPE (base), "ivtmp"); + cand->var_after = cand->var_before; + } + cand->important = important; + cand->incremented_at = incremented_at; + VEC_safe_push (iv_cand_p, heap, data->iv_candidates, cand); + + if (step + && TREE_CODE (step) != INTEGER_CST) + { + fd_ivopts_data = data; + walk_tree (&step, find_depends, &cand->depends_on, NULL); + } + + if (dump_file && (dump_flags & TDF_DETAILS)) + dump_cand (dump_file, cand); + } + + if (important && !cand->important) + { + cand->important = true; + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Candidate %d is important\n", cand->id); + } + + if (use) + { + bitmap_set_bit (use->related_cands, i); + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Candidate %d is related to use %d\n", + cand->id, use->id); + } + + return cand; +} + +/* Returns true if incrementing the induction variable at the end of the LOOP + is allowed. + + The purpose is to avoid splitting latch edge with a biv increment, thus + creating a jump, possibly confusing other optimization passes and leaving + less freedom to scheduler. So we allow IP_END_POS only if IP_NORMAL_POS + is not available (so we do not have a better alternative), or if the latch + edge is already nonempty. */ + +static bool +allow_ip_end_pos_p (struct loop *loop) +{ + if (!ip_normal_pos (loop)) + return true; + + if (!empty_block_p (ip_end_pos (loop))) + return true; + + return false; +} + +/* Adds a candidate BASE + STEP * i. Important field is set to IMPORTANT and + position to POS. If USE is not NULL, the candidate is set as related to + it. The candidate computation is scheduled on all available positions. */ + +static void +add_candidate (struct ivopts_data *data, + tree base, tree step, bool important, struct iv_use *use) +{ + if (ip_normal_pos (data->current_loop)) + add_candidate_1 (data, base, step, important, IP_NORMAL, use, NULL_TREE); + if (ip_end_pos (data->current_loop) + && allow_ip_end_pos_p (data->current_loop)) + add_candidate_1 (data, base, step, important, IP_END, use, NULL_TREE); +} + +/* Add a standard "0 + 1 * iteration" iv candidate for a + type with SIZE bits. */ + +static void +add_standard_iv_candidates_for_size (struct ivopts_data *data, + unsigned int size) +{ + tree type = lang_hooks.types.type_for_size (size, true); + add_candidate (data, build_int_cst (type, 0), build_int_cst (type, 1), + true, NULL); +} + +/* Adds standard iv candidates. */ + +static void +add_standard_iv_candidates (struct ivopts_data *data) +{ + add_standard_iv_candidates_for_size (data, INT_TYPE_SIZE); + + /* The same for a double-integer type if it is still fast enough. */ + if (BITS_PER_WORD >= INT_TYPE_SIZE * 2) + add_standard_iv_candidates_for_size (data, INT_TYPE_SIZE * 2); +} + + +/* Adds candidates bases on the old induction variable IV. */ + +static void +add_old_iv_candidates (struct ivopts_data *data, struct iv *iv) +{ + tree phi, def; + struct iv_cand *cand; + + add_candidate (data, iv->base, iv->step, true, NULL); + + /* The same, but with initial value zero. */ + add_candidate (data, + build_int_cst (TREE_TYPE (iv->base), 0), + iv->step, true, NULL); + + phi = SSA_NAME_DEF_STMT (iv->ssa_name); + if (TREE_CODE (phi) == PHI_NODE) + { + /* Additionally record the possibility of leaving the original iv + untouched. */ + def = PHI_ARG_DEF_FROM_EDGE (phi, loop_latch_edge (data->current_loop)); + cand = add_candidate_1 (data, + iv->base, iv->step, true, IP_ORIGINAL, NULL, + SSA_NAME_DEF_STMT (def)); + cand->var_before = iv->ssa_name; + cand->var_after = def; + } +} + +/* Adds candidates based on the old induction variables. */ + +static void +add_old_ivs_candidates (struct ivopts_data *data) +{ + unsigned i; + struct iv *iv; + bitmap_iterator bi; + + EXECUTE_IF_SET_IN_BITMAP (data->relevant, 0, i, bi) + { + iv = ver_info (data, i)->iv; + if (iv && iv->biv_p && !zero_p (iv->step)) + add_old_iv_candidates (data, iv); + } +} + +/* Adds candidates based on the value of the induction variable IV and USE. */ + +static void +add_iv_value_candidates (struct ivopts_data *data, + struct iv *iv, struct iv_use *use) +{ + unsigned HOST_WIDE_INT offset; + tree base; + + add_candidate (data, iv->base, iv->step, false, use); + + /* The same, but with initial value zero. Make such variable important, + since it is generic enough so that possibly many uses may be based + on it. */ + add_candidate (data, build_int_cst (TREE_TYPE (iv->base), 0), + iv->step, true, use); + + /* Third, try removing the constant offset. */ + base = strip_offset (iv->base, &offset); + if (offset) + add_candidate (data, base, iv->step, false, use); +} + +/* Adds candidates based on the uses. */ + +static void +add_derived_ivs_candidates (struct ivopts_data *data) +{ + unsigned i; + + for (i = 0; i < n_iv_uses (data); i++) + { + struct iv_use *use = iv_use (data, i); + + if (!use) + continue; + + switch (use->type) + { + case USE_NONLINEAR_EXPR: + case USE_COMPARE: + case USE_ADDRESS: + /* Just add the ivs based on the value of the iv used here. */ + add_iv_value_candidates (data, use->iv, use); + break; + + default: + gcc_unreachable (); + } + } +} + +/* Record important candidates and add them to related_cands bitmaps + if needed. */ + +static void +record_important_candidates (struct ivopts_data *data) +{ + unsigned i; + struct iv_use *use; + + for (i = 0; i < n_iv_cands (data); i++) + { + struct iv_cand *cand = iv_cand (data, i); + + if (cand->important) + bitmap_set_bit (data->important_candidates, i); + } + + data->consider_all_candidates = (n_iv_cands (data) + <= CONSIDER_ALL_CANDIDATES_BOUND); + + if (data->consider_all_candidates) + { + /* We will not need "related_cands" bitmaps in this case, + so release them to decrease peak memory consumption. */ + for (i = 0; i < n_iv_uses (data); i++) + { + use = iv_use (data, i); + BITMAP_FREE (use->related_cands); + } + } + else + { + /* Add important candidates to the related_cands bitmaps. */ + for (i = 0; i < n_iv_uses (data); i++) + bitmap_ior_into (iv_use (data, i)->related_cands, + data->important_candidates); + } +} + +/* Finds the candidates for the induction variables. */ + +static void +find_iv_candidates (struct ivopts_data *data) +{ + /* Add commonly used ivs. */ + add_standard_iv_candidates (data); + + /* Add old induction variables. */ + add_old_ivs_candidates (data); + + /* Add induction variables derived from uses. */ + add_derived_ivs_candidates (data); + + /* Record the important candidates. */ + record_important_candidates (data); +} + +/* Allocates the data structure mapping the (use, candidate) pairs to costs. + If consider_all_candidates is true, we use a two-dimensional array, otherwise + we allocate a simple list to every use. */ + +static void +alloc_use_cost_map (struct ivopts_data *data) +{ + unsigned i, size, s, j; + + for (i = 0; i < n_iv_uses (data); i++) + { + struct iv_use *use = iv_use (data, i); + bitmap_iterator bi; + + if (data->consider_all_candidates) + size = n_iv_cands (data); + else + { + s = 0; + EXECUTE_IF_SET_IN_BITMAP (use->related_cands, 0, j, bi) + { + s++; + } + + /* Round up to the power of two, so that moduling by it is fast. */ + for (size = 1; size < s; size <<= 1) + continue; + } + + use->n_map_members = size; + use->cost_map = XCNEWVEC (struct cost_pair, size); + } +} + +/* Sets cost of (USE, CANDIDATE) pair to COST and record that it depends + on invariants DEPENDS_ON and that the value used in expressing it + is VALUE.*/ + +static void +set_use_iv_cost (struct ivopts_data *data, + struct iv_use *use, struct iv_cand *cand, unsigned cost, + bitmap depends_on, tree value) +{ + unsigned i, s; + + if (cost == INFTY) + { + BITMAP_FREE (depends_on); + return; + } + + if (data->consider_all_candidates) + { + use->cost_map[cand->id].cand = cand; + use->cost_map[cand->id].cost = cost; + use->cost_map[cand->id].depends_on = depends_on; + use->cost_map[cand->id].value = value; + return; + } + + /* n_map_members is a power of two, so this computes modulo. */ + s = cand->id & (use->n_map_members - 1); + for (i = s; i < use->n_map_members; i++) + if (!use->cost_map[i].cand) + goto found; + for (i = 0; i < s; i++) + if (!use->cost_map[i].cand) + goto found; + + gcc_unreachable (); + +found: + use->cost_map[i].cand = cand; + use->cost_map[i].cost = cost; + use->cost_map[i].depends_on = depends_on; + use->cost_map[i].value = value; +} + +/* Gets cost of (USE, CANDIDATE) pair. */ + +static struct cost_pair * +get_use_iv_cost (struct ivopts_data *data, struct iv_use *use, + struct iv_cand *cand) +{ + unsigned i, s; + struct cost_pair *ret; + + if (!cand) + return NULL; + + if (data->consider_all_candidates) + { + ret = use->cost_map + cand->id; + if (!ret->cand) + return NULL; + + return ret; + } + + /* n_map_members is a power of two, so this computes modulo. */ + s = cand->id & (use->n_map_members - 1); + for (i = s; i < use->n_map_members; i++) + if (use->cost_map[i].cand == cand) + return use->cost_map + i; + + for (i = 0; i < s; i++) + if (use->cost_map[i].cand == cand) + return use->cost_map + i; + + return NULL; +} + +/* Returns estimate on cost of computing SEQ. */ + +static unsigned +seq_cost (rtx seq) +{ + unsigned cost = 0; + rtx set; + + for (; seq; seq = NEXT_INSN (seq)) + { + set = single_set (seq); + if (set) + cost += rtx_cost (set, SET); + else + cost++; + } + + return cost; +} + +/* Produce DECL_RTL for object obj so it looks like it is stored in memory. */ +static rtx +produce_memory_decl_rtl (tree obj, int *regno) +{ + rtx x; + + gcc_assert (obj); + if (TREE_STATIC (obj) || DECL_EXTERNAL (obj)) + { + const char *name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (obj)); + x = gen_rtx_SYMBOL_REF (Pmode, name); + } + else + x = gen_raw_REG (Pmode, (*regno)++); + + return gen_rtx_MEM (DECL_MODE (obj), x); +} + +/* Prepares decl_rtl for variables referred in *EXPR_P. Callback for + walk_tree. DATA contains the actual fake register number. */ + +static tree +prepare_decl_rtl (tree *expr_p, int *ws, void *data) +{ + tree obj = NULL_TREE; + rtx x = NULL_RTX; + int *regno = data; + + switch (TREE_CODE (*expr_p)) + { + case ADDR_EXPR: + for (expr_p = &TREE_OPERAND (*expr_p, 0); + handled_component_p (*expr_p); + expr_p = &TREE_OPERAND (*expr_p, 0)) + continue; + obj = *expr_p; + if (DECL_P (obj) && !DECL_RTL_SET_P (obj)) + x = produce_memory_decl_rtl (obj, regno); + break; + + case SSA_NAME: + *ws = 0; + obj = SSA_NAME_VAR (*expr_p); + if (!DECL_RTL_SET_P (obj)) + x = gen_raw_REG (DECL_MODE (obj), (*regno)++); + break; + + case VAR_DECL: + case PARM_DECL: + case RESULT_DECL: + *ws = 0; + obj = *expr_p; + + if (DECL_RTL_SET_P (obj)) + break; + + if (DECL_MODE (obj) == BLKmode) + x = produce_memory_decl_rtl (obj, regno); + else + x = gen_raw_REG (DECL_MODE (obj), (*regno)++); + + break; + + default: + break; + } + + if (x) + { + VEC_safe_push (tree, heap, decl_rtl_to_reset, obj); + SET_DECL_RTL (obj, x); + } + + return NULL_TREE; +} + +/* Determines cost of the computation of EXPR. */ + +static unsigned +computation_cost (tree expr) +{ + rtx seq, rslt; + tree type = TREE_TYPE (expr); + unsigned cost; + /* Avoid using hard regs in ways which may be unsupported. */ + int regno = LAST_VIRTUAL_REGISTER + 1; + + walk_tree (&expr, prepare_decl_rtl, ®no, NULL); + start_sequence (); + rslt = expand_expr (expr, NULL_RTX, TYPE_MODE (type), EXPAND_NORMAL); + seq = get_insns (); + end_sequence (); + + cost = seq_cost (seq); + if (MEM_P (rslt)) + cost += address_cost (XEXP (rslt, 0), TYPE_MODE (type)); + + return cost; +} + +/* Returns variable containing the value of candidate CAND at statement AT. */ + +static tree +var_at_stmt (struct loop *loop, struct iv_cand *cand, tree stmt) +{ + if (stmt_after_increment (loop, cand, stmt)) + return cand->var_after; + else + return cand->var_before; +} + +/* Return the most significant (sign) bit of T. Similar to tree_int_cst_msb, + but the bit is determined from TYPE_PRECISION, not MODE_BITSIZE. */ + +int +tree_int_cst_sign_bit (tree t) +{ + unsigned bitno = TYPE_PRECISION (TREE_TYPE (t)) - 1; + unsigned HOST_WIDE_INT w; + + if (bitno < HOST_BITS_PER_WIDE_INT) + w = TREE_INT_CST_LOW (t); + else + { + w = TREE_INT_CST_HIGH (t); + bitno -= HOST_BITS_PER_WIDE_INT; + } + + return (w >> bitno) & 1; +} + +/* If we can prove that TOP = cst * BOT for some constant cst, + store cst to MUL and return true. Otherwise return false. + The returned value is always sign-extended, regardless of the + signedness of TOP and BOT. */ + +static bool +constant_multiple_of (tree top, tree bot, double_int *mul) +{ + tree mby; + enum tree_code code; + double_int res, p0, p1; + unsigned precision = TYPE_PRECISION (TREE_TYPE (top)); + + STRIP_NOPS (top); + STRIP_NOPS (bot); + + if (operand_equal_p (top, bot, 0)) + { + *mul = double_int_one; + return true; + } + + code = TREE_CODE (top); + switch (code) + { + case MULT_EXPR: + mby = TREE_OPERAND (top, 1); + if (TREE_CODE (mby) != INTEGER_CST) + return false; + + if (!constant_multiple_of (TREE_OPERAND (top, 0), bot, &res)) + return false; + + *mul = double_int_sext (double_int_mul (res, tree_to_double_int (mby)), + precision); + return true; + + case PLUS_EXPR: + case MINUS_EXPR: + if (!constant_multiple_of (TREE_OPERAND (top, 0), bot, &p0) + || !constant_multiple_of (TREE_OPERAND (top, 1), bot, &p1)) + return false; + + if (code == MINUS_EXPR) + p1 = double_int_neg (p1); + *mul = double_int_sext (double_int_add (p0, p1), precision); + return true; + + case INTEGER_CST: + if (TREE_CODE (bot) != INTEGER_CST) + return false; + + p0 = double_int_sext (tree_to_double_int (bot), precision); + p1 = double_int_sext (tree_to_double_int (top), precision); + if (double_int_zero_p (p1)) + return false; + *mul = double_int_sext (double_int_sdivmod (p0, p1, FLOOR_DIV_EXPR, &res), + precision); + return double_int_zero_p (res); + + default: + return false; + } +} + +/* Sets COMB to CST. */ + +static void +aff_combination_const (struct affine_tree_combination *comb, tree type, + unsigned HOST_WIDE_INT cst) +{ + unsigned prec = TYPE_PRECISION (type); + + comb->type = type; + comb->mask = (((unsigned HOST_WIDE_INT) 2 << (prec - 1)) - 1); + + comb->n = 0; + comb->rest = NULL_TREE; + comb->offset = cst & comb->mask; +} + +/* Sets COMB to single element ELT. */ + +static void +aff_combination_elt (struct affine_tree_combination *comb, tree type, tree elt) +{ + unsigned prec = TYPE_PRECISION (type); + + comb->type = type; + comb->mask = (((unsigned HOST_WIDE_INT) 2 << (prec - 1)) - 1); + + comb->n = 1; + comb->elts[0] = elt; + comb->coefs[0] = 1; + comb->rest = NULL_TREE; + comb->offset = 0; +} + +/* Scales COMB by SCALE. */ + +static void +aff_combination_scale (struct affine_tree_combination *comb, + unsigned HOST_WIDE_INT scale) +{ + unsigned i, j; + + if (scale == 1) + return; + + if (scale == 0) + { + aff_combination_const (comb, comb->type, 0); + return; + } + + comb->offset = (scale * comb->offset) & comb->mask; + for (i = 0, j = 0; i < comb->n; i++) + { + comb->coefs[j] = (scale * comb->coefs[i]) & comb->mask; + comb->elts[j] = comb->elts[i]; + if (comb->coefs[j] != 0) + j++; + } + comb->n = j; + + if (comb->rest) + { + if (comb->n < MAX_AFF_ELTS) + { + comb->coefs[comb->n] = scale; + comb->elts[comb->n] = comb->rest; + comb->rest = NULL_TREE; + comb->n++; + } + else + comb->rest = fold_build2 (MULT_EXPR, comb->type, comb->rest, + build_int_cst_type (comb->type, scale)); + } +} + +/* Adds ELT * SCALE to COMB. */ + +static void +aff_combination_add_elt (struct affine_tree_combination *comb, tree elt, + unsigned HOST_WIDE_INT scale) +{ + unsigned i; + + if (scale == 0) + return; + + for (i = 0; i < comb->n; i++) + if (operand_equal_p (comb->elts[i], elt, 0)) + { + comb->coefs[i] = (comb->coefs[i] + scale) & comb->mask; + if (comb->coefs[i]) + return; + + comb->n--; + comb->coefs[i] = comb->coefs[comb->n]; + comb->elts[i] = comb->elts[comb->n]; + + if (comb->rest) + { + gcc_assert (comb->n == MAX_AFF_ELTS - 1); + comb->coefs[comb->n] = 1; + comb->elts[comb->n] = comb->rest; + comb->rest = NULL_TREE; + comb->n++; + } + return; + } + if (comb->n < MAX_AFF_ELTS) + { + comb->coefs[comb->n] = scale; + comb->elts[comb->n] = elt; + comb->n++; + return; + } + + if (scale == 1) + elt = fold_convert (comb->type, elt); + else + elt = fold_build2 (MULT_EXPR, comb->type, + fold_convert (comb->type, elt), + build_int_cst_type (comb->type, scale)); + + if (comb->rest) + comb->rest = fold_build2 (PLUS_EXPR, comb->type, comb->rest, elt); + else + comb->rest = elt; +} + +/* Adds COMB2 to COMB1. */ + +static void +aff_combination_add (struct affine_tree_combination *comb1, + struct affine_tree_combination *comb2) +{ + unsigned i; + + comb1->offset = (comb1->offset + comb2->offset) & comb1->mask; + for (i = 0; i < comb2->n; i++) + aff_combination_add_elt (comb1, comb2->elts[i], comb2->coefs[i]); + if (comb2->rest) + aff_combination_add_elt (comb1, comb2->rest, 1); +} + +/* Convert COMB to TYPE. */ + +static void +aff_combination_convert (tree type, struct affine_tree_combination *comb) +{ + unsigned prec = TYPE_PRECISION (type); + unsigned i; + + /* If the precision of both types is the same, it suffices to change the type + of the whole combination -- the elements are allowed to have another type + equivalent wrto STRIP_NOPS. */ + if (prec == TYPE_PRECISION (comb->type)) + { + comb->type = type; + return; + } + + comb->mask = (((unsigned HOST_WIDE_INT) 2 << (prec - 1)) - 1); + comb->offset = comb->offset & comb->mask; + + /* The type of the elements can be different from comb->type only as + much as what STRIP_NOPS would remove. We can just directly cast + to TYPE. */ + for (i = 0; i < comb->n; i++) + comb->elts[i] = fold_convert (type, comb->elts[i]); + if (comb->rest) + comb->rest = fold_convert (type, comb->rest); + + comb->type = type; +} + +/* Splits EXPR into an affine combination of parts. */ + +static void +tree_to_aff_combination (tree expr, tree type, + struct affine_tree_combination *comb) +{ + struct affine_tree_combination tmp; + enum tree_code code; + tree cst, core, toffset; + HOST_WIDE_INT bitpos, bitsize; + enum machine_mode mode; + int unsignedp, volatilep; + + STRIP_NOPS (expr); + + code = TREE_CODE (expr); + switch (code) + { + case INTEGER_CST: + aff_combination_const (comb, type, int_cst_value (expr)); + return; + + case PLUS_EXPR: + case MINUS_EXPR: + tree_to_aff_combination (TREE_OPERAND (expr, 0), type, comb); + tree_to_aff_combination (TREE_OPERAND (expr, 1), type, &tmp); + if (code == MINUS_EXPR) + aff_combination_scale (&tmp, -1); + aff_combination_add (comb, &tmp); + return; + + case MULT_EXPR: + cst = TREE_OPERAND (expr, 1); + if (TREE_CODE (cst) != INTEGER_CST) + break; + tree_to_aff_combination (TREE_OPERAND (expr, 0), type, comb); + aff_combination_scale (comb, int_cst_value (cst)); + return; + + case NEGATE_EXPR: + tree_to_aff_combination (TREE_OPERAND (expr, 0), type, comb); + aff_combination_scale (comb, -1); + return; + + case ADDR_EXPR: + core = get_inner_reference (TREE_OPERAND (expr, 0), &bitsize, &bitpos, + &toffset, &mode, &unsignedp, &volatilep, + false); + if (bitpos % BITS_PER_UNIT != 0) + break; + aff_combination_const (comb, type, bitpos / BITS_PER_UNIT); + core = build_fold_addr_expr (core); + if (TREE_CODE (core) == ADDR_EXPR) + aff_combination_add_elt (comb, core, 1); + else + { + tree_to_aff_combination (core, type, &tmp); + aff_combination_add (comb, &tmp); + } + if (toffset) + { + tree_to_aff_combination (toffset, type, &tmp); + aff_combination_add (comb, &tmp); + } + return; + + default: + break; + } + + aff_combination_elt (comb, type, expr); +} + +/* Creates EXPR + ELT * SCALE in TYPE. MASK is the mask for width of TYPE. */ + +static tree +add_elt_to_tree (tree expr, tree type, tree elt, unsigned HOST_WIDE_INT scale, + unsigned HOST_WIDE_INT mask) +{ + enum tree_code code; + + scale &= mask; + elt = fold_convert (type, elt); + + if (scale == 1) + { + if (!expr) + return elt; + + return fold_build2 (PLUS_EXPR, type, expr, elt); + } + + if (scale == mask) + { + if (!expr) + return fold_build1 (NEGATE_EXPR, type, elt); + + return fold_build2 (MINUS_EXPR, type, expr, elt); + } + + if (!expr) + return fold_build2 (MULT_EXPR, type, elt, + build_int_cst_type (type, scale)); + + if ((scale | (mask >> 1)) == mask) + { + /* Scale is negative. */ + code = MINUS_EXPR; + scale = (-scale) & mask; + } + else + code = PLUS_EXPR; + + elt = fold_build2 (MULT_EXPR, type, elt, + build_int_cst_type (type, scale)); + return fold_build2 (code, type, expr, elt); +} + +/* Copies the tree elements of COMB to ensure that they are not shared. */ + +static void +unshare_aff_combination (struct affine_tree_combination *comb) +{ + unsigned i; + + for (i = 0; i < comb->n; i++) + comb->elts[i] = unshare_expr (comb->elts[i]); + if (comb->rest) + comb->rest = unshare_expr (comb->rest); +} + +/* Makes tree from the affine combination COMB. */ + +static tree +aff_combination_to_tree (struct affine_tree_combination *comb) +{ + tree type = comb->type; + tree expr = comb->rest; + unsigned i; + unsigned HOST_WIDE_INT off, sgn; + + if (comb->n == 0 && comb->offset == 0) + { + if (expr) + { + /* Handle the special case produced by get_computation_aff when + the type does not fit in HOST_WIDE_INT. */ + return fold_convert (type, expr); + } + else + return build_int_cst (type, 0); + } + + gcc_assert (comb->n == MAX_AFF_ELTS || comb->rest == NULL_TREE); + + for (i = 0; i < comb->n; i++) + expr = add_elt_to_tree (expr, type, comb->elts[i], comb->coefs[i], + comb->mask); + + if ((comb->offset | (comb->mask >> 1)) == comb->mask) + { + /* Offset is negative. */ + off = (-comb->offset) & comb->mask; + sgn = comb->mask; + } + else + { + off = comb->offset; + sgn = 1; + } + return add_elt_to_tree (expr, type, build_int_cst_type (type, off), sgn, + comb->mask); +} + +/* Folds EXPR using the affine expressions framework. */ + +static tree +fold_affine_expr (tree expr) +{ + tree type = TREE_TYPE (expr); + struct affine_tree_combination comb; + + if (TYPE_PRECISION (type) > HOST_BITS_PER_WIDE_INT) + return expr; + + tree_to_aff_combination (expr, type, &comb); + return aff_combination_to_tree (&comb); +} + +/* If A is (TYPE) BA and B is (TYPE) BB, and the types of BA and BB have the + same precision that is at least as wide as the precision of TYPE, stores + BA to A and BB to B, and returns the type of BA. Otherwise, returns the + type of A and B. */ + +static tree +determine_common_wider_type (tree *a, tree *b) +{ + tree wider_type = NULL; + tree suba, subb; + tree atype = TREE_TYPE (*a); + + if ((TREE_CODE (*a) == NOP_EXPR + || TREE_CODE (*a) == CONVERT_EXPR)) + { + suba = TREE_OPERAND (*a, 0); + wider_type = TREE_TYPE (suba); + if (TYPE_PRECISION (wider_type) < TYPE_PRECISION (atype)) + return atype; + } + else + return atype; + + if ((TREE_CODE (*b) == NOP_EXPR + || TREE_CODE (*b) == CONVERT_EXPR)) + { + subb = TREE_OPERAND (*b, 0); + if (TYPE_PRECISION (wider_type) != TYPE_PRECISION (TREE_TYPE (subb))) + return atype; + } + else + return atype; + + *a = suba; + *b = subb; + return wider_type; +} + +/* Determines the expression by that USE is expressed from induction variable + CAND at statement AT in LOOP. The expression is stored in a decomposed + form into AFF. Returns false if USE cannot be expressed using CAND. */ + +static bool +get_computation_aff (struct loop *loop, + struct iv_use *use, struct iv_cand *cand, tree at, + struct affine_tree_combination *aff) +{ + tree ubase = use->iv->base; + tree ustep = use->iv->step; + tree cbase = cand->iv->base; + tree cstep = cand->iv->step; + tree utype = TREE_TYPE (ubase), ctype = TREE_TYPE (cbase); + tree common_type; + tree uutype; + tree expr, delta; + tree ratio; + unsigned HOST_WIDE_INT ustepi, cstepi; + HOST_WIDE_INT ratioi; + struct affine_tree_combination cbase_aff, expr_aff; + tree cstep_orig = cstep, ustep_orig = ustep; + double_int rat; + + if (TYPE_PRECISION (utype) > TYPE_PRECISION (ctype)) + { + /* We do not have a precision to express the values of use. */ + return false; + } + + expr = var_at_stmt (loop, cand, at); + + if (TREE_TYPE (expr) != ctype) + { + /* This may happen with the original ivs. */ + expr = fold_convert (ctype, expr); + } + + if (TYPE_UNSIGNED (utype)) + uutype = utype; + else + { + uutype = unsigned_type_for (utype); + ubase = fold_convert (uutype, ubase); + ustep = fold_convert (uutype, ustep); + } + + if (uutype != ctype) + { + expr = fold_convert (uutype, expr); + cbase = fold_convert (uutype, cbase); + cstep = fold_convert (uutype, cstep); + + /* If the conversion is not noop, we must take it into account when + considering the value of the step. */ + if (TYPE_PRECISION (utype) < TYPE_PRECISION (ctype)) + cstep_orig = cstep; + } + + if (cst_and_fits_in_hwi (cstep_orig) + && cst_and_fits_in_hwi (ustep_orig)) + { + ustepi = int_cst_value (ustep_orig); + cstepi = int_cst_value (cstep_orig); + + if (!divide (TYPE_PRECISION (uutype), ustepi, cstepi, &ratioi)) + { + /* TODO maybe consider case when ustep divides cstep and the ratio is + a power of 2 (so that the division is fast to execute)? We would + need to be much more careful with overflows etc. then. */ + return false; + } + + ratio = build_int_cst_type (uutype, ratioi); + } + else + { + if (!constant_multiple_of (ustep_orig, cstep_orig, &rat)) + return false; + ratio = double_int_to_tree (uutype, rat); + + /* Ratioi is only used to detect special cases when the multiplicative + factor is 1 or -1, so if rat does not fit to HOST_WIDE_INT, we may + set it to 0. */ + if (double_int_fits_in_shwi_p (rat)) + ratioi = double_int_to_shwi (rat); + else + ratioi = 0; + } + + /* In case both UBASE and CBASE are shortened to UUTYPE from some common + type, we achieve better folding by computing their difference in this + wider type, and cast the result to UUTYPE. We do not need to worry about + overflows, as all the arithmetics will in the end be performed in UUTYPE + anyway. */ + common_type = determine_common_wider_type (&ubase, &cbase); + + /* We may need to shift the value if we are after the increment. */ + if (stmt_after_increment (loop, cand, at)) + { + if (uutype != common_type) + cstep = fold_convert (common_type, cstep); + cbase = fold_build2 (PLUS_EXPR, common_type, cbase, cstep); + } + + /* use = ubase - ratio * cbase + ratio * var. + + In general case ubase + ratio * (var - cbase) could be better (one less + multiplication), but often it is possible to eliminate redundant parts + of computations from (ubase - ratio * cbase) term, and if it does not + happen, fold is able to apply the distributive law to obtain this form + anyway. */ + + if (TYPE_PRECISION (common_type) > HOST_BITS_PER_WIDE_INT) + { + /* Let's compute in trees and just return the result in AFF. This case + should not be very common, and fold itself is not that bad either, + so making the aff. functions more complicated to handle this case + is not that urgent. */ + if (ratioi == 1) + { + delta = fold_build2 (MINUS_EXPR, common_type, ubase, cbase); + if (uutype != common_type) + delta = fold_convert (uutype, delta); + expr = fold_build2 (PLUS_EXPR, uutype, expr, delta); + } + else if (ratioi == -1) + { + delta = fold_build2 (PLUS_EXPR, common_type, ubase, cbase); + if (uutype != common_type) + delta = fold_convert (uutype, delta); + expr = fold_build2 (MINUS_EXPR, uutype, delta, expr); + } + else + { + delta = fold_build2 (MULT_EXPR, common_type, cbase, ratio); + delta = fold_build2 (MINUS_EXPR, common_type, ubase, delta); + if (uutype != common_type) + delta = fold_convert (uutype, delta); + expr = fold_build2 (MULT_EXPR, uutype, ratio, expr); + expr = fold_build2 (PLUS_EXPR, uutype, delta, expr); + } + + aff->type = uutype; + aff->n = 0; + aff->offset = 0; + aff->mask = 0; + aff->rest = expr; + return true; + } + + /* If we got here, the types fits in HOST_WIDE_INT, thus it must be + possible to compute ratioi. */ + gcc_assert (ratioi); + + tree_to_aff_combination (ubase, common_type, aff); + tree_to_aff_combination (cbase, common_type, &cbase_aff); + tree_to_aff_combination (expr, uutype, &expr_aff); + aff_combination_scale (&cbase_aff, -ratioi); + aff_combination_scale (&expr_aff, ratioi); + aff_combination_add (aff, &cbase_aff); + if (common_type != uutype) + aff_combination_convert (uutype, aff); + aff_combination_add (aff, &expr_aff); + + return true; +} + +/* Determines the expression by that USE is expressed from induction variable + CAND at statement AT in LOOP. The computation is unshared. */ + +static tree +get_computation_at (struct loop *loop, + struct iv_use *use, struct iv_cand *cand, tree at) +{ + struct affine_tree_combination aff; + tree type = TREE_TYPE (use->iv->base); + + if (!get_computation_aff (loop, use, cand, at, &aff)) + return NULL_TREE; + unshare_aff_combination (&aff); + return fold_convert (type, aff_combination_to_tree (&aff)); +} + +/* Determines the expression by that USE is expressed from induction variable + CAND in LOOP. The computation is unshared. */ + +static tree +get_computation (struct loop *loop, struct iv_use *use, struct iv_cand *cand) +{ + return get_computation_at (loop, use, cand, use->stmt); +} + +/* Returns cost of addition in MODE. */ + +static unsigned +add_cost (enum machine_mode mode) +{ + static unsigned costs[NUM_MACHINE_MODES]; + rtx seq; + unsigned cost; + + if (costs[mode]) + return costs[mode]; + + start_sequence (); + force_operand (gen_rtx_fmt_ee (PLUS, mode, + gen_raw_REG (mode, LAST_VIRTUAL_REGISTER + 1), + gen_raw_REG (mode, LAST_VIRTUAL_REGISTER + 2)), + NULL_RTX); + seq = get_insns (); + end_sequence (); + + cost = seq_cost (seq); + if (!cost) + cost = 1; + + costs[mode] = cost; + + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Addition in %s costs %d\n", + GET_MODE_NAME (mode), cost); + return cost; +} + +/* Entry in a hashtable of already known costs for multiplication. */ +struct mbc_entry +{ + HOST_WIDE_INT cst; /* The constant to multiply by. */ + enum machine_mode mode; /* In mode. */ + unsigned cost; /* The cost. */ +}; + +/* Counts hash value for the ENTRY. */ + +static hashval_t +mbc_entry_hash (const void *entry) +{ + const struct mbc_entry *e = entry; + + return 57 * (hashval_t) e->mode + (hashval_t) (e->cst % 877); +} + +/* Compares the hash table entries ENTRY1 and ENTRY2. */ + +static int +mbc_entry_eq (const void *entry1, const void *entry2) +{ + const struct mbc_entry *e1 = entry1; + const struct mbc_entry *e2 = entry2; + + return (e1->mode == e2->mode + && e1->cst == e2->cst); +} + +/* Returns cost of multiplication by constant CST in MODE. */ + +unsigned +multiply_by_cost (HOST_WIDE_INT cst, enum machine_mode mode) +{ + static htab_t costs; + struct mbc_entry **cached, act; + rtx seq; + unsigned cost; + + if (!costs) + costs = htab_create (100, mbc_entry_hash, mbc_entry_eq, free); + + act.mode = mode; + act.cst = cst; + cached = (struct mbc_entry **) htab_find_slot (costs, &act, INSERT); + if (*cached) + return (*cached)->cost; + + *cached = XNEW (struct mbc_entry); + (*cached)->mode = mode; + (*cached)->cst = cst; + + start_sequence (); + expand_mult (mode, gen_raw_REG (mode, LAST_VIRTUAL_REGISTER + 1), + gen_int_mode (cst, mode), NULL_RTX, 0); + seq = get_insns (); + end_sequence (); + + cost = seq_cost (seq); + + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Multiplication by %d in %s costs %d\n", + (int) cst, GET_MODE_NAME (mode), cost); + + (*cached)->cost = cost; + + return cost; +} + +/* Returns true if multiplying by RATIO is allowed in address. */ + +bool +multiplier_allowed_in_address_p (HOST_WIDE_INT ratio) +{ +#define MAX_RATIO 128 + static sbitmap valid_mult; + + if (!valid_mult) + { + rtx reg1 = gen_raw_REG (Pmode, LAST_VIRTUAL_REGISTER + 1); + rtx addr; + HOST_WIDE_INT i; + + valid_mult = sbitmap_alloc (2 * MAX_RATIO + 1); + sbitmap_zero (valid_mult); + addr = gen_rtx_fmt_ee (MULT, Pmode, reg1, NULL_RTX); + for (i = -MAX_RATIO; i <= MAX_RATIO; i++) + { + XEXP (addr, 1) = gen_int_mode (i, Pmode); + if (memory_address_p (Pmode, addr)) + SET_BIT (valid_mult, i + MAX_RATIO); + } + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, " allowed multipliers:"); + for (i = -MAX_RATIO; i <= MAX_RATIO; i++) + if (TEST_BIT (valid_mult, i + MAX_RATIO)) + fprintf (dump_file, " %d", (int) i); + fprintf (dump_file, "\n"); + fprintf (dump_file, "\n"); + } + } + + if (ratio > MAX_RATIO || ratio < -MAX_RATIO) + return false; + + return TEST_BIT (valid_mult, ratio + MAX_RATIO); +} + +/* Returns cost of address in shape symbol + var + OFFSET + RATIO * index. + If SYMBOL_PRESENT is false, symbol is omitted. If VAR_PRESENT is false, + variable is omitted. The created memory accesses MODE. + + TODO -- there must be some better way. This all is quite crude. */ + +static unsigned +get_address_cost (bool symbol_present, bool var_present, + unsigned HOST_WIDE_INT offset, HOST_WIDE_INT ratio) +{ + static bool initialized = false; + static HOST_WIDE_INT rat, off; + static HOST_WIDE_INT min_offset, max_offset; + static unsigned costs[2][2][2][2]; + unsigned cost, acost; + bool offset_p, ratio_p; + HOST_WIDE_INT s_offset; + unsigned HOST_WIDE_INT mask; + unsigned bits; + + if (!initialized) + { + HOST_WIDE_INT i; + int old_cse_not_expected; + unsigned sym_p, var_p, off_p, rat_p, add_c; + rtx seq, addr, base; + rtx reg0, reg1; + + initialized = true; + + reg1 = gen_raw_REG (Pmode, LAST_VIRTUAL_REGISTER + 1); + + addr = gen_rtx_fmt_ee (PLUS, Pmode, reg1, NULL_RTX); + for (i = 1; i <= 1 << 20; i <<= 1) + { + XEXP (addr, 1) = gen_int_mode (i, Pmode); + if (!memory_address_p (Pmode, addr)) + break; + } + max_offset = i >> 1; + off = max_offset; + + for (i = 1; i <= 1 << 20; i <<= 1) + { + XEXP (addr, 1) = gen_int_mode (-i, Pmode); + if (!memory_address_p (Pmode, addr)) + break; + } + min_offset = -(i >> 1); + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "get_address_cost:\n"); + fprintf (dump_file, " min offset %d\n", (int) min_offset); + fprintf (dump_file, " max offset %d\n", (int) max_offset); + } + + rat = 1; + for (i = 2; i <= MAX_RATIO; i++) + if (multiplier_allowed_in_address_p (i)) + { + rat = i; + break; + } + + /* Compute the cost of various addressing modes. */ + acost = 0; + reg0 = gen_raw_REG (Pmode, LAST_VIRTUAL_REGISTER + 1); + reg1 = gen_raw_REG (Pmode, LAST_VIRTUAL_REGISTER + 2); + + for (i = 0; i < 16; i++) + { + sym_p = i & 1; + var_p = (i >> 1) & 1; + off_p = (i >> 2) & 1; + rat_p = (i >> 3) & 1; + + addr = reg0; + if (rat_p) + addr = gen_rtx_fmt_ee (MULT, Pmode, addr, gen_int_mode (rat, Pmode)); + + if (var_p) + addr = gen_rtx_fmt_ee (PLUS, Pmode, addr, reg1); + + if (sym_p) + { + base = gen_rtx_SYMBOL_REF (Pmode, ggc_strdup ("")); + if (off_p) + base = gen_rtx_fmt_e (CONST, Pmode, + gen_rtx_fmt_ee (PLUS, Pmode, + base, + gen_int_mode (off, Pmode))); + } + else if (off_p) + base = gen_int_mode (off, Pmode); + else + base = NULL_RTX; + + if (base) + addr = gen_rtx_fmt_ee (PLUS, Pmode, addr, base); + + start_sequence (); + /* To avoid splitting addressing modes, pretend that no cse will + follow. */ + old_cse_not_expected = cse_not_expected; + cse_not_expected = true; + addr = memory_address (Pmode, addr); + cse_not_expected = old_cse_not_expected; + seq = get_insns (); + end_sequence (); + + acost = seq_cost (seq); + acost += address_cost (addr, Pmode); + + if (!acost) + acost = 1; + costs[sym_p][var_p][off_p][rat_p] = acost; + } + + /* On some targets, it is quite expensive to load symbol to a register, + which makes addresses that contain symbols look much more expensive. + However, the symbol will have to be loaded in any case before the + loop (and quite likely we have it in register already), so it does not + make much sense to penalize them too heavily. So make some final + tweaks for the SYMBOL_PRESENT modes: + + If VAR_PRESENT is false, and the mode obtained by changing symbol to + var is cheaper, use this mode with small penalty. + If VAR_PRESENT is true, try whether the mode with + SYMBOL_PRESENT = false is cheaper even with cost of addition, and + if this is the case, use it. */ + add_c = add_cost (Pmode); + for (i = 0; i < 8; i++) + { + var_p = i & 1; + off_p = (i >> 1) & 1; + rat_p = (i >> 2) & 1; + + acost = costs[0][1][off_p][rat_p] + 1; + if (var_p) + acost += add_c; + + if (acost < costs[1][var_p][off_p][rat_p]) + costs[1][var_p][off_p][rat_p] = acost; + } + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Address costs:\n"); + + for (i = 0; i < 16; i++) + { + sym_p = i & 1; + var_p = (i >> 1) & 1; + off_p = (i >> 2) & 1; + rat_p = (i >> 3) & 1; + + fprintf (dump_file, " "); + if (sym_p) + fprintf (dump_file, "sym + "); + if (var_p) + fprintf (dump_file, "var + "); + if (off_p) + fprintf (dump_file, "cst + "); + if (rat_p) + fprintf (dump_file, "rat * "); + + acost = costs[sym_p][var_p][off_p][rat_p]; + fprintf (dump_file, "index costs %d\n", acost); + } + fprintf (dump_file, "\n"); + } + } + + bits = GET_MODE_BITSIZE (Pmode); + mask = ~(~(unsigned HOST_WIDE_INT) 0 << (bits - 1) << 1); + offset &= mask; + if ((offset >> (bits - 1) & 1)) + offset |= ~mask; + s_offset = offset; + + cost = 0; + offset_p = (s_offset != 0 + && min_offset <= s_offset && s_offset <= max_offset); + ratio_p = (ratio != 1 + && multiplier_allowed_in_address_p (ratio)); + + if (ratio != 1 && !ratio_p) + cost += multiply_by_cost (ratio, Pmode); + + if (s_offset && !offset_p && !symbol_present) + { + cost += add_cost (Pmode); + var_present = true; + } + + acost = costs[symbol_present][var_present][offset_p][ratio_p]; + return cost + acost; +} + +/* Estimates cost of forcing expression EXPR into a variable. */ + +unsigned +force_expr_to_var_cost (tree expr) +{ + static bool costs_initialized = false; + static unsigned integer_cost; + static unsigned symbol_cost; + static unsigned address_cost; + tree op0, op1; + unsigned cost0, cost1, cost; + enum machine_mode mode; + + if (!costs_initialized) + { + tree var = create_tmp_var_raw (integer_type_node, "test_var"); + rtx x = gen_rtx_MEM (DECL_MODE (var), + gen_rtx_SYMBOL_REF (Pmode, "test_var")); + tree addr; + tree type = build_pointer_type (integer_type_node); + + integer_cost = computation_cost (build_int_cst (integer_type_node, + 2000)); + + SET_DECL_RTL (var, x); + TREE_STATIC (var) = 1; + addr = build1 (ADDR_EXPR, type, var); + symbol_cost = computation_cost (addr) + 1; + + address_cost + = computation_cost (build2 (PLUS_EXPR, type, + addr, + build_int_cst (type, 2000))) + 1; + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "force_expr_to_var_cost:\n"); + fprintf (dump_file, " integer %d\n", (int) integer_cost); + fprintf (dump_file, " symbol %d\n", (int) symbol_cost); + fprintf (dump_file, " address %d\n", (int) address_cost); + fprintf (dump_file, " other %d\n", (int) target_spill_cost); + fprintf (dump_file, "\n"); + } + + costs_initialized = true; + } + + STRIP_NOPS (expr); + + if (SSA_VAR_P (expr)) + return 0; + + if (TREE_INVARIANT (expr)) + { + if (TREE_CODE (expr) == INTEGER_CST) + return integer_cost; + + if (TREE_CODE (expr) == ADDR_EXPR) + { + tree obj = TREE_OPERAND (expr, 0); + + if (TREE_CODE (obj) == VAR_DECL + || TREE_CODE (obj) == PARM_DECL + || TREE_CODE (obj) == RESULT_DECL) + return symbol_cost; + } + + return address_cost; + } + + switch (TREE_CODE (expr)) + { + case PLUS_EXPR: + case MINUS_EXPR: + case MULT_EXPR: + op0 = TREE_OPERAND (expr, 0); + op1 = TREE_OPERAND (expr, 1); + STRIP_NOPS (op0); + STRIP_NOPS (op1); + + if (is_gimple_val (op0)) + cost0 = 0; + else + cost0 = force_expr_to_var_cost (op0); + + if (is_gimple_val (op1)) + cost1 = 0; + else + cost1 = force_expr_to_var_cost (op1); + + break; + + default: + /* Just an arbitrary value, FIXME. */ + return target_spill_cost; + } + + mode = TYPE_MODE (TREE_TYPE (expr)); + switch (TREE_CODE (expr)) + { + case PLUS_EXPR: + case MINUS_EXPR: + cost = add_cost (mode); + break; + + case MULT_EXPR: + if (cst_and_fits_in_hwi (op0)) + cost = multiply_by_cost (int_cst_value (op0), mode); + else if (cst_and_fits_in_hwi (op1)) + cost = multiply_by_cost (int_cst_value (op1), mode); + else + return target_spill_cost; + break; + + default: + gcc_unreachable (); + } + + cost += cost0; + cost += cost1; + + /* Bound the cost by target_spill_cost. The parts of complicated + computations often are either loop invariant or at least can + be shared between several iv uses, so letting this grow without + limits would not give reasonable results. */ + return cost < target_spill_cost ? cost : target_spill_cost; +} + +/* Estimates cost of forcing EXPR into a variable. DEPENDS_ON is a set of the + invariants the computation depends on. */ + +static unsigned +force_var_cost (struct ivopts_data *data, + tree expr, bitmap *depends_on) +{ + if (depends_on) + { + fd_ivopts_data = data; + walk_tree (&expr, find_depends, depends_on, NULL); + } + + return force_expr_to_var_cost (expr); +} + +/* Estimates cost of expressing address ADDR as var + symbol + offset. The + value of offset is added to OFFSET, SYMBOL_PRESENT and VAR_PRESENT are set + to false if the corresponding part is missing. DEPENDS_ON is a set of the + invariants the computation depends on. */ + +static unsigned +split_address_cost (struct ivopts_data *data, + tree addr, bool *symbol_present, bool *var_present, + unsigned HOST_WIDE_INT *offset, bitmap *depends_on) +{ + tree core; + HOST_WIDE_INT bitsize; + HOST_WIDE_INT bitpos; + tree toffset; + enum machine_mode mode; + int unsignedp, volatilep; + + core = get_inner_reference (addr, &bitsize, &bitpos, &toffset, &mode, + &unsignedp, &volatilep, false); + + if (toffset != 0 + || bitpos % BITS_PER_UNIT != 0 + || TREE_CODE (core) != VAR_DECL) + { + *symbol_present = false; + *var_present = true; + fd_ivopts_data = data; + walk_tree (&addr, find_depends, depends_on, NULL); + return target_spill_cost; + } + + *offset += bitpos / BITS_PER_UNIT; + if (TREE_STATIC (core) + || DECL_EXTERNAL (core)) + { + *symbol_present = true; + *var_present = false; + return 0; + } + + *symbol_present = false; + *var_present = true; + return 0; +} + +/* Estimates cost of expressing difference of addresses E1 - E2 as + var + symbol + offset. The value of offset is added to OFFSET, + SYMBOL_PRESENT and VAR_PRESENT are set to false if the corresponding + part is missing. DEPENDS_ON is a set of the invariants the computation + depends on. */ + +static unsigned +ptr_difference_cost (struct ivopts_data *data, + tree e1, tree e2, bool *symbol_present, bool *var_present, + unsigned HOST_WIDE_INT *offset, bitmap *depends_on) +{ + HOST_WIDE_INT diff = 0; + unsigned cost; + + gcc_assert (TREE_CODE (e1) == ADDR_EXPR); + + if (ptr_difference_const (e1, e2, &diff)) + { + *offset += diff; + *symbol_present = false; + *var_present = false; + return 0; + } + + if (e2 == integer_zero_node) + return split_address_cost (data, TREE_OPERAND (e1, 0), + symbol_present, var_present, offset, depends_on); + + *symbol_present = false; + *var_present = true; + + cost = force_var_cost (data, e1, depends_on); + cost += force_var_cost (data, e2, depends_on); + cost += add_cost (Pmode); + + return cost; +} + +/* Estimates cost of expressing difference E1 - E2 as + var + symbol + offset. The value of offset is added to OFFSET, + SYMBOL_PRESENT and VAR_PRESENT are set to false if the corresponding + part is missing. DEPENDS_ON is a set of the invariants the computation + depends on. */ + +static unsigned +difference_cost (struct ivopts_data *data, + tree e1, tree e2, bool *symbol_present, bool *var_present, + unsigned HOST_WIDE_INT *offset, bitmap *depends_on) +{ + unsigned cost; + enum machine_mode mode = TYPE_MODE (TREE_TYPE (e1)); + unsigned HOST_WIDE_INT off1, off2; + + e1 = strip_offset (e1, &off1); + e2 = strip_offset (e2, &off2); + *offset += off1 - off2; + + STRIP_NOPS (e1); + STRIP_NOPS (e2); + + if (TREE_CODE (e1) == ADDR_EXPR) + return ptr_difference_cost (data, e1, e2, symbol_present, var_present, offset, + depends_on); + *symbol_present = false; + + if (operand_equal_p (e1, e2, 0)) + { + *var_present = false; + return 0; + } + *var_present = true; + if (zero_p (e2)) + return force_var_cost (data, e1, depends_on); + + if (zero_p (e1)) + { + cost = force_var_cost (data, e2, depends_on); + cost += multiply_by_cost (-1, mode); + + return cost; + } + + cost = force_var_cost (data, e1, depends_on); + cost += force_var_cost (data, e2, depends_on); + cost += add_cost (mode); + + return cost; +} + +/* Determines the cost of the computation by that USE is expressed + from induction variable CAND. If ADDRESS_P is true, we just need + to create an address from it, otherwise we want to get it into + register. A set of invariants we depend on is stored in + DEPENDS_ON. AT is the statement at that the value is computed. */ + +static unsigned +get_computation_cost_at (struct ivopts_data *data, + struct iv_use *use, struct iv_cand *cand, + bool address_p, bitmap *depends_on, tree at) +{ + tree ubase = use->iv->base, ustep = use->iv->step; + tree cbase, cstep; + tree utype = TREE_TYPE (ubase), ctype; + unsigned HOST_WIDE_INT ustepi, cstepi, offset = 0; + HOST_WIDE_INT ratio, aratio; + bool var_present, symbol_present; + unsigned cost = 0, n_sums; + + *depends_on = NULL; + + /* Only consider real candidates. */ + if (!cand->iv) + return INFTY; + + cbase = cand->iv->base; + cstep = cand->iv->step; + ctype = TREE_TYPE (cbase); + + if (TYPE_PRECISION (utype) > TYPE_PRECISION (ctype)) + { + /* We do not have a precision to express the values of use. */ + return INFTY; + } + + if (address_p) + { + /* Do not try to express address of an object with computation based + on address of a different object. This may cause problems in rtl + level alias analysis (that does not expect this to be happening, + as this is illegal in C), and would be unlikely to be useful + anyway. */ + if (use->iv->base_object + && cand->iv->base_object + && !operand_equal_p (use->iv->base_object, cand->iv->base_object, 0)) + return INFTY; + } + + if (TYPE_PRECISION (utype) != TYPE_PRECISION (ctype)) + { + /* TODO -- add direct handling of this case. */ + goto fallback; + } + + /* CSTEPI is removed from the offset in case statement is after the + increment. If the step is not constant, we use zero instead. + This is a bit imprecise (there is the extra addition), but + redundancy elimination is likely to transform the code so that + it uses value of the variable before increment anyway, + so it is not that much unrealistic. */ + if (cst_and_fits_in_hwi (cstep)) + cstepi = int_cst_value (cstep); + else + cstepi = 0; + + if (cst_and_fits_in_hwi (ustep) + && cst_and_fits_in_hwi (cstep)) + { + ustepi = int_cst_value (ustep); + + if (!divide (TYPE_PRECISION (utype), ustepi, cstepi, &ratio)) + return INFTY; + } + else + { + double_int rat; + + if (!constant_multiple_of (ustep, cstep, &rat)) + return INFTY; + + if (double_int_fits_in_shwi_p (rat)) + ratio = double_int_to_shwi (rat); + else + return INFTY; + } + + /* use = ubase + ratio * (var - cbase). If either cbase is a constant + or ratio == 1, it is better to handle this like + + ubase - ratio * cbase + ratio * var + + (also holds in the case ratio == -1, TODO. */ + + if (cst_and_fits_in_hwi (cbase)) + { + offset = - ratio * int_cst_value (cbase); + cost += difference_cost (data, + ubase, integer_zero_node, + &symbol_present, &var_present, &offset, + depends_on); + } + else if (ratio == 1) + { + cost += difference_cost (data, + ubase, cbase, + &symbol_present, &var_present, &offset, + depends_on); + } + else + { + cost += force_var_cost (data, cbase, depends_on); + cost += add_cost (TYPE_MODE (ctype)); + cost += difference_cost (data, + ubase, integer_zero_node, + &symbol_present, &var_present, &offset, + depends_on); + } + + /* If we are after the increment, the value of the candidate is higher by + one iteration. */ + if (stmt_after_increment (data->current_loop, cand, at)) + offset -= ratio * cstepi; + + /* Now the computation is in shape symbol + var1 + const + ratio * var2. + (symbol/var/const parts may be omitted). If we are looking for an address, + find the cost of addressing this. */ + if (address_p) + return cost + get_address_cost (symbol_present, var_present, offset, ratio); + + /* Otherwise estimate the costs for computing the expression. */ + aratio = ratio > 0 ? ratio : -ratio; + if (!symbol_present && !var_present && !offset) + { + if (ratio != 1) + cost += multiply_by_cost (ratio, TYPE_MODE (ctype)); + + return cost; + } + + if (aratio != 1) + cost += multiply_by_cost (aratio, TYPE_MODE (ctype)); + + n_sums = 1; + if (var_present + /* Symbol + offset should be compile-time computable. */ + && (symbol_present || offset)) + n_sums++; + + return cost + n_sums * add_cost (TYPE_MODE (ctype)); + +fallback: + { + /* Just get the expression, expand it and measure the cost. */ + tree comp = get_computation_at (data->current_loop, use, cand, at); + + if (!comp) + return INFTY; + + if (address_p) + comp = build1 (INDIRECT_REF, TREE_TYPE (TREE_TYPE (comp)), comp); + + return computation_cost (comp); + } +} + +/* Determines the cost of the computation by that USE is expressed + from induction variable CAND. If ADDRESS_P is true, we just need + to create an address from it, otherwise we want to get it into + register. A set of invariants we depend on is stored in + DEPENDS_ON. */ + +static unsigned +get_computation_cost (struct ivopts_data *data, + struct iv_use *use, struct iv_cand *cand, + bool address_p, bitmap *depends_on) +{ + return get_computation_cost_at (data, + use, cand, address_p, depends_on, use->stmt); +} + +/* Determines cost of basing replacement of USE on CAND in a generic + expression. */ + +static bool +determine_use_iv_cost_generic (struct ivopts_data *data, + struct iv_use *use, struct iv_cand *cand) +{ + bitmap depends_on; + unsigned cost; + + /* The simple case first -- if we need to express value of the preserved + original biv, the cost is 0. This also prevents us from counting the + cost of increment twice -- once at this use and once in the cost of + the candidate. */ + if (cand->pos == IP_ORIGINAL + && cand->incremented_at == use->stmt) + { + set_use_iv_cost (data, use, cand, 0, NULL, NULL_TREE); + return true; + } + + cost = get_computation_cost (data, use, cand, false, &depends_on); + set_use_iv_cost (data, use, cand, cost, depends_on, NULL_TREE); + + return cost != INFTY; +} + +/* Determines cost of basing replacement of USE on CAND in an address. */ + +static bool +determine_use_iv_cost_address (struct ivopts_data *data, + struct iv_use *use, struct iv_cand *cand) +{ + bitmap depends_on; + unsigned cost = get_computation_cost (data, use, cand, true, &depends_on); + + set_use_iv_cost (data, use, cand, cost, depends_on, NULL_TREE); + + return cost != INFTY; +} + +/* Computes value of induction variable IV in iteration NITER. */ + +static tree +iv_value (struct iv *iv, tree niter) +{ + tree val; + tree type = TREE_TYPE (iv->base); + + niter = fold_convert (type, niter); + val = fold_build2 (MULT_EXPR, type, iv->step, niter); + + return fold_build2 (PLUS_EXPR, type, iv->base, val); +} + +/* Computes value of candidate CAND at position AT in iteration NITER. */ + +static tree +cand_value_at (struct loop *loop, struct iv_cand *cand, tree at, tree niter) +{ + tree val = iv_value (cand->iv, niter); + tree type = TREE_TYPE (cand->iv->base); + + if (stmt_after_increment (loop, cand, at)) + val = fold_build2 (PLUS_EXPR, type, val, cand->iv->step); + + return val; +} + +/* Returns period of induction variable iv. */ + +static tree +iv_period (struct iv *iv) +{ + tree step = iv->step, period, type; + tree pow2div; + + gcc_assert (step && TREE_CODE (step) == INTEGER_CST); + + /* Period of the iv is gcd (step, type range). Since type range is power + of two, it suffices to determine the maximum power of two that divides + step. */ + pow2div = num_ending_zeros (step); + type = unsigned_type_for (TREE_TYPE (step)); + + period = build_low_bits_mask (type, + (TYPE_PRECISION (type) + - tree_low_cst (pow2div, 1))); + + return period; +} + +/* Returns the comparison operator used when eliminating the iv USE. */ + +static enum tree_code +iv_elimination_compare (struct ivopts_data *data, struct iv_use *use) +{ + struct loop *loop = data->current_loop; + basic_block ex_bb; + edge exit; + + ex_bb = bb_for_stmt (use->stmt); + exit = EDGE_SUCC (ex_bb, 0); + if (flow_bb_inside_loop_p (loop, exit->dest)) + exit = EDGE_SUCC (ex_bb, 1); + + return (exit->flags & EDGE_TRUE_VALUE ? EQ_EXPR : NE_EXPR); +} + +/* Check whether it is possible to express the condition in USE by comparison + of candidate CAND. If so, store the value compared with to BOUND. */ + +static bool +may_eliminate_iv (struct ivopts_data *data, + struct iv_use *use, struct iv_cand *cand, tree *bound) +{ + basic_block ex_bb; + edge exit; + tree nit, nit_type; + tree wider_type, period, per_type; + struct loop *loop = data->current_loop; + + if (TREE_CODE (cand->iv->step) != INTEGER_CST) + return false; + + /* For now works only for exits that dominate the loop latch. TODO -- extend + for other conditions inside loop body. */ + ex_bb = bb_for_stmt (use->stmt); + if (use->stmt != last_stmt (ex_bb) + || TREE_CODE (use->stmt) != COND_EXPR) + return false; + if (!dominated_by_p (CDI_DOMINATORS, loop->latch, ex_bb)) + return false; + + exit = EDGE_SUCC (ex_bb, 0); + if (flow_bb_inside_loop_p (loop, exit->dest)) + exit = EDGE_SUCC (ex_bb, 1); + if (flow_bb_inside_loop_p (loop, exit->dest)) + return false; + + nit = niter_for_exit (data, exit); + if (!nit) + return false; + + nit_type = TREE_TYPE (nit); + + /* Determine whether we may use the variable to test whether niter iterations + elapsed. This is the case iff the period of the induction variable is + greater than the number of iterations. */ + period = iv_period (cand->iv); + if (!period) + return false; + per_type = TREE_TYPE (period); + + wider_type = TREE_TYPE (period); + if (TYPE_PRECISION (nit_type) < TYPE_PRECISION (per_type)) + wider_type = per_type; + else + wider_type = nit_type; + + if (!integer_nonzerop (fold_build2 (GE_EXPR, boolean_type_node, + fold_convert (wider_type, period), + fold_convert (wider_type, nit)))) + return false; + + *bound = fold_affine_expr (cand_value_at (loop, cand, use->stmt, nit)); + return true; +} + +/* Determines cost of basing replacement of USE on CAND in a condition. */ + +static bool +determine_use_iv_cost_condition (struct ivopts_data *data, + struct iv_use *use, struct iv_cand *cand) +{ + tree bound = NULL_TREE, op, cond; + bitmap depends_on = NULL; + unsigned cost; + + /* Only consider real candidates. */ + if (!cand->iv) + { + set_use_iv_cost (data, use, cand, INFTY, NULL, NULL_TREE); + return false; + } + + if (may_eliminate_iv (data, use, cand, &bound)) + { + cost = force_var_cost (data, bound, &depends_on); + + set_use_iv_cost (data, use, cand, cost, depends_on, bound); + return cost != INFTY; + } + + /* The induction variable elimination failed; just express the original + giv. If it is compared with an invariant, note that we cannot get + rid of it. */ + cost = get_computation_cost (data, use, cand, false, &depends_on); + + cond = *use->op_p; + if (TREE_CODE (cond) != SSA_NAME) + { + op = TREE_OPERAND (cond, 0); + if (TREE_CODE (op) == SSA_NAME && !zero_p (get_iv (data, op)->step)) + op = TREE_OPERAND (cond, 1); + if (TREE_CODE (op) == SSA_NAME) + { + op = get_iv (data, op)->base; + fd_ivopts_data = data; + walk_tree (&op, find_depends, &depends_on, NULL); + } + } + + set_use_iv_cost (data, use, cand, cost, depends_on, NULL); + return cost != INFTY; +} + +/* Determines cost of basing replacement of USE on CAND. Returns false + if USE cannot be based on CAND. */ + +static bool +determine_use_iv_cost (struct ivopts_data *data, + struct iv_use *use, struct iv_cand *cand) +{ + switch (use->type) + { + case USE_NONLINEAR_EXPR: + return determine_use_iv_cost_generic (data, use, cand); + + case USE_ADDRESS: + return determine_use_iv_cost_address (data, use, cand); + + case USE_COMPARE: + return determine_use_iv_cost_condition (data, use, cand); + + default: + gcc_unreachable (); + } +} + +/* Determines costs of basing the use of the iv on an iv candidate. */ + +static void +determine_use_iv_costs (struct ivopts_data *data) +{ + unsigned i, j; + struct iv_use *use; + struct iv_cand *cand; + bitmap to_clear = BITMAP_ALLOC (NULL); + + alloc_use_cost_map (data); + + for (i = 0; i < n_iv_uses (data); i++) + { + use = iv_use (data, i); + + if (data->consider_all_candidates) + { + for (j = 0; j < n_iv_cands (data); j++) + { + cand = iv_cand (data, j); + determine_use_iv_cost (data, use, cand); + } + } + else + { + bitmap_iterator bi; + + EXECUTE_IF_SET_IN_BITMAP (use->related_cands, 0, j, bi) + { + cand = iv_cand (data, j); + if (!determine_use_iv_cost (data, use, cand)) + bitmap_set_bit (to_clear, j); + } + + /* Remove the candidates for that the cost is infinite from + the list of related candidates. */ + bitmap_and_compl_into (use->related_cands, to_clear); + bitmap_clear (to_clear); + } + } + + BITMAP_FREE (to_clear); + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Use-candidate costs:\n"); + + for (i = 0; i < n_iv_uses (data); i++) + { + use = iv_use (data, i); + + fprintf (dump_file, "Use %d:\n", i); + fprintf (dump_file, " cand\tcost\tdepends on\n"); + for (j = 0; j < use->n_map_members; j++) + { + if (!use->cost_map[j].cand + || use->cost_map[j].cost == INFTY) + continue; + + fprintf (dump_file, " %d\t%d\t", + use->cost_map[j].cand->id, + use->cost_map[j].cost); + if (use->cost_map[j].depends_on) + bitmap_print (dump_file, + use->cost_map[j].depends_on, "",""); + fprintf (dump_file, "\n"); + } + + fprintf (dump_file, "\n"); + } + fprintf (dump_file, "\n"); + } +} + +/* Determines cost of the candidate CAND. */ + +static void +determine_iv_cost (struct ivopts_data *data, struct iv_cand *cand) +{ + unsigned cost_base, cost_step; + tree base; + + if (!cand->iv) + { + cand->cost = 0; + return; + } + + /* There are two costs associated with the candidate -- its increment + and its initialization. The second is almost negligible for any loop + that rolls enough, so we take it just very little into account. */ + + base = cand->iv->base; + cost_base = force_var_cost (data, base, NULL); + cost_step = add_cost (TYPE_MODE (TREE_TYPE (base))); + + cand->cost = cost_step + cost_base / AVG_LOOP_NITER (current_loop); + + /* Prefer the original iv unless we may gain something by replacing it; + this is not really relevant for artificial ivs created by other + passes. */ + if (cand->pos == IP_ORIGINAL + && !DECL_ARTIFICIAL (SSA_NAME_VAR (cand->var_before))) + cand->cost--; + + /* Prefer not to insert statements into latch unless there are some + already (so that we do not create unnecessary jumps). */ + if (cand->pos == IP_END + && empty_block_p (ip_end_pos (data->current_loop))) + cand->cost++; +} + +/* Determines costs of computation of the candidates. */ + +static void +determine_iv_costs (struct ivopts_data *data) +{ + unsigned i; + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Candidate costs:\n"); + fprintf (dump_file, " cand\tcost\n"); + } + + for (i = 0; i < n_iv_cands (data); i++) + { + struct iv_cand *cand = iv_cand (data, i); + + determine_iv_cost (data, cand); + + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, " %d\t%d\n", i, cand->cost); + } + +if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "\n"); +} + +/* Calculates cost for having SIZE induction variables. */ + +static unsigned +ivopts_global_cost_for_size (struct ivopts_data *data, unsigned size) +{ + return global_cost_for_size (size, data->regs_used, n_iv_uses (data)); +} + +/* For each size of the induction variable set determine the penalty. */ + +static void +determine_set_costs (struct ivopts_data *data) +{ + unsigned j, n; + tree phi, op; + struct loop *loop = data->current_loop; + bitmap_iterator bi; + + /* We use the following model (definitely improvable, especially the + cost function -- TODO): + + We estimate the number of registers available (using MD data), name it A. + + We estimate the number of registers used by the loop, name it U. This + number is obtained as the number of loop phi nodes (not counting virtual + registers and bivs) + the number of variables from outside of the loop. + + We set a reserve R (free regs that are used for temporary computations, + etc.). For now the reserve is a constant 3. + + Let I be the number of induction variables. + + -- if U + I + R <= A, the cost is I * SMALL_COST (just not to encourage + make a lot of ivs without a reason). + -- if A - R < U + I <= A, the cost is I * PRES_COST + -- if U + I > A, the cost is I * PRES_COST and + number of uses * SPILL_COST * (U + I - A) / (U + I) is added. */ + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Global costs:\n"); + fprintf (dump_file, " target_avail_regs %d\n", target_avail_regs); + fprintf (dump_file, " target_small_cost %d\n", target_small_cost); + fprintf (dump_file, " target_pres_cost %d\n", target_pres_cost); + fprintf (dump_file, " target_spill_cost %d\n", target_spill_cost); + } + + n = 0; + for (phi = phi_nodes (loop->header); phi; phi = PHI_CHAIN (phi)) + { + op = PHI_RESULT (phi); + + if (!is_gimple_reg (op)) + continue; + + if (get_iv (data, op)) + continue; + + n++; + } + + EXECUTE_IF_SET_IN_BITMAP (data->relevant, 0, j, bi) + { + struct version_info *info = ver_info (data, j); + + if (info->inv_id && info->has_nonlin_use) + n++; + } + + data->regs_used = n; + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, " regs_used %d\n", n); + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, " cost for size:\n"); + fprintf (dump_file, " ivs\tcost\n"); + for (j = 0; j <= 2 * target_avail_regs; j++) + fprintf (dump_file, " %d\t%d\n", j, + ivopts_global_cost_for_size (data, j)); + fprintf (dump_file, "\n"); + } +} + +/* Returns true if A is a cheaper cost pair than B. */ + +static bool +cheaper_cost_pair (struct cost_pair *a, struct cost_pair *b) +{ + if (!a) + return false; + + if (!b) + return true; + + if (a->cost < b->cost) + return true; + + if (a->cost > b->cost) + return false; + + /* In case the costs are the same, prefer the cheaper candidate. */ + if (a->cand->cost < b->cand->cost) + return true; + + return false; +} + +/* Computes the cost field of IVS structure. */ + +static void +iv_ca_recount_cost (struct ivopts_data *data, struct iv_ca *ivs) +{ + unsigned cost = 0; + + cost += ivs->cand_use_cost; + cost += ivs->cand_cost; + cost += ivopts_global_cost_for_size (data, ivs->n_regs); + + ivs->cost = cost; +} + +/* Remove invariants in set INVS to set IVS. */ + +static void +iv_ca_set_remove_invariants (struct iv_ca *ivs, bitmap invs) +{ + bitmap_iterator bi; + unsigned iid; + + if (!invs) + return; + + EXECUTE_IF_SET_IN_BITMAP (invs, 0, iid, bi) + { + ivs->n_invariant_uses[iid]--; + if (ivs->n_invariant_uses[iid] == 0) + ivs->n_regs--; + } +} + +/* Set USE not to be expressed by any candidate in IVS. */ + +static void +iv_ca_set_no_cp (struct ivopts_data *data, struct iv_ca *ivs, + struct iv_use *use) +{ + unsigned uid = use->id, cid; + struct cost_pair *cp; + + cp = ivs->cand_for_use[uid]; + if (!cp) + return; + cid = cp->cand->id; + + ivs->bad_uses++; + ivs->cand_for_use[uid] = NULL; + ivs->n_cand_uses[cid]--; + + if (ivs->n_cand_uses[cid] == 0) + { + bitmap_clear_bit (ivs->cands, cid); + /* Do not count the pseudocandidates. */ + if (cp->cand->iv) + ivs->n_regs--; + ivs->n_cands--; + ivs->cand_cost -= cp->cand->cost; + + iv_ca_set_remove_invariants (ivs, cp->cand->depends_on); + } + + ivs->cand_use_cost -= cp->cost; + + iv_ca_set_remove_invariants (ivs, cp->depends_on); + iv_ca_recount_cost (data, ivs); +} + +/* Add invariants in set INVS to set IVS. */ + +static void +iv_ca_set_add_invariants (struct iv_ca *ivs, bitmap invs) +{ + bitmap_iterator bi; + unsigned iid; + + if (!invs) + return; + + EXECUTE_IF_SET_IN_BITMAP (invs, 0, iid, bi) + { + ivs->n_invariant_uses[iid]++; + if (ivs->n_invariant_uses[iid] == 1) + ivs->n_regs++; + } +} + +/* Set cost pair for USE in set IVS to CP. */ + +static void +iv_ca_set_cp (struct ivopts_data *data, struct iv_ca *ivs, + struct iv_use *use, struct cost_pair *cp) +{ + unsigned uid = use->id, cid; + + if (ivs->cand_for_use[uid] == cp) + return; + + if (ivs->cand_for_use[uid]) + iv_ca_set_no_cp (data, ivs, use); + + if (cp) + { + cid = cp->cand->id; + + ivs->bad_uses--; + ivs->cand_for_use[uid] = cp; + ivs->n_cand_uses[cid]++; + if (ivs->n_cand_uses[cid] == 1) + { + bitmap_set_bit (ivs->cands, cid); + /* Do not count the pseudocandidates. */ + if (cp->cand->iv) + ivs->n_regs++; + ivs->n_cands++; + ivs->cand_cost += cp->cand->cost; + + iv_ca_set_add_invariants (ivs, cp->cand->depends_on); + } + + ivs->cand_use_cost += cp->cost; + iv_ca_set_add_invariants (ivs, cp->depends_on); + iv_ca_recount_cost (data, ivs); + } +} + +/* Extend set IVS by expressing USE by some of the candidates in it + if possible. */ + +static void +iv_ca_add_use (struct ivopts_data *data, struct iv_ca *ivs, + struct iv_use *use) +{ + struct cost_pair *best_cp = NULL, *cp; + bitmap_iterator bi; + unsigned i; + + gcc_assert (ivs->upto >= use->id); + + if (ivs->upto == use->id) + { + ivs->upto++; + ivs->bad_uses++; + } + + EXECUTE_IF_SET_IN_BITMAP (ivs->cands, 0, i, bi) + { + cp = get_use_iv_cost (data, use, iv_cand (data, i)); + + if (cheaper_cost_pair (cp, best_cp)) + best_cp = cp; + } + + iv_ca_set_cp (data, ivs, use, best_cp); +} + +/* Get cost for assignment IVS. */ + +static unsigned +iv_ca_cost (struct iv_ca *ivs) +{ + return (ivs->bad_uses ? INFTY : ivs->cost); +} + +/* Returns true if all dependences of CP are among invariants in IVS. */ + +static bool +iv_ca_has_deps (struct iv_ca *ivs, struct cost_pair *cp) +{ + unsigned i; + bitmap_iterator bi; + + if (!cp->depends_on) + return true; + + EXECUTE_IF_SET_IN_BITMAP (cp->depends_on, 0, i, bi) + { + if (ivs->n_invariant_uses[i] == 0) + return false; + } + + return true; +} + +/* Creates change of expressing USE by NEW_CP instead of OLD_CP and chains + it before NEXT_CHANGE. */ + +static struct iv_ca_delta * +iv_ca_delta_add (struct iv_use *use, struct cost_pair *old_cp, + struct cost_pair *new_cp, struct iv_ca_delta *next_change) +{ + struct iv_ca_delta *change = XNEW (struct iv_ca_delta); + + change->use = use; + change->old_cp = old_cp; + change->new_cp = new_cp; + change->next_change = next_change; + + return change; +} + +/* Joins two lists of changes L1 and L2. Destructive -- old lists + are rewritten. */ + +static struct iv_ca_delta * +iv_ca_delta_join (struct iv_ca_delta *l1, struct iv_ca_delta *l2) +{ + struct iv_ca_delta *last; + + if (!l2) + return l1; + + if (!l1) + return l2; + + for (last = l1; last->next_change; last = last->next_change) + continue; + last->next_change = l2; + + return l1; +} + +/* Returns candidate by that USE is expressed in IVS. */ + +static struct cost_pair * +iv_ca_cand_for_use (struct iv_ca *ivs, struct iv_use *use) +{ + return ivs->cand_for_use[use->id]; +} + +/* Reverse the list of changes DELTA, forming the inverse to it. */ + +static struct iv_ca_delta * +iv_ca_delta_reverse (struct iv_ca_delta *delta) +{ + struct iv_ca_delta *act, *next, *prev = NULL; + struct cost_pair *tmp; + + for (act = delta; act; act = next) + { + next = act->next_change; + act->next_change = prev; + prev = act; + + tmp = act->old_cp; + act->old_cp = act->new_cp; + act->new_cp = tmp; + } + + return prev; +} + +/* Commit changes in DELTA to IVS. If FORWARD is false, the changes are + reverted instead. */ + +static void +iv_ca_delta_commit (struct ivopts_data *data, struct iv_ca *ivs, + struct iv_ca_delta *delta, bool forward) +{ + struct cost_pair *from, *to; + struct iv_ca_delta *act; + + if (!forward) + delta = iv_ca_delta_reverse (delta); + + for (act = delta; act; act = act->next_change) + { + from = act->old_cp; + to = act->new_cp; + gcc_assert (iv_ca_cand_for_use (ivs, act->use) == from); + iv_ca_set_cp (data, ivs, act->use, to); + } + + if (!forward) + iv_ca_delta_reverse (delta); +} + +/* Returns true if CAND is used in IVS. */ + +static bool +iv_ca_cand_used_p (struct iv_ca *ivs, struct iv_cand *cand) +{ + return ivs->n_cand_uses[cand->id] > 0; +} + +/* Returns number of induction variable candidates in the set IVS. */ + +static unsigned +iv_ca_n_cands (struct iv_ca *ivs) +{ + return ivs->n_cands; +} + +/* Free the list of changes DELTA. */ + +static void +iv_ca_delta_free (struct iv_ca_delta **delta) +{ + struct iv_ca_delta *act, *next; + + for (act = *delta; act; act = next) + { + next = act->next_change; + free (act); + } + + *delta = NULL; +} + +/* Allocates new iv candidates assignment. */ + +static struct iv_ca * +iv_ca_new (struct ivopts_data *data) +{ + struct iv_ca *nw = XNEW (struct iv_ca); + + nw->upto = 0; + nw->bad_uses = 0; + nw->cand_for_use = XCNEWVEC (struct cost_pair *, n_iv_uses (data)); + nw->n_cand_uses = XCNEWVEC (unsigned, n_iv_cands (data)); + nw->cands = BITMAP_ALLOC (NULL); + nw->n_cands = 0; + nw->n_regs = 0; + nw->cand_use_cost = 0; + nw->cand_cost = 0; + nw->n_invariant_uses = XCNEWVEC (unsigned, data->max_inv_id + 1); + nw->cost = 0; + + return nw; +} + +/* Free memory occupied by the set IVS. */ + +static void +iv_ca_free (struct iv_ca **ivs) +{ + free ((*ivs)->cand_for_use); + free ((*ivs)->n_cand_uses); + BITMAP_FREE ((*ivs)->cands); + free ((*ivs)->n_invariant_uses); + free (*ivs); + *ivs = NULL; +} + +/* Dumps IVS to FILE. */ + +static void +iv_ca_dump (struct ivopts_data *data, FILE *file, struct iv_ca *ivs) +{ + const char *pref = " invariants "; + unsigned i; + + fprintf (file, " cost %d\n", iv_ca_cost (ivs)); + bitmap_print (file, ivs->cands, " candidates ","\n"); + + for (i = 1; i <= data->max_inv_id; i++) + if (ivs->n_invariant_uses[i]) + { + fprintf (file, "%s%d", pref, i); + pref = ", "; + } + fprintf (file, "\n"); +} + +/* Try changing candidate in IVS to CAND for each use. Return cost of the + new set, and store differences in DELTA. Number of induction variables + in the new set is stored to N_IVS. */ + +static unsigned +iv_ca_extend (struct ivopts_data *data, struct iv_ca *ivs, + struct iv_cand *cand, struct iv_ca_delta **delta, + unsigned *n_ivs) +{ + unsigned i, cost; + struct iv_use *use; + struct cost_pair *old_cp, *new_cp; + + *delta = NULL; + for (i = 0; i < ivs->upto; i++) + { + use = iv_use (data, i); + old_cp = iv_ca_cand_for_use (ivs, use); + + if (old_cp + && old_cp->cand == cand) + continue; + + new_cp = get_use_iv_cost (data, use, cand); + if (!new_cp) + continue; + + if (!iv_ca_has_deps (ivs, new_cp)) + continue; + + if (!cheaper_cost_pair (new_cp, old_cp)) + continue; + + *delta = iv_ca_delta_add (use, old_cp, new_cp, *delta); + } + + iv_ca_delta_commit (data, ivs, *delta, true); + cost = iv_ca_cost (ivs); + if (n_ivs) + *n_ivs = iv_ca_n_cands (ivs); + iv_ca_delta_commit (data, ivs, *delta, false); + + return cost; +} + +/* Try narrowing set IVS by removing CAND. Return the cost of + the new set and store the differences in DELTA. */ + +static unsigned +iv_ca_narrow (struct ivopts_data *data, struct iv_ca *ivs, + struct iv_cand *cand, struct iv_ca_delta **delta) +{ + unsigned i, ci; + struct iv_use *use; + struct cost_pair *old_cp, *new_cp, *cp; + bitmap_iterator bi; + struct iv_cand *cnd; + unsigned cost; + + *delta = NULL; + for (i = 0; i < n_iv_uses (data); i++) + { + use = iv_use (data, i); + + old_cp = iv_ca_cand_for_use (ivs, use); + if (old_cp->cand != cand) + continue; + + new_cp = NULL; + + if (data->consider_all_candidates) + { + EXECUTE_IF_SET_IN_BITMAP (ivs->cands, 0, ci, bi) + { + if (ci == cand->id) + continue; + + cnd = iv_cand (data, ci); + + cp = get_use_iv_cost (data, use, cnd); + if (!cp) + continue; + if (!iv_ca_has_deps (ivs, cp)) + continue; + + if (!cheaper_cost_pair (cp, new_cp)) + continue; + + new_cp = cp; + } + } + else + { + EXECUTE_IF_AND_IN_BITMAP (use->related_cands, ivs->cands, 0, ci, bi) + { + if (ci == cand->id) + continue; + + cnd = iv_cand (data, ci); + + cp = get_use_iv_cost (data, use, cnd); + if (!cp) + continue; + if (!iv_ca_has_deps (ivs, cp)) + continue; + + if (!cheaper_cost_pair (cp, new_cp)) + continue; + + new_cp = cp; + } + } + + if (!new_cp) + { + iv_ca_delta_free (delta); + return INFTY; + } + + *delta = iv_ca_delta_add (use, old_cp, new_cp, *delta); + } + + iv_ca_delta_commit (data, ivs, *delta, true); + cost = iv_ca_cost (ivs); + iv_ca_delta_commit (data, ivs, *delta, false); + + return cost; +} + +/* Try optimizing the set of candidates IVS by removing candidates different + from to EXCEPT_CAND from it. Return cost of the new set, and store + differences in DELTA. */ + +static unsigned +iv_ca_prune (struct ivopts_data *data, struct iv_ca *ivs, + struct iv_cand *except_cand, struct iv_ca_delta **delta) +{ + bitmap_iterator bi; + struct iv_ca_delta *act_delta, *best_delta; + unsigned i, best_cost, acost; + struct iv_cand *cand; + + best_delta = NULL; + best_cost = iv_ca_cost (ivs); + + EXECUTE_IF_SET_IN_BITMAP (ivs->cands, 0, i, bi) + { + cand = iv_cand (data, i); + + if (cand == except_cand) + continue; + + acost = iv_ca_narrow (data, ivs, cand, &act_delta); + + if (acost < best_cost) + { + best_cost = acost; + iv_ca_delta_free (&best_delta); + best_delta = act_delta; + } + else + iv_ca_delta_free (&act_delta); + } + + if (!best_delta) + { + *delta = NULL; + return best_cost; + } + + /* Recurse to possibly remove other unnecessary ivs. */ + iv_ca_delta_commit (data, ivs, best_delta, true); + best_cost = iv_ca_prune (data, ivs, except_cand, delta); + iv_ca_delta_commit (data, ivs, best_delta, false); + *delta = iv_ca_delta_join (best_delta, *delta); + return best_cost; +} + +/* Tries to extend the sets IVS in the best possible way in order + to express the USE. */ + +static bool +try_add_cand_for (struct ivopts_data *data, struct iv_ca *ivs, + struct iv_use *use) +{ + unsigned best_cost, act_cost; + unsigned i; + bitmap_iterator bi; + struct iv_cand *cand; + struct iv_ca_delta *best_delta = NULL, *act_delta; + struct cost_pair *cp; + + iv_ca_add_use (data, ivs, use); + best_cost = iv_ca_cost (ivs); + + cp = iv_ca_cand_for_use (ivs, use); + if (cp) + { + best_delta = iv_ca_delta_add (use, NULL, cp, NULL); + iv_ca_set_no_cp (data, ivs, use); + } + + /* First try important candidates. Only if it fails, try the specific ones. + Rationale -- in loops with many variables the best choice often is to use + just one generic biv. If we added here many ivs specific to the uses, + the optimization algorithm later would be likely to get stuck in a local + minimum, thus causing us to create too many ivs. The approach from + few ivs to more seems more likely to be successful -- starting from few + ivs, replacing an expensive use by a specific iv should always be a + win. */ + EXECUTE_IF_SET_IN_BITMAP (data->important_candidates, 0, i, bi) + { + cand = iv_cand (data, i); + + if (iv_ca_cand_used_p (ivs, cand)) + continue; + + cp = get_use_iv_cost (data, use, cand); + if (!cp) + continue; + + iv_ca_set_cp (data, ivs, use, cp); + act_cost = iv_ca_extend (data, ivs, cand, &act_delta, NULL); + iv_ca_set_no_cp (data, ivs, use); + act_delta = iv_ca_delta_add (use, NULL, cp, act_delta); + + if (act_cost < best_cost) + { + best_cost = act_cost; + + iv_ca_delta_free (&best_delta); + best_delta = act_delta; + } + else + iv_ca_delta_free (&act_delta); + } + + if (best_cost == INFTY) + { + for (i = 0; i < use->n_map_members; i++) + { + cp = use->cost_map + i; + cand = cp->cand; + if (!cand) + continue; + + /* Already tried this. */ + if (cand->important) + continue; + + if (iv_ca_cand_used_p (ivs, cand)) + continue; + + act_delta = NULL; + iv_ca_set_cp (data, ivs, use, cp); + act_cost = iv_ca_extend (data, ivs, cand, &act_delta, NULL); + iv_ca_set_no_cp (data, ivs, use); + act_delta = iv_ca_delta_add (use, iv_ca_cand_for_use (ivs, use), + cp, act_delta); + + if (act_cost < best_cost) + { + best_cost = act_cost; + + if (best_delta) + iv_ca_delta_free (&best_delta); + best_delta = act_delta; + } + else + iv_ca_delta_free (&act_delta); + } + } + + iv_ca_delta_commit (data, ivs, best_delta, true); + iv_ca_delta_free (&best_delta); + + return (best_cost != INFTY); +} + +/* Finds an initial assignment of candidates to uses. */ + +static struct iv_ca * +get_initial_solution (struct ivopts_data *data) +{ + struct iv_ca *ivs = iv_ca_new (data); + unsigned i; + + for (i = 0; i < n_iv_uses (data); i++) + if (!try_add_cand_for (data, ivs, iv_use (data, i))) + { + iv_ca_free (&ivs); + return NULL; + } + + return ivs; +} + +/* Tries to improve set of induction variables IVS. */ + +static bool +try_improve_iv_set (struct ivopts_data *data, struct iv_ca *ivs) +{ + unsigned i, acost, best_cost = iv_ca_cost (ivs), n_ivs; + struct iv_ca_delta *best_delta = NULL, *act_delta, *tmp_delta; + struct iv_cand *cand; + + /* Try extending the set of induction variables by one. */ + for (i = 0; i < n_iv_cands (data); i++) + { + cand = iv_cand (data, i); + + if (iv_ca_cand_used_p (ivs, cand)) + continue; + + acost = iv_ca_extend (data, ivs, cand, &act_delta, &n_ivs); + if (!act_delta) + continue; + + /* If we successfully added the candidate and the set is small enough, + try optimizing it by removing other candidates. */ + if (n_ivs <= ALWAYS_PRUNE_CAND_SET_BOUND) + { + iv_ca_delta_commit (data, ivs, act_delta, true); + acost = iv_ca_prune (data, ivs, cand, &tmp_delta); + iv_ca_delta_commit (data, ivs, act_delta, false); + act_delta = iv_ca_delta_join (act_delta, tmp_delta); + } + + if (acost < best_cost) + { + best_cost = acost; + iv_ca_delta_free (&best_delta); + best_delta = act_delta; + } + else + iv_ca_delta_free (&act_delta); + } + + if (!best_delta) + { + /* Try removing the candidates from the set instead. */ + best_cost = iv_ca_prune (data, ivs, NULL, &best_delta); + + /* Nothing more we can do. */ + if (!best_delta) + return false; + } + + iv_ca_delta_commit (data, ivs, best_delta, true); + gcc_assert (best_cost == iv_ca_cost (ivs)); + iv_ca_delta_free (&best_delta); + return true; +} + +/* Attempts to find the optimal set of induction variables. We do simple + greedy heuristic -- we try to replace at most one candidate in the selected + solution and remove the unused ivs while this improves the cost. */ + +static struct iv_ca * +find_optimal_iv_set (struct ivopts_data *data) +{ + unsigned i; + struct iv_ca *set; + struct iv_use *use; + + /* Get the initial solution. */ + set = get_initial_solution (data); + if (!set) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Unable to substitute for ivs, failed.\n"); + return NULL; + } + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Initial set of candidates:\n"); + iv_ca_dump (data, dump_file, set); + } + + while (try_improve_iv_set (data, set)) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Improved to:\n"); + iv_ca_dump (data, dump_file, set); + } + } + + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Final cost %d\n\n", iv_ca_cost (set)); + + for (i = 0; i < n_iv_uses (data); i++) + { + use = iv_use (data, i); + use->selected = iv_ca_cand_for_use (set, use)->cand; + } + + return set; +} + +/* Creates a new induction variable corresponding to CAND. */ + +static void +create_new_iv (struct ivopts_data *data, struct iv_cand *cand) +{ + block_stmt_iterator incr_pos; + tree base; + bool after = false; + + if (!cand->iv) + return; + + switch (cand->pos) + { + case IP_NORMAL: + incr_pos = bsi_last (ip_normal_pos (data->current_loop)); + break; + + case IP_END: + incr_pos = bsi_last (ip_end_pos (data->current_loop)); + after = true; + break; + + case IP_ORIGINAL: + /* Mark that the iv is preserved. */ + name_info (data, cand->var_before)->preserve_biv = true; + name_info (data, cand->var_after)->preserve_biv = true; + + /* Rewrite the increment so that it uses var_before directly. */ + find_interesting_uses_op (data, cand->var_after)->selected = cand; + + return; + } + + gimple_add_tmp_var (cand->var_before); + add_referenced_var (cand->var_before); + + base = unshare_expr (cand->iv->base); + + create_iv (base, unshare_expr (cand->iv->step), + cand->var_before, data->current_loop, + &incr_pos, after, &cand->var_before, &cand->var_after); +} + +/* Creates new induction variables described in SET. */ + +static void +create_new_ivs (struct ivopts_data *data, struct iv_ca *set) +{ + unsigned i; + struct iv_cand *cand; + bitmap_iterator bi; + + EXECUTE_IF_SET_IN_BITMAP (set->cands, 0, i, bi) + { + cand = iv_cand (data, i); + create_new_iv (data, cand); + } +} + +/* Removes statement STMT (real or a phi node). If INCLUDING_DEFINED_NAME + is true, remove also the ssa name defined by the statement. */ + +static void +remove_statement (tree stmt, bool including_defined_name) +{ + if (TREE_CODE (stmt) == PHI_NODE) + { + if (!including_defined_name) + { + /* Prevent the ssa name defined by the statement from being removed. */ + SET_PHI_RESULT (stmt, NULL); + } + remove_phi_node (stmt, NULL_TREE); + } + else + { + block_stmt_iterator bsi = bsi_for_stmt (stmt); + + bsi_remove (&bsi, true); + } +} + +/* Rewrites USE (definition of iv used in a nonlinear expression) + using candidate CAND. */ + +static void +rewrite_use_nonlinear_expr (struct ivopts_data *data, + struct iv_use *use, struct iv_cand *cand) +{ + tree comp; + tree op, stmts, tgt, ass; + block_stmt_iterator bsi, pbsi; + + /* An important special case -- if we are asked to express value of + the original iv by itself, just exit; there is no need to + introduce a new computation (that might also need casting the + variable to unsigned and back). */ + if (cand->pos == IP_ORIGINAL + && cand->incremented_at == use->stmt) + { + tree step, ctype, utype; + enum tree_code incr_code = PLUS_EXPR; + + gcc_assert (TREE_CODE (use->stmt) == MODIFY_EXPR); + gcc_assert (TREE_OPERAND (use->stmt, 0) == cand->var_after); + + step = cand->iv->step; + ctype = TREE_TYPE (step); + utype = TREE_TYPE (cand->var_after); + if (TREE_CODE (step) == NEGATE_EXPR) + { + incr_code = MINUS_EXPR; + step = TREE_OPERAND (step, 0); + } + + /* Check whether we may leave the computation unchanged. + This is the case only if it does not rely on other + computations in the loop -- otherwise, the computation + we rely upon may be removed in remove_unused_ivs, + thus leading to ICE. */ + op = TREE_OPERAND (use->stmt, 1); + if (TREE_CODE (op) == PLUS_EXPR + || TREE_CODE (op) == MINUS_EXPR) + { + if (TREE_OPERAND (op, 0) == cand->var_before) + op = TREE_OPERAND (op, 1); + else if (TREE_CODE (op) == PLUS_EXPR + && TREE_OPERAND (op, 1) == cand->var_before) + op = TREE_OPERAND (op, 0); + else + op = NULL_TREE; + } + else + op = NULL_TREE; + + if (op + && (TREE_CODE (op) == INTEGER_CST + || operand_equal_p (op, step, 0))) + return; + + /* Otherwise, add the necessary computations to express + the iv. */ + op = fold_convert (ctype, cand->var_before); + comp = fold_convert (utype, + build2 (incr_code, ctype, op, + unshare_expr (step))); + } + else + comp = get_computation (data->current_loop, use, cand); + + switch (TREE_CODE (use->stmt)) + { + case PHI_NODE: + tgt = PHI_RESULT (use->stmt); + + /* If we should keep the biv, do not replace it. */ + if (name_info (data, tgt)->preserve_biv) + return; + + pbsi = bsi = bsi_start (bb_for_stmt (use->stmt)); + while (!bsi_end_p (pbsi) + && TREE_CODE (bsi_stmt (pbsi)) == LABEL_EXPR) + { + bsi = pbsi; + bsi_next (&pbsi); + } + break; + + case MODIFY_EXPR: + tgt = TREE_OPERAND (use->stmt, 0); + bsi = bsi_for_stmt (use->stmt); + break; + + default: + gcc_unreachable (); + } + + op = force_gimple_operand (comp, &stmts, false, SSA_NAME_VAR (tgt)); + + if (TREE_CODE (use->stmt) == PHI_NODE) + { + if (stmts) + bsi_insert_after (&bsi, stmts, BSI_CONTINUE_LINKING); + ass = build2 (MODIFY_EXPR, TREE_TYPE (tgt), tgt, op); + bsi_insert_after (&bsi, ass, BSI_NEW_STMT); + remove_statement (use->stmt, false); + SSA_NAME_DEF_STMT (tgt) = ass; + } + else + { + if (stmts) + bsi_insert_before (&bsi, stmts, BSI_SAME_STMT); + TREE_OPERAND (use->stmt, 1) = op; + } +} + +/* Replaces ssa name in index IDX by its basic variable. Callback for + for_each_index. */ + +static bool +idx_remove_ssa_names (tree base, tree *idx, + void *data ATTRIBUTE_UNUSED) +{ + tree *op; + + if (TREE_CODE (*idx) == SSA_NAME) + *idx = SSA_NAME_VAR (*idx); + + if (TREE_CODE (base) == ARRAY_REF) + { + op = &TREE_OPERAND (base, 2); + if (*op + && TREE_CODE (*op) == SSA_NAME) + *op = SSA_NAME_VAR (*op); + op = &TREE_OPERAND (base, 3); + if (*op + && TREE_CODE (*op) == SSA_NAME) + *op = SSA_NAME_VAR (*op); + } + + return true; +} + +/* Unshares REF and replaces ssa names inside it by their basic variables. */ + +static tree +unshare_and_remove_ssa_names (tree ref) +{ + ref = unshare_expr (ref); + for_each_index (&ref, idx_remove_ssa_names, NULL); + + return ref; +} + +/* Extract the alias analysis info for the memory reference REF. There are + several ways how this information may be stored and what precisely is + its semantics depending on the type of the reference, but there always is + somewhere hidden one _DECL node that is used to determine the set of + virtual operands for the reference. The code below deciphers this jungle + and extracts this single useful piece of information. */ + +static tree +get_ref_tag (tree ref, tree orig) +{ + tree var = get_base_address (ref); + tree aref = NULL_TREE, tag, sv; + HOST_WIDE_INT offset, size, maxsize; + + for (sv = orig; handled_component_p (sv); sv = TREE_OPERAND (sv, 0)) + { + aref = get_ref_base_and_extent (sv, &offset, &size, &maxsize); + if (ref) + break; + } + + if (aref && SSA_VAR_P (aref) && get_subvars_for_var (aref)) + return unshare_expr (sv); + + if (!var) + return NULL_TREE; + + if (TREE_CODE (var) == INDIRECT_REF) + { + /* If the base is a dereference of a pointer, first check its name memory + tag. If it does not have one, use its symbol memory tag. */ + var = TREE_OPERAND (var, 0); + if (TREE_CODE (var) != SSA_NAME) + return NULL_TREE; + + if (SSA_NAME_PTR_INFO (var)) + { + tag = SSA_NAME_PTR_INFO (var)->name_mem_tag; + if (tag) + return tag; + } + + var = SSA_NAME_VAR (var); + tag = var_ann (var)->symbol_mem_tag; + gcc_assert (tag != NULL_TREE); + return tag; + } + else + { + if (!DECL_P (var)) + return NULL_TREE; + + tag = var_ann (var)->symbol_mem_tag; + if (tag) + return tag; + + return var; + } +} + +/* Copies the reference information from OLD_REF to NEW_REF. */ + +static void +copy_ref_info (tree new_ref, tree old_ref) +{ + if (TREE_CODE (old_ref) == TARGET_MEM_REF) + copy_mem_ref_info (new_ref, old_ref); + else + { + TMR_ORIGINAL (new_ref) = unshare_and_remove_ssa_names (old_ref); + TMR_TAG (new_ref) = get_ref_tag (old_ref, TMR_ORIGINAL (new_ref)); + } +} + +/* Rewrites USE (address that is an iv) using candidate CAND. */ + +static void +rewrite_use_address (struct ivopts_data *data, + struct iv_use *use, struct iv_cand *cand) +{ + struct affine_tree_combination aff; + block_stmt_iterator bsi = bsi_for_stmt (use->stmt); + tree ref; + + get_computation_aff (data->current_loop, use, cand, use->stmt, &aff); + unshare_aff_combination (&aff); + + ref = create_mem_ref (&bsi, TREE_TYPE (*use->op_p), &aff); + copy_ref_info (ref, *use->op_p); + *use->op_p = ref; +} + +/* Rewrites USE (the condition such that one of the arguments is an iv) using + candidate CAND. */ + +static void +rewrite_use_compare (struct ivopts_data *data, + struct iv_use *use, struct iv_cand *cand) +{ + tree comp; + tree *op_p, cond, op, stmts, bound; + block_stmt_iterator bsi = bsi_for_stmt (use->stmt); + enum tree_code compare; + struct cost_pair *cp = get_use_iv_cost (data, use, cand); + + bound = cp->value; + if (bound) + { + tree var = var_at_stmt (data->current_loop, cand, use->stmt); + tree var_type = TREE_TYPE (var); + + compare = iv_elimination_compare (data, use); + bound = fold_convert (var_type, bound); + op = force_gimple_operand (unshare_expr (bound), &stmts, + true, NULL_TREE); + + if (stmts) + bsi_insert_before (&bsi, stmts, BSI_SAME_STMT); + + *use->op_p = build2 (compare, boolean_type_node, var, op); + update_stmt (use->stmt); + return; + } + + /* The induction variable elimination failed; just express the original + giv. */ + comp = get_computation (data->current_loop, use, cand); + + cond = *use->op_p; + op_p = &TREE_OPERAND (cond, 0); + if (TREE_CODE (*op_p) != SSA_NAME + || zero_p (get_iv (data, *op_p)->step)) + op_p = &TREE_OPERAND (cond, 1); + + op = force_gimple_operand (comp, &stmts, true, SSA_NAME_VAR (*op_p)); + if (stmts) + bsi_insert_before (&bsi, stmts, BSI_SAME_STMT); + + *op_p = op; +} + +/* Rewrites USE using candidate CAND. */ + +static void +rewrite_use (struct ivopts_data *data, + struct iv_use *use, struct iv_cand *cand) +{ + switch (use->type) + { + case USE_NONLINEAR_EXPR: + rewrite_use_nonlinear_expr (data, use, cand); + break; + + case USE_ADDRESS: + rewrite_use_address (data, use, cand); + break; + + case USE_COMPARE: + rewrite_use_compare (data, use, cand); + break; + + default: + gcc_unreachable (); + } + mark_new_vars_to_rename (use->stmt); +} + +/* Rewrite the uses using the selected induction variables. */ + +static void +rewrite_uses (struct ivopts_data *data) +{ + unsigned i; + struct iv_cand *cand; + struct iv_use *use; + + for (i = 0; i < n_iv_uses (data); i++) + { + use = iv_use (data, i); + cand = use->selected; + gcc_assert (cand); + + rewrite_use (data, use, cand); + } +} + +/* Removes the ivs that are not used after rewriting. */ + +static void +remove_unused_ivs (struct ivopts_data *data) +{ + unsigned j; + bitmap_iterator bi; + + EXECUTE_IF_SET_IN_BITMAP (data->relevant, 0, j, bi) + { + struct version_info *info; + + info = ver_info (data, j); + if (info->iv + && !zero_p (info->iv->step) + && !info->inv_id + && !info->iv->have_use_for + && !info->preserve_biv) + remove_statement (SSA_NAME_DEF_STMT (info->iv->ssa_name), true); + } +} + +/* Frees data allocated by the optimization of a single loop. */ + +static void +free_loop_data (struct ivopts_data *data) +{ + unsigned i, j; + bitmap_iterator bi; + tree obj; + + htab_empty (data->niters); + + EXECUTE_IF_SET_IN_BITMAP (data->relevant, 0, i, bi) + { + struct version_info *info; + + info = ver_info (data, i); + if (info->iv) + free (info->iv); + info->iv = NULL; + info->has_nonlin_use = false; + info->preserve_biv = false; + info->inv_id = 0; + } + bitmap_clear (data->relevant); + bitmap_clear (data->important_candidates); + + for (i = 0; i < n_iv_uses (data); i++) + { + struct iv_use *use = iv_use (data, i); + + free (use->iv); + BITMAP_FREE (use->related_cands); + for (j = 0; j < use->n_map_members; j++) + if (use->cost_map[j].depends_on) + BITMAP_FREE (use->cost_map[j].depends_on); + free (use->cost_map); + free (use); + } + VEC_truncate (iv_use_p, data->iv_uses, 0); + + for (i = 0; i < n_iv_cands (data); i++) + { + struct iv_cand *cand = iv_cand (data, i); + + if (cand->iv) + free (cand->iv); + if (cand->depends_on) + BITMAP_FREE (cand->depends_on); + free (cand); + } + VEC_truncate (iv_cand_p, data->iv_candidates, 0); + + if (data->version_info_size < num_ssa_names) + { + data->version_info_size = 2 * num_ssa_names; + free (data->version_info); + data->version_info = XCNEWVEC (struct version_info, data->version_info_size); + } + + data->max_inv_id = 0; + + for (i = 0; VEC_iterate (tree, decl_rtl_to_reset, i, obj); i++) + SET_DECL_RTL (obj, NULL_RTX); + + VEC_truncate (tree, decl_rtl_to_reset, 0); +} + +/* Finalizes data structures used by the iv optimization pass. LOOPS is the + loop tree. */ + +static void +tree_ssa_iv_optimize_finalize (struct ivopts_data *data) +{ + free_loop_data (data); + free (data->version_info); + BITMAP_FREE (data->relevant); + BITMAP_FREE (data->important_candidates); + htab_delete (data->niters); + + VEC_free (tree, heap, decl_rtl_to_reset); + VEC_free (iv_use_p, heap, data->iv_uses); + VEC_free (iv_cand_p, heap, data->iv_candidates); +} + +/* Optimizes the LOOP. Returns true if anything changed. */ + +static bool +tree_ssa_iv_optimize_loop (struct ivopts_data *data, struct loop *loop) +{ + bool changed = false; + struct iv_ca *iv_ca; + edge exit; + + data->current_loop = loop; + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Processing loop %d\n", loop->num); + + exit = single_dom_exit (loop); + if (exit) + { + fprintf (dump_file, " single exit %d -> %d, exit condition ", + exit->src->index, exit->dest->index); + print_generic_expr (dump_file, last_stmt (exit->src), TDF_SLIM); + fprintf (dump_file, "\n"); + } + + fprintf (dump_file, "\n"); + } + + /* For each ssa name determines whether it behaves as an induction variable + in some loop. */ + if (!find_induction_variables (data)) + goto finish; + + /* Finds interesting uses (item 1). */ + find_interesting_uses (data); + if (n_iv_uses (data) > MAX_CONSIDERED_USES) + goto finish; + + /* Finds candidates for the induction variables (item 2). */ + find_iv_candidates (data); + + /* Calculates the costs (item 3, part 1). */ + determine_use_iv_costs (data); + determine_iv_costs (data); + determine_set_costs (data); + + /* Find the optimal set of induction variables (item 3, part 2). */ + iv_ca = find_optimal_iv_set (data); + if (!iv_ca) + goto finish; + changed = true; + + /* Create the new induction variables (item 4, part 1). */ + create_new_ivs (data, iv_ca); + iv_ca_free (&iv_ca); + + /* Rewrite the uses (item 4, part 2). */ + rewrite_uses (data); + + /* Remove the ivs that are unused after rewriting. */ + remove_unused_ivs (data); + + /* We have changed the structure of induction variables; it might happen + that definitions in the scev database refer to some of them that were + eliminated. */ + scev_reset (); + +finish: + free_loop_data (data); + + return changed; +} + +/* Main entry point. Optimizes induction variables in LOOPS. */ + +void +tree_ssa_iv_optimize (struct loops *loops) +{ + struct loop *loop; + struct ivopts_data data; + + tree_ssa_iv_optimize_init (&data); + + /* Optimize the loops starting with the innermost ones. */ + loop = loops->tree_root; + while (loop->inner) + loop = loop->inner; + + /* Scan the loops, inner ones first. */ + while (loop != loops->tree_root) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + flow_loop_dump (loop, dump_file, NULL, 1); + + tree_ssa_iv_optimize_loop (&data, loop); + + if (loop->next) + { + loop = loop->next; + while (loop->inner) + loop = loop->inner; + } + else + loop = loop->outer; + } + + tree_ssa_iv_optimize_finalize (&data); +} |
