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Diffstat (limited to 'gcc/tree-into-ssa.c')
| -rw-r--r-- | gcc/tree-into-ssa.c | 3157 |
1 files changed, 3157 insertions, 0 deletions
diff --git a/gcc/tree-into-ssa.c b/gcc/tree-into-ssa.c new file mode 100644 index 0000000..14a50b6 --- /dev/null +++ b/gcc/tree-into-ssa.c @@ -0,0 +1,3157 @@ +/* Rewrite a program in Normal form into SSA. + Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc. + Contributed by Diego Novillo <dnovillo@redhat.com> + +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. */ + +#include "config.h" +#include "system.h" +#include "coretypes.h" +#include "tm.h" +#include "tree.h" +#include "flags.h" +#include "rtl.h" +#include "tm_p.h" +#include "langhooks.h" +#include "hard-reg-set.h" +#include "basic-block.h" +#include "output.h" +#include "expr.h" +#include "function.h" +#include "diagnostic.h" +#include "bitmap.h" +#include "tree-flow.h" +#include "tree-gimple.h" +#include "tree-inline.h" +#include "varray.h" +#include "timevar.h" +#include "hashtab.h" +#include "tree-dump.h" +#include "tree-pass.h" +#include "cfgloop.h" +#include "domwalk.h" +#include "ggc.h" +#include "params.h" +#include "vecprim.h" + +/* This file builds the SSA form for a function as described in: + R. Cytron, J. Ferrante, B. Rosen, M. Wegman, and K. Zadeck. Efficiently + Computing Static Single Assignment Form and the Control Dependence + Graph. ACM Transactions on Programming Languages and Systems, + 13(4):451-490, October 1991. */ + +/* True if the code is in ssa form. */ +bool in_ssa_p; + +/* Structure to map a variable VAR to the set of blocks that contain + definitions for VAR. */ +struct def_blocks_d +{ + /* The variable. */ + tree var; + + /* Blocks that contain definitions of VAR. Bit I will be set if the + Ith block contains a definition of VAR. */ + bitmap def_blocks; + + /* Blocks that contain a PHI node for VAR. */ + bitmap phi_blocks; + + /* Blocks where VAR is live-on-entry. Similar semantics as + DEF_BLOCKS. */ + bitmap livein_blocks; +}; + + +/* Each entry in DEF_BLOCKS contains an element of type STRUCT + DEF_BLOCKS_D, mapping a variable VAR to a bitmap describing all the + basic blocks where VAR is defined (assigned a new value). It also + contains a bitmap of all the blocks where VAR is live-on-entry + (i.e., there is a use of VAR in block B without a preceding + definition in B). The live-on-entry information is used when + computing PHI pruning heuristics. */ +static htab_t def_blocks; + +/* Stack of trees used to restore the global currdefs to its original + state after completing rewriting of a block and its dominator + children. Its elements have the following properties: + + - An SSA_NAME indicates that the current definition of the + underlying variable should be set to the given SSA_NAME. + + - A _DECL node indicates that the underlying variable has no + current definition. + + - A NULL node is used to mark the last node associated with the + current block. + + - A NULL node at the top entry is used to mark the last node + associated with the current block. */ +static VEC(tree,heap) *block_defs_stack; + +/* Set of existing SSA names being replaced by update_ssa. */ +static sbitmap old_ssa_names; + +/* Set of new SSA names being added by update_ssa. Note that both + NEW_SSA_NAMES and OLD_SSA_NAMES are dense bitmaps because most of + the operations done on them are presence tests. */ +static sbitmap new_ssa_names; + +/* Symbols whose SSA form needs to be updated or created for the first + time. */ +static bitmap syms_to_rename; + +/* Set of SSA names that have been marked to be released after they + were registered in the replacement table. They will be finally + released after we finish updating the SSA web. */ +static bitmap names_to_release; + +/* For each block, the phi nodes that need to be rewritten are stored into + these vectors. */ + +typedef VEC(tree, heap) *tree_vec; +DEF_VEC_P (tree_vec); +DEF_VEC_ALLOC_P (tree_vec, heap); + +static VEC(tree_vec, heap) *phis_to_rewrite; + +/* The bitmap of non-NULL elements of PHIS_TO_REWRITE. */ + +static bitmap blocks_with_phis_to_rewrite; + +/* Growth factor for NEW_SSA_NAMES and OLD_SSA_NAMES. These sets need + to grow as the callers to register_new_name_mapping will typically + create new names on the fly. FIXME. Currently set to 1/3 to avoid + frequent reallocations but still need to find a reasonable growth + strategy. */ +#define NAME_SETS_GROWTH_FACTOR (MAX (3, num_ssa_names / 3)) + +/* Tuple used to represent replacement mappings. */ +struct repl_map_d +{ + tree name; + bitmap set; +}; + +/* NEW -> OLD_SET replacement table. If we are replacing several + existing SSA names O_1, O_2, ..., O_j with a new name N_i, + then REPL_TBL[N_i] = { O_1, O_2, ..., O_j }. */ +static htab_t repl_tbl; + +/* true if register_new_name_mapping needs to initialize the data + structures needed by update_ssa. */ +static bool need_to_initialize_update_ssa_p = true; + +/* true if update_ssa needs to update virtual operands. */ +static bool need_to_update_vops_p = false; + +/* Statistics kept by update_ssa to use in the virtual mapping + heuristic. If the number of virtual mappings is beyond certain + threshold, the updater will switch from using the mappings into + renaming the virtual symbols from scratch. In some cases, the + large number of name mappings for virtual names causes significant + slowdowns in the PHI insertion code. */ +struct update_ssa_stats_d +{ + unsigned num_virtual_mappings; + unsigned num_total_mappings; + bitmap virtual_symbols; + unsigned num_virtual_symbols; +}; +static struct update_ssa_stats_d update_ssa_stats; + +/* Global data to attach to the main dominator walk structure. */ +struct mark_def_sites_global_data +{ + /* This bitmap contains the variables which are set before they + are used in a basic block. */ + bitmap kills; + + /* Bitmap of names to rename. */ + sbitmap names_to_rename; + + /* Set of blocks that mark_def_sites deems interesting for the + renamer to process. */ + sbitmap interesting_blocks; +}; + + +/* Information stored for SSA names. */ +struct ssa_name_info +{ + /* The actual definition of the ssa name. */ + tree current_def; + + /* This field indicates whether or not the variable may need PHI nodes. + See the enum's definition for more detailed information about the + states. */ + ENUM_BITFIELD (need_phi_state) need_phi_state : 2; + + /* Age of this record (so that info_for_ssa_name table can be cleared + quicky); if AGE < CURRENT_INFO_FOR_SSA_NAME_AGE, then the fields + are assumed to be null. */ + unsigned age; +}; + +/* The information associated with names. */ +typedef struct ssa_name_info *ssa_name_info_p; +DEF_VEC_P (ssa_name_info_p); +DEF_VEC_ALLOC_P (ssa_name_info_p, heap); + +static VEC(ssa_name_info_p, heap) *info_for_ssa_name; +static unsigned current_info_for_ssa_name_age; + +/* The set of blocks affected by update_ssa. */ + +static bitmap blocks_to_update; + +/* The main entry point to the SSA renamer (rewrite_blocks) may be + called several times to do different, but related, tasks. + Initially, we need it to rename the whole program into SSA form. + At other times, we may need it to only rename into SSA newly + exposed symbols. Finally, we can also call it to incrementally fix + an already built SSA web. */ +enum rewrite_mode { + /* Convert the whole function into SSA form. */ + REWRITE_ALL, + + /* Incrementally update the SSA web by replacing existing SSA + names with new ones. See update_ssa for details. */ + REWRITE_UPDATE +}; + + +/* Use TREE_VISITED to keep track of which statements we want to + rename. When renaming a subset of the variables, not all + statements will be processed. This is decided in mark_def_sites. */ +#define REWRITE_THIS_STMT(T) TREE_VISITED (T) + +/* Use the unsigned flag to keep track of which statements we want to + visit when marking new definition sites. This is slightly + different than REWRITE_THIS_STMT: it's used by update_ssa to + distinguish statements that need to have both uses and defs + processed from those that only need to have their defs processed. + Statements that define new SSA names only need to have their defs + registered, but they don't need to have their uses renamed. */ +#define REGISTER_DEFS_IN_THIS_STMT(T) (T)->common.unsigned_flag + + +/* Prototypes for debugging functions. */ +extern void dump_tree_ssa (FILE *); +extern void debug_tree_ssa (void); +extern void debug_def_blocks (void); +extern void dump_tree_ssa_stats (FILE *); +extern void debug_tree_ssa_stats (void); +void dump_update_ssa (FILE *); +void debug_update_ssa (void); +void dump_names_replaced_by (FILE *, tree); +void debug_names_replaced_by (tree); + +/* Get the information associated with NAME. */ + +static inline struct ssa_name_info * +get_ssa_name_ann (tree name) +{ + unsigned ver = SSA_NAME_VERSION (name); + unsigned len = VEC_length (ssa_name_info_p, info_for_ssa_name); + struct ssa_name_info *info; + + if (ver >= len) + { + unsigned new_len = num_ssa_names; + + VEC_reserve (ssa_name_info_p, heap, info_for_ssa_name, new_len); + while (len++ < new_len) + { + struct ssa_name_info *info = XCNEW (struct ssa_name_info); + info->age = current_info_for_ssa_name_age; + VEC_quick_push (ssa_name_info_p, info_for_ssa_name, info); + } + } + + info = VEC_index (ssa_name_info_p, info_for_ssa_name, ver); + if (info->age < current_info_for_ssa_name_age) + { + info->need_phi_state = 0; + info->current_def = NULL_TREE; + info->age = current_info_for_ssa_name_age; + } + + return info; +} + +/* Clears info for ssa names. */ + +static void +clear_ssa_name_info (void) +{ + current_info_for_ssa_name_age++; +} + +/* Gets phi_state field for VAR. */ + +static inline enum need_phi_state +get_phi_state (tree var) +{ + if (TREE_CODE (var) == SSA_NAME) + return get_ssa_name_ann (var)->need_phi_state; + else + return var_ann (var)->need_phi_state; +} + + +/* Sets phi_state field for VAR to STATE. */ + +static inline void +set_phi_state (tree var, enum need_phi_state state) +{ + if (TREE_CODE (var) == SSA_NAME) + get_ssa_name_ann (var)->need_phi_state = state; + else + var_ann (var)->need_phi_state = state; +} + + +/* Return the current definition for VAR. */ + +tree +get_current_def (tree var) +{ + if (TREE_CODE (var) == SSA_NAME) + return get_ssa_name_ann (var)->current_def; + else + return var_ann (var)->current_def; +} + + +/* Sets current definition of VAR to DEF. */ + +void +set_current_def (tree var, tree def) +{ + if (TREE_CODE (var) == SSA_NAME) + get_ssa_name_ann (var)->current_def = def; + else + var_ann (var)->current_def = def; +} + + +/* Compute global livein information given the set of blockx where + an object is locally live at the start of the block (LIVEIN) + and the set of blocks where the object is defined (DEF_BLOCKS). + + Note: This routine augments the existing local livein information + to include global livein (i.e., it modifies the underlying bitmap + for LIVEIN). */ + +void +compute_global_livein (bitmap livein, bitmap def_blocks) +{ + basic_block bb, *worklist, *tos; + unsigned i; + bitmap_iterator bi; + + tos = worklist + = (basic_block *) xmalloc (sizeof (basic_block) * (last_basic_block + 1)); + + EXECUTE_IF_SET_IN_BITMAP (livein, 0, i, bi) + { + *tos++ = BASIC_BLOCK (i); + } + + /* Iterate until the worklist is empty. */ + while (tos != worklist) + { + edge e; + edge_iterator ei; + + /* Pull a block off the worklist. */ + bb = *--tos; + + /* For each predecessor block. */ + FOR_EACH_EDGE (e, ei, bb->preds) + { + basic_block pred = e->src; + int pred_index = pred->index; + + /* None of this is necessary for the entry block. */ + if (pred != ENTRY_BLOCK_PTR + && ! bitmap_bit_p (livein, pred_index) + && ! bitmap_bit_p (def_blocks, pred_index)) + { + *tos++ = pred; + bitmap_set_bit (livein, pred_index); + } + } + } + + free (worklist); +} + + +/* Cleans up the REWRITE_THIS_STMT and REGISTER_DEFS_IN_THIS_STMT flags for + all statements in basic block BB. */ + +static void +initialize_flags_in_bb (basic_block bb) +{ + tree phi, stmt; + block_stmt_iterator bsi; + + for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) + { + REWRITE_THIS_STMT (phi) = 0; + REGISTER_DEFS_IN_THIS_STMT (phi) = 0; + } + + for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) + { + stmt = bsi_stmt (bsi); + /* We are going to use the operand cache API, such as + SET_USE, SET_DEF, and FOR_EACH_IMM_USE_FAST. The operand + cache for each statement should be up-to-date. */ + gcc_assert (!stmt_modified_p (stmt)); + REWRITE_THIS_STMT (stmt) = 0; + REGISTER_DEFS_IN_THIS_STMT (stmt) = 0; + } +} + +/* Mark block BB as interesting for update_ssa. */ + +static void +mark_block_for_update (basic_block bb) +{ + gcc_assert (blocks_to_update != NULL); + if (bitmap_bit_p (blocks_to_update, bb->index)) + return; + bitmap_set_bit (blocks_to_update, bb->index); + initialize_flags_in_bb (bb); +} + +/* Return the set of blocks where variable VAR is defined and the blocks + where VAR is live on entry (livein). If no entry is found in + DEF_BLOCKS, a new one is created and returned. */ + +static inline struct def_blocks_d * +get_def_blocks_for (tree var) +{ + struct def_blocks_d db, *db_p; + void **slot; + + db.var = var; + slot = htab_find_slot (def_blocks, (void *) &db, INSERT); + if (*slot == NULL) + { + db_p = XNEW (struct def_blocks_d); + db_p->var = var; + db_p->def_blocks = BITMAP_ALLOC (NULL); + db_p->phi_blocks = BITMAP_ALLOC (NULL); + db_p->livein_blocks = BITMAP_ALLOC (NULL); + *slot = (void *) db_p; + } + else + db_p = (struct def_blocks_d *) *slot; + + return db_p; +} + + +/* Mark block BB as the definition site for variable VAR. PHI_P is true if + VAR is defined by a PHI node. */ + +static void +set_def_block (tree var, basic_block bb, bool phi_p) +{ + struct def_blocks_d *db_p; + enum need_phi_state state; + + state = get_phi_state (var); + db_p = get_def_blocks_for (var); + + /* Set the bit corresponding to the block where VAR is defined. */ + bitmap_set_bit (db_p->def_blocks, bb->index); + if (phi_p) + bitmap_set_bit (db_p->phi_blocks, bb->index); + + /* Keep track of whether or not we may need to insert PHI nodes. + + If we are in the UNKNOWN state, then this is the first definition + of VAR. Additionally, we have not seen any uses of VAR yet, so + we do not need a PHI node for this variable at this time (i.e., + transition to NEED_PHI_STATE_NO). + + If we are in any other state, then we either have multiple definitions + of this variable occurring in different blocks or we saw a use of the + variable which was not dominated by the block containing the + definition(s). In this case we may need a PHI node, so enter + state NEED_PHI_STATE_MAYBE. */ + if (state == NEED_PHI_STATE_UNKNOWN) + set_phi_state (var, NEED_PHI_STATE_NO); + else + set_phi_state (var, NEED_PHI_STATE_MAYBE); +} + + +/* Mark block BB as having VAR live at the entry to BB. */ + +static void +set_livein_block (tree var, basic_block bb) +{ + struct def_blocks_d *db_p; + enum need_phi_state state = get_phi_state (var); + + db_p = get_def_blocks_for (var); + + /* Set the bit corresponding to the block where VAR is live in. */ + bitmap_set_bit (db_p->livein_blocks, bb->index); + + /* Keep track of whether or not we may need to insert PHI nodes. + + If we reach here in NEED_PHI_STATE_NO, see if this use is dominated + by the single block containing the definition(s) of this variable. If + it is, then we remain in NEED_PHI_STATE_NO, otherwise we transition to + NEED_PHI_STATE_MAYBE. */ + if (state == NEED_PHI_STATE_NO) + { + int def_block_index = bitmap_first_set_bit (db_p->def_blocks); + + if (def_block_index == -1 + || ! dominated_by_p (CDI_DOMINATORS, bb, + BASIC_BLOCK (def_block_index))) + set_phi_state (var, NEED_PHI_STATE_MAYBE); + } + else + set_phi_state (var, NEED_PHI_STATE_MAYBE); +} + + +/* Return true if symbol SYM is marked for renaming. */ + +static inline bool +symbol_marked_for_renaming (tree sym) +{ + gcc_assert (DECL_P (sym)); + return bitmap_bit_p (syms_to_rename, DECL_UID (sym)); +} + + +/* Return true if NAME is in OLD_SSA_NAMES. */ + +static inline bool +is_old_name (tree name) +{ + unsigned ver = SSA_NAME_VERSION (name); + return ver < new_ssa_names->n_bits && TEST_BIT (old_ssa_names, ver); +} + + +/* Return true if NAME is in NEW_SSA_NAMES. */ + +static inline bool +is_new_name (tree name) +{ + unsigned ver = SSA_NAME_VERSION (name); + return ver < new_ssa_names->n_bits && TEST_BIT (new_ssa_names, ver); +} + + +/* Hashing and equality functions for REPL_TBL. */ + +static hashval_t +repl_map_hash (const void *p) +{ + return htab_hash_pointer ((const void *)((const struct repl_map_d *)p)->name); +} + +static int +repl_map_eq (const void *p1, const void *p2) +{ + return ((const struct repl_map_d *)p1)->name + == ((const struct repl_map_d *)p2)->name; +} + +static void +repl_map_free (void *p) +{ + BITMAP_FREE (((struct repl_map_d *)p)->set); + free (p); +} + + +/* Return the names replaced by NEW (i.e., REPL_TBL[NEW].SET). */ + +static inline bitmap +names_replaced_by (tree new) +{ + struct repl_map_d m; + void **slot; + + m.name = new; + slot = htab_find_slot (repl_tbl, (void *) &m, NO_INSERT); + + /* If N was not registered in the replacement table, return NULL. */ + if (slot == NULL || *slot == NULL) + return NULL; + + return ((struct repl_map_d *) *slot)->set; +} + + +/* Add OLD to REPL_TBL[NEW].SET. */ + +static inline void +add_to_repl_tbl (tree new, tree old) +{ + struct repl_map_d m, *mp; + void **slot; + + m.name = new; + slot = htab_find_slot (repl_tbl, (void *) &m, INSERT); + if (*slot == NULL) + { + mp = XNEW (struct repl_map_d); + mp->name = new; + mp->set = BITMAP_ALLOC (NULL); + *slot = (void *) mp; + } + else + mp = (struct repl_map_d *) *slot; + + bitmap_set_bit (mp->set, SSA_NAME_VERSION (old)); +} + + +/* Add a new mapping NEW -> OLD REPL_TBL. Every entry N_i in REPL_TBL + represents the set of names O_1 ... O_j replaced by N_i. This is + used by update_ssa and its helpers to introduce new SSA names in an + already formed SSA web. */ + +static void +add_new_name_mapping (tree new, tree old) +{ + timevar_push (TV_TREE_SSA_INCREMENTAL); + + /* OLD and NEW must be different SSA names for the same symbol. */ + gcc_assert (new != old && SSA_NAME_VAR (new) == SSA_NAME_VAR (old)); + + /* We may need to grow NEW_SSA_NAMES and OLD_SSA_NAMES because our + caller may have created new names since the set was created. */ + if (new_ssa_names->n_bits <= num_ssa_names - 1) + { + unsigned int new_sz = num_ssa_names + NAME_SETS_GROWTH_FACTOR; + new_ssa_names = sbitmap_resize (new_ssa_names, new_sz, 0); + old_ssa_names = sbitmap_resize (old_ssa_names, new_sz, 0); + } + + /* If this mapping is for virtual names, we will need to update + virtual operands. */ + if (!is_gimple_reg (new)) + { + tree sym; + size_t uid; + + need_to_update_vops_p = true; + + /* Keep counts of virtual mappings and symbols to use in the + virtual mapping heuristic. If we have large numbers of + virtual mappings for a relatively low number of symbols, it + will make more sense to rename the symbols from scratch. + Otherwise, the insertion of PHI nodes for each of the old + names in these mappings will be very slow. */ + sym = SSA_NAME_VAR (new); + uid = DECL_UID (sym); + update_ssa_stats.num_virtual_mappings++; + if (!bitmap_bit_p (update_ssa_stats.virtual_symbols, uid)) + { + bitmap_set_bit (update_ssa_stats.virtual_symbols, uid); + update_ssa_stats.num_virtual_symbols++; + } + } + + /* Update the REPL_TBL table. */ + add_to_repl_tbl (new, old); + + /* If OLD had already been registered as a new name, then all the + names that OLD replaces should also be replaced by NEW. */ + if (is_new_name (old)) + bitmap_ior_into (names_replaced_by (new), names_replaced_by (old)); + + /* Register NEW and OLD in NEW_SSA_NAMES and OLD_SSA_NAMES, + respectively. */ + SET_BIT (new_ssa_names, SSA_NAME_VERSION (new)); + SET_BIT (old_ssa_names, SSA_NAME_VERSION (old)); + + /* Update mapping counter to use in the virtual mapping heuristic. */ + update_ssa_stats.num_total_mappings++; + + timevar_pop (TV_TREE_SSA_INCREMENTAL); +} + + +/* Call back for walk_dominator_tree used to collect definition sites + for every variable in the function. For every statement S in block + BB: + + 1- Variables defined by S in the DEFS of S are marked in the bitmap + WALK_DATA->GLOBAL_DATA->KILLS. + + 2- If S uses a variable VAR and there is no preceding kill of VAR, + then it is marked in the LIVEIN_BLOCKS bitmap associated with VAR. + + This information is used to determine which variables are live + across block boundaries to reduce the number of PHI nodes + we create. */ + +static void +mark_def_sites (struct dom_walk_data *walk_data, + basic_block bb, + block_stmt_iterator bsi) +{ + struct mark_def_sites_global_data *gd = + (struct mark_def_sites_global_data *) walk_data->global_data; + bitmap kills = gd->kills; + tree stmt, def; + use_operand_p use_p; + def_operand_p def_p; + ssa_op_iter iter; + + stmt = bsi_stmt (bsi); + update_stmt_if_modified (stmt); + + gcc_assert (blocks_to_update == NULL); + REGISTER_DEFS_IN_THIS_STMT (stmt) = 0; + REWRITE_THIS_STMT (stmt) = 0; + + /* If a variable is used before being set, then the variable is live + across a block boundary, so mark it live-on-entry to BB. */ + FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, + SSA_OP_USE | SSA_OP_VUSE | SSA_OP_VMUSTKILL) + { + tree sym = USE_FROM_PTR (use_p); + gcc_assert (DECL_P (sym)); + if (!bitmap_bit_p (kills, DECL_UID (sym))) + set_livein_block (sym, bb); + REWRITE_THIS_STMT (stmt) = 1; + } + + /* Note that virtual definitions are irrelevant for computing KILLS + because a V_MAY_DEF does not constitute a killing definition of the + variable. However, the operand of a virtual definitions is a use + of the variable, so it may cause the variable to be considered + live-on-entry. */ + FOR_EACH_SSA_MAYDEF_OPERAND (def_p, use_p, stmt, iter) + { + tree sym = USE_FROM_PTR (use_p); + gcc_assert (DECL_P (sym)); + set_livein_block (sym, bb); + set_def_block (sym, bb, false); + REGISTER_DEFS_IN_THIS_STMT (stmt) = 1; + REWRITE_THIS_STMT (stmt) = 1; + } + + /* Now process the defs and must-defs made by this statement. */ + FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF | SSA_OP_VMUSTDEF) + { + gcc_assert (DECL_P (def)); + set_def_block (def, bb, false); + bitmap_set_bit (kills, DECL_UID (def)); + REGISTER_DEFS_IN_THIS_STMT (stmt) = 1; + } + + /* If we found the statement interesting then also mark the block BB + as interesting. */ + if (REWRITE_THIS_STMT (stmt) || REGISTER_DEFS_IN_THIS_STMT (stmt)) + SET_BIT (gd->interesting_blocks, bb->index); +} + +/* Structure used by prune_unused_phi_nodes to record bounds of the intervals + in the dfs numbering of the dominance tree. */ + +struct dom_dfsnum +{ + /* Basic block whose index this entry corresponds to. */ + unsigned bb_index; + + /* The dfs number of this node. */ + unsigned dfs_num; +}; + +/* Compares two entries of type struct dom_dfsnum by dfs_num field. Callback + for qsort. */ + +static int +cmp_dfsnum (const void *a, const void *b) +{ + const struct dom_dfsnum *da = a; + const struct dom_dfsnum *db = b; + + return (int) da->dfs_num - (int) db->dfs_num; +} + +/* Among the intervals starting at the N points specified in DEFS, find + the one that contains S, and return its bb_index. */ + +static unsigned +find_dfsnum_interval (struct dom_dfsnum *defs, unsigned n, unsigned s) +{ + unsigned f = 0, t = n, m; + + while (t > f + 1) + { + m = (f + t) / 2; + if (defs[m].dfs_num <= s) + f = m; + else + t = m; + } + + return defs[f].bb_index; +} + +/* Clean bits from PHIS for phi nodes whose value cannot be used in USES. + KILLS is a bitmap of blocks where the value is defined before any use. */ + +static void +prune_unused_phi_nodes (bitmap phis, bitmap kills, bitmap uses) +{ + VEC(int, heap) *worklist; + bitmap_iterator bi; + unsigned i, b, p, u, top; + bitmap live_phis; + basic_block def_bb, use_bb; + edge e; + edge_iterator ei; + bitmap to_remove; + struct dom_dfsnum *defs; + unsigned n_defs, adef; + + if (bitmap_empty_p (uses)) + { + bitmap_clear (phis); + return; + } + + /* The phi must dominate a use, or an argument of a live phi. Also, we + do not create any phi nodes in def blocks, unless they are also livein. */ + to_remove = BITMAP_ALLOC (NULL); + bitmap_and_compl (to_remove, kills, uses); + bitmap_and_compl_into (phis, to_remove); + if (bitmap_empty_p (phis)) + { + BITMAP_FREE (to_remove); + return; + } + + /* We want to remove the unnecessary phi nodes, but we do not want to compute + liveness information, as that may be linear in the size of CFG, and if + there are lot of different variables to rewrite, this may lead to quadratic + behavior. + + Instead, we basically emulate standard dce. We put all uses to worklist, + then for each of them find the nearest def that dominates them. If this + def is a phi node, we mark it live, and if it was not live before, we + add the predecessors of its basic block to the worklist. + + To quickly locate the nearest def that dominates use, we use dfs numbering + of the dominance tree (that is already available in order to speed up + queries). For each def, we have the interval given by the dfs number on + entry to and on exit from the corresponding subtree in the dominance tree. + The nearest dominator for a given use is the smallest of these intervals + that contains entry and exit dfs numbers for the basic block with the use. + If we store the bounds for all the uses to an array and sort it, we can + locate the nearest dominating def in logarithmic time by binary search.*/ + bitmap_ior (to_remove, kills, phis); + n_defs = bitmap_count_bits (to_remove); + defs = XNEWVEC (struct dom_dfsnum, 2 * n_defs + 1); + defs[0].bb_index = 1; + defs[0].dfs_num = 0; + adef = 1; + EXECUTE_IF_SET_IN_BITMAP (to_remove, 0, i, bi) + { + def_bb = BASIC_BLOCK (i); + defs[adef].bb_index = i; + defs[adef].dfs_num = bb_dom_dfs_in (CDI_DOMINATORS, def_bb); + defs[adef + 1].bb_index = i; + defs[adef + 1].dfs_num = bb_dom_dfs_out (CDI_DOMINATORS, def_bb); + adef += 2; + } + BITMAP_FREE (to_remove); + gcc_assert (adef == 2 * n_defs + 1); + qsort (defs, adef, sizeof (struct dom_dfsnum), cmp_dfsnum); + gcc_assert (defs[0].bb_index == 1); + + /* Now each DEFS entry contains the number of the basic block to that the + dfs number corresponds. Change them to the number of basic block that + corresponds to the interval following the dfs number. Also, for the + dfs_out numbers, increase the dfs number by one (so that it corresponds + to the start of the following interval, not to the end of the current + one). We use WORKLIST as a stack. */ + worklist = VEC_alloc (int, heap, n_defs + 1); + VEC_quick_push (int, worklist, 1); + top = 1; + n_defs = 1; + for (i = 1; i < adef; i++) + { + b = defs[i].bb_index; + if (b == top) + { + /* This is a closing element. Interval corresponding to the top + of the stack after removing it follows. */ + VEC_pop (int, worklist); + top = VEC_index (int, worklist, VEC_length (int, worklist) - 1); + defs[n_defs].bb_index = top; + defs[n_defs].dfs_num = defs[i].dfs_num + 1; + } + else + { + /* Opening element. Nothing to do, just push it to the stack and move + it to the correct position. */ + defs[n_defs].bb_index = defs[i].bb_index; + defs[n_defs].dfs_num = defs[i].dfs_num; + VEC_quick_push (int, worklist, b); + top = b; + } + + /* If this interval starts at the same point as the previous one, cancel + the previous one. */ + if (defs[n_defs].dfs_num == defs[n_defs - 1].dfs_num) + defs[n_defs - 1].bb_index = defs[n_defs].bb_index; + else + n_defs++; + } + VEC_pop (int, worklist); + gcc_assert (VEC_empty (int, worklist)); + + /* Now process the uses. */ + live_phis = BITMAP_ALLOC (NULL); + EXECUTE_IF_SET_IN_BITMAP (uses, 0, i, bi) + { + VEC_safe_push (int, heap, worklist, i); + } + + while (!VEC_empty (int, worklist)) + { + b = VEC_pop (int, worklist); + if (b == ENTRY_BLOCK) + continue; + + /* If there is a phi node in USE_BB, it is made live. Otherwise, + find the def that dominates the immediate dominator of USE_BB + (the kill in USE_BB does not dominate the use). */ + if (bitmap_bit_p (phis, b)) + p = b; + else + { + use_bb = get_immediate_dominator (CDI_DOMINATORS, BASIC_BLOCK (b)); + p = find_dfsnum_interval (defs, n_defs, + bb_dom_dfs_in (CDI_DOMINATORS, use_bb)); + if (!bitmap_bit_p (phis, p)) + continue; + } + + /* If the phi node is already live, there is nothing to do. */ + if (bitmap_bit_p (live_phis, p)) + continue; + + /* Mark the phi as live, and add the new uses to the worklist. */ + bitmap_set_bit (live_phis, p); + def_bb = BASIC_BLOCK (p); + FOR_EACH_EDGE (e, ei, def_bb->preds) + { + u = e->src->index; + if (bitmap_bit_p (uses, u)) + continue; + + /* In case there is a kill directly in the use block, do not record + the use (this is also necessary for correctness, as we assume that + uses dominated by a def directly in their block have been filtered + out before). */ + if (bitmap_bit_p (kills, u)) + continue; + + bitmap_set_bit (uses, u); + VEC_safe_push (int, heap, worklist, u); + } + } + + VEC_free (int, heap, worklist); + bitmap_copy (phis, live_phis); + BITMAP_FREE (live_phis); + free (defs); +} + +/* Given a set of blocks with variable definitions (DEF_BLOCKS), + return a bitmap with all the blocks in the iterated dominance + frontier of the blocks in DEF_BLOCKS. DFS contains dominance + frontier information as returned by compute_dominance_frontiers. + + The resulting set of blocks are the potential sites where PHI nodes + are needed. The caller is responsible from freeing the memory + allocated for the return value. */ + +static bitmap +find_idf (bitmap def_blocks, bitmap *dfs) +{ + bitmap_iterator bi; + unsigned bb_index; + VEC(int,heap) *work_stack; + bitmap phi_insertion_points; + + work_stack = VEC_alloc (int, heap, n_basic_blocks); + phi_insertion_points = BITMAP_ALLOC (NULL); + + /* Seed the work list with all the blocks in DEF_BLOCKS. */ + EXECUTE_IF_SET_IN_BITMAP (def_blocks, 0, bb_index, bi) + /* We use VEC_quick_push here for speed. This is safe because we + know that the number of definition blocks is no greater than + the number of basic blocks, which is the initial capacity of + WORK_STACK. */ + VEC_quick_push (int, work_stack, bb_index); + + /* Pop a block off the worklist, add every block that appears in + the original block's DF that we have not already processed to + the worklist. Iterate until the worklist is empty. Blocks + which are added to the worklist are potential sites for + PHI nodes. */ + while (VEC_length (int, work_stack) > 0) + { + bb_index = VEC_pop (int, work_stack); + + /* Since the registration of NEW -> OLD name mappings is done + separately from the call to update_ssa, when updating the SSA + form, the basic blocks where new and/or old names are defined + may have disappeared by CFG cleanup calls. In this case, + we may pull a non-existing block from the work stack. */ + gcc_assert (bb_index < (unsigned) last_basic_block); + + EXECUTE_IF_AND_COMPL_IN_BITMAP (dfs[bb_index], phi_insertion_points, + 0, bb_index, bi) + { + /* Use a safe push because if there is a definition of VAR + in every basic block, then WORK_STACK may eventually have + more than N_BASIC_BLOCK entries. */ + VEC_safe_push (int, heap, work_stack, bb_index); + bitmap_set_bit (phi_insertion_points, bb_index); + } + } + + VEC_free (int, heap, work_stack); + + return phi_insertion_points; +} + + +/* Return the set of blocks where variable VAR is defined and the blocks + where VAR is live on entry (livein). Return NULL, if no entry is + found in DEF_BLOCKS. */ + +static inline struct def_blocks_d * +find_def_blocks_for (tree var) +{ + struct def_blocks_d dm; + dm.var = var; + return (struct def_blocks_d *) htab_find (def_blocks, &dm); +} + + +/* Retrieve or create a default definition for symbol SYM. */ + +static inline tree +get_default_def_for (tree sym) +{ + tree ddef = default_def (sym); + + if (ddef == NULL_TREE) + { + ddef = make_ssa_name (sym, build_empty_stmt ()); + set_default_def (sym, ddef); + } + + return ddef; +} + + +/* Marks phi node PHI in basic block BB for rewrite. */ + +static void +mark_phi_for_rewrite (basic_block bb, tree phi) +{ + tree_vec phis; + unsigned i, idx = bb->index; + + if (REWRITE_THIS_STMT (phi)) + return; + REWRITE_THIS_STMT (phi) = 1; + + if (!blocks_with_phis_to_rewrite) + return; + + bitmap_set_bit (blocks_with_phis_to_rewrite, idx); + VEC_reserve (tree_vec, heap, phis_to_rewrite, last_basic_block + 1); + for (i = VEC_length (tree_vec, phis_to_rewrite); i <= idx; i++) + VEC_quick_push (tree_vec, phis_to_rewrite, NULL); + + phis = VEC_index (tree_vec, phis_to_rewrite, idx); + if (!phis) + phis = VEC_alloc (tree, heap, 10); + + VEC_safe_push (tree, heap, phis, phi); + VEC_replace (tree_vec, phis_to_rewrite, idx, phis); +} + +/* Insert PHI nodes for variable VAR using the iterated dominance + frontier given in PHI_INSERTION_POINTS. If UPDATE_P is true, this + function assumes that the caller is incrementally updating the SSA + form, in which case (1) VAR is assumed to be an SSA name, (2) a new + SSA name is created for VAR's symbol, and, (3) all the arguments + for the newly created PHI node are set to VAR. + + PHI_INSERTION_POINTS is updated to reflect nodes that already had a + PHI node for VAR. On exit, only the nodes that received a PHI node + for VAR will be present in PHI_INSERTION_POINTS. */ + +static void +insert_phi_nodes_for (tree var, bitmap phi_insertion_points, bool update_p) +{ + unsigned bb_index; + edge e; + tree phi; + basic_block bb; + bitmap_iterator bi; + struct def_blocks_d *def_map; + + def_map = find_def_blocks_for (var); + gcc_assert (def_map); + + /* Remove the blocks where we already have PHI nodes for VAR. */ + bitmap_and_compl_into (phi_insertion_points, def_map->phi_blocks); + + /* Remove obviously useless phi nodes. */ + prune_unused_phi_nodes (phi_insertion_points, def_map->def_blocks, + def_map->livein_blocks); + + /* And insert the PHI nodes. */ + EXECUTE_IF_SET_IN_BITMAP (phi_insertion_points, 0, bb_index, bi) + { + bb = BASIC_BLOCK (bb_index); + if (update_p) + mark_block_for_update (bb); + + if (update_p && TREE_CODE (var) == SSA_NAME) + { + /* If we are rewriting SSA names, create the LHS of the PHI + node by duplicating VAR. This is useful in the case of + pointers, to also duplicate pointer attributes (alias + information, in particular). */ + edge_iterator ei; + tree new_lhs; + + phi = create_phi_node (var, bb); + new_lhs = duplicate_ssa_name (var, phi); + SET_PHI_RESULT (phi, new_lhs); + add_new_name_mapping (new_lhs, var); + + /* Add VAR to every argument slot of PHI. We need VAR in + every argument so that rewrite_update_phi_arguments knows + which name is this PHI node replacing. If VAR is a + symbol marked for renaming, this is not necessary, the + renamer will use the symbol on the LHS to get its + reaching definition. */ + FOR_EACH_EDGE (e, ei, bb->preds) + add_phi_arg (phi, var, e); + } + else + { + tree sym = DECL_P (var) ? var : SSA_NAME_VAR (var); + phi = create_phi_node (sym, bb); + } + + /* Mark this PHI node as interesting for update_ssa. */ + REGISTER_DEFS_IN_THIS_STMT (phi) = 1; + mark_phi_for_rewrite (bb, phi); + } +} + + +/* Insert PHI nodes at the dominance frontier of blocks with variable + definitions. DFS contains the dominance frontier information for + the flowgraph. PHI nodes will only be inserted at the dominance + frontier of definition blocks for variables whose NEED_PHI_STATE + annotation is marked as ``maybe'' or ``unknown'' (computed by + mark_def_sites). */ + +static void +insert_phi_nodes (bitmap *dfs) +{ + referenced_var_iterator rvi; + tree var; + + timevar_push (TV_TREE_INSERT_PHI_NODES); + + FOR_EACH_REFERENCED_VAR (var, rvi) + { + struct def_blocks_d *def_map; + bitmap idf; + + def_map = find_def_blocks_for (var); + if (def_map == NULL) + continue; + + if (get_phi_state (var) != NEED_PHI_STATE_NO) + { + idf = find_idf (def_map->def_blocks, dfs); + insert_phi_nodes_for (var, idf, false); + BITMAP_FREE (idf); + } + } + + timevar_pop (TV_TREE_INSERT_PHI_NODES); +} + + +/* Register DEF (an SSA_NAME) to be a new definition for its underlying + variable (SSA_NAME_VAR (DEF)) and push VAR's current reaching definition + into the stack pointed to by BLOCK_DEFS_P. */ + +void +register_new_def (tree def, VEC(tree,heap) **block_defs_p) +{ + tree var = SSA_NAME_VAR (def); + tree currdef; + + /* If this variable is set in a single basic block and all uses are + dominated by the set(s) in that single basic block, then there is + no reason to record anything for this variable in the block local + definition stacks. Doing so just wastes time and memory. + + This is the same test to prune the set of variables which may + need PHI nodes. So we just use that information since it's already + computed and available for us to use. */ + if (get_phi_state (var) == NEED_PHI_STATE_NO) + { + set_current_def (var, def); + return; + } + + currdef = get_current_def (var); + + /* Push the current reaching definition into *BLOCK_DEFS_P. This stack is + later used by the dominator tree callbacks to restore the reaching + definitions for all the variables defined in the block after a recursive + visit to all its immediately dominated blocks. If there is no current + reaching definition, then just record the underlying _DECL node. */ + VEC_safe_push (tree, heap, *block_defs_p, currdef ? currdef : var); + + /* Set the current reaching definition for VAR to be DEF. */ + set_current_def (var, def); +} + + +/* Perform a depth-first traversal of the dominator tree looking for + variables to rename. BB is the block where to start searching. + Renaming is a five step process: + + 1- Every definition made by PHI nodes at the start of the blocks is + registered as the current definition for the corresponding variable. + + 2- Every statement in BB is rewritten. USE and VUSE operands are + rewritten with their corresponding reaching definition. DEF and + VDEF targets are registered as new definitions. + + 3- All the PHI nodes in successor blocks of BB are visited. The + argument corresponding to BB is replaced with its current reaching + definition. + + 4- Recursively rewrite every dominator child block of BB. + + 5- Restore (in reverse order) the current reaching definition for every + new definition introduced in this block. This is done so that when + we return from the recursive call, all the current reaching + definitions are restored to the names that were valid in the + dominator parent of BB. */ + +/* SSA Rewriting Step 1. Initialization, create a block local stack + of reaching definitions for new SSA names produced in this block + (BLOCK_DEFS). Register new definitions for every PHI node in the + block. */ + +static void +rewrite_initialize_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED, + basic_block bb) +{ + tree phi; + + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "\n\nRenaming block #%d\n\n", bb->index); + + /* Mark the unwind point for this block. */ + VEC_safe_push (tree, heap, block_defs_stack, NULL_TREE); + + /* Step 1. Register new definitions for every PHI node in the block. + Conceptually, all the PHI nodes are executed in parallel and each PHI + node introduces a new version for the associated variable. */ + for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) + { + tree result = PHI_RESULT (phi); + register_new_def (result, &block_defs_stack); + } +} + + +/* Return the current definition for variable VAR. If none is found, + create a new SSA name to act as the zeroth definition for VAR. If VAR + is call clobbered and there exists a more recent definition of + GLOBAL_VAR, return the definition for GLOBAL_VAR. This means that VAR + has been clobbered by a function call since its last assignment. */ + +static tree +get_reaching_def (tree var) +{ + tree currdef_var, avar; + + /* Lookup the current reaching definition for VAR. */ + currdef_var = get_current_def (var); + + /* If there is no reaching definition for VAR, create and register a + default definition for it (if needed). */ + if (currdef_var == NULL_TREE) + { + avar = DECL_P (var) ? var : SSA_NAME_VAR (var); + currdef_var = get_default_def_for (avar); + set_current_def (var, currdef_var); + } + + /* Return the current reaching definition for VAR, or the default + definition, if we had to create one. */ + return currdef_var; +} + + +/* SSA Rewriting Step 2. Rewrite every variable used in each statement in + the block with its immediate reaching definitions. Update the current + definition of a variable when a new real or virtual definition is found. */ + +static void +rewrite_stmt (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED, + basic_block bb ATTRIBUTE_UNUSED, + block_stmt_iterator si) +{ + tree stmt; + use_operand_p use_p; + def_operand_p def_p; + ssa_op_iter iter; + + stmt = bsi_stmt (si); + + /* If mark_def_sites decided that we don't need to rewrite this + statement, ignore it. */ + gcc_assert (blocks_to_update == NULL); + if (!REWRITE_THIS_STMT (stmt) && !REGISTER_DEFS_IN_THIS_STMT (stmt)) + return; + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Renaming statement "); + print_generic_stmt (dump_file, stmt, TDF_SLIM); + fprintf (dump_file, "\n"); + } + + /* Step 1. Rewrite USES and VUSES in the statement. */ + if (REWRITE_THIS_STMT (stmt)) + FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, + SSA_OP_ALL_USES|SSA_OP_ALL_KILLS) + { + tree var = USE_FROM_PTR (use_p); + gcc_assert (DECL_P (var)); + SET_USE (use_p, get_reaching_def (var)); + } + + /* Step 2. Register the statement's DEF and VDEF operands. */ + if (REGISTER_DEFS_IN_THIS_STMT (stmt)) + FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, iter, SSA_OP_ALL_DEFS) + { + tree var = DEF_FROM_PTR (def_p); + gcc_assert (DECL_P (var)); + SET_DEF (def_p, make_ssa_name (var, stmt)); + register_new_def (DEF_FROM_PTR (def_p), &block_defs_stack); + } +} + + +/* SSA Rewriting Step 3. Visit all the successor blocks of BB looking for + PHI nodes. For every PHI node found, add a new argument containing the + current reaching definition for the variable and the edge through which + that definition is reaching the PHI node. */ + +static void +rewrite_add_phi_arguments (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED, + basic_block bb) +{ + edge e; + edge_iterator ei; + + FOR_EACH_EDGE (e, ei, bb->succs) + { + tree phi; + + for (phi = phi_nodes (e->dest); phi; phi = PHI_CHAIN (phi)) + { + tree currdef; + currdef = get_reaching_def (SSA_NAME_VAR (PHI_RESULT (phi))); + add_phi_arg (phi, currdef, e); + } + } +} + + +/* Called after visiting basic block BB. Restore CURRDEFS to its + original value. */ + +static void +rewrite_finalize_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED, + basic_block bb ATTRIBUTE_UNUSED) +{ + /* Restore CURRDEFS to its original state. */ + while (VEC_length (tree, block_defs_stack) > 0) + { + tree tmp = VEC_pop (tree, block_defs_stack); + tree saved_def, var; + + if (tmp == NULL_TREE) + break; + + /* If we recorded an SSA_NAME, then make the SSA_NAME the current + definition of its underlying variable. If we recorded anything + else, it must have been an _DECL node and its current reaching + definition must have been NULL. */ + if (TREE_CODE (tmp) == SSA_NAME) + { + saved_def = tmp; + var = SSA_NAME_VAR (saved_def); + } + else + { + saved_def = NULL; + var = tmp; + } + + set_current_def (var, saved_def); + } +} + + +/* Dump SSA information to FILE. */ + +void +dump_tree_ssa (FILE *file) +{ + basic_block bb; + const char *funcname + = lang_hooks.decl_printable_name (current_function_decl, 2); + + fprintf (file, "SSA information for %s\n\n", funcname); + + FOR_EACH_BB (bb) + { + dump_bb (bb, file, 0); + fputs (" ", file); + print_generic_stmt (file, phi_nodes (bb), dump_flags); + fputs ("\n\n", file); + } +} + + +/* Dump SSA information to stderr. */ + +void +debug_tree_ssa (void) +{ + dump_tree_ssa (stderr); +} + + +/* Dump statistics for the hash table HTAB. */ + +static void +htab_statistics (FILE *file, htab_t htab) +{ + fprintf (file, "size %ld, %ld elements, %f collision/search ratio\n", + (long) htab_size (htab), + (long) htab_elements (htab), + htab_collisions (htab)); +} + + +/* Dump SSA statistics on FILE. */ + +void +dump_tree_ssa_stats (FILE *file) +{ + fprintf (file, "\nHash table statistics:\n"); + + fprintf (file, " def_blocks: "); + htab_statistics (file, def_blocks); + + fprintf (file, "\n"); +} + + +/* Dump SSA statistics on stderr. */ + +void +debug_tree_ssa_stats (void) +{ + dump_tree_ssa_stats (stderr); +} + + +/* Hashing and equality functions for DEF_BLOCKS. */ + +static hashval_t +def_blocks_hash (const void *p) +{ + return htab_hash_pointer + ((const void *)((const struct def_blocks_d *)p)->var); +} + +static int +def_blocks_eq (const void *p1, const void *p2) +{ + return ((const struct def_blocks_d *)p1)->var + == ((const struct def_blocks_d *)p2)->var; +} + + +/* Free memory allocated by one entry in DEF_BLOCKS. */ + +static void +def_blocks_free (void *p) +{ + struct def_blocks_d *entry = (struct def_blocks_d *) p; + BITMAP_FREE (entry->def_blocks); + BITMAP_FREE (entry->phi_blocks); + BITMAP_FREE (entry->livein_blocks); + free (entry); +} + + +/* Callback for htab_traverse to dump the DEF_BLOCKS hash table. */ + +static int +debug_def_blocks_r (void **slot, void *data ATTRIBUTE_UNUSED) +{ + struct def_blocks_d *db_p = (struct def_blocks_d *) *slot; + + fprintf (stderr, "VAR: "); + print_generic_expr (stderr, db_p->var, dump_flags); + bitmap_print (stderr, db_p->def_blocks, ", DEF_BLOCKS: { ", "}"); + bitmap_print (stderr, db_p->livein_blocks, ", LIVEIN_BLOCKS: { ", "}\n"); + + return 1; +} + + +/* Dump the DEF_BLOCKS hash table on stderr. */ + +void +debug_def_blocks (void) +{ + htab_traverse (def_blocks, debug_def_blocks_r, NULL); +} + + +/* Register NEW_NAME to be the new reaching definition for OLD_NAME. */ + +static inline void +register_new_update_single (tree new_name, tree old_name) +{ + tree currdef = get_current_def (old_name); + + /* Push the current reaching definition into *BLOCK_DEFS_P. + This stack is later used by the dominator tree callbacks to + restore the reaching definitions for all the variables + defined in the block after a recursive visit to all its + immediately dominated blocks. */ + VEC_reserve (tree, heap, block_defs_stack, 2); + VEC_quick_push (tree, block_defs_stack, currdef); + VEC_quick_push (tree, block_defs_stack, old_name); + + /* Set the current reaching definition for OLD_NAME to be + NEW_NAME. */ + set_current_def (old_name, new_name); +} + + +/* Register NEW_NAME to be the new reaching definition for all the + names in OLD_NAMES. Used by the incremental SSA update routines to + replace old SSA names with new ones. */ + +static inline void +register_new_update_set (tree new_name, bitmap old_names) +{ + bitmap_iterator bi; + unsigned i; + + EXECUTE_IF_SET_IN_BITMAP (old_names, 0, i, bi) + register_new_update_single (new_name, ssa_name (i)); +} + + +/* Initialization of block data structures for the incremental SSA + update pass. Create a block local stack of reaching definitions + for new SSA names produced in this block (BLOCK_DEFS). Register + new definitions for every PHI node in the block. */ + +static void +rewrite_update_init_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED, + basic_block bb) +{ + edge e; + edge_iterator ei; + tree phi; + bool is_abnormal_phi; + + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "\n\nRegistering new PHI nodes in block #%d\n\n", + bb->index); + + /* Mark the unwind point for this block. */ + VEC_safe_push (tree, heap, block_defs_stack, NULL_TREE); + + if (!bitmap_bit_p (blocks_to_update, bb->index)) + return; + + /* Mark the LHS if any of the arguments flows through an abnormal + edge. */ + is_abnormal_phi = false; + FOR_EACH_EDGE (e, ei, bb->preds) + if (e->flags & EDGE_ABNORMAL) + { + is_abnormal_phi = true; + break; + } + + /* If any of the PHI nodes is a replacement for a name in + OLD_SSA_NAMES or it's one of the names in NEW_SSA_NAMES, then + register it as a new definition for its corresponding name. Also + register definitions for names whose underlying symbols are + marked for renaming. */ + + for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) + { + tree lhs, lhs_sym; + + if (!REGISTER_DEFS_IN_THIS_STMT (phi)) + continue; + + lhs = PHI_RESULT (phi); + lhs_sym = SSA_NAME_VAR (lhs); + + if (symbol_marked_for_renaming (lhs_sym)) + register_new_update_single (lhs, lhs_sym); + else + { + /* If LHS is a new name, register a new definition for all + the names replaced by LHS. */ + if (is_new_name (lhs)) + register_new_update_set (lhs, names_replaced_by (lhs)); + + /* If LHS is an OLD name, register it as a new definition + for itself. */ + if (is_old_name (lhs)) + register_new_update_single (lhs, lhs); + } + + if (is_abnormal_phi) + SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs) = 1; + } +} + + +/* Called after visiting block BB. Unwind BLOCK_DEFS_STACK to restore + the current reaching definition of every name re-written in BB to + the original reaching definition before visiting BB. This + unwinding must be done in the opposite order to what is done in + register_new_update_set. */ + +static void +rewrite_update_fini_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED, + basic_block bb ATTRIBUTE_UNUSED) +{ + while (VEC_length (tree, block_defs_stack) > 0) + { + tree var = VEC_pop (tree, block_defs_stack); + tree saved_def; + + /* NULL indicates the unwind stop point for this block (see + rewrite_update_init_block). */ + if (var == NULL) + return; + + saved_def = VEC_pop (tree, block_defs_stack); + set_current_def (var, saved_def); + } +} + + +/* If the operand pointed to by USE_P is a name in OLD_SSA_NAMES or + it is a symbol marked for renaming, replace it with USE_P's current + reaching definition. */ + +static inline void +maybe_replace_use (use_operand_p use_p) +{ + tree rdef = NULL_TREE; + tree use = USE_FROM_PTR (use_p); + tree sym = DECL_P (use) ? use : SSA_NAME_VAR (use); + + if (symbol_marked_for_renaming (sym)) + rdef = get_reaching_def (sym); + else if (is_old_name (use)) + rdef = get_reaching_def (use); + + if (rdef && rdef != use) + SET_USE (use_p, rdef); +} + + +/* If the operand pointed to by DEF_P is an SSA name in NEW_SSA_NAMES + or OLD_SSA_NAMES, or if it is a symbol marked for renaming, + register it as the current definition for the names replaced by + DEF_P. */ + +static inline void +maybe_register_def (def_operand_p def_p, tree stmt) +{ + tree def = DEF_FROM_PTR (def_p); + tree sym = DECL_P (def) ? def : SSA_NAME_VAR (def); + + /* If DEF is a naked symbol that needs renaming, create a + new name for it. */ + if (symbol_marked_for_renaming (sym)) + { + if (DECL_P (def)) + { + def = make_ssa_name (def, stmt); + SET_DEF (def_p, def); + } + + register_new_update_single (def, sym); + } + else + { + /* If DEF is a new name, register it as a new definition + for all the names replaced by DEF. */ + if (is_new_name (def)) + register_new_update_set (def, names_replaced_by (def)); + + /* If DEF is an old name, register DEF as a new + definition for itself. */ + if (is_old_name (def)) + register_new_update_single (def, def); + } +} + + +/* Update every variable used in the statement pointed-to by SI. The + statement is assumed to be in SSA form already. Names in + OLD_SSA_NAMES used by SI will be updated to their current reaching + definition. Names in OLD_SSA_NAMES or NEW_SSA_NAMES defined by SI + will be registered as a new definition for their corresponding name + in OLD_SSA_NAMES. */ + +static void +rewrite_update_stmt (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED, + basic_block bb ATTRIBUTE_UNUSED, + block_stmt_iterator si) +{ + stmt_ann_t ann; + tree stmt; + use_operand_p use_p; + def_operand_p def_p; + ssa_op_iter iter; + + stmt = bsi_stmt (si); + ann = stmt_ann (stmt); + + gcc_assert (bitmap_bit_p (blocks_to_update, bb->index)); + + /* Only update marked statements. */ + if (!REWRITE_THIS_STMT (stmt) && !REGISTER_DEFS_IN_THIS_STMT (stmt)) + return; + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Updating SSA information for statement "); + print_generic_stmt (dump_file, stmt, TDF_SLIM); + fprintf (dump_file, "\n"); + } + + /* Rewrite USES included in OLD_SSA_NAMES and USES whose underlying + symbol is marked for renaming. */ + if (REWRITE_THIS_STMT (stmt)) + { + FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE) + maybe_replace_use (use_p); + + if (need_to_update_vops_p) + FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, + SSA_OP_VIRTUAL_USES | SSA_OP_VIRTUAL_KILLS) + maybe_replace_use (use_p); + } + + /* Register definitions of names in NEW_SSA_NAMES and OLD_SSA_NAMES. + Also register definitions for names whose underlying symbol is + marked for renaming. */ + if (REGISTER_DEFS_IN_THIS_STMT (stmt)) + { + FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, iter, SSA_OP_DEF) + maybe_register_def (def_p, stmt); + + if (need_to_update_vops_p) + FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, iter, SSA_OP_VIRTUAL_DEFS) + maybe_register_def (def_p, stmt); + } +} + + +/* Replace the operand pointed to by USE_P with USE's current reaching + definition. */ + +static inline void +replace_use (use_operand_p use_p, tree use) +{ + tree rdef = get_reaching_def (use); + if (rdef != use) + SET_USE (use_p, rdef); +} + + +/* Visit all the successor blocks of BB looking for PHI nodes. For + every PHI node found, check if any of its arguments is in + OLD_SSA_NAMES. If so, and if the argument has a current reaching + definition, replace it. */ + +static void +rewrite_update_phi_arguments (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED, + basic_block bb) +{ + edge e; + edge_iterator ei; + unsigned i; + + FOR_EACH_EDGE (e, ei, bb->succs) + { + tree phi; + tree_vec phis; + + if (!bitmap_bit_p (blocks_with_phis_to_rewrite, e->dest->index)) + continue; + + phis = VEC_index (tree_vec, phis_to_rewrite, e->dest->index); + for (i = 0; VEC_iterate (tree, phis, i, phi); i++) + { + tree arg; + use_operand_p arg_p; + + gcc_assert (REWRITE_THIS_STMT (phi)); + + arg_p = PHI_ARG_DEF_PTR_FROM_EDGE (phi, e); + arg = USE_FROM_PTR (arg_p); + + if (arg && !DECL_P (arg) && TREE_CODE (arg) != SSA_NAME) + continue; + + if (arg == NULL_TREE) + { + /* When updating a PHI node for a recently introduced + symbol we may find NULL arguments. That's why we + take the symbol from the LHS of the PHI node. */ + replace_use (arg_p, SSA_NAME_VAR (PHI_RESULT (phi))); + } + else + { + tree sym = DECL_P (arg) ? arg : SSA_NAME_VAR (arg); + + if (symbol_marked_for_renaming (sym)) + replace_use (arg_p, sym); + else if (is_old_name (arg)) + replace_use (arg_p, arg); + } + + if (e->flags & EDGE_ABNORMAL) + SSA_NAME_OCCURS_IN_ABNORMAL_PHI (USE_FROM_PTR (arg_p)) = 1; + } + } +} + + +/* Rewrite the actual blocks, statements, and PHI arguments, to be in SSA + form. + + ENTRY indicates the block where to start. Every block dominated by + ENTRY will be rewritten. + + WHAT indicates what actions will be taken by the renamer (see enum + rewrite_mode). + + BLOCKS are the set of interesting blocks for the dominator walker + to process. If this set is NULL, then all the nodes dominated + by ENTRY are walked. Otherwise, blocks dominated by ENTRY that + are not present in BLOCKS are ignored. */ + +static void +rewrite_blocks (basic_block entry, enum rewrite_mode what, sbitmap blocks) +{ + struct dom_walk_data walk_data; + + /* Rewrite all the basic blocks in the program. */ + timevar_push (TV_TREE_SSA_REWRITE_BLOCKS); + + /* Setup callbacks for the generic dominator tree walker. */ + memset (&walk_data, 0, sizeof (walk_data)); + + walk_data.dom_direction = CDI_DOMINATORS; + walk_data.interesting_blocks = blocks; + + if (what == REWRITE_UPDATE) + walk_data.before_dom_children_before_stmts = rewrite_update_init_block; + else + walk_data.before_dom_children_before_stmts = rewrite_initialize_block; + + if (what == REWRITE_ALL) + walk_data.before_dom_children_walk_stmts = rewrite_stmt; + else if (what == REWRITE_UPDATE) + walk_data.before_dom_children_walk_stmts = rewrite_update_stmt; + else + gcc_unreachable (); + + if (what == REWRITE_ALL) + walk_data.before_dom_children_after_stmts = rewrite_add_phi_arguments; + else if (what == REWRITE_UPDATE) + walk_data.before_dom_children_after_stmts = rewrite_update_phi_arguments; + else + gcc_unreachable (); + + if (what == REWRITE_ALL) + walk_data.after_dom_children_after_stmts = rewrite_finalize_block; + else if (what == REWRITE_UPDATE) + walk_data.after_dom_children_after_stmts = rewrite_update_fini_block; + else + gcc_unreachable (); + + block_defs_stack = VEC_alloc (tree, heap, 10); + + /* Initialize the dominator walker. */ + init_walk_dominator_tree (&walk_data); + + /* Recursively walk the dominator tree rewriting each statement in + each basic block. */ + walk_dominator_tree (&walk_data, entry); + + /* Finalize the dominator walker. */ + fini_walk_dominator_tree (&walk_data); + + /* Debugging dumps. */ + if (dump_file && (dump_flags & TDF_STATS)) + { + dump_dfa_stats (dump_file); + if (def_blocks) + dump_tree_ssa_stats (dump_file); + } + + if (def_blocks) + { + htab_delete (def_blocks); + def_blocks = NULL; + } + + VEC_free (tree, heap, block_defs_stack); + + timevar_pop (TV_TREE_SSA_REWRITE_BLOCKS); +} + + +/* Block initialization routine for mark_def_sites. Clear the + KILLS bitmap at the start of each block. */ + +static void +mark_def_sites_initialize_block (struct dom_walk_data *walk_data, + basic_block bb ATTRIBUTE_UNUSED) +{ + struct mark_def_sites_global_data *gd = + (struct mark_def_sites_global_data *) walk_data->global_data; + bitmap kills = gd->kills; + bitmap_clear (kills); +} + + +/* Mark the definition site blocks for each variable, so that we know + where the variable is actually live. + + INTERESTING_BLOCKS will be filled in with all the blocks that + should be processed by the renamer. It is assumed to be + initialized and zeroed by the caller. */ + +static void +mark_def_site_blocks (sbitmap interesting_blocks) +{ + struct dom_walk_data walk_data; + struct mark_def_sites_global_data mark_def_sites_global_data; + referenced_var_iterator rvi; + tree var; + + /* Allocate memory for the DEF_BLOCKS hash table. */ + def_blocks = htab_create (num_referenced_vars, + def_blocks_hash, def_blocks_eq, def_blocks_free); + FOR_EACH_REFERENCED_VAR(var, rvi) + set_current_def (var, NULL_TREE); + + /* Setup callbacks for the generic dominator tree walker to find and + mark definition sites. */ + walk_data.walk_stmts_backward = false; + walk_data.dom_direction = CDI_DOMINATORS; + walk_data.initialize_block_local_data = NULL; + walk_data.before_dom_children_before_stmts = mark_def_sites_initialize_block; + walk_data.before_dom_children_walk_stmts = mark_def_sites; + walk_data.before_dom_children_after_stmts = NULL; + walk_data.after_dom_children_before_stmts = NULL; + walk_data.after_dom_children_walk_stmts = NULL; + walk_data.after_dom_children_after_stmts = NULL; + walk_data.interesting_blocks = NULL; + + /* Notice that this bitmap is indexed using variable UIDs, so it must be + large enough to accommodate all the variables referenced in the + function, not just the ones we are renaming. */ + mark_def_sites_global_data.kills = BITMAP_ALLOC (NULL); + + /* Create the set of interesting blocks that will be filled by + mark_def_sites. */ + mark_def_sites_global_data.interesting_blocks = interesting_blocks; + walk_data.global_data = &mark_def_sites_global_data; + + /* We do not have any local data. */ + walk_data.block_local_data_size = 0; + + /* Initialize the dominator walker. */ + init_walk_dominator_tree (&walk_data); + + /* Recursively walk the dominator tree. */ + walk_dominator_tree (&walk_data, ENTRY_BLOCK_PTR); + + /* Finalize the dominator walker. */ + fini_walk_dominator_tree (&walk_data); + + /* We no longer need this bitmap, clear and free it. */ + BITMAP_FREE (mark_def_sites_global_data.kills); +} + + +/* Main entry point into the SSA builder. The renaming process + proceeds in four main phases: + + 1- Compute dominance frontier and immediate dominators, needed to + insert PHI nodes and rename the function in dominator tree + order. + + 2- Find and mark all the blocks that define variables + (mark_def_site_blocks). + + 3- Insert PHI nodes at dominance frontiers (insert_phi_nodes). + + 4- Rename all the blocks (rewrite_blocks) and statements in the program. + + Steps 3 and 4 are done using the dominator tree walker + (walk_dominator_tree). */ + +static unsigned int +rewrite_into_ssa (void) +{ + bitmap *dfs; + basic_block bb; + sbitmap interesting_blocks; + + timevar_push (TV_TREE_SSA_OTHER); + + /* Initialize operand data structures. */ + init_ssa_operands (); + + /* Initialize the set of interesting blocks. The callback + mark_def_sites will add to this set those blocks that the renamer + should process. */ + interesting_blocks = sbitmap_alloc (last_basic_block); + sbitmap_zero (interesting_blocks); + + /* Initialize dominance frontier. */ + dfs = (bitmap *) xmalloc (last_basic_block * sizeof (bitmap)); + FOR_EACH_BB (bb) + dfs[bb->index] = BITMAP_ALLOC (NULL); + + /* 1- Compute dominance frontiers. */ + calculate_dominance_info (CDI_DOMINATORS); + compute_dominance_frontiers (dfs); + + /* 2- Find and mark definition sites. */ + mark_def_site_blocks (interesting_blocks); + + /* 3- Insert PHI nodes at dominance frontiers of definition blocks. */ + insert_phi_nodes (dfs); + + /* 4- Rename all the blocks. */ + rewrite_blocks (ENTRY_BLOCK_PTR, REWRITE_ALL, interesting_blocks); + + /* Free allocated memory. */ + FOR_EACH_BB (bb) + BITMAP_FREE (dfs[bb->index]); + free (dfs); + sbitmap_free (interesting_blocks); + + timevar_pop (TV_TREE_SSA_OTHER); + in_ssa_p = true; + return 0; +} + + +struct tree_opt_pass pass_build_ssa = +{ + "ssa", /* name */ + NULL, /* gate */ + rewrite_into_ssa, /* execute */ + NULL, /* sub */ + NULL, /* next */ + 0, /* static_pass_number */ + 0, /* tv_id */ + PROP_cfg | PROP_referenced_vars, /* properties_required */ + PROP_ssa, /* properties_provided */ + 0, /* properties_destroyed */ + 0, /* todo_flags_start */ + TODO_dump_func + | TODO_verify_ssa + | TODO_remove_unused_locals, /* todo_flags_finish */ + 0 /* letter */ +}; + + +/* Mark the definition of VAR at STMT and BB as interesting for the + renamer. BLOCKS is the set of blocks that need updating. */ + +static void +mark_def_interesting (tree var, tree stmt, basic_block bb, bool insert_phi_p) +{ + gcc_assert (bitmap_bit_p (blocks_to_update, bb->index)); + REGISTER_DEFS_IN_THIS_STMT (stmt) = 1; + + if (insert_phi_p) + { + bool is_phi_p = TREE_CODE (stmt) == PHI_NODE; + + set_def_block (var, bb, is_phi_p); + + /* If VAR is an SSA name in NEW_SSA_NAMES, this is a definition + site for both itself and all the old names replaced by it. */ + if (TREE_CODE (var) == SSA_NAME && is_new_name (var)) + { + bitmap_iterator bi; + unsigned i; + bitmap set = names_replaced_by (var); + if (set) + EXECUTE_IF_SET_IN_BITMAP (set, 0, i, bi) + set_def_block (ssa_name (i), bb, is_phi_p); + } + } +} + + +/* Mark the use of VAR at STMT and BB as interesting for the + renamer. INSERT_PHI_P is true if we are going to insert new PHI + nodes. */ + +static inline void +mark_use_interesting (tree var, tree stmt, basic_block bb, bool insert_phi_p) +{ + basic_block def_bb = bb_for_stmt (stmt); + + mark_block_for_update (def_bb); + mark_block_for_update (bb); + + if (TREE_CODE (stmt) == PHI_NODE) + mark_phi_for_rewrite (def_bb, stmt); + else + REWRITE_THIS_STMT (stmt) = 1; + + /* If VAR has not been defined in BB, then it is live-on-entry + to BB. Note that we cannot just use the block holding VAR's + definition because if VAR is one of the names in OLD_SSA_NAMES, + it will have several definitions (itself and all the names that + replace it). */ + if (insert_phi_p) + { + struct def_blocks_d *db_p = get_def_blocks_for (var); + if (!bitmap_bit_p (db_p->def_blocks, bb->index)) + set_livein_block (var, bb); + } +} + + +/* Do a dominator walk starting at BB processing statements that + reference symbols in SYMS_TO_RENAME. This is very similar to + mark_def_sites, but the scan handles statements whose operands may + already be SSA names. + + If INSERT_PHI_P is true, mark those uses as live in the + corresponding block. This is later used by the PHI placement + algorithm to make PHI pruning decisions. */ + +static void +prepare_block_for_update (basic_block bb, bool insert_phi_p) +{ + basic_block son; + block_stmt_iterator si; + tree phi; + edge e; + edge_iterator ei; + + mark_block_for_update (bb); + + /* Process PHI nodes marking interesting those that define or use + the symbols that we are interested in. */ + for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) + { + tree lhs_sym, lhs = PHI_RESULT (phi); + + lhs_sym = DECL_P (lhs) ? lhs : SSA_NAME_VAR (lhs); + + if (!symbol_marked_for_renaming (lhs_sym)) + continue; + mark_def_interesting (lhs_sym, phi, bb, insert_phi_p); + + /* Mark the uses in phi nodes as interesting. It would be more correct + to process the arguments of the phi nodes of the successor edges of + BB at the end of prepare_block_for_update, however, that turns out + to be significantly more expensive. Doing it here is conservatively + correct -- it may only cause us to believe a value to be live in a + block that also contains its definition, and thus insert a few more + phi nodes for it. */ + FOR_EACH_EDGE (e, ei, bb->preds) + { + mark_use_interesting (lhs_sym, phi, e->src, insert_phi_p); + } + } + + /* Process the statements. */ + for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si)) + { + tree stmt; + ssa_op_iter i; + use_operand_p use_p; + def_operand_p def_p; + + stmt = bsi_stmt (si); + + FOR_EACH_SSA_USE_OPERAND (use_p, stmt, i, SSA_OP_USE) + { + tree use = USE_FROM_PTR (use_p); + tree sym = DECL_P (use) ? use : SSA_NAME_VAR (use); + if (symbol_marked_for_renaming (sym)) + mark_use_interesting (use, stmt, bb, insert_phi_p); + } + + FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, i, SSA_OP_DEF) + { + tree def = DEF_FROM_PTR (def_p); + tree sym = DECL_P (def) ? def : SSA_NAME_VAR (def); + + if (symbol_marked_for_renaming (sym)) + mark_def_interesting (def, stmt, bb, insert_phi_p); + } + + FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, i, SSA_OP_VIRTUAL_DEFS) + { + tree def = DEF_FROM_PTR (def_p); + tree sym = DECL_P (def) ? def : SSA_NAME_VAR (def); + + if (symbol_marked_for_renaming (sym)) + { + mark_use_interesting (sym, stmt, bb, insert_phi_p); + mark_def_interesting (sym, stmt, bb, insert_phi_p); + } + } + + FOR_EACH_SSA_USE_OPERAND (use_p, stmt, i, SSA_OP_VUSE) + { + tree use = USE_FROM_PTR (use_p); + tree sym = DECL_P (use) ? use : SSA_NAME_VAR (use); + + if (symbol_marked_for_renaming (sym)) + mark_use_interesting (sym, stmt, bb, insert_phi_p); + } + } + + /* Now visit all the blocks dominated by BB. */ + for (son = first_dom_son (CDI_DOMINATORS, bb); + son; + son = next_dom_son (CDI_DOMINATORS, son)) + prepare_block_for_update (son, insert_phi_p); +} + + +/* Helper for prepare_names_to_update. Mark all the use sites for + NAME as interesting. BLOCKS and INSERT_PHI_P are as in + prepare_names_to_update. */ + +static void +prepare_use_sites_for (tree name, bool insert_phi_p) +{ + use_operand_p use_p; + imm_use_iterator iter; + + FOR_EACH_IMM_USE_FAST (use_p, iter, name) + { + tree stmt = USE_STMT (use_p); + basic_block bb = bb_for_stmt (stmt); + + if (TREE_CODE (stmt) == PHI_NODE) + { + int ix = PHI_ARG_INDEX_FROM_USE (use_p); + edge e = PHI_ARG_EDGE (stmt, ix); + mark_use_interesting (name, stmt, e->src, insert_phi_p); + } + else + { + /* For regular statements, mark this as an interesting use + for NAME. */ + mark_use_interesting (name, stmt, bb, insert_phi_p); + } + } +} + + +/* Helper for prepare_names_to_update. Mark the definition site for + NAME as interesting. BLOCKS and INSERT_PHI_P are as in + prepare_names_to_update. */ + +static void +prepare_def_site_for (tree name, bool insert_phi_p) +{ + tree stmt; + basic_block bb; + + gcc_assert (names_to_release == NULL + || !bitmap_bit_p (names_to_release, SSA_NAME_VERSION (name))); + + stmt = SSA_NAME_DEF_STMT (name); + bb = bb_for_stmt (stmt); + if (bb) + { + gcc_assert (bb->index < last_basic_block); + mark_block_for_update (bb); + mark_def_interesting (name, stmt, bb, insert_phi_p); + } +} + + +/* Mark definition and use sites of names in NEW_SSA_NAMES and + OLD_SSA_NAMES. INSERT_PHI_P is true if the caller wants to insert + PHI nodes for newly created names. */ + +static void +prepare_names_to_update (bool insert_phi_p) +{ + unsigned i = 0; + bitmap_iterator bi; + sbitmap_iterator sbi; + + /* If a name N from NEW_SSA_NAMES is also marked to be released, + remove it from NEW_SSA_NAMES so that we don't try to visit its + defining basic block (which most likely doesn't exist). Notice + that we cannot do the same with names in OLD_SSA_NAMES because we + want to replace existing instances. */ + if (names_to_release) + EXECUTE_IF_SET_IN_BITMAP (names_to_release, 0, i, bi) + RESET_BIT (new_ssa_names, i); + + /* First process names in NEW_SSA_NAMES. Otherwise, uses of old + names may be considered to be live-in on blocks that contain + definitions for their replacements. */ + EXECUTE_IF_SET_IN_SBITMAP (new_ssa_names, 0, i, sbi) + prepare_def_site_for (ssa_name (i), insert_phi_p); + + /* If an old name is in NAMES_TO_RELEASE, we cannot remove it from + OLD_SSA_NAMES, but we have to ignore its definition site. */ + EXECUTE_IF_SET_IN_SBITMAP (old_ssa_names, 0, i, sbi) + { + if (names_to_release == NULL || !bitmap_bit_p (names_to_release, i)) + prepare_def_site_for (ssa_name (i), insert_phi_p); + prepare_use_sites_for (ssa_name (i), insert_phi_p); + } +} + + +/* Dump all the names replaced by NAME to FILE. */ + +void +dump_names_replaced_by (FILE *file, tree name) +{ + unsigned i; + bitmap old_set; + bitmap_iterator bi; + + print_generic_expr (file, name, 0); + fprintf (file, " -> { "); + + old_set = names_replaced_by (name); + EXECUTE_IF_SET_IN_BITMAP (old_set, 0, i, bi) + { + print_generic_expr (file, ssa_name (i), 0); + fprintf (file, " "); + } + + fprintf (file, "}\n"); +} + + +/* Dump all the names replaced by NAME to stderr. */ + +void +debug_names_replaced_by (tree name) +{ + dump_names_replaced_by (stderr, name); +} + + +/* Dump SSA update information to FILE. */ + +void +dump_update_ssa (FILE *file) +{ + unsigned i = 0; + bitmap_iterator bi; + + if (!need_ssa_update_p ()) + return; + + if (new_ssa_names && sbitmap_first_set_bit (new_ssa_names) >= 0) + { + sbitmap_iterator sbi; + + fprintf (file, "\nSSA replacement table\n"); + fprintf (file, "N_i -> { O_1 ... O_j } means that N_i replaces " + "O_1, ..., O_j\n\n"); + + EXECUTE_IF_SET_IN_SBITMAP (new_ssa_names, 0, i, sbi) + dump_names_replaced_by (file, ssa_name (i)); + + fprintf (file, "\n"); + fprintf (file, "Number of virtual NEW -> OLD mappings: %7u\n", + update_ssa_stats.num_virtual_mappings); + fprintf (file, "Number of real NEW -> OLD mappings: %7u\n", + update_ssa_stats.num_total_mappings + - update_ssa_stats.num_virtual_mappings); + fprintf (file, "Number of total NEW -> OLD mappings: %7u\n", + update_ssa_stats.num_total_mappings); + + fprintf (file, "\nNumber of virtual symbols: %u\n", + update_ssa_stats.num_virtual_symbols); + } + + if (syms_to_rename && !bitmap_empty_p (syms_to_rename)) + { + fprintf (file, "\n\nSymbols to be put in SSA form\n\n"); + EXECUTE_IF_SET_IN_BITMAP (syms_to_rename, 0, i, bi) + { + print_generic_expr (file, referenced_var (i), 0); + fprintf (file, " "); + } + } + + if (names_to_release && !bitmap_empty_p (names_to_release)) + { + fprintf (file, "\n\nSSA names to release after updating the SSA web\n\n"); + EXECUTE_IF_SET_IN_BITMAP (names_to_release, 0, i, bi) + { + print_generic_expr (file, ssa_name (i), 0); + fprintf (file, " "); + } + } + + fprintf (file, "\n\n"); +} + + +/* Dump SSA update information to stderr. */ + +void +debug_update_ssa (void) +{ + dump_update_ssa (stderr); +} + + +/* Initialize data structures used for incremental SSA updates. */ + +static void +init_update_ssa (void) +{ + /* Reserve more space than the current number of names. The calls to + add_new_name_mapping are typically done after creating new SSA + names, so we'll need to reallocate these arrays. */ + old_ssa_names = sbitmap_alloc (num_ssa_names + NAME_SETS_GROWTH_FACTOR); + sbitmap_zero (old_ssa_names); + + new_ssa_names = sbitmap_alloc (num_ssa_names + NAME_SETS_GROWTH_FACTOR); + sbitmap_zero (new_ssa_names); + + repl_tbl = htab_create (20, repl_map_hash, repl_map_eq, repl_map_free); + need_to_initialize_update_ssa_p = false; + need_to_update_vops_p = false; + syms_to_rename = BITMAP_ALLOC (NULL); + names_to_release = NULL; + memset (&update_ssa_stats, 0, sizeof (update_ssa_stats)); + update_ssa_stats.virtual_symbols = BITMAP_ALLOC (NULL); +} + + +/* Deallocate data structures used for incremental SSA updates. */ + +void +delete_update_ssa (void) +{ + unsigned i; + bitmap_iterator bi; + + sbitmap_free (old_ssa_names); + old_ssa_names = NULL; + + sbitmap_free (new_ssa_names); + new_ssa_names = NULL; + + htab_delete (repl_tbl); + repl_tbl = NULL; + + need_to_initialize_update_ssa_p = true; + need_to_update_vops_p = false; + BITMAP_FREE (syms_to_rename); + BITMAP_FREE (update_ssa_stats.virtual_symbols); + + if (names_to_release) + { + EXECUTE_IF_SET_IN_BITMAP (names_to_release, 0, i, bi) + release_ssa_name (ssa_name (i)); + BITMAP_FREE (names_to_release); + } + + clear_ssa_name_info (); +} + + +/* Create a new name for OLD_NAME in statement STMT and replace the + operand pointed to by DEF_P with the newly created name. Return + the new name and register the replacement mapping <NEW, OLD> in + update_ssa's tables. */ + +tree +create_new_def_for (tree old_name, tree stmt, def_operand_p def) +{ + tree new_name = duplicate_ssa_name (old_name, stmt); + + SET_DEF (def, new_name); + + if (TREE_CODE (stmt) == PHI_NODE) + { + edge e; + edge_iterator ei; + basic_block bb = bb_for_stmt (stmt); + + /* If needed, mark NEW_NAME as occurring in an abnormal PHI node. */ + FOR_EACH_EDGE (e, ei, bb->preds) + if (e->flags & EDGE_ABNORMAL) + { + SSA_NAME_OCCURS_IN_ABNORMAL_PHI (new_name) = 1; + break; + } + } + + register_new_name_mapping (new_name, old_name); + + /* For the benefit of passes that will be updating the SSA form on + their own, set the current reaching definition of OLD_NAME to be + NEW_NAME. */ + set_current_def (old_name, new_name); + + return new_name; +} + + +/* Register name NEW to be a replacement for name OLD. This function + must be called for every replacement that should be performed by + update_ssa. */ + +void +register_new_name_mapping (tree new, tree old) +{ + if (need_to_initialize_update_ssa_p) + init_update_ssa (); + + add_new_name_mapping (new, old); +} + + +/* Register symbol SYM to be renamed by update_ssa. */ + +void +mark_sym_for_renaming (tree sym) +{ + if (need_to_initialize_update_ssa_p) + init_update_ssa (); + + bitmap_set_bit (syms_to_rename, DECL_UID (sym)); + + if (!is_gimple_reg (sym)) + need_to_update_vops_p = true; +} + + +/* Register all the symbols in SET to be renamed by update_ssa. */ + +void +mark_set_for_renaming (bitmap set) +{ + bitmap_iterator bi; + unsigned i; + + if (bitmap_empty_p (set)) + return; + + if (need_to_initialize_update_ssa_p) + init_update_ssa (); + + bitmap_ior_into (syms_to_rename, set); + + EXECUTE_IF_SET_IN_BITMAP (set, 0, i, bi) + if (!is_gimple_reg (referenced_var (i))) + { + need_to_update_vops_p = true; + break; + } +} + + +/* Return true if there is any work to be done by update_ssa. */ + +bool +need_ssa_update_p (void) +{ + return syms_to_rename || old_ssa_names || new_ssa_names; +} + + +/* Return true if name N has been registered in the replacement table. */ + +bool +name_registered_for_update_p (tree n) +{ + if (!need_ssa_update_p ()) + return false; + + return is_new_name (n) + || is_old_name (n) + || symbol_marked_for_renaming (SSA_NAME_VAR (n)); +} + + +/* Return the set of all the SSA names marked to be replaced. */ + +bitmap +ssa_names_to_replace (void) +{ + unsigned i = 0; + bitmap ret; + sbitmap_iterator sbi; + + ret = BITMAP_ALLOC (NULL); + EXECUTE_IF_SET_IN_SBITMAP (old_ssa_names, 0, i, sbi) + bitmap_set_bit (ret, i); + + return ret; +} + + +/* Mark NAME to be released after update_ssa has finished. */ + +void +release_ssa_name_after_update_ssa (tree name) +{ + gcc_assert (!need_to_initialize_update_ssa_p); + + if (names_to_release == NULL) + names_to_release = BITMAP_ALLOC (NULL); + + bitmap_set_bit (names_to_release, SSA_NAME_VERSION (name)); +} + + +/* Insert new PHI nodes to replace VAR. DFS contains dominance + frontier information. BLOCKS is the set of blocks to be updated. + + This is slightly different than the regular PHI insertion + algorithm. The value of UPDATE_FLAGS controls how PHI nodes for + real names (i.e., GIMPLE registers) are inserted: + + - If UPDATE_FLAGS == TODO_update_ssa, we are only interested in PHI + nodes inside the region affected by the block that defines VAR + and the blocks that define all its replacements. All these + definition blocks are stored in DEF_BLOCKS[VAR]->DEF_BLOCKS. + + First, we compute the entry point to the region (ENTRY). This is + given by the nearest common dominator to all the definition + blocks. When computing the iterated dominance frontier (IDF), any + block not strictly dominated by ENTRY is ignored. + + We then call the standard PHI insertion algorithm with the pruned + IDF. + + - If UPDATE_FLAGS == TODO_update_ssa_full_phi, the IDF for real + names is not pruned. PHI nodes are inserted at every IDF block. */ + +static void +insert_updated_phi_nodes_for (tree var, bitmap *dfs, bitmap blocks, + unsigned update_flags) +{ + basic_block entry; + struct def_blocks_d *db; + bitmap idf, pruned_idf; + bitmap_iterator bi; + unsigned i; + +#if defined ENABLE_CHECKING + if (TREE_CODE (var) == SSA_NAME) + gcc_assert (is_old_name (var)); + else + gcc_assert (symbol_marked_for_renaming (var)); +#endif + + /* Get all the definition sites for VAR. */ + db = find_def_blocks_for (var); + + /* No need to do anything if there were no definitions to VAR. */ + if (db == NULL || bitmap_empty_p (db->def_blocks)) + return; + + /* Compute the initial iterated dominance frontier. */ + idf = find_idf (db->def_blocks, dfs); + pruned_idf = BITMAP_ALLOC (NULL); + + if (TREE_CODE (var) == SSA_NAME) + { + if (update_flags == TODO_update_ssa) + { + /* If doing regular SSA updates for GIMPLE registers, we are + only interested in IDF blocks dominated by the nearest + common dominator of all the definition blocks. */ + entry = nearest_common_dominator_for_set (CDI_DOMINATORS, + db->def_blocks); + + if (entry != ENTRY_BLOCK_PTR) + EXECUTE_IF_SET_IN_BITMAP (idf, 0, i, bi) + if (BASIC_BLOCK (i) != entry + && dominated_by_p (CDI_DOMINATORS, BASIC_BLOCK (i), entry)) + bitmap_set_bit (pruned_idf, i); + } + else + { + /* Otherwise, do not prune the IDF for VAR. */ + gcc_assert (update_flags == TODO_update_ssa_full_phi); + bitmap_copy (pruned_idf, idf); + } + } + else + { + /* Otherwise, VAR is a symbol that needs to be put into SSA form + for the first time, so we need to compute the full IDF for + it. */ + bitmap_copy (pruned_idf, idf); + } + + if (!bitmap_empty_p (pruned_idf)) + { + /* Make sure that PRUNED_IDF blocks and all their feeding blocks + are included in the region to be updated. The feeding blocks + are important to guarantee that the PHI arguments are renamed + properly. */ + bitmap_ior_into (blocks, pruned_idf); + EXECUTE_IF_SET_IN_BITMAP (pruned_idf, 0, i, bi) + { + edge e; + edge_iterator ei; + basic_block bb = BASIC_BLOCK (i); + + FOR_EACH_EDGE (e, ei, bb->preds) + if (e->src->index >= 0) + bitmap_set_bit (blocks, e->src->index); + } + + insert_phi_nodes_for (var, pruned_idf, true); + } + + BITMAP_FREE (pruned_idf); + BITMAP_FREE (idf); +} + + +/* Heuristic to determine whether SSA name mappings for virtual names + should be discarded and their symbols rewritten from scratch. When + there is a large number of mappings for virtual names, the + insertion of PHI nodes for the old names in the mappings takes + considerable more time than if we inserted PHI nodes for the + symbols instead. + + Currently the heuristic takes these stats into account: + + - Number of mappings for virtual SSA names. + - Number of distinct virtual symbols involved in those mappings. + + If the number of virtual mappings is much larger than the number of + virtual symbols, then it will be faster to compute PHI insertion + spots for the symbols. Even if this involves traversing the whole + CFG, which is what happens when symbols are renamed from scratch. */ + +static bool +switch_virtuals_to_full_rewrite_p (void) +{ + if (update_ssa_stats.num_virtual_mappings < (unsigned) MIN_VIRTUAL_MAPPINGS) + return false; + + if (update_ssa_stats.num_virtual_mappings + > (unsigned) VIRTUAL_MAPPINGS_TO_SYMS_RATIO + * update_ssa_stats.num_virtual_symbols) + return true; + + return false; +} + + +/* Remove every virtual mapping and mark all the affected virtual + symbols for renaming. */ + +static void +switch_virtuals_to_full_rewrite (void) +{ + unsigned i = 0; + sbitmap_iterator sbi; + + if (dump_file) + { + fprintf (dump_file, "\nEnabled virtual name mapping heuristic.\n"); + fprintf (dump_file, "\tNumber of virtual mappings: %7u\n", + update_ssa_stats.num_virtual_mappings); + fprintf (dump_file, "\tNumber of unique virtual symbols: %7u\n", + update_ssa_stats.num_virtual_symbols); + fprintf (dump_file, "Updating FUD-chains from top of CFG will be " + "faster than processing\nthe name mappings.\n\n"); + } + + /* Remove all virtual names from NEW_SSA_NAMES and OLD_SSA_NAMES. + Note that it is not really necessary to remove the mappings from + REPL_TBL, that would only waste time. */ + EXECUTE_IF_SET_IN_SBITMAP (new_ssa_names, 0, i, sbi) + if (!is_gimple_reg (ssa_name (i))) + RESET_BIT (new_ssa_names, i); + + EXECUTE_IF_SET_IN_SBITMAP (old_ssa_names, 0, i, sbi) + if (!is_gimple_reg (ssa_name (i))) + RESET_BIT (old_ssa_names, i); + + bitmap_ior_into (syms_to_rename, update_ssa_stats.virtual_symbols); +} + + +/* Given a set of newly created SSA names (NEW_SSA_NAMES) and a set of + existing SSA names (OLD_SSA_NAMES), update the SSA form so that: + + 1- The names in OLD_SSA_NAMES dominated by the definitions of + NEW_SSA_NAMES are all re-written to be reached by the + appropriate definition from NEW_SSA_NAMES. + + 2- If needed, new PHI nodes are added to the iterated dominance + frontier of the blocks where each of NEW_SSA_NAMES are defined. + + The mapping between OLD_SSA_NAMES and NEW_SSA_NAMES is setup by + calling register_new_name_mapping for every pair of names that the + caller wants to replace. + + The caller identifies the new names that have been inserted and the + names that need to be replaced by calling register_new_name_mapping + for every pair <NEW, OLD>. Note that the function assumes that the + new names have already been inserted in the IL. + + For instance, given the following code: + + 1 L0: + 2 x_1 = PHI (0, x_5) + 3 if (x_1 < 10) + 4 if (x_1 > 7) + 5 y_2 = 0 + 6 else + 7 y_3 = x_1 + x_7 + 8 endif + 9 x_5 = x_1 + 1 + 10 goto L0; + 11 endif + + Suppose that we insert new names x_10 and x_11 (lines 4 and 8). + + 1 L0: + 2 x_1 = PHI (0, x_5) + 3 if (x_1 < 10) + 4 x_10 = ... + 5 if (x_1 > 7) + 6 y_2 = 0 + 7 else + 8 x_11 = ... + 9 y_3 = x_1 + x_7 + 10 endif + 11 x_5 = x_1 + 1 + 12 goto L0; + 13 endif + + We want to replace all the uses of x_1 with the new definitions of + x_10 and x_11. Note that the only uses that should be replaced are + those at lines 5, 9 and 11. Also, the use of x_7 at line 9 should + *not* be replaced (this is why we cannot just mark symbol 'x' for + renaming). + + Additionally, we may need to insert a PHI node at line 11 because + that is a merge point for x_10 and x_11. So the use of x_1 at line + 11 will be replaced with the new PHI node. The insertion of PHI + nodes is optional. They are not strictly necessary to preserve the + SSA form, and depending on what the caller inserted, they may not + even be useful for the optimizers. UPDATE_FLAGS controls various + aspects of how update_ssa operates, see the documentation for + TODO_update_ssa*. */ + +void +update_ssa (unsigned update_flags) +{ + basic_block bb, start_bb; + bitmap_iterator bi; + unsigned i = 0; + sbitmap tmp; + bool insert_phi_p; + sbitmap_iterator sbi; + + if (!need_ssa_update_p ()) + return; + + timevar_push (TV_TREE_SSA_INCREMENTAL); + + blocks_with_phis_to_rewrite = BITMAP_ALLOC (NULL); + if (!phis_to_rewrite) + phis_to_rewrite = VEC_alloc (tree_vec, heap, last_basic_block); + blocks_to_update = BITMAP_ALLOC (NULL); + + /* Ensure that the dominance information is up-to-date. */ + calculate_dominance_info (CDI_DOMINATORS); + + /* Only one update flag should be set. */ + gcc_assert (update_flags == TODO_update_ssa + || update_flags == TODO_update_ssa_no_phi + || update_flags == TODO_update_ssa_full_phi + || update_flags == TODO_update_ssa_only_virtuals); + + /* If we only need to update virtuals, remove all the mappings for + real names before proceeding. The caller is responsible for + having dealt with the name mappings before calling update_ssa. */ + if (update_flags == TODO_update_ssa_only_virtuals) + { + sbitmap_zero (old_ssa_names); + sbitmap_zero (new_ssa_names); + htab_empty (repl_tbl); + } + + insert_phi_p = (update_flags != TODO_update_ssa_no_phi); + + if (insert_phi_p) + { + /* If the caller requested PHI nodes to be added, initialize + live-in information data structures (DEF_BLOCKS). */ + + /* For each SSA name N, the DEF_BLOCKS table describes where the + name is defined, which blocks have PHI nodes for N, and which + blocks have uses of N (i.e., N is live-on-entry in those + blocks). */ + def_blocks = htab_create (num_ssa_names, def_blocks_hash, + def_blocks_eq, def_blocks_free); + } + else + { + def_blocks = NULL; + } + + /* Heuristic to avoid massive slow downs when the replacement + mappings include lots of virtual names. */ + if (insert_phi_p && switch_virtuals_to_full_rewrite_p ()) + switch_virtuals_to_full_rewrite (); + + /* If there are names defined in the replacement table, prepare + definition and use sites for all the names in NEW_SSA_NAMES and + OLD_SSA_NAMES. */ + if (sbitmap_first_set_bit (new_ssa_names) >= 0) + { + prepare_names_to_update (insert_phi_p); + + /* If all the names in NEW_SSA_NAMES had been marked for + removal, and there are no symbols to rename, then there's + nothing else to do. */ + if (sbitmap_first_set_bit (new_ssa_names) < 0 + && bitmap_empty_p (syms_to_rename)) + goto done; + } + + /* Next, determine the block at which to start the renaming process. */ + if (!bitmap_empty_p (syms_to_rename)) + { + /* If we have to rename some symbols from scratch, we need to + start the process at the root of the CFG. FIXME, it should + be possible to determine the nearest block that had a + definition for each of the symbols that are marked for + updating. For now this seems more work than it's worth. */ + start_bb = ENTRY_BLOCK_PTR; + + /* Traverse the CFG looking for definitions and uses of symbols + in SYMS_TO_RENAME. Mark interesting blocks and statements + and set local live-in information for the PHI placement + heuristics. */ + prepare_block_for_update (start_bb, insert_phi_p); + } + else + { + /* Otherwise, the entry block to the region is the nearest + common dominator for the blocks in BLOCKS. */ + start_bb = nearest_common_dominator_for_set (CDI_DOMINATORS, + blocks_to_update); + } + + /* If requested, insert PHI nodes at the iterated dominance frontier + of every block, creating new definitions for names in OLD_SSA_NAMES + and for symbols in SYMS_TO_RENAME. */ + if (insert_phi_p) + { + bitmap *dfs; + + /* If the caller requested PHI nodes to be added, compute + dominance frontiers. */ + dfs = XNEWVEC (bitmap, last_basic_block); + FOR_EACH_BB (bb) + dfs[bb->index] = BITMAP_ALLOC (NULL); + compute_dominance_frontiers (dfs); + + if (sbitmap_first_set_bit (old_ssa_names) >= 0) + { + sbitmap_iterator sbi; + + /* insert_update_phi_nodes_for will call add_new_name_mapping + when inserting new PHI nodes, so the set OLD_SSA_NAMES + will grow while we are traversing it (but it will not + gain any new members). Copy OLD_SSA_NAMES to a temporary + for traversal. */ + sbitmap tmp = sbitmap_alloc (old_ssa_names->n_bits); + sbitmap_copy (tmp, old_ssa_names); + EXECUTE_IF_SET_IN_SBITMAP (tmp, 0, i, sbi) + insert_updated_phi_nodes_for (ssa_name (i), dfs, blocks_to_update, + update_flags); + sbitmap_free (tmp); + } + + EXECUTE_IF_SET_IN_BITMAP (syms_to_rename, 0, i, bi) + insert_updated_phi_nodes_for (referenced_var (i), dfs, + blocks_to_update, update_flags); + + FOR_EACH_BB (bb) + BITMAP_FREE (dfs[bb->index]); + free (dfs); + + /* Insertion of PHI nodes may have added blocks to the region. + We need to re-compute START_BB to include the newly added + blocks. */ + if (start_bb != ENTRY_BLOCK_PTR) + start_bb = nearest_common_dominator_for_set (CDI_DOMINATORS, + blocks_to_update); + } + + /* Reset the current definition for name and symbol before renaming + the sub-graph. */ + EXECUTE_IF_SET_IN_SBITMAP (old_ssa_names, 0, i, sbi) + set_current_def (ssa_name (i), NULL_TREE); + + EXECUTE_IF_SET_IN_BITMAP (syms_to_rename, 0, i, bi) + set_current_def (referenced_var (i), NULL_TREE); + + /* Now start the renaming process at START_BB. */ + tmp = sbitmap_alloc (last_basic_block); + sbitmap_zero (tmp); + EXECUTE_IF_SET_IN_BITMAP (blocks_to_update, 0, i, bi) + SET_BIT (tmp, i); + + rewrite_blocks (start_bb, REWRITE_UPDATE, tmp); + + sbitmap_free (tmp); + + /* Debugging dumps. */ + if (dump_file) + { + int c; + unsigned i; + + dump_update_ssa (dump_file); + + fprintf (dump_file, "Incremental SSA update started at block: %d\n\n", + start_bb->index); + + c = 0; + EXECUTE_IF_SET_IN_BITMAP (blocks_to_update, 0, i, bi) + c++; + fprintf (dump_file, "Number of blocks in CFG: %d\n", last_basic_block); + fprintf (dump_file, "Number of blocks to update: %d (%3.0f%%)\n\n", + c, PERCENT (c, last_basic_block)); + + if (dump_flags & TDF_DETAILS) + { + fprintf (dump_file, "Affected blocks: "); + EXECUTE_IF_SET_IN_BITMAP (blocks_to_update, 0, i, bi) + fprintf (dump_file, "%u ", i); + fprintf (dump_file, "\n"); + } + + fprintf (dump_file, "\n\n"); + } + + /* Free allocated memory. */ +done: + EXECUTE_IF_SET_IN_BITMAP (blocks_with_phis_to_rewrite, 0, i, bi) + { + tree_vec phis = VEC_index (tree_vec, phis_to_rewrite, i); + + VEC_free (tree, heap, phis); + VEC_replace (tree_vec, phis_to_rewrite, i, NULL); + } + BITMAP_FREE (blocks_with_phis_to_rewrite); + BITMAP_FREE (blocks_to_update); + delete_update_ssa (); + + timevar_pop (TV_TREE_SSA_INCREMENTAL); +} |
