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[/] [openrisc/] [trunk/] [gnu-src/] [gcc-4.5.1/] [gcc/] [cfgloop.c] - Rev 298
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/* Natural loop discovery code for GNU compiler. Copyright (C) 2000, 2001, 2003, 2004, 2005, 2006, 2007, 2008 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 3, 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 COPYING3. If not see <http://www.gnu.org/licenses/>. */ #include "config.h" #include "system.h" #include "coretypes.h" #include "tm.h" #include "rtl.h" #include "hard-reg-set.h" #include "obstack.h" #include "function.h" #include "basic-block.h" #include "toplev.h" #include "cfgloop.h" #include "flags.h" #include "tree.h" #include "tree-flow.h" #include "pointer-set.h" #include "output.h" #include "ggc.h" static void flow_loops_cfg_dump (FILE *); /* Dump loop related CFG information. */ static void flow_loops_cfg_dump (FILE *file) { basic_block bb; if (!file) return; FOR_EACH_BB (bb) { edge succ; edge_iterator ei; fprintf (file, ";; %d succs { ", bb->index); FOR_EACH_EDGE (succ, ei, bb->succs) fprintf (file, "%d ", succ->dest->index); fprintf (file, "}\n"); } } /* Return nonzero if the nodes of LOOP are a subset of OUTER. */ bool flow_loop_nested_p (const struct loop *outer, const struct loop *loop) { unsigned odepth = loop_depth (outer); return (loop_depth (loop) > odepth && VEC_index (loop_p, loop->superloops, odepth) == outer); } /* Returns the loop such that LOOP is nested DEPTH (indexed from zero) loops within LOOP. */ struct loop * superloop_at_depth (struct loop *loop, unsigned depth) { unsigned ldepth = loop_depth (loop); gcc_assert (depth <= ldepth); if (depth == ldepth) return loop; return VEC_index (loop_p, loop->superloops, depth); } /* Returns the list of the latch edges of LOOP. */ static VEC (edge, heap) * get_loop_latch_edges (const struct loop *loop) { edge_iterator ei; edge e; VEC (edge, heap) *ret = NULL; FOR_EACH_EDGE (e, ei, loop->header->preds) { if (dominated_by_p (CDI_DOMINATORS, e->src, loop->header)) VEC_safe_push (edge, heap, ret, e); } return ret; } /* Dump the loop information specified by LOOP to the stream FILE using auxiliary dump callback function LOOP_DUMP_AUX if non null. */ void flow_loop_dump (const struct loop *loop, FILE *file, void (*loop_dump_aux) (const struct loop *, FILE *, int), int verbose) { basic_block *bbs; unsigned i; VEC (edge, heap) *latches; edge e; if (! loop || ! loop->header) return; fprintf (file, ";;\n;; Loop %d\n", loop->num); fprintf (file, ";; header %d, ", loop->header->index); if (loop->latch) fprintf (file, "latch %d\n", loop->latch->index); else { fprintf (file, "multiple latches:"); latches = get_loop_latch_edges (loop); for (i = 0; VEC_iterate (edge, latches, i, e); i++) fprintf (file, " %d", e->src->index); VEC_free (edge, heap, latches); fprintf (file, "\n"); } fprintf (file, ";; depth %d, outer %ld\n", loop_depth (loop), (long) (loop_outer (loop) ? loop_outer (loop)->num : -1)); fprintf (file, ";; nodes:"); bbs = get_loop_body (loop); for (i = 0; i < loop->num_nodes; i++) fprintf (file, " %d", bbs[i]->index); free (bbs); fprintf (file, "\n"); if (loop_dump_aux) loop_dump_aux (loop, file, verbose); } /* Dump the loop information about loops to the stream FILE, using auxiliary dump callback function LOOP_DUMP_AUX if non null. */ void flow_loops_dump (FILE *file, void (*loop_dump_aux) (const struct loop *, FILE *, int), int verbose) { loop_iterator li; struct loop *loop; if (!current_loops || ! file) return; fprintf (file, ";; %d loops found\n", number_of_loops ()); FOR_EACH_LOOP (li, loop, LI_INCLUDE_ROOT) { flow_loop_dump (loop, file, loop_dump_aux, verbose); } if (verbose) flow_loops_cfg_dump (file); } /* Free data allocated for LOOP. */ void flow_loop_free (struct loop *loop) { struct loop_exit *exit, *next; VEC_free (loop_p, gc, loop->superloops); /* Break the list of the loop exit records. They will be freed when the corresponding edge is rescanned or removed, and this avoids accessing the (already released) head of the list stored in the loop structure. */ for (exit = loop->exits->next; exit != loop->exits; exit = next) { next = exit->next; exit->next = exit; exit->prev = exit; } ggc_free (loop->exits); ggc_free (loop); } /* Free all the memory allocated for LOOPS. */ void flow_loops_free (struct loops *loops) { if (loops->larray) { unsigned i; loop_p loop; /* Free the loop descriptors. */ for (i = 0; VEC_iterate (loop_p, loops->larray, i, loop); i++) { if (!loop) continue; flow_loop_free (loop); } VEC_free (loop_p, gc, loops->larray); } } /* Find the nodes contained within the LOOP with header HEADER. Return the number of nodes within the loop. */ int flow_loop_nodes_find (basic_block header, struct loop *loop) { VEC (basic_block, heap) *stack = NULL; int num_nodes = 1; edge latch; edge_iterator latch_ei; unsigned depth = loop_depth (loop); header->loop_father = loop; header->loop_depth = depth; FOR_EACH_EDGE (latch, latch_ei, loop->header->preds) { if (latch->src->loop_father == loop || !dominated_by_p (CDI_DOMINATORS, latch->src, loop->header)) continue; num_nodes++; VEC_safe_push (basic_block, heap, stack, latch->src); latch->src->loop_father = loop; latch->src->loop_depth = depth; while (!VEC_empty (basic_block, stack)) { basic_block node; edge e; edge_iterator ei; node = VEC_pop (basic_block, stack); FOR_EACH_EDGE (e, ei, node->preds) { basic_block ancestor = e->src; if (ancestor->loop_father != loop) { ancestor->loop_father = loop; ancestor->loop_depth = depth; num_nodes++; VEC_safe_push (basic_block, heap, stack, ancestor); } } } } VEC_free (basic_block, heap, stack); return num_nodes; } /* Records the vector of superloops of the loop LOOP, whose immediate superloop is FATHER. */ static void establish_preds (struct loop *loop, struct loop *father) { loop_p ploop; unsigned depth = loop_depth (father) + 1; unsigned i; VEC_truncate (loop_p, loop->superloops, 0); VEC_reserve (loop_p, gc, loop->superloops, depth); for (i = 0; VEC_iterate (loop_p, father->superloops, i, ploop); i++) VEC_quick_push (loop_p, loop->superloops, ploop); VEC_quick_push (loop_p, loop->superloops, father); for (ploop = loop->inner; ploop; ploop = ploop->next) establish_preds (ploop, loop); } /* Add LOOP to the loop hierarchy tree where FATHER is father of the added loop. If LOOP has some children, take care of that their pred field will be initialized correctly. */ void flow_loop_tree_node_add (struct loop *father, struct loop *loop) { loop->next = father->inner; father->inner = loop; establish_preds (loop, father); } /* Remove LOOP from the loop hierarchy tree. */ void flow_loop_tree_node_remove (struct loop *loop) { struct loop *prev, *father; father = loop_outer (loop); /* Remove loop from the list of sons. */ if (father->inner == loop) father->inner = loop->next; else { for (prev = father->inner; prev->next != loop; prev = prev->next) continue; prev->next = loop->next; } VEC_truncate (loop_p, loop->superloops, 0); } /* Allocates and returns new loop structure. */ struct loop * alloc_loop (void) { struct loop *loop = GGC_CNEW (struct loop); loop->exits = GGC_CNEW (struct loop_exit); loop->exits->next = loop->exits->prev = loop->exits; loop->can_be_parallel = false; loop->single_iv = NULL_TREE; return loop; } /* Initializes loops structure LOOPS, reserving place for NUM_LOOPS loops (including the root of the loop tree). */ static void init_loops_structure (struct loops *loops, unsigned num_loops) { struct loop *root; memset (loops, 0, sizeof *loops); loops->larray = VEC_alloc (loop_p, gc, num_loops); /* Dummy loop containing whole function. */ root = alloc_loop (); root->num_nodes = n_basic_blocks; root->latch = EXIT_BLOCK_PTR; root->header = ENTRY_BLOCK_PTR; ENTRY_BLOCK_PTR->loop_father = root; EXIT_BLOCK_PTR->loop_father = root; VEC_quick_push (loop_p, loops->larray, root); loops->tree_root = root; } /* Find all the natural loops in the function and save in LOOPS structure and recalculate loop_depth information in basic block structures. Return the number of natural loops found. */ int flow_loops_find (struct loops *loops) { int b; int num_loops; edge e; sbitmap headers; int *dfs_order; int *rc_order; basic_block header; basic_block bb; /* Ensure that the dominators are computed. */ calculate_dominance_info (CDI_DOMINATORS); /* Taking care of this degenerate case makes the rest of this code simpler. */ if (n_basic_blocks == NUM_FIXED_BLOCKS) { init_loops_structure (loops, 1); return 1; } dfs_order = NULL; rc_order = NULL; /* Count the number of loop headers. This should be the same as the number of natural loops. */ headers = sbitmap_alloc (last_basic_block); sbitmap_zero (headers); num_loops = 0; FOR_EACH_BB (header) { edge_iterator ei; header->loop_depth = 0; /* If we have an abnormal predecessor, do not consider the loop (not worth the problems). */ FOR_EACH_EDGE (e, ei, header->preds) if (e->flags & EDGE_ABNORMAL) break; if (e) continue; FOR_EACH_EDGE (e, ei, header->preds) { basic_block latch = e->src; gcc_assert (!(e->flags & EDGE_ABNORMAL)); /* Look for back edges where a predecessor is dominated by this block. A natural loop has a single entry node (header) that dominates all the nodes in the loop. It also has single back edge to the header from a latch node. */ if (latch != ENTRY_BLOCK_PTR && dominated_by_p (CDI_DOMINATORS, latch, header)) { /* Shared headers should be eliminated by now. */ SET_BIT (headers, header->index); num_loops++; } } } /* Allocate loop structures. */ init_loops_structure (loops, num_loops + 1); /* Find and record information about all the natural loops in the CFG. */ FOR_EACH_BB (bb) bb->loop_father = loops->tree_root; if (num_loops) { /* Compute depth first search order of the CFG so that outer natural loops will be found before inner natural loops. */ dfs_order = XNEWVEC (int, n_basic_blocks); rc_order = XNEWVEC (int, n_basic_blocks); pre_and_rev_post_order_compute (dfs_order, rc_order, false); num_loops = 1; for (b = 0; b < n_basic_blocks - NUM_FIXED_BLOCKS; b++) { struct loop *loop; edge_iterator ei; /* Search the nodes of the CFG in reverse completion order so that we can find outer loops first. */ if (!TEST_BIT (headers, rc_order[b])) continue; header = BASIC_BLOCK (rc_order[b]); loop = alloc_loop (); VEC_quick_push (loop_p, loops->larray, loop); loop->header = header; loop->num = num_loops; num_loops++; flow_loop_tree_node_add (header->loop_father, loop); loop->num_nodes = flow_loop_nodes_find (loop->header, loop); /* Look for the latch for this header block, if it has just a single one. */ FOR_EACH_EDGE (e, ei, header->preds) { basic_block latch = e->src; if (flow_bb_inside_loop_p (loop, latch)) { if (loop->latch != NULL) { /* More than one latch edge. */ loop->latch = NULL; break; } loop->latch = latch; } } } free (dfs_order); free (rc_order); } sbitmap_free (headers); loops->exits = NULL; return VEC_length (loop_p, loops->larray); } /* Ratio of frequencies of edges so that one of more latch edges is considered to belong to inner loop with same header. */ #define HEAVY_EDGE_RATIO 8 /* Minimum number of samples for that we apply find_subloop_latch_edge_by_profile heuristics. */ #define HEAVY_EDGE_MIN_SAMPLES 10 /* If the profile info is available, finds an edge in LATCHES that much more frequent than the remaining edges. Returns such an edge, or NULL if we do not find one. We do not use guessed profile here, only the measured one. The guessed profile is usually too flat and unreliable for this (and it is mostly based on the loop structure of the program, so it does not make much sense to derive the loop structure from it). */ static edge find_subloop_latch_edge_by_profile (VEC (edge, heap) *latches) { unsigned i; edge e, me = NULL; gcov_type mcount = 0, tcount = 0; for (i = 0; VEC_iterate (edge, latches, i, e); i++) { if (e->count > mcount) { me = e; mcount = e->count; } tcount += e->count; } if (tcount < HEAVY_EDGE_MIN_SAMPLES || (tcount - mcount) * HEAVY_EDGE_RATIO > tcount) return NULL; if (dump_file) fprintf (dump_file, "Found latch edge %d -> %d using profile information.\n", me->src->index, me->dest->index); return me; } /* Among LATCHES, guesses a latch edge of LOOP corresponding to subloop, based on the structure of induction variables. Returns this edge, or NULL if we do not find any. We are quite conservative, and look just for an obvious simple innermost loop (which is the case where we would lose the most performance by not disambiguating the loop). More precisely, we look for the following situation: The source of the chosen latch edge dominates sources of all the other latch edges. Additionally, the header does not contain a phi node such that the argument from the chosen edge is equal to the argument from another edge. */ static edge find_subloop_latch_edge_by_ivs (struct loop *loop ATTRIBUTE_UNUSED, VEC (edge, heap) *latches) { edge e, latch = VEC_index (edge, latches, 0); unsigned i; gimple phi; gimple_stmt_iterator psi; tree lop; basic_block bb; /* Find the candidate for the latch edge. */ for (i = 1; VEC_iterate (edge, latches, i, e); i++) if (dominated_by_p (CDI_DOMINATORS, latch->src, e->src)) latch = e; /* Verify that it dominates all the latch edges. */ for (i = 0; VEC_iterate (edge, latches, i, e); i++) if (!dominated_by_p (CDI_DOMINATORS, e->src, latch->src)) return NULL; /* Check for a phi node that would deny that this is a latch edge of a subloop. */ for (psi = gsi_start_phis (loop->header); !gsi_end_p (psi); gsi_next (&psi)) { phi = gsi_stmt (psi); lop = PHI_ARG_DEF_FROM_EDGE (phi, latch); /* Ignore the values that are not changed inside the subloop. */ if (TREE_CODE (lop) != SSA_NAME || SSA_NAME_DEF_STMT (lop) == phi) continue; bb = gimple_bb (SSA_NAME_DEF_STMT (lop)); if (!bb || !flow_bb_inside_loop_p (loop, bb)) continue; for (i = 0; VEC_iterate (edge, latches, i, e); i++) if (e != latch && PHI_ARG_DEF_FROM_EDGE (phi, e) == lop) return NULL; } if (dump_file) fprintf (dump_file, "Found latch edge %d -> %d using iv structure.\n", latch->src->index, latch->dest->index); return latch; } /* If we can determine that one of the several latch edges of LOOP behaves as a latch edge of a separate subloop, returns this edge. Otherwise returns NULL. */ static edge find_subloop_latch_edge (struct loop *loop) { VEC (edge, heap) *latches = get_loop_latch_edges (loop); edge latch = NULL; if (VEC_length (edge, latches) > 1) { latch = find_subloop_latch_edge_by_profile (latches); if (!latch /* We consider ivs to guess the latch edge only in SSA. Perhaps we should use cfghook for this, but it is hard to imagine it would be useful elsewhere. */ && current_ir_type () == IR_GIMPLE) latch = find_subloop_latch_edge_by_ivs (loop, latches); } VEC_free (edge, heap, latches); return latch; } /* Callback for make_forwarder_block. Returns true if the edge E is marked in the set MFB_REIS_SET. */ static struct pointer_set_t *mfb_reis_set; static bool mfb_redirect_edges_in_set (edge e) { return pointer_set_contains (mfb_reis_set, e); } /* Creates a subloop of LOOP with latch edge LATCH. */ static void form_subloop (struct loop *loop, edge latch) { edge_iterator ei; edge e, new_entry; struct loop *new_loop; mfb_reis_set = pointer_set_create (); FOR_EACH_EDGE (e, ei, loop->header->preds) { if (e != latch) pointer_set_insert (mfb_reis_set, e); } new_entry = make_forwarder_block (loop->header, mfb_redirect_edges_in_set, NULL); pointer_set_destroy (mfb_reis_set); loop->header = new_entry->src; /* Find the blocks and subloops that belong to the new loop, and add it to the appropriate place in the loop tree. */ new_loop = alloc_loop (); new_loop->header = new_entry->dest; new_loop->latch = latch->src; add_loop (new_loop, loop); } /* Make all the latch edges of LOOP to go to a single forwarder block -- a new latch of LOOP. */ static void merge_latch_edges (struct loop *loop) { VEC (edge, heap) *latches = get_loop_latch_edges (loop); edge latch, e; unsigned i; gcc_assert (VEC_length (edge, latches) > 0); if (VEC_length (edge, latches) == 1) loop->latch = VEC_index (edge, latches, 0)->src; else { if (dump_file) fprintf (dump_file, "Merged latch edges of loop %d\n", loop->num); mfb_reis_set = pointer_set_create (); for (i = 0; VEC_iterate (edge, latches, i, e); i++) pointer_set_insert (mfb_reis_set, e); latch = make_forwarder_block (loop->header, mfb_redirect_edges_in_set, NULL); pointer_set_destroy (mfb_reis_set); loop->header = latch->dest; loop->latch = latch->src; } VEC_free (edge, heap, latches); } /* LOOP may have several latch edges. Transform it into (possibly several) loops with single latch edge. */ static void disambiguate_multiple_latches (struct loop *loop) { edge e; /* We eliminate the multiple latches by splitting the header to the forwarder block F and the rest R, and redirecting the edges. There are two cases: 1) If there is a latch edge E that corresponds to a subloop (we guess that based on profile -- if it is taken much more often than the remaining edges; and on trees, using the information about induction variables of the loops), we redirect E to R, all the remaining edges to F, then rescan the loops and try again for the outer loop. 2) If there is no such edge, we redirect all latch edges to F, and the entry edges to R, thus making F the single latch of the loop. */ if (dump_file) fprintf (dump_file, "Disambiguating loop %d with multiple latches\n", loop->num); /* During latch merging, we may need to redirect the entry edges to a new block. This would cause problems if the entry edge was the one from the entry block. To avoid having to handle this case specially, split such entry edge. */ e = find_edge (ENTRY_BLOCK_PTR, loop->header); if (e) split_edge (e); while (1) { e = find_subloop_latch_edge (loop); if (!e) break; form_subloop (loop, e); } merge_latch_edges (loop); } /* Split loops with multiple latch edges. */ void disambiguate_loops_with_multiple_latches (void) { loop_iterator li; struct loop *loop; FOR_EACH_LOOP (li, loop, 0) { if (!loop->latch) disambiguate_multiple_latches (loop); } } /* Return nonzero if basic block BB belongs to LOOP. */ bool flow_bb_inside_loop_p (const struct loop *loop, const_basic_block bb) { struct loop *source_loop; if (bb == ENTRY_BLOCK_PTR || bb == EXIT_BLOCK_PTR) return 0; source_loop = bb->loop_father; return loop == source_loop || flow_loop_nested_p (loop, source_loop); } /* Enumeration predicate for get_loop_body_with_size. */ static bool glb_enum_p (const_basic_block bb, const void *glb_loop) { const struct loop *const loop = (const struct loop *) glb_loop; return (bb != loop->header && dominated_by_p (CDI_DOMINATORS, bb, loop->header)); } /* Gets basic blocks of a LOOP. Header is the 0-th block, rest is in dfs order against direction of edges from latch. Specially, if header != latch, latch is the 1-st block. LOOP cannot be the fake loop tree root, and its size must be at most MAX_SIZE. The blocks in the LOOP body are stored to BODY, and the size of the LOOP is returned. */ unsigned get_loop_body_with_size (const struct loop *loop, basic_block *body, unsigned max_size) { return dfs_enumerate_from (loop->header, 1, glb_enum_p, body, max_size, loop); } /* Gets basic blocks of a LOOP. Header is the 0-th block, rest is in dfs order against direction of edges from latch. Specially, if header != latch, latch is the 1-st block. */ basic_block * get_loop_body (const struct loop *loop) { basic_block *body, bb; unsigned tv = 0; gcc_assert (loop->num_nodes); body = XCNEWVEC (basic_block, loop->num_nodes); if (loop->latch == EXIT_BLOCK_PTR) { /* There may be blocks unreachable from EXIT_BLOCK, hence we need to special-case the fake loop that contains the whole function. */ gcc_assert (loop->num_nodes == (unsigned) n_basic_blocks); body[tv++] = loop->header; body[tv++] = EXIT_BLOCK_PTR; FOR_EACH_BB (bb) body[tv++] = bb; } else tv = get_loop_body_with_size (loop, body, loop->num_nodes); gcc_assert (tv == loop->num_nodes); return body; } /* Fills dominance descendants inside LOOP of the basic block BB into array TOVISIT from index *TV. */ static void fill_sons_in_loop (const struct loop *loop, basic_block bb, basic_block *tovisit, int *tv) { basic_block son, postpone = NULL; tovisit[(*tv)++] = bb; for (son = first_dom_son (CDI_DOMINATORS, bb); son; son = next_dom_son (CDI_DOMINATORS, son)) { if (!flow_bb_inside_loop_p (loop, son)) continue; if (dominated_by_p (CDI_DOMINATORS, loop->latch, son)) { postpone = son; continue; } fill_sons_in_loop (loop, son, tovisit, tv); } if (postpone) fill_sons_in_loop (loop, postpone, tovisit, tv); } /* Gets body of a LOOP (that must be different from the outermost loop) sorted by dominance relation. Additionally, if a basic block s dominates the latch, then only blocks dominated by s are be after it. */ basic_block * get_loop_body_in_dom_order (const struct loop *loop) { basic_block *tovisit; int tv; gcc_assert (loop->num_nodes); tovisit = XCNEWVEC (basic_block, loop->num_nodes); gcc_assert (loop->latch != EXIT_BLOCK_PTR); tv = 0; fill_sons_in_loop (loop, loop->header, tovisit, &tv); gcc_assert (tv == (int) loop->num_nodes); return tovisit; } /* Gets body of a LOOP sorted via provided BB_COMPARATOR. */ basic_block * get_loop_body_in_custom_order (const struct loop *loop, int (*bb_comparator) (const void *, const void *)) { basic_block *bbs = get_loop_body (loop); qsort (bbs, loop->num_nodes, sizeof (basic_block), bb_comparator); return bbs; } /* Get body of a LOOP in breadth first sort order. */ basic_block * get_loop_body_in_bfs_order (const struct loop *loop) { basic_block *blocks; basic_block bb; bitmap visited; unsigned int i = 0; unsigned int vc = 1; gcc_assert (loop->num_nodes); gcc_assert (loop->latch != EXIT_BLOCK_PTR); blocks = XCNEWVEC (basic_block, loop->num_nodes); visited = BITMAP_ALLOC (NULL); bb = loop->header; while (i < loop->num_nodes) { edge e; edge_iterator ei; if (!bitmap_bit_p (visited, bb->index)) { /* This basic block is now visited */ bitmap_set_bit (visited, bb->index); blocks[i++] = bb; } FOR_EACH_EDGE (e, ei, bb->succs) { if (flow_bb_inside_loop_p (loop, e->dest)) { if (!bitmap_bit_p (visited, e->dest->index)) { bitmap_set_bit (visited, e->dest->index); blocks[i++] = e->dest; } } } gcc_assert (i >= vc); bb = blocks[vc++]; } BITMAP_FREE (visited); return blocks; } /* Hash function for struct loop_exit. */ static hashval_t loop_exit_hash (const void *ex) { const struct loop_exit *const exit = (const struct loop_exit *) ex; return htab_hash_pointer (exit->e); } /* Equality function for struct loop_exit. Compares with edge. */ static int loop_exit_eq (const void *ex, const void *e) { const struct loop_exit *const exit = (const struct loop_exit *) ex; return exit->e == e; } /* Frees the list of loop exit descriptions EX. */ static void loop_exit_free (void *ex) { struct loop_exit *exit = (struct loop_exit *) ex, *next; for (; exit; exit = next) { next = exit->next_e; exit->next->prev = exit->prev; exit->prev->next = exit->next; ggc_free (exit); } } /* Returns the list of records for E as an exit of a loop. */ static struct loop_exit * get_exit_descriptions (edge e) { return (struct loop_exit *) htab_find_with_hash (current_loops->exits, e, htab_hash_pointer (e)); } /* Updates the lists of loop exits in that E appears. If REMOVED is true, E is being removed, and we just remove it from the lists of exits. If NEW_EDGE is true and E is not a loop exit, we do not try to remove it from loop exit lists. */ void rescan_loop_exit (edge e, bool new_edge, bool removed) { void **slot; struct loop_exit *exits = NULL, *exit; struct loop *aloop, *cloop; if (!loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS)) return; if (!removed && e->src->loop_father != NULL && e->dest->loop_father != NULL && !flow_bb_inside_loop_p (e->src->loop_father, e->dest)) { cloop = find_common_loop (e->src->loop_father, e->dest->loop_father); for (aloop = e->src->loop_father; aloop != cloop; aloop = loop_outer (aloop)) { exit = GGC_NEW (struct loop_exit); exit->e = e; exit->next = aloop->exits->next; exit->prev = aloop->exits; exit->next->prev = exit; exit->prev->next = exit; exit->next_e = exits; exits = exit; } } if (!exits && new_edge) return; slot = htab_find_slot_with_hash (current_loops->exits, e, htab_hash_pointer (e), exits ? INSERT : NO_INSERT); if (!slot) return; if (exits) { if (*slot) loop_exit_free (*slot); *slot = exits; } else htab_clear_slot (current_loops->exits, slot); } /* For each loop, record list of exit edges, and start maintaining these lists. */ void record_loop_exits (void) { basic_block bb; edge_iterator ei; edge e; if (!current_loops) return; if (loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS)) return; loops_state_set (LOOPS_HAVE_RECORDED_EXITS); gcc_assert (current_loops->exits == NULL); current_loops->exits = htab_create_alloc (2 * number_of_loops (), loop_exit_hash, loop_exit_eq, loop_exit_free, ggc_calloc, ggc_free); FOR_EACH_BB (bb) { FOR_EACH_EDGE (e, ei, bb->succs) { rescan_loop_exit (e, true, false); } } } /* Dumps information about the exit in *SLOT to FILE. Callback for htab_traverse. */ static int dump_recorded_exit (void **slot, void *file) { struct loop_exit *exit = (struct loop_exit *) *slot; unsigned n = 0; edge e = exit->e; for (; exit != NULL; exit = exit->next_e) n++; fprintf ((FILE*) file, "Edge %d->%d exits %u loops\n", e->src->index, e->dest->index, n); return 1; } /* Dumps the recorded exits of loops to FILE. */ extern void dump_recorded_exits (FILE *); void dump_recorded_exits (FILE *file) { if (!current_loops->exits) return; htab_traverse (current_loops->exits, dump_recorded_exit, file); } /* Releases lists of loop exits. */ void release_recorded_exits (void) { gcc_assert (loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS)); htab_delete (current_loops->exits); current_loops->exits = NULL; loops_state_clear (LOOPS_HAVE_RECORDED_EXITS); } /* Returns the list of the exit edges of a LOOP. */ VEC (edge, heap) * get_loop_exit_edges (const struct loop *loop) { VEC (edge, heap) *edges = NULL; edge e; unsigned i; basic_block *body; edge_iterator ei; struct loop_exit *exit; gcc_assert (loop->latch != EXIT_BLOCK_PTR); /* If we maintain the lists of exits, use them. Otherwise we must scan the body of the loop. */ if (loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS)) { for (exit = loop->exits->next; exit->e; exit = exit->next) VEC_safe_push (edge, heap, edges, exit->e); } else { body = get_loop_body (loop); for (i = 0; i < loop->num_nodes; i++) FOR_EACH_EDGE (e, ei, body[i]->succs) { if (!flow_bb_inside_loop_p (loop, e->dest)) VEC_safe_push (edge, heap, edges, e); } free (body); } return edges; } /* Counts the number of conditional branches inside LOOP. */ unsigned num_loop_branches (const struct loop *loop) { unsigned i, n; basic_block * body; gcc_assert (loop->latch != EXIT_BLOCK_PTR); body = get_loop_body (loop); n = 0; for (i = 0; i < loop->num_nodes; i++) if (EDGE_COUNT (body[i]->succs) >= 2) n++; free (body); return n; } /* Adds basic block BB to LOOP. */ void add_bb_to_loop (basic_block bb, struct loop *loop) { unsigned i; loop_p ploop; edge_iterator ei; edge e; gcc_assert (bb->loop_father == NULL); bb->loop_father = loop; bb->loop_depth = loop_depth (loop); loop->num_nodes++; for (i = 0; VEC_iterate (loop_p, loop->superloops, i, ploop); i++) ploop->num_nodes++; FOR_EACH_EDGE (e, ei, bb->succs) { rescan_loop_exit (e, true, false); } FOR_EACH_EDGE (e, ei, bb->preds) { rescan_loop_exit (e, true, false); } } /* Remove basic block BB from loops. */ void remove_bb_from_loops (basic_block bb) { int i; struct loop *loop = bb->loop_father; loop_p ploop; edge_iterator ei; edge e; gcc_assert (loop != NULL); loop->num_nodes--; for (i = 0; VEC_iterate (loop_p, loop->superloops, i, ploop); i++) ploop->num_nodes--; bb->loop_father = NULL; bb->loop_depth = 0; FOR_EACH_EDGE (e, ei, bb->succs) { rescan_loop_exit (e, false, true); } FOR_EACH_EDGE (e, ei, bb->preds) { rescan_loop_exit (e, false, true); } } /* Finds nearest common ancestor in loop tree for given loops. */ struct loop * find_common_loop (struct loop *loop_s, struct loop *loop_d) { unsigned sdepth, ddepth; if (!loop_s) return loop_d; if (!loop_d) return loop_s; sdepth = loop_depth (loop_s); ddepth = loop_depth (loop_d); if (sdepth < ddepth) loop_d = VEC_index (loop_p, loop_d->superloops, sdepth); else if (sdepth > ddepth) loop_s = VEC_index (loop_p, loop_s->superloops, ddepth); while (loop_s != loop_d) { loop_s = loop_outer (loop_s); loop_d = loop_outer (loop_d); } return loop_s; } /* Removes LOOP from structures and frees its data. */ void delete_loop (struct loop *loop) { /* Remove the loop from structure. */ flow_loop_tree_node_remove (loop); /* Remove loop from loops array. */ VEC_replace (loop_p, current_loops->larray, loop->num, NULL); /* Free loop data. */ flow_loop_free (loop); } /* Cancels the LOOP; it must be innermost one. */ static void cancel_loop (struct loop *loop) { basic_block *bbs; unsigned i; struct loop *outer = loop_outer (loop); gcc_assert (!loop->inner); /* Move blocks up one level (they should be removed as soon as possible). */ bbs = get_loop_body (loop); for (i = 0; i < loop->num_nodes; i++) bbs[i]->loop_father = outer; delete_loop (loop); } /* Cancels LOOP and all its subloops. */ void cancel_loop_tree (struct loop *loop) { while (loop->inner) cancel_loop_tree (loop->inner); cancel_loop (loop); } /* Checks that information about loops is correct -- sizes of loops are all right -- results of get_loop_body really belong to the loop -- loop header have just single entry edge and single latch edge -- loop latches have only single successor that is header of their loop -- irreducible loops are correctly marked */ void verify_loop_structure (void) { unsigned *sizes, i, j; sbitmap irreds; basic_block *bbs, bb; struct loop *loop; int err = 0; edge e; unsigned num = number_of_loops (); loop_iterator li; struct loop_exit *exit, *mexit; /* Check sizes. */ sizes = XCNEWVEC (unsigned, num); sizes[0] = 2; FOR_EACH_BB (bb) for (loop = bb->loop_father; loop; loop = loop_outer (loop)) sizes[loop->num]++; FOR_EACH_LOOP (li, loop, LI_INCLUDE_ROOT) { i = loop->num; if (loop->num_nodes != sizes[i]) { error ("size of loop %d should be %d, not %d", i, sizes[i], loop->num_nodes); err = 1; } } /* Check get_loop_body. */ FOR_EACH_LOOP (li, loop, 0) { bbs = get_loop_body (loop); for (j = 0; j < loop->num_nodes; j++) if (!flow_bb_inside_loop_p (loop, bbs[j])) { error ("bb %d do not belong to loop %d", bbs[j]->index, loop->num); err = 1; } free (bbs); } /* Check headers and latches. */ FOR_EACH_LOOP (li, loop, 0) { i = loop->num; if (loops_state_satisfies_p (LOOPS_HAVE_PREHEADERS) && EDGE_COUNT (loop->header->preds) != 2) { error ("loop %d's header does not have exactly 2 entries", i); err = 1; } if (loops_state_satisfies_p (LOOPS_HAVE_SIMPLE_LATCHES)) { if (!single_succ_p (loop->latch)) { error ("loop %d's latch does not have exactly 1 successor", i); err = 1; } if (single_succ (loop->latch) != loop->header) { error ("loop %d's latch does not have header as successor", i); err = 1; } if (loop->latch->loop_father != loop) { error ("loop %d's latch does not belong directly to it", i); err = 1; } } if (loop->header->loop_father != loop) { error ("loop %d's header does not belong directly to it", i); err = 1; } if (loops_state_satisfies_p (LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS) && (loop_latch_edge (loop)->flags & EDGE_IRREDUCIBLE_LOOP)) { error ("loop %d's latch is marked as part of irreducible region", i); err = 1; } } /* Check irreducible loops. */ if (loops_state_satisfies_p (LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)) { /* Record old info. */ irreds = sbitmap_alloc (last_basic_block); FOR_EACH_BB (bb) { edge_iterator ei; if (bb->flags & BB_IRREDUCIBLE_LOOP) SET_BIT (irreds, bb->index); else RESET_BIT (irreds, bb->index); FOR_EACH_EDGE (e, ei, bb->succs) if (e->flags & EDGE_IRREDUCIBLE_LOOP) e->flags |= EDGE_ALL_FLAGS + 1; } /* Recount it. */ mark_irreducible_loops (); /* Compare. */ FOR_EACH_BB (bb) { edge_iterator ei; if ((bb->flags & BB_IRREDUCIBLE_LOOP) && !TEST_BIT (irreds, bb->index)) { error ("basic block %d should be marked irreducible", bb->index); err = 1; } else if (!(bb->flags & BB_IRREDUCIBLE_LOOP) && TEST_BIT (irreds, bb->index)) { error ("basic block %d should not be marked irreducible", bb->index); err = 1; } FOR_EACH_EDGE (e, ei, bb->succs) { if ((e->flags & EDGE_IRREDUCIBLE_LOOP) && !(e->flags & (EDGE_ALL_FLAGS + 1))) { error ("edge from %d to %d should be marked irreducible", e->src->index, e->dest->index); err = 1; } else if (!(e->flags & EDGE_IRREDUCIBLE_LOOP) && (e->flags & (EDGE_ALL_FLAGS + 1))) { error ("edge from %d to %d should not be marked irreducible", e->src->index, e->dest->index); err = 1; } e->flags &= ~(EDGE_ALL_FLAGS + 1); } } free (irreds); } /* Check the recorded loop exits. */ FOR_EACH_LOOP (li, loop, 0) { if (!loop->exits || loop->exits->e != NULL) { error ("corrupted head of the exits list of loop %d", loop->num); err = 1; } else { /* Check that the list forms a cycle, and all elements except for the head are nonnull. */ for (mexit = loop->exits, exit = mexit->next, i = 0; exit->e && exit != mexit; exit = exit->next) { if (i++ & 1) mexit = mexit->next; } if (exit != loop->exits) { error ("corrupted exits list of loop %d", loop->num); err = 1; } } if (!loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS)) { if (loop->exits->next != loop->exits) { error ("nonempty exits list of loop %d, but exits are not recorded", loop->num); err = 1; } } } if (loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS)) { unsigned n_exits = 0, eloops; memset (sizes, 0, sizeof (unsigned) * num); FOR_EACH_BB (bb) { edge_iterator ei; if (bb->loop_father == current_loops->tree_root) continue; FOR_EACH_EDGE (e, ei, bb->succs) { if (flow_bb_inside_loop_p (bb->loop_father, e->dest)) continue; n_exits++; exit = get_exit_descriptions (e); if (!exit) { error ("Exit %d->%d not recorded", e->src->index, e->dest->index); err = 1; } eloops = 0; for (; exit; exit = exit->next_e) eloops++; for (loop = bb->loop_father; loop != e->dest->loop_father; loop = loop_outer (loop)) { eloops--; sizes[loop->num]++; } if (eloops != 0) { error ("Wrong list of exited loops for edge %d->%d", e->src->index, e->dest->index); err = 1; } } } if (n_exits != htab_elements (current_loops->exits)) { error ("Too many loop exits recorded"); err = 1; } FOR_EACH_LOOP (li, loop, 0) { eloops = 0; for (exit = loop->exits->next; exit->e; exit = exit->next) eloops++; if (eloops != sizes[loop->num]) { error ("%d exits recorded for loop %d (having %d exits)", eloops, loop->num, sizes[loop->num]); err = 1; } } } gcc_assert (!err); free (sizes); } /* Returns latch edge of LOOP. */ edge loop_latch_edge (const struct loop *loop) { return find_edge (loop->latch, loop->header); } /* Returns preheader edge of LOOP. */ edge loop_preheader_edge (const struct loop *loop) { edge e; edge_iterator ei; gcc_assert (loops_state_satisfies_p (LOOPS_HAVE_PREHEADERS)); FOR_EACH_EDGE (e, ei, loop->header->preds) if (e->src != loop->latch) break; return e; } /* Returns true if E is an exit of LOOP. */ bool loop_exit_edge_p (const struct loop *loop, const_edge e) { return (flow_bb_inside_loop_p (loop, e->src) && !flow_bb_inside_loop_p (loop, e->dest)); } /* Returns the single exit edge of LOOP, or NULL if LOOP has either no exit or more than one exit. If loops do not have the exits recorded, NULL is returned always. */ edge single_exit (const struct loop *loop) { struct loop_exit *exit = loop->exits->next; if (!loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS)) return NULL; if (exit->e && exit->next == loop->exits) return exit->e; else return NULL; } /* Returns true when BB has an edge exiting LOOP. */ bool is_loop_exit (struct loop *loop, basic_block bb) { edge e; edge_iterator ei; FOR_EACH_EDGE (e, ei, bb->preds) if (loop_exit_edge_p (loop, e)) return true; return false; }
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