X-Git-Url: https://oss.titaniummirror.com/gitweb/?a=blobdiff_plain;f=gcc%2Fcfgloop.c;fp=gcc%2Fcfgloop.c;h=e74284e8988d42b695074eca5836de2758a89660;hb=6fed43773c9b0ce596dca5686f37ac3fc0fa11c0;hp=2bd0d4c44bf72a45902ed9167781164e534ad335;hpb=27b11d56b743098deb193d510b337ba22dc52e5c;p=msp430-gcc.git diff --git a/gcc/cfgloop.c b/gcc/cfgloop.c index 2bd0d4c4..e74284e8 100644 --- a/gcc/cfgloop.c +++ b/gcc/cfgloop.c @@ -1,11 +1,12 @@ /* Natural loop discovery code for GNU compiler. - Copyright (C) 2000, 2001 Free Software Foundation, Inc. + 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 2, or (at your option) any later +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 @@ -14,823 +15,1623 @@ 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. */ +along with GCC; see the file COPYING3. If not see +. */ #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" - -static void flow_loops_cfg_dump PARAMS ((const struct loops *, - FILE *)); -static int flow_loop_nested_p PARAMS ((struct loop *, - struct loop *)); -static int flow_loop_entry_edges_find PARAMS ((basic_block, const sbitmap, - edge **)); -static int flow_loop_exit_edges_find PARAMS ((const sbitmap, edge **)); -static int flow_loop_nodes_find PARAMS ((basic_block, basic_block, - sbitmap)); -static void flow_loop_pre_header_scan PARAMS ((struct loop *)); -static basic_block flow_loop_pre_header_find PARAMS ((basic_block, - const sbitmap *)); -static void flow_loop_tree_node_add PARAMS ((struct loop *, - struct loop *)); -static void flow_loops_tree_build PARAMS ((struct loops *)); -static int flow_loop_level_compute PARAMS ((struct loop *, int)); -static int flow_loops_level_compute PARAMS ((struct loops *)); +#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 (loops, file) - const struct loops *loops; - FILE *file; +flow_loops_cfg_dump (FILE *file) { - int i; + basic_block bb; - if (! loops->num || ! file || ! loops->cfg.dom) + if (!file) return; - for (i = 0; i < n_basic_blocks; i++) + FOR_EACH_BB (bb) { edge succ; + edge_iterator ei; - fprintf (file, ";; %d succs { ", i); - for (succ = BASIC_BLOCK (i)->succ; succ; succ = succ->succ_next) + fprintf (file, ";; %d succs { ", bb->index); + FOR_EACH_EDGE (succ, ei, bb->succs) fprintf (file, "%d ", succ->dest->index); - flow_nodes_print ("} dom", loops->cfg.dom[i], file); + fprintf (file, "}\n"); } +} - /* Dump the DFS node order. */ - if (loops->cfg.dfs_order) - { - fputs (";; DFS order: ", file); - for (i = 0; i < n_basic_blocks; i++) - fprintf (file, "%d ", loops->cfg.dfs_order[i]); +/* Return nonzero if the nodes of LOOP are a subset of OUTER. */ - fputs ("\n", file); - } +bool +flow_loop_nested_p (const struct loop *outer, const struct loop *loop) +{ + unsigned odepth = loop_depth (outer); - /* Dump the reverse completion node order. */ - if (loops->cfg.rc_order) - { - fputs (";; RC order: ", file); - for (i = 0; i < n_basic_blocks; i++) - fprintf (file, "%d ", loops->cfg.rc_order[i]); + return (loop_depth (loop) > odepth + && VEC_index (loop_p, loop->superloops, odepth) == outer); +} - fputs ("\n", file); - } +/* 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); } -/* Return non-zero if the nodes of LOOP are a subset of OUTER. */ +/* Returns the list of the latch edges of LOOP. */ -static int -flow_loop_nested_p (outer, loop) - struct loop *outer; - struct loop *loop; +static VEC (edge, heap) * +get_loop_latch_edges (const struct loop *loop) { - return sbitmap_a_subset_b_p (loop->nodes, outer->nodes); + 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 (loop, file, loop_dump_aux, verbose) - const struct loop *loop; - FILE *file; - void (*loop_dump_aux) PARAMS((const struct loop *, FILE *, int)); - int verbose; +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; - if (loop->first->head && loop->last->end) - fprintf (file, ";;\n;; Loop %d (%d to %d):%s%s\n", - loop->num, INSN_UID (loop->first->head), - INSN_UID (loop->last->end), - loop->shared ? " shared" : "", loop->invalid ? " invalid" : ""); + 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, ";;\n;; Loop %d:%s%s\n", loop->num, - loop->shared ? " shared" : "", loop->invalid ? " invalid" : ""); - - fprintf (file, ";; header %d, latch %d, pre-header %d, first %d, last %d\n", - loop->header->index, loop->latch->index, - loop->pre_header ? loop->pre_header->index : -1, - loop->first->index, loop->last->index); - fprintf (file, ";; depth %d, level %d, outer %ld\n", - loop->depth, loop->level, - (long) (loop->outer ? loop->outer->num : -1)); - - if (loop->pre_header_edges) - flow_edge_list_print (";; pre-header edges", loop->pre_header_edges, - loop->num_pre_header_edges, file); - - flow_edge_list_print (";; entry edges", loop->entry_edges, - loop->num_entries, file); - fprintf (file, ";; %d", loop->num_nodes); - flow_nodes_print (" nodes", loop->nodes, file); - flow_edge_list_print (";; exit edges", loop->exit_edges, - loop->num_exits, file); - - if (loop->exits_doms) - flow_nodes_print (";; exit doms", loop->exits_doms, file); + { + 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 specified by LOOPS to the stream FILE, +/* 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 (loops, file, loop_dump_aux, verbose) - const struct loops *loops; - FILE *file; - void (*loop_dump_aux) PARAMS((const struct loop *, FILE *, int)); - int verbose; +flow_loops_dump (FILE *file, void (*loop_dump_aux) (const struct loop *, FILE *, int), int verbose) { - int i, j; - int num_loops; + loop_iterator li; + struct loop *loop; - num_loops = loops->num; - if (! num_loops || ! file) + if (!current_loops || ! file) return; - fprintf (file, ";; %d loops found, %d levels\n", num_loops, loops->levels); - for (i = 0; i < num_loops; i++) - { - struct loop *loop = &loops->array[i]; + 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 (loop->shared) - for (j = 0; j < i; j++) - { - struct loop *oloop = &loops->array[j]; - - if (loop->header == oloop->header) - { - int disjoint; - int smaller; - - smaller = loop->num_nodes < oloop->num_nodes; - - /* If the union of LOOP and OLOOP is different than - the larger of LOOP and OLOOP then LOOP and OLOOP - must be disjoint. */ - disjoint = ! flow_loop_nested_p (smaller ? loop : oloop, - smaller ? oloop : loop); - fprintf (file, - ";; loop header %d shared by loops %d, %d %s\n", - loop->header->index, i, j, - disjoint ? "disjoint" : "nested"); - } - } } if (verbose) - flow_loops_cfg_dump (loops, file); + flow_loops_cfg_dump (file); } -/* Free all the memory allocated for LOOPS. */ +/* Free data allocated for LOOP. */ void -flow_loops_free (loops) - struct loops *loops; +flow_loop_free (struct loop *loop) { - if (loops->array) + 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) { - int i; + next = exit->next; + exit->next = exit; + exit->prev = exit; + } + + ggc_free (loop->exits); + ggc_free (loop); +} - if (! loops->num) - abort (); +/* 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; i < loops->num; i++) + for (i = 0; VEC_iterate (loop_p, loops->larray, i, loop); i++) { - struct loop *loop = &loops->array[i]; - - if (loop->pre_header_edges) - free (loop->pre_header_edges); - if (loop->nodes) - sbitmap_free (loop->nodes); - if (loop->entry_edges) - free (loop->entry_edges); - if (loop->exit_edges) - free (loop->exit_edges); - if (loop->exits_doms) - sbitmap_free (loop->exits_doms); + 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. */ - free (loops->array); - loops->array = NULL; +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); +} - if (loops->cfg.dom) - sbitmap_vector_free (loops->cfg.dom); +/* 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. */ - if (loops->cfg.dfs_order) - free (loops->cfg.dfs_order); +void +flow_loop_tree_node_add (struct loop *father, struct loop *loop) +{ + loop->next = father->inner; + father->inner = loop; - if (loops->shared_headers) - sbitmap_free (loops->shared_headers); + 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); } -/* Find the entry edges into the loop with header HEADER and nodes - NODES and store in ENTRY_EDGES array. Return the number of entry - edges from the loop. */ +/* Allocates and returns new loop structure. */ -static int -flow_loop_entry_edges_find (header, nodes, entry_edges) - basic_block header; - const sbitmap nodes; - edge **entry_edges; +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; + + 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; - int num_entries; + sbitmap headers; + int *dfs_order; + int *rc_order; + basic_block header; + basic_block bb; - *entry_edges = NULL; + /* Ensure that the dominators are computed. */ + calculate_dominance_info (CDI_DOMINATORS); - num_entries = 0; - for (e = header->pred; e; e = e->pred_next) + /* Taking care of this degenerate case makes the rest of + this code simpler. */ + if (n_basic_blocks == NUM_FIXED_BLOCKS) { - basic_block src = e->src; + 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); - if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index)) - num_entries++; + 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); } - if (! num_entries) - abort (); + sbitmap_free (headers); + + loops->exits = NULL; + return VEC_length (loop_p, loops->larray); +} - *entry_edges = (edge *) xmalloc (num_entries * sizeof (edge)); +/* 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; - num_entries = 0; - for (e = header->pred; e; e = e->pred_next) + for (i = 0; VEC_iterate (edge, latches, i, e); i++) { - basic_block src = e->src; + 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. */ - if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index)) - (*entry_edges)[num_entries++] = e; +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; } - return num_entries; + if (dump_file) + fprintf (dump_file, + "Found latch edge %d -> %d using iv structure.\n", + latch->src->index, latch->dest->index); + return latch; } -/* Find the exit edges from the loop using the bitmap of loop nodes - NODES and store in EXIT_EDGES array. Return the number of - exit edges from the loop. */ +/* 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 int -flow_loop_exit_edges_find (nodes, exit_edges) - const sbitmap nodes; - edge **exit_edges; +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; - int node; - int num_exits; - - *exit_edges = NULL; - - /* Check all nodes within the loop to see if there are any - successors not in the loop. Note that a node may have multiple - exiting edges ????? A node can have one jumping edge and one fallthru - edge so only one of these can exit the loop. */ - num_exits = 0; - EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, { - for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next) - { - basic_block dest = e->dest; - - if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index)) - num_exits++; - } - }); - - if (! num_exits) + + /* 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; - *exit_edges = (edge *) xmalloc (num_exits * sizeof (edge)); + source_loop = bb->loop_father; + return loop == source_loop || flow_loop_nested_p (loop, source_loop); +} - /* Store all exiting edges into an array. */ - num_exits = 0; - EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, { - for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next) - { - basic_block dest = e->dest; +/* 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)); +} - if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index)) - (*exit_edges)[num_exits++] = e; - } - }); +/* 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. */ - return num_exits; +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); } -/* Find the nodes contained within the loop with header HEADER and - latch LATCH and store in NODES. Return the number of nodes within - the 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. */ -static int -flow_loop_nodes_find (header, latch, nodes) - basic_block header; - basic_block latch; - sbitmap nodes; +basic_block * +get_loop_body (const struct loop *loop) { - basic_block *stack; - int sp; - int num_nodes = 0; + basic_block *body, bb; + unsigned tv = 0; - stack = (basic_block *) xmalloc (n_basic_blocks * sizeof (basic_block)); - sp = 0; + gcc_assert (loop->num_nodes); - /* Start with only the loop header in the set of loop nodes. */ - sbitmap_zero (nodes); - SET_BIT (nodes, header->index); - num_nodes++; - header->loop_depth++; + body = XCNEWVEC (basic_block, loop->num_nodes); - /* Push the loop latch on to the stack. */ - if (! TEST_BIT (nodes, latch->index)) + if (loop->latch == EXIT_BLOCK_PTR) { - SET_BIT (nodes, latch->index); - latch->loop_depth++; - num_nodes++; - stack[sp++] = latch; + /* 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; +} - while (sp) +/* 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)) { - basic_block node; - edge e; + if (!flow_bb_inside_loop_p (loop, son)) + continue; - node = stack[--sp]; - for (e = node->pred; e; e = e->pred_next) + if (dominated_by_p (CDI_DOMINATORS, loop->latch, son)) { - basic_block ancestor = e->src; - - /* If each ancestor not marked as part of loop, add to set of - loop nodes and push on to stack. */ - if (ancestor != ENTRY_BLOCK_PTR - && ! TEST_BIT (nodes, ancestor->index)) - { - SET_BIT (nodes, ancestor->index); - ancestor->loop_depth++; - num_nodes++; - stack[sp++] = ancestor; - } + postpone = son; + continue; } + fill_sons_in_loop (loop, son, tovisit, tv); } - free (stack); - return num_nodes; + + if (postpone) + fill_sons_in_loop (loop, postpone, tovisit, tv); } -/* Find the root node of the loop pre-header extended basic block and - the edges along the trace from the root node to the loop header. */ +/* 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. */ -static void -flow_loop_pre_header_scan (loop) - struct loop *loop; +basic_block * +get_loop_body_in_dom_order (const struct loop *loop) { - int num; - basic_block ebb; - edge e; + basic_block *tovisit; + int tv; - loop->num_pre_header_edges = 0; - if (loop->num_entries != 1) - return; + gcc_assert (loop->num_nodes); - ebb = loop->entry_edges[0]->src; - if (ebb == ENTRY_BLOCK_PTR) - return; + tovisit = XCNEWVEC (basic_block, loop->num_nodes); + + gcc_assert (loop->latch != EXIT_BLOCK_PTR); - /* Count number of edges along trace from loop header to - root of pre-header extended basic block. Usually this is - only one or two edges. */ - for (num = 1; ebb->pred->src != ENTRY_BLOCK_PTR && ! ebb->pred->pred_next; - num++) - ebb = ebb->pred->src; + tv = 0; + fill_sons_in_loop (loop, loop->header, tovisit, &tv); - loop->pre_header_edges = (edge *) xmalloc (num * sizeof (edge)); - loop->num_pre_header_edges = num; + gcc_assert (tv == (int) loop->num_nodes); - /* Store edges in order that they are followed. The source of the first edge - is the root node of the pre-header extended basic block and the - destination of the last last edge is the loop header. */ - for (e = loop->entry_edges[0]; num; e = e->src->pred) - loop->pre_header_edges[--num] = e; + return tovisit; } -/* Return the block for the pre-header of the loop with header - HEADER where DOM specifies the dominator information. Return NULL if - there is no pre-header. */ +/* Gets body of a LOOP sorted via provided BB_COMPARATOR. */ -static basic_block -flow_loop_pre_header_find (header, dom) - basic_block header; - const sbitmap *dom; +basic_block * +get_loop_body_in_custom_order (const struct loop *loop, + int (*bb_comparator) (const void *, const void *)) { - basic_block pre_header; - edge e; + 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); - /* If block p is a predecessor of the header and is the only block - that the header does not dominate, then it is the pre-header. */ - pre_header = NULL; - for (e = header->pred; e; e = e->pred_next) + blocks = XCNEWVEC (basic_block, loop->num_nodes); + visited = BITMAP_ALLOC (NULL); + + bb = loop->header; + while (i < loop->num_nodes) { - basic_block node = e->src; + edge e; + edge_iterator ei; - if (node != ENTRY_BLOCK_PTR - && ! TEST_BIT (dom[node->index], header->index)) + if (!bitmap_bit_p (visited, bb->index)) { - if (pre_header == NULL) - pre_header = node; - else + /* 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)) { - /* There are multiple edges into the header from outside - the loop so there is no pre-header block. */ - pre_header = NULL; - break; + 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++]; } - return pre_header; + 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); } -/* Add LOOP to the loop hierarchy tree where PREVLOOP was the loop - previously added. The insertion algorithm assumes that the loops - are added in the order found by a depth first search of the CFG. */ +/* 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 -flow_loop_tree_node_add (prevloop, loop) - struct loop *prevloop; - struct loop *loop; +loop_exit_free (void *ex) { + struct loop_exit *exit = (struct loop_exit *) ex, *next; - if (flow_loop_nested_p (prevloop, loop)) + for (; exit; exit = next) { - prevloop->inner = loop; - loop->outer = prevloop; - return; + next = exit->next_e; + + exit->next->prev = exit->prev; + exit->prev->next = exit->next; + + ggc_free (exit); } +} - for (; prevloop->outer; prevloop = prevloop->outer) - if (flow_loop_nested_p (prevloop->outer, loop)) - { - prevloop->next = loop; - loop->outer = prevloop->outer; - return; - } +/* Returns the list of records for E as an exit of a loop. */ - prevloop->next = loop; - loop->outer = NULL; +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)); } -/* Build the loop hierarchy tree for LOOPS. */ +/* 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. */ -static void -flow_loops_tree_build (loops) - struct loops *loops; +void +rescan_loop_exit (edge e, bool new_edge, bool removed) { - int i; - int num_loops; + 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; + } + } - num_loops = loops->num; - if (! num_loops) + if (!exits && new_edge) return; - /* Root the loop hierarchy tree with the first loop found. - Since we used a depth first search this should be the - outermost loop. */ - loops->tree_root = &loops->array[0]; - loops->tree_root->outer = loops->tree_root->inner - = loops->tree_root->next = NULL; + slot = htab_find_slot_with_hash (current_loops->exits, e, + htab_hash_pointer (e), + exits ? INSERT : NO_INSERT); + if (!slot) + return; - /* Add the remaining loops to the tree. */ - for (i = 1; i < num_loops; i++) - flow_loop_tree_node_add (&loops->array[i - 1], &loops->array[i]); + if (exits) + { + if (*slot) + loop_exit_free (*slot); + *slot = exits; + } + else + htab_clear_slot (current_loops->exits, slot); } -/* Helper function to compute loop nesting depth and enclosed loop level - for the natural loop specified by LOOP at the loop depth DEPTH. - Returns the loop level. */ +/* For each loop, record list of exit edges, and start maintaining these + lists. */ -static int -flow_loop_level_compute (loop, depth) - struct loop *loop; - int depth; +void +record_loop_exits (void) { - struct loop *inner; - int level = 1; + basic_block bb; + edge_iterator ei; + edge e; - if (! loop) - return 0; + if (!current_loops) + return; - /* Traverse loop tree assigning depth and computing level as the - maximum level of all the inner loops of this loop. The loop - level is equivalent to the height of the loop in the loop tree - and corresponds to the number of enclosed loop levels (including - itself). */ - for (inner = loop->inner; inner; inner = inner->next) - { - int ilevel = flow_loop_level_compute (inner, depth + 1) + 1; + if (loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS)) + return; + loops_state_set (LOOPS_HAVE_RECORDED_EXITS); - level = MAX (ilevel, level); - } + 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); - loop->level = level; - loop->depth = depth; - return level; + FOR_EACH_BB (bb) + { + FOR_EACH_EDGE (e, ei, bb->succs) + { + rescan_loop_exit (e, true, false); + } + } } -/* Compute the loop nesting depth and enclosed loop level for the loop - hierarchy tree specified by LOOPS. Return the maximum enclosed loop - level. */ +/* Dumps information about the exit in *SLOT to FILE. + Callback for htab_traverse. */ static int -flow_loops_level_compute (loops) - struct loops *loops; +dump_recorded_exit (void **slot, void *file) { - int levels = 0; - struct loop *loop; - int level; + struct loop_exit *exit = (struct loop_exit *) *slot; + unsigned n = 0; + edge e = exit->e; + + for (; exit != NULL; exit = exit->next_e) + n++; - /* Traverse all the outer level loops. */ - for (loop = loops->tree_root; loop; loop = loop->next) + 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)) { - level = flow_loop_level_compute (loop, 1); - levels = MAX (levels, level); + 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 levels; + return edges; } -/* Scan a single natural loop specified by LOOP collecting information - about it specified by FLAGS. */ +/* Counts the number of conditional branches inside LOOP. */ -int -flow_loop_scan (loops, loop, flags) - struct loops *loops; - struct loop *loop; - int flags; +unsigned +num_loop_branches (const struct loop *loop) { - /* Determine prerequisites. */ - if ((flags & LOOP_EXITS_DOMS) && ! loop->exit_edges) - flags |= LOOP_EXIT_EDGES; + unsigned i, n; + basic_block * body; - if (flags & LOOP_ENTRY_EDGES) - /* Find edges which enter the loop header. Note that the entry edges - should only enter the header of a natural loop. */ - loop->num_entries = flow_loop_entry_edges_find (loop->header, loop->nodes, - &loop->entry_edges); + gcc_assert (loop->latch != EXIT_BLOCK_PTR); - if (flags & LOOP_EXIT_EDGES) - /* Find edges which exit the loop. */ - loop->num_exits - = flow_loop_exit_edges_find (loop->nodes, &loop->exit_edges); + 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); - if (flags & LOOP_EXITS_DOMS) - { - int j; + return n; +} - /* Determine which loop nodes dominate all the exits - of the loop. */ - loop->exits_doms = sbitmap_alloc (n_basic_blocks); - sbitmap_copy (loop->exits_doms, loop->nodes); - for (j = 0; j < loop->num_exits; j++) - sbitmap_a_and_b (loop->exits_doms, loop->exits_doms, - loops->cfg.dom[loop->exit_edges[j]->src->index]); +/* 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; - /* The header of a natural loop must dominate - all exits. */ - if (! TEST_BIT (loop->exits_doms, loop->header->index)) - abort (); + 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); } +} - if (flags & LOOP_PRE_HEADER) +/* 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) { - /* Look to see if the loop has a pre-header node. */ - loop->pre_header - = flow_loop_pre_header_find (loop->header, loops->cfg.dom); + rescan_loop_exit (e, false, true); + } + FOR_EACH_EDGE (e, ei, bb->preds) + { + rescan_loop_exit (e, false, true); + } +} - /* Find the blocks within the extended basic block of - the loop pre-header. */ - flow_loop_pre_header_scan (loop); +/* 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; +} - return 1; +/* 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); } -/* Find all the natural loops in the function and save in LOOPS structure and - recalculate loop_depth information in basic block structures. FLAGS - controls which loop information is collected. Return the number of natural - loops found. */ +/* Cancels the LOOP; it must be innermost one. */ -int -flow_loops_find (loops, flags) - struct loops *loops; - int flags; +static void +cancel_loop (struct loop *loop) { - int i; - int b; - int num_loops; - edge e; - sbitmap headers; - sbitmap *dom; - int *dfs_order; - int *rc_order; + basic_block *bbs; + unsigned i; + struct loop *outer = loop_outer (loop); - /* This function cannot be repeatedly called with different - flags to build up the loop information. The loop tree - must always be built if this function is called. */ - if (! (flags & LOOP_TREE)) - abort (); + gcc_assert (!loop->inner); - memset (loops, 0, sizeof *loops); + /* 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; - /* Taking care of this degenerate case makes the rest of - this code simpler. */ - if (n_basic_blocks == 0) - return 0; + delete_loop (loop); +} - dfs_order = NULL; - rc_order = NULL; +/* Cancels LOOP and all its subloops. */ +void +cancel_loop_tree (struct loop *loop) +{ + while (loop->inner) + cancel_loop_tree (loop->inner); + cancel_loop (loop); +} - /* Compute the dominators. */ - dom = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks); - calculate_dominance_info (NULL, dom, CDI_DOMINATORS); +/* 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; - /* Count the number of loop edges (back edges). This should be the - same as the number of natural loops. */ - num_loops = 0; - for (b = 0; b < n_basic_blocks; b++) - { - basic_block header; + /* Check sizes. */ + sizes = XCNEWVEC (unsigned, num); + sizes[0] = 2; - header = BASIC_BLOCK (b); - header->loop_depth = 0; + 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; - for (e = header->pred; e; e = e->pred_next) + if (loop->num_nodes != sizes[i]) { - basic_block latch = e->src; + error ("size of loop %d should be %d, not %d", + i, sizes[i], loop->num_nodes); + err = 1; + } + } - /* 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. Note that multiple natural loops - may share the same header. */ - if (b != header->index) - abort (); + /* 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 (latch != ENTRY_BLOCK_PTR && TEST_BIT (dom[latch->index], b)) - num_loops++; + 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; } } - if (num_loops) + /* Check irreducible loops. */ + if (loops_state_satisfies_p (LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)) { - /* Compute depth first search order of the CFG so that outer - natural loops will be found before inner natural loops. */ - dfs_order = (int *) xmalloc (n_basic_blocks * sizeof (int)); - rc_order = (int *) xmalloc (n_basic_blocks * sizeof (int)); - flow_depth_first_order_compute (dfs_order, rc_order); + /* 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; + } - /* Save CFG derived information to avoid recomputing it. */ - loops->cfg.dom = dom; - loops->cfg.dfs_order = dfs_order; - loops->cfg.rc_order = rc_order; + /* Recount it. */ + mark_irreducible_loops (); - /* Allocate loop structures. */ - loops->array - = (struct loop *) xcalloc (num_loops, sizeof (struct loop)); + /* Compare. */ + FOR_EACH_BB (bb) + { + edge_iterator ei; - headers = sbitmap_alloc (n_basic_blocks); - sbitmap_zero (headers); + 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); + } - loops->shared_headers = sbitmap_alloc (n_basic_blocks); - sbitmap_zero (loops->shared_headers); + /* 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; + } + } - /* Find and record information about all the natural loops - in the CFG. */ - num_loops = 0; - for (b = n_basic_blocks - 1; b >= 0; b--) + if (!loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS)) { - basic_block latch; + if (loop->exits->next != loop->exits) + { + error ("nonempty exits list of loop %d, but exits are not recorded", + loop->num); + err = 1; + } + } + } - /* Search the nodes of the CFG in reverse completion order - so that we can find outer loops first. */ - latch = BASIC_BLOCK (rc_order[b]); + if (loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS)) + { + unsigned n_exits = 0, eloops; - /* Look for all the possible headers for this latch block. */ - for (e = latch->succ; e; e = e->succ_next) + 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) { - basic_block header = e->dest; - - /* Look for forward edges where this block is dominated by - a successor of 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. Note that multiple natural loops may share - the same header. */ - if (header != EXIT_BLOCK_PTR - && TEST_BIT (dom[latch->index], header->index)) - { - struct loop *loop; + if (flow_bb_inside_loop_p (bb->loop_father, e->dest)) + continue; - loop = loops->array + num_loops; + 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++; - loop->header = header; - loop->latch = latch; - loop->num = num_loops; + for (loop = bb->loop_father; + loop != e->dest->loop_father; + loop = loop_outer (loop)) + { + eloops--; + sizes[loop->num]++; + } - num_loops++; + if (eloops != 0) + { + error ("Wrong list of exited loops for edge %d->%d", + e->src->index, e->dest->index); + err = 1; } } } - for (i = 0; i < num_loops; i++) + if (n_exits != htab_elements (current_loops->exits)) { - struct loop *loop = &loops->array[i]; - - /* Keep track of blocks that are loop headers so - that we can tell which loops should be merged. */ - if (TEST_BIT (headers, loop->header->index)) - SET_BIT (loops->shared_headers, loop->header->index); - SET_BIT (headers, loop->header->index); - - /* Find nodes contained within the loop. */ - loop->nodes = sbitmap_alloc (n_basic_blocks); - loop->num_nodes - = flow_loop_nodes_find (loop->header, loop->latch, loop->nodes); - - /* Compute first and last blocks within the loop. - These are often the same as the loop header and - loop latch respectively, but this is not always - the case. */ - loop->first - = BASIC_BLOCK (sbitmap_first_set_bit (loop->nodes)); - loop->last - = BASIC_BLOCK (sbitmap_last_set_bit (loop->nodes)); - - flow_loop_scan (loops, loop, flags); + error ("Too many loop exits recorded"); + err = 1; } - /* Natural loops with shared headers may either be disjoint or - nested. Disjoint loops with shared headers cannot be inner - loops and should be merged. For now just mark loops that share - headers. */ - for (i = 0; i < num_loops; i++) - if (TEST_BIT (loops->shared_headers, loops->array[i].header->index)) - loops->array[i].shared = 1; - - sbitmap_free (headers); + 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; + } + } } - else - sbitmap_vector_free (dom); - loops->num = num_loops; + 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; - /* Build the loop hierarchy tree. */ - flow_loops_tree_build (loops); + gcc_assert (loops_state_satisfies_p (LOOPS_HAVE_PREHEADERS)); - /* Assign the loop nesting depth and enclosed loop level for each - loop. */ - loops->levels = flow_loops_level_compute (loops); + FOR_EACH_EDGE (e, ei, loop->header->preds) + if (e->src != loop->latch) + break; - return num_loops; + return e; } -/* Update the information regarding the loops in the CFG - specified by LOOPS. */ +/* Returns true if E is an exit of LOOP. */ -int -flow_loops_update (loops, flags) - struct loops *loops; - int flags; +bool +loop_exit_edge_p (const struct loop *loop, const_edge e) { - /* One day we may want to update the current loop data. For now - throw away the old stuff and rebuild what we need. */ - if (loops->array) - flow_loops_free (loops); + 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. */ - return flow_loops_find (loops, flags); +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; } -/* Return non-zero if edge E enters header of LOOP from outside of LOOP. */ +/* Returns true when BB has an edge exiting LOOP. */ -int -flow_loop_outside_edge_p (loop, e) - const struct loop *loop; - edge e; +bool +is_loop_exit (struct loop *loop, basic_block bb) { - if (e->dest != loop->header) - abort (); + edge e; + edge_iterator ei; + + FOR_EACH_EDGE (e, ei, bb->preds) + if (loop_exit_edge_p (loop, e)) + return true; - return (e->src == ENTRY_BLOCK_PTR) - || ! TEST_BIT (loop->nodes, e->src->index); + return false; }