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Diffstat (limited to 'contrib/gcc/cfgloopmanip.c')
-rw-r--r-- | contrib/gcc/cfgloopmanip.c | 1244 |
1 files changed, 1244 insertions, 0 deletions
diff --git a/contrib/gcc/cfgloopmanip.c b/contrib/gcc/cfgloopmanip.c new file mode 100644 index 0000000..6a877d8 --- /dev/null +++ b/contrib/gcc/cfgloopmanip.c @@ -0,0 +1,1244 @@ +/* Loop manipulation code for GNU compiler. + Copyright (C) 2002, 2003 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, 59 Temple Place - Suite 330, Boston, MA +02111-1307, USA. */ + +#include "config.h" +#include "system.h" +#include "coretypes.h" +#include "tm.h" +#include "rtl.h" +#include "hard-reg-set.h" +#include "basic-block.h" +#include "cfgloop.h" +#include "cfglayout.h" +#include "output.h" + +static struct loop * duplicate_loop (struct loops *, struct loop *, + struct loop *); +static void duplicate_subloops (struct loops *, struct loop *, struct loop *); +static void copy_loops_to (struct loops *, struct loop **, int, + struct loop *); +static void loop_redirect_edge (edge, basic_block); +static bool loop_delete_branch_edge (edge, int); +static void remove_bbs (basic_block *, int); +static bool rpe_enum_p (basic_block, void *); +static int find_path (edge, basic_block **); +static bool alp_enum_p (basic_block, void *); +static void add_loop (struct loops *, struct loop *); +static void fix_loop_placements (struct loops *, struct loop *); +static bool fix_bb_placement (struct loops *, basic_block); +static void fix_bb_placements (struct loops *, basic_block); +static void place_new_loop (struct loops *, struct loop *); +static void scale_loop_frequencies (struct loop *, int, int); +static void scale_bbs_frequencies (basic_block *, int, int, int); +static basic_block create_preheader (struct loop *, int); +static void fix_irreducible_loops (basic_block); + +/* Splits basic block BB after INSN, returns created edge. Updates loops + and dominators. */ +edge +split_loop_bb (basic_block bb, rtx insn) +{ + edge e; + + /* Split the block. */ + e = split_block (bb, insn); + + /* Add dest to loop. */ + add_bb_to_loop (e->dest, e->src->loop_father); + + /* Fix dominators. */ + add_to_dominance_info (CDI_DOMINATORS, e->dest); + redirect_immediate_dominators (CDI_DOMINATORS, e->src, e->dest); + set_immediate_dominator (CDI_DOMINATORS, e->dest, e->src); + + return e; +} + +/* Checks whether basic block BB is dominated by DATA. */ +static bool +rpe_enum_p (basic_block bb, void *data) +{ + return dominated_by_p (CDI_DOMINATORS, bb, data); +} + +/* Remove basic blocks BBS from loop structure and dominance info, + and delete them afterwards. */ +static void +remove_bbs (basic_block *bbs, int nbbs) +{ + int i; + + for (i = 0; i < nbbs; i++) + { + remove_bb_from_loops (bbs[i]); + delete_from_dominance_info (CDI_DOMINATORS, bbs[i]); + delete_block (bbs[i]); + } +} + +/* Find path -- i.e. the basic blocks dominated by edge E and put them + into array BBS, that will be allocated large enough to contain them. + E->dest must have exactly one predecessor for this to work (it is + easy to achieve and we do not put it here because we do not want to + alter anything by this function). The number of basic blocks in the + path is returned. */ +static int +find_path (edge e, basic_block **bbs) +{ + if (e->dest->pred->pred_next) + abort (); + + /* Find bbs in the path. */ + *bbs = xcalloc (n_basic_blocks, sizeof (basic_block)); + return dfs_enumerate_from (e->dest, 0, rpe_enum_p, *bbs, + n_basic_blocks, e->dest); +} + +/* Fix placement of basic block BB inside loop hierarchy stored in LOOPS -- + Let L be a loop to that BB belongs. Then every successor of BB must either + 1) belong to some superloop of loop L, or + 2) be a header of loop K such that K->outer is superloop of L + Returns true if we had to move BB into other loop to enforce this condition, + false if the placement of BB was already correct (provided that placements + of its successors are correct). */ +static bool +fix_bb_placement (struct loops *loops, basic_block bb) +{ + edge e; + struct loop *loop = loops->tree_root, *act; + + for (e = bb->succ; e; e = e->succ_next) + { + if (e->dest == EXIT_BLOCK_PTR) + continue; + + act = e->dest->loop_father; + if (act->header == e->dest) + act = act->outer; + + if (flow_loop_nested_p (loop, act)) + loop = act; + } + + if (loop == bb->loop_father) + return false; + + remove_bb_from_loops (bb); + add_bb_to_loop (bb, loop); + + return true; +} + +/* Fix placements of basic blocks inside loop hierarchy stored in loops; i.e. + enforce condition condition stated in description of fix_bb_placement. We + start from basic block FROM that had some of its successors removed, so that + his placement no longer has to be correct, and iteratively fix placement of + its predecessors that may change if placement of FROM changed. Also fix + placement of subloops of FROM->loop_father, that might also be altered due + to this change; the condition for them is similar, except that instead of + successors we consider edges coming out of the loops. */ +static void +fix_bb_placements (struct loops *loops, basic_block from) +{ + sbitmap in_queue; + basic_block *queue, *qtop, *qbeg, *qend; + struct loop *base_loop; + edge e; + + /* We pass through blocks back-reachable from FROM, testing whether some + of their successors moved to outer loop. It may be necessary to + iterate several times, but it is finite, as we stop unless we move + the basic block up the loop structure. The whole story is a bit + more complicated due to presence of subloops, those are moved using + fix_loop_placement. */ + + base_loop = from->loop_father; + if (base_loop == loops->tree_root) + return; + + in_queue = sbitmap_alloc (last_basic_block); + sbitmap_zero (in_queue); + SET_BIT (in_queue, from->index); + /* Prevent us from going out of the base_loop. */ + SET_BIT (in_queue, base_loop->header->index); + + queue = xmalloc ((base_loop->num_nodes + 1) * sizeof (basic_block)); + qtop = queue + base_loop->num_nodes + 1; + qbeg = queue; + qend = queue + 1; + *qbeg = from; + + while (qbeg != qend) + { + from = *qbeg; + qbeg++; + if (qbeg == qtop) + qbeg = queue; + RESET_BIT (in_queue, from->index); + + if (from->loop_father->header == from) + { + /* Subloop header, maybe move the loop upward. */ + if (!fix_loop_placement (from->loop_father)) + continue; + } + else + { + /* Ordinary basic block. */ + if (!fix_bb_placement (loops, from)) + continue; + } + + /* Something has changed, insert predecessors into queue. */ + for (e = from->pred; e; e = e->pred_next) + { + basic_block pred = e->src; + struct loop *nca; + + if (TEST_BIT (in_queue, pred->index)) + continue; + + /* If it is subloop, then it either was not moved, or + the path up the loop tree from base_loop do not contain + it. */ + nca = find_common_loop (pred->loop_father, base_loop); + if (pred->loop_father != base_loop + && (nca == base_loop + || nca != pred->loop_father)) + pred = pred->loop_father->header; + else if (!flow_loop_nested_p (from->loop_father, pred->loop_father)) + { + /* No point in processing it. */ + continue; + } + + if (TEST_BIT (in_queue, pred->index)) + continue; + + /* Schedule the basic block. */ + *qend = pred; + qend++; + if (qend == qtop) + qend = queue; + SET_BIT (in_queue, pred->index); + } + } + free (in_queue); + free (queue); +} + +/* Basic block from has lost one or more of its predecessors, so it might + mo longer be part irreducible loop. Fix it and proceed recursively + for its successors if needed. */ +static void +fix_irreducible_loops (basic_block from) +{ + basic_block bb; + basic_block *stack; + int stack_top; + sbitmap on_stack; + edge *edges, e; + unsigned n_edges, i; + + if (!(from->flags & BB_IRREDUCIBLE_LOOP)) + return; + + on_stack = sbitmap_alloc (last_basic_block); + sbitmap_zero (on_stack); + SET_BIT (on_stack, from->index); + stack = xmalloc (from->loop_father->num_nodes * sizeof (basic_block)); + stack[0] = from; + stack_top = 1; + + while (stack_top) + { + bb = stack[--stack_top]; + RESET_BIT (on_stack, bb->index); + + for (e = bb->pred; e; e = e->pred_next) + if (e->flags & EDGE_IRREDUCIBLE_LOOP) + break; + if (e) + continue; + + bb->flags &= ~BB_IRREDUCIBLE_LOOP; + if (bb->loop_father->header == bb) + edges = get_loop_exit_edges (bb->loop_father, &n_edges); + else + { + n_edges = 0; + for (e = bb->succ; e; e = e->succ_next) + n_edges++; + edges = xmalloc (n_edges * sizeof (edge)); + n_edges = 0; + for (e = bb->succ; e; e = e->succ_next) + edges[n_edges++] = e; + } + + for (i = 0; i < n_edges; i++) + { + e = edges[i]; + + if (e->flags & EDGE_IRREDUCIBLE_LOOP) + { + if (!flow_bb_inside_loop_p (from->loop_father, e->dest)) + continue; + + e->flags &= ~EDGE_IRREDUCIBLE_LOOP; + if (TEST_BIT (on_stack, e->dest->index)) + continue; + + SET_BIT (on_stack, e->dest->index); + stack[stack_top++] = e->dest; + } + } + free (edges); + } + + free (on_stack); + free (stack); +} + +/* Removes path beginning at edge E, i.e. remove basic blocks dominated by E + and update loop structure stored in LOOPS and dominators. Return true if + we were able to remove the path, false otherwise (and nothing is affected + then). */ +bool +remove_path (struct loops *loops, edge e) +{ + edge ae; + basic_block *rem_bbs, *bord_bbs, *dom_bbs, from, bb; + int i, nrem, n_bord_bbs, n_dom_bbs; + sbitmap seen; + + if (!loop_delete_branch_edge (e, 0)) + return false; + + /* We need to check whether basic blocks are dominated by the edge + e, but we only have basic block dominators. This is easy to + fix -- when e->dest has exactly one predecessor, this corresponds + to blocks dominated by e->dest, if not, split the edge. */ + if (e->dest->pred->pred_next) + e = loop_split_edge_with (e, NULL_RTX)->pred; + + /* It may happen that by removing path we remove one or more loops + we belong to. In this case first unloop the loops, then proceed + normally. We may assume that e->dest is not a header of any loop, + as it now has exactly one predecessor. */ + while (e->src->loop_father->outer + && dominated_by_p (CDI_DOMINATORS, + e->src->loop_father->latch, e->dest)) + unloop (loops, e->src->loop_father); + + /* Identify the path. */ + nrem = find_path (e, &rem_bbs); + + n_bord_bbs = 0; + bord_bbs = xcalloc (n_basic_blocks, sizeof (basic_block)); + seen = sbitmap_alloc (last_basic_block); + sbitmap_zero (seen); + + /* Find "border" hexes -- i.e. those with predecessor in removed path. */ + for (i = 0; i < nrem; i++) + SET_BIT (seen, rem_bbs[i]->index); + for (i = 0; i < nrem; i++) + { + bb = rem_bbs[i]; + for (ae = rem_bbs[i]->succ; ae; ae = ae->succ_next) + if (ae->dest != EXIT_BLOCK_PTR && !TEST_BIT (seen, ae->dest->index)) + { + SET_BIT (seen, ae->dest->index); + bord_bbs[n_bord_bbs++] = ae->dest; + } + } + + /* Remove the path. */ + from = e->src; + if (!loop_delete_branch_edge (e, 1)) + abort (); + dom_bbs = xcalloc (n_basic_blocks, sizeof (basic_block)); + + /* Cancel loops contained in the path. */ + for (i = 0; i < nrem; i++) + if (rem_bbs[i]->loop_father->header == rem_bbs[i]) + cancel_loop_tree (loops, rem_bbs[i]->loop_father); + + remove_bbs (rem_bbs, nrem); + free (rem_bbs); + + /* Find blocks whose dominators may be affected. */ + n_dom_bbs = 0; + sbitmap_zero (seen); + for (i = 0; i < n_bord_bbs; i++) + { + basic_block ldom; + + bb = get_immediate_dominator (CDI_DOMINATORS, bord_bbs[i]); + if (TEST_BIT (seen, bb->index)) + continue; + SET_BIT (seen, bb->index); + + for (ldom = first_dom_son (CDI_DOMINATORS, bb); + ldom; + ldom = next_dom_son (CDI_DOMINATORS, ldom)) + if (!dominated_by_p (CDI_DOMINATORS, from, ldom)) + dom_bbs[n_dom_bbs++] = ldom; + } + + free (seen); + + /* Recount dominators. */ + iterate_fix_dominators (CDI_DOMINATORS, dom_bbs, n_dom_bbs); + free (dom_bbs); + + /* These blocks have lost some predecessor(s), thus their irreducible + status could be changed. */ + for (i = 0; i < n_bord_bbs; i++) + fix_irreducible_loops (bord_bbs[i]); + free (bord_bbs); + + /* Fix placements of basic blocks inside loops and the placement of + loops in the loop tree. */ + fix_bb_placements (loops, from); + fix_loop_placements (loops, from->loop_father); + + return true; +} + +/* Predicate for enumeration in add_loop. */ +static bool +alp_enum_p (basic_block bb, void *alp_header) +{ + return bb != (basic_block) alp_header; +} + +/* Given LOOP structure with filled header and latch, find the body of the + corresponding loop and add it to LOOPS tree. */ +static void +add_loop (struct loops *loops, struct loop *loop) +{ + basic_block *bbs; + int i, n; + + /* Add it to loop structure. */ + place_new_loop (loops, loop); + loop->level = 1; + + /* Find its nodes. */ + bbs = xcalloc (n_basic_blocks, sizeof (basic_block)); + n = dfs_enumerate_from (loop->latch, 1, alp_enum_p, + bbs, n_basic_blocks, loop->header); + + for (i = 0; i < n; i++) + add_bb_to_loop (bbs[i], loop); + add_bb_to_loop (loop->header, loop); + + free (bbs); +} + +/* Multiply all frequencies of basic blocks in array BBS of length NBBS + by NUM/DEN. */ +static void +scale_bbs_frequencies (basic_block *bbs, int nbbs, int num, int den) +{ + int i; + edge e; + + for (i = 0; i < nbbs; i++) + { + bbs[i]->frequency = (bbs[i]->frequency * num) / den; + bbs[i]->count = (bbs[i]->count * num) / den; + for (e = bbs[i]->succ; e; e = e->succ_next) + e->count = (e->count * num) /den; + } +} + +/* Multiply all frequencies in LOOP by NUM/DEN. */ +static void +scale_loop_frequencies (struct loop *loop, int num, int den) +{ + basic_block *bbs; + + bbs = get_loop_body (loop); + scale_bbs_frequencies (bbs, loop->num_nodes, num, den); + free (bbs); +} + +/* Make area between HEADER_EDGE and LATCH_EDGE a loop by connecting + latch to header and update loop tree stored in LOOPS and dominators + accordingly. Everything between them plus LATCH_EDGE destination must + be dominated by HEADER_EDGE destination, and back-reachable from + LATCH_EDGE source. HEADER_EDGE is redirected to basic block SWITCH_BB, + SWITCH_BB->succ to original destination of LATCH_EDGE and + SWITCH_BB->succ->succ_next to original destination of HEADER_EDGE. + Returns newly created loop. */ +struct loop * +loopify (struct loops *loops, edge latch_edge, edge header_edge, basic_block switch_bb) +{ + basic_block succ_bb = latch_edge->dest; + basic_block pred_bb = header_edge->src; + basic_block *dom_bbs, *body; + unsigned n_dom_bbs, i; + sbitmap seen; + struct loop *loop = xcalloc (1, sizeof (struct loop)); + struct loop *outer = succ_bb->loop_father->outer; + int freq, prob, tot_prob; + gcov_type cnt; + edge e; + + loop->header = header_edge->dest; + loop->latch = latch_edge->src; + + freq = EDGE_FREQUENCY (header_edge); + cnt = header_edge->count; + prob = switch_bb->succ->probability; + tot_prob = prob + switch_bb->succ->succ_next->probability; + if (tot_prob == 0) + tot_prob = 1; + + /* Redirect edges. */ + loop_redirect_edge (latch_edge, loop->header); + loop_redirect_edge (header_edge, switch_bb); + loop_redirect_edge (switch_bb->succ->succ_next, loop->header); + loop_redirect_edge (switch_bb->succ, succ_bb); + + /* Update dominators. */ + set_immediate_dominator (CDI_DOMINATORS, switch_bb, pred_bb); + set_immediate_dominator (CDI_DOMINATORS, loop->header, switch_bb); + set_immediate_dominator (CDI_DOMINATORS, succ_bb, switch_bb); + + /* Compute new loop. */ + add_loop (loops, loop); + flow_loop_tree_node_add (outer, loop); + + /* Add switch_bb to appropriate loop. */ + add_bb_to_loop (switch_bb, outer); + + /* Fix frequencies. */ + switch_bb->frequency = freq; + switch_bb->count = cnt; + for (e = switch_bb->succ; e; e = e->succ_next) + e->count = (switch_bb->count * e->probability) / REG_BR_PROB_BASE; + scale_loop_frequencies (loop, prob, tot_prob); + scale_loop_frequencies (succ_bb->loop_father, tot_prob - prob, tot_prob); + + /* Update dominators of blocks outside of LOOP. */ + dom_bbs = xcalloc (n_basic_blocks, sizeof (basic_block)); + n_dom_bbs = 0; + seen = sbitmap_alloc (last_basic_block); + sbitmap_zero (seen); + body = get_loop_body (loop); + + for (i = 0; i < loop->num_nodes; i++) + SET_BIT (seen, body[i]->index); + + for (i = 0; i < loop->num_nodes; i++) + { + basic_block ldom; + + for (ldom = first_dom_son (CDI_DOMINATORS, body[i]); + ldom; + ldom = next_dom_son (CDI_DOMINATORS, ldom)) + if (!TEST_BIT (seen, ldom->index)) + { + SET_BIT (seen, ldom->index); + dom_bbs[n_dom_bbs++] = ldom; + } + } + + iterate_fix_dominators (CDI_DOMINATORS, dom_bbs, n_dom_bbs); + + free (body); + free (seen); + free (dom_bbs); + + return loop; +} + +/* Remove the latch edge of a LOOP and update LOOPS tree to indicate that + the LOOP was removed. After this function, original loop latch will + have no successor, which caller is expected to fix somehow. */ +void +unloop (struct loops *loops, struct loop *loop) +{ + basic_block *body; + struct loop *ploop; + unsigned i, n; + basic_block latch = loop->latch; + edge *edges; + unsigned n_edges; + + /* This is relatively straightforward. The dominators are unchanged, as + loop header dominates loop latch, so the only thing we have to care of + is the placement of loops and basic blocks inside the loop tree. We + move them all to the loop->outer, and then let fix_bb_placements do + its work. */ + + body = get_loop_body (loop); + edges = get_loop_exit_edges (loop, &n_edges); + n = loop->num_nodes; + for (i = 0; i < n; i++) + if (body[i]->loop_father == loop) + { + remove_bb_from_loops (body[i]); + add_bb_to_loop (body[i], loop->outer); + } + free(body); + + while (loop->inner) + { + ploop = loop->inner; + flow_loop_tree_node_remove (ploop); + flow_loop_tree_node_add (loop->outer, ploop); + } + + /* Remove the loop and free its data. */ + flow_loop_tree_node_remove (loop); + loops->parray[loop->num] = NULL; + flow_loop_free (loop); + + remove_edge (latch->succ); + fix_bb_placements (loops, latch); + + /* If the loop was inside an irreducible region, we would have to somehow + update the irreducible marks inside its body. While it is certainly + possible to do, it is a bit complicated and this situation should be + very rare, so we just remark all loops in this case. */ + for (i = 0; i < n_edges; i++) + if (edges[i]->flags & EDGE_IRREDUCIBLE_LOOP) + break; + if (i != n_edges) + mark_irreducible_loops (loops); + free (edges); +} + +/* Fix placement of LOOP inside loop tree, i.e. find the innermost superloop + FATHER of LOOP such that all of the edges coming out of LOOP belong to + FATHER, and set it as outer loop of LOOP. Return 1 if placement of + LOOP changed. */ +int +fix_loop_placement (struct loop *loop) +{ + basic_block *body; + unsigned i; + edge e; + struct loop *father = loop->pred[0], *act; + + body = get_loop_body (loop); + for (i = 0; i < loop->num_nodes; i++) + for (e = body[i]->succ; e; e = e->succ_next) + if (!flow_bb_inside_loop_p (loop, e->dest)) + { + act = find_common_loop (loop, e->dest->loop_father); + if (flow_loop_nested_p (father, act)) + father = act; + } + free (body); + + if (father != loop->outer) + { + for (act = loop->outer; act != father; act = act->outer) + act->num_nodes -= loop->num_nodes; + flow_loop_tree_node_remove (loop); + flow_loop_tree_node_add (father, loop); + return 1; + } + return 0; +} + +/* Fix placement of superloops of LOOP inside loop tree, i.e. ensure that + condition stated in description of fix_loop_placement holds for them. + It is used in case when we removed some edges coming out of LOOP, which + may cause the right placement of LOOP inside loop tree to change. */ +static void +fix_loop_placements (struct loops *loops, struct loop *loop) +{ + struct loop *outer; + + while (loop->outer) + { + outer = loop->outer; + if (!fix_loop_placement (loop)) + break; + + /* Changing the placement of a loop in the loop tree may alter the + validity of condition 2) of the description of fix_bb_placement + for its preheader, because the successor is the header and belongs + to the loop. So call fix_bb_placements to fix up the placement + of the preheader and (possibly) of its predecessors. */ + fix_bb_placements (loops, loop_preheader_edge (loop)->src); + loop = outer; + } +} + +/* Creates place for a new LOOP in LOOPS structure. */ +static void +place_new_loop (struct loops *loops, struct loop *loop) +{ + loops->parray = + xrealloc (loops->parray, (loops->num + 1) * sizeof (struct loop *)); + loops->parray[loops->num] = loop; + + loop->num = loops->num++; +} + +/* Copies copy of LOOP as subloop of TARGET loop, placing newly + created loop into LOOPS structure. */ +static struct loop * +duplicate_loop (struct loops *loops, struct loop *loop, struct loop *target) +{ + struct loop *cloop; + cloop = xcalloc (1, sizeof (struct loop)); + place_new_loop (loops, cloop); + + /* Initialize copied loop. */ + cloop->level = loop->level; + + /* Set it as copy of loop. */ + loop->copy = cloop; + + /* Add it to target. */ + flow_loop_tree_node_add (target, cloop); + + return cloop; +} + +/* Copies structure of subloops of LOOP into TARGET loop, placing + newly created loops into loop tree stored in LOOPS. */ +static void +duplicate_subloops (struct loops *loops, struct loop *loop, struct loop *target) +{ + struct loop *aloop, *cloop; + + for (aloop = loop->inner; aloop; aloop = aloop->next) + { + cloop = duplicate_loop (loops, aloop, target); + duplicate_subloops (loops, aloop, cloop); + } +} + +/* Copies structure of subloops of N loops, stored in array COPIED_LOOPS, + into TARGET loop, placing newly created loops into loop tree LOOPS. */ +static void +copy_loops_to (struct loops *loops, struct loop **copied_loops, int n, struct loop *target) +{ + struct loop *aloop; + int i; + + for (i = 0; i < n; i++) + { + aloop = duplicate_loop (loops, copied_loops[i], target); + duplicate_subloops (loops, copied_loops[i], aloop); + } +} + +/* Redirects edge E to basic block DEST. */ +static void +loop_redirect_edge (edge e, basic_block dest) +{ + if (e->dest == dest) + return; + + redirect_edge_and_branch_force (e, dest); +} + +/* Deletes edge E from a branch if possible. Unless REALLY_DELETE is set, + just test whether it is possible to remove the edge. */ +static bool +loop_delete_branch_edge (edge e, int really_delete) +{ + basic_block src = e->src; + int irr; + edge snd; + + if (src->succ->succ_next) + { + basic_block newdest; + + /* Cannot handle more than two exit edges. */ + if (src->succ->succ_next->succ_next) + return false; + /* And it must be just a simple branch. */ + if (!any_condjump_p (BB_END (src))) + return false; + + snd = e == src->succ ? src->succ->succ_next : src->succ; + newdest = snd->dest; + if (newdest == EXIT_BLOCK_PTR) + return false; + + /* Hopefully the above conditions should suffice. */ + if (!really_delete) + return true; + + /* Redirecting behaves wrongly wrto this flag. */ + irr = snd->flags & EDGE_IRREDUCIBLE_LOOP; + + if (!redirect_edge_and_branch (e, newdest)) + return false; + src->succ->flags &= ~EDGE_IRREDUCIBLE_LOOP; + src->succ->flags |= irr; + + return true; + } + else + { + /* Cannot happen -- we are using this only to remove an edge + from branch. */ + abort (); + } + + return false; /* To avoid warning, cannot get here. */ +} + +/* Check whether LOOP's body can be duplicated. */ +bool +can_duplicate_loop_p (struct loop *loop) +{ + int ret; + basic_block *bbs = get_loop_body (loop); + + ret = can_copy_bbs_p (bbs, loop->num_nodes); + free (bbs); + + return ret; +} + +#define RDIV(X,Y) (((X) + (Y) / 2) / (Y)) + +/* Duplicates body of LOOP to given edge E NDUPL times. Takes care of updating + LOOPS structure and dominators. E's destination must be LOOP header for + this to work, i.e. it must be entry or latch edge of this loop; these are + unique, as the loops must have preheaders for this function to work + correctly (in case E is latch, the function unrolls the loop, if E is entry + edge, it peels the loop). Store edges created by copying ORIG edge from + copies corresponding to set bits in WONT_EXIT bitmap (bit 0 corresponds to + original LOOP body, the other copies are numbered in order given by control + flow through them) into TO_REMOVE array. Returns false if duplication is + impossible. */ +int +duplicate_loop_to_header_edge (struct loop *loop, edge e, struct loops *loops, + unsigned int ndupl, sbitmap wont_exit, + edge orig, edge *to_remove, + unsigned int *n_to_remove, int flags) +{ + struct loop *target, *aloop; + struct loop **orig_loops; + unsigned n_orig_loops; + basic_block header = loop->header, latch = loop->latch; + basic_block *new_bbs, *bbs, *first_active; + basic_block new_bb, bb, first_active_latch = NULL; + edge ae, latch_edge; + edge spec_edges[2], new_spec_edges[2]; +#define SE_LATCH 0 +#define SE_ORIG 1 + unsigned i, j, n; + int is_latch = (latch == e->src); + int scale_act = 0, *scale_step = NULL, scale_main = 0; + int p, freq_in, freq_le, freq_out_orig; + int prob_pass_thru, prob_pass_wont_exit, prob_pass_main; + int add_irreducible_flag; + + if (e->dest != loop->header) + abort (); + if (ndupl <= 0) + abort (); + + if (orig) + { + /* Orig must be edge out of the loop. */ + if (!flow_bb_inside_loop_p (loop, orig->src)) + abort (); + if (flow_bb_inside_loop_p (loop, orig->dest)) + abort (); + } + + bbs = get_loop_body (loop); + + /* Check whether duplication is possible. */ + if (!can_copy_bbs_p (bbs, loop->num_nodes)) + { + free (bbs); + return false; + } + new_bbs = xmalloc (sizeof (basic_block) * loop->num_nodes); + + /* In case we are doing loop peeling and the loop is in the middle of + irreducible region, the peeled copies will be inside it too. */ + add_irreducible_flag = e->flags & EDGE_IRREDUCIBLE_LOOP; + if (is_latch && add_irreducible_flag) + abort (); + + /* Find edge from latch. */ + latch_edge = loop_latch_edge (loop); + + if (flags & DLTHE_FLAG_UPDATE_FREQ) + { + /* Calculate coefficients by that we have to scale frequencies + of duplicated loop bodies. */ + freq_in = header->frequency; + freq_le = EDGE_FREQUENCY (latch_edge); + if (freq_in == 0) + freq_in = 1; + if (freq_in < freq_le) + freq_in = freq_le; + freq_out_orig = orig ? EDGE_FREQUENCY (orig) : freq_in - freq_le; + if (freq_out_orig > freq_in - freq_le) + freq_out_orig = freq_in - freq_le; + prob_pass_thru = RDIV (REG_BR_PROB_BASE * freq_le, freq_in); + prob_pass_wont_exit = + RDIV (REG_BR_PROB_BASE * (freq_le + freq_out_orig), freq_in); + + scale_step = xmalloc (ndupl * sizeof (int)); + + for (i = 1; i <= ndupl; i++) + scale_step[i - 1] = TEST_BIT (wont_exit, i) + ? prob_pass_wont_exit + : prob_pass_thru; + + if (is_latch) + { + prob_pass_main = TEST_BIT (wont_exit, 0) + ? prob_pass_wont_exit + : prob_pass_thru; + p = prob_pass_main; + scale_main = REG_BR_PROB_BASE; + for (i = 0; i < ndupl; i++) + { + scale_main += p; + p = RDIV (p * scale_step[i], REG_BR_PROB_BASE); + } + scale_main = RDIV (REG_BR_PROB_BASE * REG_BR_PROB_BASE, scale_main); + scale_act = RDIV (scale_main * prob_pass_main, REG_BR_PROB_BASE); + } + else + { + scale_main = REG_BR_PROB_BASE; + for (i = 0; i < ndupl; i++) + scale_main = RDIV (scale_main * scale_step[i], REG_BR_PROB_BASE); + scale_act = REG_BR_PROB_BASE - prob_pass_thru; + } + for (i = 0; i < ndupl; i++) + if (scale_step[i] < 0 || scale_step[i] > REG_BR_PROB_BASE) + abort (); + if (scale_main < 0 || scale_main > REG_BR_PROB_BASE + || scale_act < 0 || scale_act > REG_BR_PROB_BASE) + abort (); + } + + /* Loop the new bbs will belong to. */ + target = e->src->loop_father; + + /* Original loops. */ + n_orig_loops = 0; + for (aloop = loop->inner; aloop; aloop = aloop->next) + n_orig_loops++; + orig_loops = xcalloc (n_orig_loops, sizeof (struct loop *)); + for (aloop = loop->inner, i = 0; aloop; aloop = aloop->next, i++) + orig_loops[i] = aloop; + + loop->copy = target; + + n = loop->num_nodes; + + first_active = xmalloc (n * sizeof (basic_block)); + if (is_latch) + { + memcpy (first_active, bbs, n * sizeof (basic_block)); + first_active_latch = latch; + } + + /* Record exit edge in original loop body. */ + if (orig && TEST_BIT (wont_exit, 0)) + to_remove[(*n_to_remove)++] = orig; + + spec_edges[SE_ORIG] = orig; + spec_edges[SE_LATCH] = latch_edge; + + for (j = 0; j < ndupl; j++) + { + /* Copy loops. */ + copy_loops_to (loops, orig_loops, n_orig_loops, target); + + /* Copy bbs. */ + copy_bbs (bbs, n, new_bbs, spec_edges, 2, new_spec_edges, loop); + + /* Note whether the blocks and edges belong to an irreducible loop. */ + if (add_irreducible_flag) + { + for (i = 0; i < n; i++) + new_bbs[i]->rbi->duplicated = 1; + for (i = 0; i < n; i++) + { + new_bb = new_bbs[i]; + if (new_bb->loop_father == target) + new_bb->flags |= BB_IRREDUCIBLE_LOOP; + + for (ae = new_bb->succ; ae; ae = ae->succ_next) + if (ae->dest->rbi->duplicated + && (ae->src->loop_father == target + || ae->dest->loop_father == target)) + ae->flags |= EDGE_IRREDUCIBLE_LOOP; + } + for (i = 0; i < n; i++) + new_bbs[i]->rbi->duplicated = 0; + } + + /* Redirect the special edges. */ + if (is_latch) + { + redirect_edge_and_branch_force (latch_edge, new_bbs[0]); + redirect_edge_and_branch_force (new_spec_edges[SE_LATCH], + loop->header); + set_immediate_dominator (CDI_DOMINATORS, new_bbs[0], latch); + latch = loop->latch = new_bbs[1]; + e = latch_edge = new_spec_edges[SE_LATCH]; + } + else + { + redirect_edge_and_branch_force (new_spec_edges[SE_LATCH], + loop->header); + redirect_edge_and_branch_force (e, new_bbs[0]); + set_immediate_dominator (CDI_DOMINATORS, new_bbs[0], e->src); + e = new_spec_edges[SE_LATCH]; + } + + /* Record exit edge in this copy. */ + if (orig && TEST_BIT (wont_exit, j + 1)) + to_remove[(*n_to_remove)++] = new_spec_edges[SE_ORIG]; + + /* Record the first copy in the control flow order if it is not + the original loop (i.e. in case of peeling). */ + if (!first_active_latch) + { + memcpy (first_active, new_bbs, n * sizeof (basic_block)); + first_active_latch = new_bbs[1]; + } + + /* Set counts and frequencies. */ + if (flags & DLTHE_FLAG_UPDATE_FREQ) + { + scale_bbs_frequencies (new_bbs, n, scale_act, REG_BR_PROB_BASE); + scale_act = RDIV (scale_act * scale_step[j], REG_BR_PROB_BASE); + } + } + free (new_bbs); + free (orig_loops); + + /* Update the original loop. */ + if (!is_latch) + set_immediate_dominator (CDI_DOMINATORS, e->dest, e->src); + if (flags & DLTHE_FLAG_UPDATE_FREQ) + { + scale_bbs_frequencies (bbs, n, scale_main, REG_BR_PROB_BASE); + free (scale_step); + } + + /* Update dominators of outer blocks if affected. */ + for (i = 0; i < n; i++) + { + basic_block dominated, dom_bb, *dom_bbs; + int n_dom_bbs,j; + + bb = bbs[i]; + n_dom_bbs = get_dominated_by (CDI_DOMINATORS, bb, &dom_bbs); + for (j = 0; j < n_dom_bbs; j++) + { + dominated = dom_bbs[j]; + if (flow_bb_inside_loop_p (loop, dominated)) + continue; + dom_bb = nearest_common_dominator ( + CDI_DOMINATORS, first_active[i], first_active_latch); + set_immediate_dominator (CDI_DOMINATORS, dominated, dom_bb); + } + free (dom_bbs); + } + free (first_active); + + free (bbs); + + return true; +} + +/* Creates a pre-header for a LOOP. Returns newly created block. Unless + CP_SIMPLE_PREHEADERS is set in FLAGS, we only force LOOP to have single + entry; otherwise we also force preheader block to have only one successor. + The function also updates dominators stored in DOM. */ +static basic_block +create_preheader (struct loop *loop, int flags) +{ + edge e, fallthru; + basic_block dummy; + basic_block jump, src = 0; + struct loop *cloop, *ploop; + int nentry = 0; + rtx insn; + + cloop = loop->outer; + + for (e = loop->header->pred; e; e = e->pred_next) + { + if (e->src == loop->latch) + continue; + nentry++; + } + if (!nentry) + abort (); + if (nentry == 1) + { + for (e = loop->header->pred; e->src == loop->latch; e = e->pred_next); + if (!(flags & CP_SIMPLE_PREHEADERS) + || !e->src->succ->succ_next) + return NULL; + } + + insn = first_insn_after_basic_block_note (loop->header); + if (insn) + insn = PREV_INSN (insn); + else + insn = get_last_insn (); + if (insn == BB_END (loop->header)) + { + /* Split_block would not split block after its end. */ + emit_note_after (NOTE_INSN_DELETED, insn); + } + fallthru = split_block (loop->header, insn); + dummy = fallthru->src; + loop->header = fallthru->dest; + + /* The header could be a latch of some superloop(s); due to design of + split_block, it would now move to fallthru->dest. */ + for (ploop = loop; ploop; ploop = ploop->outer) + if (ploop->latch == dummy) + ploop->latch = fallthru->dest; + + add_to_dominance_info (CDI_DOMINATORS, fallthru->dest); + + /* Redirect edges. */ + for (e = dummy->pred; e; e = e->pred_next) + { + src = e->src; + if (src == loop->latch) + break; + } + if (!e) + abort (); + + dummy->frequency -= EDGE_FREQUENCY (e); + dummy->count -= e->count; + fallthru->count -= e->count; + jump = redirect_edge_and_branch_force (e, loop->header); + if (jump) + { + add_to_dominance_info (CDI_DOMINATORS, jump); + set_immediate_dominator (CDI_DOMINATORS, jump, src); + add_bb_to_loop (jump, loop); + loop->latch = jump; + } + + /* Update structures. */ + redirect_immediate_dominators (CDI_DOMINATORS, dummy, loop->header); + set_immediate_dominator (CDI_DOMINATORS, loop->header, dummy); + loop->header->loop_father = loop; + add_bb_to_loop (dummy, cloop); + if (rtl_dump_file) + fprintf (rtl_dump_file, "Created preheader block for loop %i\n", + loop->num); + + return dummy; +} + +/* Create preheaders for each loop from loop tree stored in LOOPS; for meaning + of FLAGS see create_preheader. */ +void +create_preheaders (struct loops *loops, int flags) +{ + unsigned i; + for (i = 1; i < loops->num; i++) + create_preheader (loops->parray[i], flags); + loops->state |= LOOPS_HAVE_PREHEADERS; +} + +/* Forces all loop latches of loops from loop tree LOOPS to have only single + successor. */ +void +force_single_succ_latches (struct loops *loops) +{ + unsigned i; + struct loop *loop; + edge e; + + for (i = 1; i < loops->num; i++) + { + loop = loops->parray[i]; + if (loop->latch != loop->header + && !loop->latch->succ->succ_next) + continue; + + for (e = loop->header->pred; e->src != loop->latch; e = e->pred_next) + continue; + + loop_split_edge_with (e, NULL_RTX); + } + loops->state |= LOOPS_HAVE_SIMPLE_LATCHES; +} + +/* A quite stupid function to put INSNS on edge E. They are supposed to form + just one basic block. Jumps in INSNS are not handled, so cfg do not have to + be ok after this function. The created block is placed on correct place + in LOOPS structure and its dominator is set. */ +basic_block +loop_split_edge_with (edge e, rtx insns) +{ + basic_block src, dest, new_bb; + struct loop *loop_c; + edge new_e; + + src = e->src; + dest = e->dest; + + loop_c = find_common_loop (src->loop_father, dest->loop_father); + + /* Create basic block for it. */ + + new_bb = split_edge (e); + add_to_dominance_info (CDI_DOMINATORS, new_bb); + add_bb_to_loop (new_bb, loop_c); + new_bb->flags = insns ? BB_SUPERBLOCK : 0; + + new_e = new_bb->succ; + if (e->flags & EDGE_IRREDUCIBLE_LOOP) + { + new_bb->flags |= BB_IRREDUCIBLE_LOOP; + new_e->flags |= EDGE_IRREDUCIBLE_LOOP; + } + + if (insns) + emit_insn_after (insns, BB_END (new_bb)); + + set_immediate_dominator (CDI_DOMINATORS, new_bb, src); + set_immediate_dominator (CDI_DOMINATORS, dest, + recount_dominator (CDI_DOMINATORS, dest)); + + if (dest->loop_father->latch == src) + dest->loop_father->latch = new_bb; + + return new_bb; +} |