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Diffstat (limited to 'gcc-4.8.3/gcc/cfgloop.c')
| -rw-r--r-- | gcc-4.8.3/gcc/cfgloop.c | 1766 |
1 files changed, 1766 insertions, 0 deletions
diff --git a/gcc-4.8.3/gcc/cfgloop.c b/gcc-4.8.3/gcc/cfgloop.c new file mode 100644 index 000000000..751da5a2c --- /dev/null +++ b/gcc-4.8.3/gcc/cfgloop.c @@ -0,0 +1,1766 @@ +/* Natural loop discovery code for GNU compiler. + Copyright (C) 2000-2013 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 "function.h" +#include "basic-block.h" +#include "cfgloop.h" +#include "diagnostic-core.h" +#include "flags.h" +#include "tree.h" +#include "tree-flow.h" +#include "pointer-set.h" +#include "ggc.h" +#include "dumpfile.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 + && (*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 (*loop->superloops)[depth]; +} + +/* Returns the list of the latch edges of LOOP. */ + +static vec<edge> +get_loop_latch_edges (const struct loop *loop) +{ + edge_iterator ei; + edge e; + vec<edge> ret = vNULL; + + FOR_EACH_EDGE (e, ei, loop->header->preds) + { + if (dominated_by_p (CDI_DOMINATORS, e->src, loop->header)) + ret.safe_push (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> 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_EACH_VEC_ELT (latches, i, e) + fprintf (file, " %d", e->src->index); + latches.release (); + 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->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_EACH_VEC_SAFE_ELT (loops->larray, i, loop) + { + if (!loop) + continue; + + flow_loop_free (loop); + } + + vec_free (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> stack = vNULL; + int num_nodes = 1; + edge latch; + edge_iterator latch_ei; + + header->loop_father = loop; + + 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++; + stack.safe_push (latch->src); + latch->src->loop_father = loop; + + while (!stack.is_empty ()) + { + basic_block node; + edge e; + edge_iterator ei; + + node = stack.pop (); + + FOR_EACH_EDGE (e, ei, node->preds) + { + basic_block ancestor = e->src; + + if (ancestor->loop_father != loop) + { + ancestor->loop_father = loop; + num_nodes++; + stack.safe_push (ancestor); + } + } + } + } + stack.release (); + + 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; + + loop->superloops = 0; + vec_alloc (loop->superloops, depth); + FOR_EACH_VEC_SAFE_ELT (father->superloops, i, ploop) + loop->superloops->quick_push (ploop); + loop->superloops->quick_push (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; + } + + loop->superloops = NULL; +} + +/* Allocates and returns new loop structure. */ + +struct loop * +alloc_loop (void) +{ + struct loop *loop = ggc_alloc_cleared_loop (); + + loop->exits = ggc_alloc_cleared_loop_exit (); + loop->exits->next = loop->exits->prev = loop->exits; + loop->can_be_parallel = false; + + 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); + vec_alloc (loops->larray, 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; + + loops->larray->quick_push (root); + loops->tree_root = root; +} + +/* Returns whether HEADER is a loop header. */ + +bool +bb_loop_header_p (basic_block header) +{ + edge_iterator ei; + edge e; + + /* If we have an abnormal predecessor, do not consider the + loop (not worth the problems). */ + if (bb_has_abnormal_pred (header)) + return false; + + /* 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. */ + FOR_EACH_EDGE (e, ei, header->preds) + { + basic_block latch = e->src; + if (latch != ENTRY_BLOCK_PTR + && dominated_by_p (CDI_DOMINATORS, latch, header)) + return true; + } + + return false; +} + +/* Find all the natural loops in the function and save in LOOPS structure and + recalculate loop_father information in basic block structures. + If LOOPS is non-NULL then the loop structures for already recorded loops + will be re-used and their number will not change. We assume that no + stale loops exist in LOOPS. + When LOOPS is NULL it is allocated and re-built from scratch. + Return the built LOOPS structure. */ + +struct loops * +flow_loops_find (struct loops *loops) +{ + bool from_scratch = (loops == NULL); + int *rc_order; + int b; + unsigned i; + vec<loop_p> larray; + + /* Ensure that the dominators are computed. */ + calculate_dominance_info (CDI_DOMINATORS); + + if (!loops) + { + loops = ggc_alloc_cleared_loops (); + init_loops_structure (loops, 1); + } + + /* Ensure that loop exits were released. */ + gcc_assert (loops->exits == NULL); + + /* Taking care of this degenerate case makes the rest of + this code simpler. */ + if (n_basic_blocks == NUM_FIXED_BLOCKS) + return loops; + + /* The root loop node contains all basic-blocks. */ + loops->tree_root->num_nodes = n_basic_blocks; + + /* Compute depth first search order of the CFG so that outer + natural loops will be found before inner natural loops. */ + rc_order = XNEWVEC (int, n_basic_blocks); + pre_and_rev_post_order_compute (NULL, rc_order, false); + + /* Gather all loop headers in reverse completion order and allocate + loop structures for loops that are not already present. */ + larray.create (loops->larray->length()); + for (b = 0; b < n_basic_blocks - NUM_FIXED_BLOCKS; b++) + { + basic_block header = BASIC_BLOCK (rc_order[b]); + if (bb_loop_header_p (header)) + { + struct loop *loop; + + /* The current active loop tree has valid loop-fathers for + header blocks. */ + if (!from_scratch + && header->loop_father->header == header) + { + loop = header->loop_father; + /* If we found an existing loop remove it from the + loop tree. It is going to be inserted again + below. */ + flow_loop_tree_node_remove (loop); + } + else + { + /* Otherwise allocate a new loop structure for the loop. */ + loop = alloc_loop (); + /* ??? We could re-use unused loop slots here. */ + loop->num = loops->larray->length (); + vec_safe_push (loops->larray, loop); + loop->header = header; + + if (!from_scratch + && dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "flow_loops_find: discovered new " + "loop %d with header %d\n", + loop->num, header->index); + } + /* Reset latch, we recompute it below. */ + loop->latch = NULL; + larray.safe_push (loop); + } + + /* Make blocks part of the loop root node at start. */ + header->loop_father = loops->tree_root; + } + + free (rc_order); + + /* Now iterate over the loops found, insert them into the loop tree + and assign basic-block ownership. */ + for (i = 0; i < larray.length (); ++i) + { + struct loop *loop = larray[i]; + basic_block header = loop->header; + edge_iterator ei; + edge e; + + 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; + } + } + } + + larray.release(); + + return loops; +} + +/* 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> latches) +{ + unsigned i; + edge e, me = NULL; + gcov_type mcount = 0, tcount = 0; + + FOR_EACH_VEC_ELT (latches, i, e) + { + 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> latches) +{ + edge e, latch = 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; latches.iterate (i, &e); i++) + if (dominated_by_p (CDI_DOMINATORS, latch->src, e->src)) + latch = e; + + /* Verify that it dominates all the latch edges. */ + FOR_EACH_VEC_ELT (latches, i, e) + 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_EACH_VEC_ELT (latches, i, e) + 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> latches = get_loop_latch_edges (loop); + edge latch = NULL; + + if (latches.length () > 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); + } + + latches.release (); + 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> latches = get_loop_latch_edges (loop); + edge latch, e; + unsigned i; + + gcc_assert (latches.length () > 0); + + if (latches.length () == 1) + loop->latch = 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_EACH_VEC_ELT (latches, i, e) + 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; + } + + latches.release (); +} + +/* 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 = XNEWVEC (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 = XNEWVEC (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 = XNEWVEC (basic_block, loop->num_nodes); + visited = BITMAP_ALLOC (NULL); + + bb = loop->header; + while (i < loop->num_nodes) + { + edge e; + edge_iterator ei; + + if (bitmap_set_bit (visited, bb->index)) + /* This basic block is now visited */ + blocks[i++] = bb; + + FOR_EACH_EDGE (e, ei, bb->succs) + { + if (flow_bb_inside_loop_p (loop, e->dest)) + { + if (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_alloc_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_ggc (2 * number_of_loops (), + loop_exit_hash, loop_exit_eq, + loop_exit_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> +get_loop_exit_edges (const struct loop *loop) +{ + vec<edge> edges = vNULL; + 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) + edges.safe_push (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)) + edges.safe_push (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; + loop->num_nodes++; + FOR_EACH_VEC_SAFE_ELT (loop->superloops, i, ploop) + 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) +{ + unsigned i; + struct loop *loop = bb->loop_father; + loop_p ploop; + edge_iterator ei; + edge e; + + gcc_assert (loop != NULL); + loop->num_nodes--; + FOR_EACH_VEC_SAFE_ELT (loop->superloops, i, ploop) + ploop->num_nodes--; + bb->loop_father = NULL; + + 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 = (*loop_d->superloops)[sdepth]; + else if (sdepth > ddepth) + loop_s = (*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. */ + (*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; + + free (bbs); + 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 + -- the cached loop depth and loop father of each bb is correct + */ +DEBUG_FUNCTION void +verify_loop_structure (void) +{ + unsigned *sizes, i, j; + sbitmap irreds; + basic_block bb; + struct loop *loop; + int err = 0; + edge e; + unsigned num = number_of_loops (); + loop_iterator li; + struct loop_exit *exit, *mexit; + bool dom_available = dom_info_available_p (CDI_DOMINATORS); + sbitmap visited; + + /* We need up-to-date dominators, compute or verify them. */ + if (!dom_available) + calculate_dominance_info (CDI_DOMINATORS); + else + verify_dominators (CDI_DOMINATORS); + + /* 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 the headers. */ + FOR_EACH_BB (bb) + if (bb_loop_header_p (bb) + && bb->loop_father->header != bb) + { + error ("loop with header %d not in loop tree", bb->index); + err = 1; + } + + /* Check get_loop_body. */ + visited = sbitmap_alloc (last_basic_block); + bitmap_clear (visited); + FOR_EACH_LOOP (li, loop, LI_FROM_INNERMOST) + { + basic_block *bbs = get_loop_body (loop); + + for (j = 0; j < loop->num_nodes; j++) + { + bb = bbs[j]; + + if (!flow_bb_inside_loop_p (loop, bb)) + { + error ("bb %d does not belong to loop %d", + bb->index, loop->num); + err = 1; + } + + /* Ignore this block if it is in an inner loop. */ + if (bitmap_bit_p (visited, bb->index)) + continue; + bitmap_set_bit (visited, bb->index); + + if (bb->loop_father != loop) + { + error ("bb %d has father loop %d, should be loop %d", + bb->index, bb->loop_father->num, loop->num); + err = 1; + } + } + + free (bbs); + } + sbitmap_free (visited); + + /* Check headers and latches. */ + FOR_EACH_LOOP (li, loop, 0) + { + i = loop->num; + + if (!bb_loop_header_p (loop->header)) + { + error ("loop %d%'s header is not a loop header", i); + err = 1; + } + 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 (loop->latch) + { + if (!find_edge (loop->latch, loop->header)) + { + error ("loop %d%'s latch does not have an edge to its header", i); + err = 1; + } + if (!dominated_by_p (CDI_DOMINATORS, loop->latch, loop->header)) + { + error ("loop %d%'s latch is not dominated by its header", 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) + bitmap_set_bit (irreds, bb->index); + else + bitmap_clear_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) + && !bitmap_bit_p (irreds, bb->index)) + { + error ("basic block %d should be marked irreducible", bb->index); + err = 1; + } + else if (!(bb->flags & BB_IRREDUCIBLE_LOOP) + && bitmap_bit_p (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 + /* When a loop exit is also an entry edge which + can happen when avoiding CFG manipulations + then the last loop exited is the outer loop + of the loop entered. */ + && loop != loop_outer (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); + if (!dom_available) + free_dominance_info (CDI_DOMINATORS); +} + +/* 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 incoming edge exiting LOOP. */ + +bool +loop_exits_to_bb_p (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; +} + +/* Returns true when BB has an outgoing edge exiting LOOP. */ + +bool +loop_exits_from_bb_p (struct loop *loop, basic_block bb) +{ + edge e; + edge_iterator ei; + + FOR_EACH_EDGE (e, ei, bb->succs) + if (loop_exit_edge_p (loop, e)) + return true; + + return false; +} + +/* Return location corresponding to the loop control condition if possible. */ + +location_t +get_loop_location (struct loop *loop) +{ + rtx insn = NULL; + struct niter_desc *desc = NULL; + edge exit; + + /* For a for or while loop, we would like to return the location + of the for or while statement, if possible. To do this, look + for the branch guarding the loop back-edge. */ + + /* If this is a simple loop with an in_edge, then the loop control + branch is typically at the end of its source. */ + desc = get_simple_loop_desc (loop); + if (desc->in_edge) + { + FOR_BB_INSNS_REVERSE (desc->in_edge->src, insn) + { + if (INSN_P (insn) && INSN_HAS_LOCATION (insn)) + return INSN_LOCATION (insn); + } + } + /* If loop has a single exit, then the loop control branch + must be at the end of its source. */ + if ((exit = single_exit (loop))) + { + FOR_BB_INSNS_REVERSE (exit->src, insn) + { + if (INSN_P (insn) && INSN_HAS_LOCATION (insn)) + return INSN_LOCATION (insn); + } + } + /* Next check the latch, to see if it is non-empty. */ + FOR_BB_INSNS_REVERSE (loop->latch, insn) + { + if (INSN_P (insn) && INSN_HAS_LOCATION (insn)) + return INSN_LOCATION (insn); + } + /* Finally, if none of the above identifies the loop control branch, + return the first location in the loop header. */ + FOR_BB_INSNS (loop->header, insn) + { + if (INSN_P (insn) && INSN_HAS_LOCATION (insn)) + return INSN_LOCATION (insn); + } + /* If all else fails, simply return the current function location. */ + return DECL_SOURCE_LOCATION (current_function_decl); +} + |