/* Natural loop discovery code for GNU compiler.
- Copyright (C) 2000, 2001 Free Software Foundation, Inc.
+ Copyright (C) 2000-2019 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
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
+<http://www.gnu.org/licenses/>. */
#include "config.h"
#include "system.h"
#include "coretypes.h"
-#include "tm.h"
+#include "backend.h"
#include "rtl.h"
-#include "hard-reg-set.h"
-#include "basic-block.h"
-#include "toplev.h"
-
-/* 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
-
-static void flow_loops_cfg_dump PARAMS ((const struct loops *,
- FILE *));
-static void flow_loop_entry_edges_find PARAMS ((struct loop *));
-static void flow_loop_exit_edges_find PARAMS ((struct loop *));
-static int flow_loop_nodes_find PARAMS ((basic_block, struct loop *));
-static void flow_loop_pre_header_scan PARAMS ((struct loop *));
-static basic_block flow_loop_pre_header_find PARAMS ((basic_block,
- dominance_info));
-static int flow_loop_level_compute PARAMS ((struct loop *));
-static int flow_loops_level_compute PARAMS ((struct loops *));
-static basic_block make_forwarder_block PARAMS ((basic_block, int, int,
- edge, int));
-static void canonicalize_loop_headers PARAMS ((void));
-static bool glb_enum_p PARAMS ((basic_block, void *));
-static void redirect_edge_with_latch_update PARAMS ((edge, basic_block));
-static void flow_loop_free PARAMS ((struct loop *));
+#include "tree.h"
+#include "gimple.h"
+#include "cfghooks.h"
+#include "gimple-ssa.h"
+#include "diagnostic-core.h"
+#include "cfganal.h"
+#include "cfgloop.h"
+#include "gimple-iterator.h"
+#include "dumpfile.h"
+
+static void flow_loops_cfg_dump (FILE *);
\f
/* 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_EACH_BB (bb)
+ FOR_EACH_BB_FN (bb, cfun)
{
edge succ;
+ edge_iterator ei;
fprintf (file, ";; %d succs { ", bb->index);
- for (succ = bb->succ; succ; succ = succ->succ_next)
+ FOR_EACH_EDGE (succ, ei, bb->succs)
fprintf (file, "%d ", succ->dest->index);
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
+ && (*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 (*loop->superloops)[depth];
}
-/* Return nonzero if the nodes of LOOP are a subset of OUTER. */
+/* Returns the list of the latch edges of LOOP. */
-bool
-flow_loop_nested_p (outer, loop)
- const struct loop *outer;
- const struct loop *loop;
+static vec<edge>
+get_loop_latch_edges (const struct loop *loop)
{
- return loop->depth > outer->depth
- && loop->pred[outer->depth] == outer;
+ 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 (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;
- int i;
+ unsigned i;
+ vec<edge> latches;
+ edge e;
if (! loop || ! loop->header)
return;
- fprintf (file, ";;\n;; Loop %d:%s\n", loop->num,
- 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, "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, ";; header %d, latch %d, pre-header %d\n",
- loop->header->index, loop->latch->index,
- loop->pre_header ? loop->pre_header->index : -1);
- fprintf (file, ";; depth %d, level %d, outer %ld\n",
- loop->depth, loop->level,
- (long) (loop->outer ? loop->outer->num : -1));
+ fprintf (file, ";; depth %d, outer %ld\n",
+ loop_depth (loop), (long) (loop_outer (loop)
+ ? loop_outer (loop)->num : -1));
- if (loop->pre_header_edges)
- flow_edge_list_print (";; pre-header edges", loop->pre_header_edges,
- loop->num_pre_header_edges, file);
+ if (loop->latch)
+ {
+ bool read_profile_p;
+ gcov_type nit = expected_loop_iterations_unbounded (loop, &read_profile_p);
+ if (read_profile_p && !loop->any_estimate)
+ fprintf (file, ";; profile-based iteration count: %" PRIu64 "\n",
+ (uint64_t) nit);
+ }
- flow_edge_list_print (";; entry edges", loop->entry_edges,
- loop->num_entries, file);
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");
- flow_edge_list_print (";; exit edges", loop->exit_edges,
- loop->num_exits, file);
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;
- int num_loops;
+ 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);
+ fprintf (file, ";; %d loops found\n", number_of_loops (cfun));
- for (i = 0; i < num_loops; i++)
+ FOR_EACH_LOOP (loop, LI_INCLUDE_ROOT)
{
- struct loop *loop = loops->parray[i];
-
- if (!loop)
- continue;
-
flow_loop_dump (loop, file, loop_dump_aux, verbose);
}
if (verbose)
- flow_loops_cfg_dump (loops, file);
+ flow_loops_cfg_dump (file);
}
/* Free data allocated for LOOP. */
-static void
-flow_loop_free (loop)
- struct loop *loop;
-{
- if (loop->pre_header_edges)
- free (loop->pre_header_edges);
- if (loop->entry_edges)
- free (loop->entry_edges);
- if (loop->exit_edges)
- free (loop->exit_edges);
- if (loop->pred)
- free (loop->pred);
- free (loop);
-}
-
-/* Free all the memory allocated for LOOPS. */
void
-flow_loops_free (loops)
- struct loops *loops;
-{
- if (loops->parray)
- {
- int i;
-
- if (! loops->num)
- abort ();
-
- /* Free the loop descriptors. */
- for (i = 0; i < loops->num; i++)
- {
- struct loop *loop = loops->parray[i];
-
- if (!loop)
- continue;
-
- flow_loop_free (loop);
- }
-
- free (loops->parray);
- loops->parray = NULL;
-
- if (loops->cfg.dom)
- free_dominance_info (loops->cfg.dom);
-
- if (loops->cfg.dfs_order)
- free (loops->cfg.dfs_order);
- if (loops->cfg.rc_order)
- free (loops->cfg.rc_order);
-
- }
-}
-
-/* Find the entry edges into the LOOP. */
-
-static void
-flow_loop_entry_edges_find (loop)
- struct loop *loop;
+flow_loop_free (struct loop *loop)
{
- edge e;
- int num_entries;
+ struct loop_exit *exit, *next;
- num_entries = 0;
- for (e = loop->header->pred; e; e = e->pred_next)
- {
- if (flow_loop_outside_edge_p (loop, e))
- num_entries++;
- }
-
- if (! num_entries)
- abort ();
-
- loop->entry_edges = (edge *) xmalloc (num_entries * sizeof (edge *));
+ vec_free (loop->superloops);
- num_entries = 0;
- for (e = loop->header->pred; e; e = e->pred_next)
+ /* 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)
{
- if (flow_loop_outside_edge_p (loop, e))
- loop->entry_edges[num_entries++] = e;
+ next = exit->next;
+ exit->next = exit;
+ exit->prev = exit;
}
- loop->num_entries = num_entries;
+ ggc_free (loop->exits);
+ ggc_free (loop);
}
-/* Find the exit edges from the LOOP. */
+/* Free all the memory allocated for LOOPS. */
-static void
-flow_loop_exit_edges_find (loop)
- struct loop *loop;
+void
+flow_loops_free (struct loops *loops)
{
- edge e;
- basic_block node, *bbs;
- int num_exits, i;
-
- loop->exit_edges = NULL;
- loop->num_exits = 0;
-
- /* 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. */
- num_exits = 0;
- bbs = get_loop_body (loop);
- for (i = 0; i < loop->num_nodes; i++)
+ if (loops->larray)
{
- node = bbs[i];
- for (e = node->succ; e; e = e->succ_next)
+ unsigned i;
+ loop_p loop;
+
+ /* Free the loop descriptors. */
+ FOR_EACH_VEC_SAFE_ELT (loops->larray, i, loop)
{
- basic_block dest = e->dest;
+ if (!loop)
+ continue;
- if (!flow_bb_inside_loop_p (loop, dest))
- num_exits++;
+ flow_loop_free (loop);
}
- }
-
- if (! num_exits)
- {
- free (bbs);
- return;
- }
-
- loop->exit_edges = (edge *) xmalloc (num_exits * sizeof (edge *));
-
- /* Store all exiting edges into an array. */
- num_exits = 0;
- for (i = 0; i < loop->num_nodes; i++)
- {
- node = bbs[i];
- for (e = node->succ; e; e = e->succ_next)
- {
- basic_block dest = e->dest;
- if (!flow_bb_inside_loop_p (loop, dest))
- loop->exit_edges[num_exits++] = e;
- }
+ vec_free (loops->larray);
}
- free (bbs);
- loop->num_exits = num_exits;
}
/* Find the nodes contained within the LOOP with header HEADER.
Return the number of nodes within the loop. */
-static int
-flow_loop_nodes_find (header, loop)
- basic_block header;
- struct loop *loop;
+int
+flow_loop_nodes_find (basic_block header, struct loop *loop)
{
- basic_block *stack;
- int sp;
+ vec<basic_block> stack = vNULL;
int num_nodes = 1;
+ edge latch;
+ edge_iterator latch_ei;
header->loop_father = loop;
- header->loop_depth = loop->depth;
- if (loop->latch->loop_father != loop)
+ FOR_EACH_EDGE (latch, latch_ei, loop->header->preds)
{
- stack = (basic_block *) xmalloc (n_basic_blocks * sizeof (basic_block));
- sp = 0;
+ if (latch->src->loop_father == loop
+ || !dominated_by_p (CDI_DOMINATORS, latch->src, loop->header))
+ continue;
+
num_nodes++;
- stack[sp++] = loop->latch;
- loop->latch->loop_father = loop;
- loop->latch->loop_depth = loop->depth;
-
- while (sp)
+ 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 ();
- node = stack[--sp];
-
- for (e = node->pred; e; e = e->pred_next)
+ FOR_EACH_EDGE (e, ei, node->preds)
{
basic_block ancestor = e->src;
- if (ancestor != ENTRY_BLOCK_PTR
- && ancestor->loop_father != loop)
+ if (ancestor->loop_father != loop)
{
ancestor->loop_father = loop;
- ancestor->loop_depth = loop->depth;
num_nodes++;
- stack[sp++] = ancestor;
+ stack.safe_push (ancestor);
}
}
}
- free (stack);
}
+ stack.release ();
+
return num_nodes;
}
-/* 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. */
+/* Records the vector of superloops of the loop LOOP, whose immediate
+ superloop is FATHER. */
static void
-flow_loop_pre_header_scan (loop)
- struct loop *loop;
-{
- int num;
- basic_block ebb;
- edge e;
-
- loop->num_pre_header_edges = 0;
- if (loop->num_entries != 1)
- return;
-
- ebb = loop->entry_edges[0]->src;
- if (ebb == ENTRY_BLOCK_PTR)
- return;
-
- /* 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;
-
- loop->pre_header_edges = (edge *) xmalloc (num * sizeof (edge));
- loop->num_pre_header_edges = num;
-
- /* 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 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. */
-
-static basic_block
-flow_loop_pre_header_find (header, dom)
- basic_block header;
- dominance_info dom;
+establish_preds (struct loop *loop, struct loop *father)
{
- basic_block pre_header;
- edge e;
-
- /* 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)
- {
- basic_block node = e->src;
-
- if (node != ENTRY_BLOCK_PTR
- && ! dominated_by_p (dom, node, header))
- {
- if (pre_header == NULL)
- pre_header = node;
- else
- {
- /* There are multiple edges into the header from outside
- the loop so there is no pre-header block. */
- pre_header = NULL;
- break;
- }
- }
- }
-
- return pre_header;
+ 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. */
+ added loop. If LOOP has some children, take care of that their
+ pred field will be initialized correctly. If AFTER is non-null
+ then it's expected it's a pointer into FATHERs inner sibling
+ list and LOOP is added behind AFTER, otherwise it's added in front
+ of FATHERs siblings. */
void
-flow_loop_tree_node_add (father, loop)
- struct loop *father;
- struct loop *loop;
+flow_loop_tree_node_add (struct loop *father, struct loop *loop,
+ struct loop *after)
{
- loop->next = father->inner;
- father->inner = loop;
- loop->outer = father;
+ if (after)
+ {
+ loop->next = after->next;
+ after->next = loop;
+ }
+ else
+ {
+ loop->next = father->inner;
+ father->inner = loop;
+ }
- loop->depth = father->depth + 1;
- loop->pred = xmalloc (sizeof (struct loop *) * loop->depth);
- memcpy (loop->pred, father->pred, sizeof (struct loop *) * father->depth);
- loop->pred[father->depth] = father;
+ establish_preds (loop, father);
}
/* Remove LOOP from the loop hierarchy tree. */
void
-flow_loop_tree_node_remove (loop)
- struct loop *loop;
+flow_loop_tree_node_remove (struct loop *loop)
{
struct loop *prev, *father;
- father = loop->outer;
- loop->outer = NULL;
+ 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);
+ for (prev = father->inner; prev->next != loop; prev = prev->next)
+ continue;
prev->next = loop->next;
}
- loop->depth = -1;
- free (loop->pred);
- loop->pred = NULL;
+ loop->superloops = NULL;
}
-/* Helper function to compute loop nesting depth and enclosed loop level
- for the natural loop specified by LOOP. Returns the loop level. */
+/* Allocates and returns new loop structure. */
-static int
-flow_loop_level_compute (loop)
- struct loop *loop;
+struct loop *
+alloc_loop (void)
{
- struct loop *inner;
- int level = 1;
-
- if (! loop)
- return 0;
-
- /* 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) + 1;
-
- if (ilevel > level)
- level = ilevel;
- }
-
- loop->level = level;
- return level;
+ struct loop *loop = ggc_cleared_alloc<struct loop> ();
+
+ loop->exits = ggc_cleared_alloc<loop_exit> ();
+ loop->exits->next = loop->exits->prev = loop->exits;
+ loop->can_be_parallel = false;
+ loop->constraints = 0;
+ loop->nb_iterations_upper_bound = 0;
+ loop->nb_iterations_likely_upper_bound = 0;
+ loop->nb_iterations_estimate = 0;
+ return loop;
}
-/* Compute the loop nesting depth and enclosed loop level for the loop
- hierarchy tree specified by LOOPS. Return the maximum enclosed loop
- level. */
+/* Initializes loops structure LOOPS, reserving place for NUM_LOOPS loops
+ (including the root of the loop tree). */
-static int
-flow_loops_level_compute (loops)
- struct loops *loops;
+void
+init_loops_structure (struct function *fn,
+ struct loops *loops, unsigned num_loops)
{
- return flow_loop_level_compute (loops->tree_root);
+ 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_for_fn (fn);
+ root->latch = EXIT_BLOCK_PTR_FOR_FN (fn);
+ root->header = ENTRY_BLOCK_PTR_FOR_FN (fn);
+ ENTRY_BLOCK_PTR_FOR_FN (fn)->loop_father = root;
+ EXIT_BLOCK_PTR_FOR_FN (fn)->loop_father = root;
+
+ loops->larray->quick_push (root);
+ loops->tree_root = root;
}
-/* Scan a single natural loop specified by LOOP collecting information
- about it specified by FLAGS. */
+/* Returns whether HEADER is a loop header. */
-int
-flow_loop_scan (loops, loop, flags)
- struct loops *loops;
- struct loop *loop;
- int flags;
+bool
+bb_loop_header_p (basic_block header)
{
- 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. */
- flow_loop_entry_edges_find (loop);
- }
-
- if (flags & LOOP_EXIT_EDGES)
- {
- /* Find edges which exit the loop. */
- flow_loop_exit_edges_find (loop);
- }
+ edge_iterator ei;
+ edge e;
- if (flags & LOOP_PRE_HEADER)
+ /* 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)
{
- /* Look to see if the loop has a pre-header node. */
- loop->pre_header
- = flow_loop_pre_header_find (loop->header, loops->cfg.dom);
-
- /* Find the blocks within the extended basic block of
- the loop pre-header. */
- flow_loop_pre_header_scan (loop);
+ basic_block latch = e->src;
+ if (latch != ENTRY_BLOCK_PTR_FOR_FN (cfun)
+ && dominated_by_p (CDI_DOMINATORS, latch, header))
+ return true;
}
- return 1;
+ return false;
}
-#define HEADER_BLOCK(B) (* (int *) (B)->aux)
-#define LATCH_EDGE(E) (*(int *) (E)->aux)
-
-/* Redirect edge and update latch and header info. */
-static void
-redirect_edge_with_latch_update (e, to)
- edge e;
- basic_block to;
+/* 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)
{
- basic_block jump;
+ bool from_scratch = (loops == NULL);
+ int *rc_order;
+ int b;
+ unsigned i;
- jump = redirect_edge_and_branch_force (e, to);
- if (jump)
+ /* Ensure that the dominators are computed. */
+ calculate_dominance_info (CDI_DOMINATORS);
+
+ if (!loops)
{
- alloc_aux_for_block (jump, sizeof (int));
- HEADER_BLOCK (jump) = 0;
- alloc_aux_for_edge (jump->pred, sizeof (int));
- LATCH_EDGE (jump->succ) = LATCH_EDGE (e);
- LATCH_EDGE (jump->pred) = 0;
+ loops = ggc_cleared_alloc<struct loops> ();
+ init_loops_structure (cfun, loops, 1);
}
-}
-/* Split BB into entry part and rest; if REDIRECT_LATCH, redirect edges
- marked as latch into entry part, analogically for REDIRECT_NONLATCH.
- In both of these cases, ignore edge EXCEPT. If CONN_LATCH, set edge
- between created entry part and BB as latch one. Return created entry
- part. */
+ /* Ensure that loop exits were released. */
+ gcc_assert (loops->exits == NULL);
-static basic_block
-make_forwarder_block (bb, redirect_latch, redirect_nonlatch, except,
- conn_latch)
- basic_block bb;
- int redirect_latch;
- int redirect_nonlatch;
- edge except;
- int conn_latch;
-{
- edge e, next_e, fallthru;
- basic_block dummy;
- rtx insn;
-
- insn = PREV_INSN (first_insn_after_basic_block_note (bb));
+ /* Taking care of this degenerate case makes the rest of
+ this code simpler. */
+ if (n_basic_blocks_for_fn (cfun) == NUM_FIXED_BLOCKS)
+ return loops;
- fallthru = split_block (bb, insn);
- dummy = fallthru->src;
- bb = fallthru->dest;
+ /* The root loop node contains all basic-blocks. */
+ loops->tree_root->num_nodes = n_basic_blocks_for_fn (cfun);
- bb->aux = xmalloc (sizeof (int));
- HEADER_BLOCK (dummy) = 0;
- HEADER_BLOCK (bb) = 1;
+ /* 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_for_fn (cfun));
+ pre_and_rev_post_order_compute (NULL, rc_order, false);
- /* Redirect back edges we want to keep. */
- for (e = dummy->pred; e; e = next_e)
+ /* Gather all loop headers in reverse completion order and allocate
+ loop structures for loops that are not already present. */
+ auto_vec<loop_p> larray (loops->larray->length ());
+ for (b = 0; b < n_basic_blocks_for_fn (cfun) - NUM_FIXED_BLOCKS; b++)
{
- next_e = e->pred_next;
- if (e == except
- || !((redirect_latch && LATCH_EDGE (e))
- || (redirect_nonlatch && !LATCH_EDGE (e))))
+ basic_block header = BASIC_BLOCK_FOR_FN (cfun, rc_order[b]);
+ if (bb_loop_header_p (header))
{
- dummy->frequency -= EDGE_FREQUENCY (e);
- dummy->count -= e->count;
- if (dummy->frequency < 0)
- dummy->frequency = 0;
- if (dummy->count < 0)
- dummy->count = 0;
- redirect_edge_with_latch_update (e, bb);
- }
- }
-
- alloc_aux_for_edge (fallthru, sizeof (int));
- LATCH_EDGE (fallthru) = conn_latch;
+ struct loop *loop;
- return dummy;
-}
+ /* 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);
+ }
-/* Takes care of merging natural loops with shared headers. */
-static void
-canonicalize_loop_headers ()
-{
- dominance_info dom;
- basic_block header;
- edge e;
-
- /* Compute the dominators. */
- dom = calculate_dominance_info (CDI_DOMINATORS);
+ /* Make blocks part of the loop root node at start. */
+ header->loop_father = loops->tree_root;
+ }
- alloc_aux_for_blocks (sizeof (int));
- alloc_aux_for_edges (sizeof (int));
+ free (rc_order);
- /* Split blocks so that each loop has only single latch. */
- FOR_EACH_BB (header)
+ /* Now iterate over the loops found, insert them into the loop tree
+ and assign basic-block ownership. */
+ for (i = 0; i < larray.length (); ++i)
{
- int num_latches = 0;
- int have_abnormal_edge = 0;
+ 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);
- for (e = header->pred; e; e = e->pred_next)
+ /* 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 (e->flags & EDGE_ABNORMAL)
- have_abnormal_edge = 1;
-
- if (latch != ENTRY_BLOCK_PTR
- && dominated_by_p (dom, latch, header))
+ if (flow_bb_inside_loop_p (loop, latch))
{
- num_latches++;
- LATCH_EDGE (e) = 1;
+ if (loop->latch != NULL)
+ {
+ /* More than one latch edge. */
+ loop->latch = NULL;
+ break;
+ }
+ loop->latch = latch;
}
}
- if (have_abnormal_edge)
- HEADER_BLOCK (header) = 0;
- else
- HEADER_BLOCK (header) = num_latches;
- }
-
- if (HEADER_BLOCK (ENTRY_BLOCK_PTR->succ->dest))
- {
- basic_block bb;
-
- /* We could not redirect edges freely here. On the other hand,
- we can simply split the edge from entry block. */
- bb = split_edge (ENTRY_BLOCK_PTR->succ);
-
- alloc_aux_for_edge (bb->succ, sizeof (int));
- LATCH_EDGE (bb->succ) = 0;
- alloc_aux_for_block (bb, sizeof (int));
- HEADER_BLOCK (bb) = 0;
}
- FOR_EACH_BB (header)
- {
- int num_latch;
- int want_join_latch;
- int max_freq, is_heavy;
- edge heavy;
-
- if (!HEADER_BLOCK (header))
- continue;
+ return loops;
+}
- num_latch = HEADER_BLOCK (header);
+/* qsort helper for sort_sibling_loops. */
- want_join_latch = (num_latch > 1);
+static int *sort_sibling_loops_cmp_rpo;
+static int
+sort_sibling_loops_cmp (const void *la_, const void *lb_)
+{
+ const struct loop *la = *(const struct loop * const *)la_;
+ const struct loop *lb = *(const struct loop * const *)lb_;
+ return (sort_sibling_loops_cmp_rpo[la->header->index]
+ - sort_sibling_loops_cmp_rpo[lb->header->index]);
+}
- if (!want_join_latch)
- continue;
+/* Sort sibling loops in RPO order. */
- /* Find a heavy edge. */
- is_heavy = 1;
- heavy = NULL;
- max_freq = 0;
- for (e = header->pred; e; e = e->pred_next)
- if (LATCH_EDGE (e) &&
- EDGE_FREQUENCY (e) > max_freq)
- max_freq = EDGE_FREQUENCY (e);
- for (e = header->pred; e; e = e->pred_next)
- if (LATCH_EDGE (e) &&
- EDGE_FREQUENCY (e) >= max_freq / HEAVY_EDGE_RATIO)
+void
+sort_sibling_loops (function *fn)
+{
+ /* Match flow_loops_find in the order we sort sibling loops. */
+ sort_sibling_loops_cmp_rpo = XNEWVEC (int, last_basic_block_for_fn (cfun));
+ int *rc_order = XNEWVEC (int, n_basic_blocks_for_fn (cfun));
+ pre_and_rev_post_order_compute_fn (fn, NULL, rc_order, false);
+ for (int i = 0; i < n_basic_blocks_for_fn (cfun) - NUM_FIXED_BLOCKS; ++i)
+ sort_sibling_loops_cmp_rpo[rc_order[i]] = i;
+ free (rc_order);
+
+ auto_vec<loop_p, 3> siblings;
+ loop_p loop;
+ FOR_EACH_LOOP_FN (fn, loop, LI_INCLUDE_ROOT)
+ if (loop->inner && loop->inner->next)
+ {
+ loop_p sibling = loop->inner;
+ do
+ {
+ siblings.safe_push (sibling);
+ sibling = sibling->next;
+ }
+ while (sibling);
+ siblings.qsort (sort_sibling_loops_cmp);
+ loop_p *siblingp = &loop->inner;
+ for (unsigned i = 0; i < siblings.length (); ++i)
{
- if (heavy)
- {
- is_heavy = 0;
- break;
- }
- else
- heavy = e;
+ *siblingp = siblings[i];
+ siblingp = &(*siblingp)->next;
}
+ *siblingp = NULL;
+ siblings.truncate (0);
+ }
+
+ free (sort_sibling_loops_cmp_rpo);
+ sort_sibling_loops_cmp_rpo = NULL;
+}
+
+/* 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 (is_heavy)
+/* 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;
+ profile_count mcount = profile_count::zero (), tcount = profile_count::zero ();
+
+ FOR_EACH_VEC_ELT (latches, i, e)
+ {
+ if (e->count ()> mcount)
{
- basic_block new_header =
- make_forwarder_block (header, true, true, heavy, 0);
- if (num_latch > 2)
- make_forwarder_block (new_header, true, false, NULL, 1);
+ me = e;
+ mcount = e->count();
}
- else
- make_forwarder_block (header, true, false, NULL, 1);
+ tcount += e->count();
}
- free_aux_for_blocks ();
- free_aux_for_edges ();
- free_dominance_info (dom);
+ if (!tcount.initialized_p () || !(tcount.ipa () > HEAVY_EDGE_MIN_SAMPLES)
+ || (tcount - mcount).apply_scale (HEAVY_EDGE_RATIO, 1) > 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;
}
-/* 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. */
+/* 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.
-int
-flow_loops_find (loops, flags)
- struct loops *loops;
- int flags;
+ 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)
{
- int i;
- int b;
- int num_loops;
- edge e;
- sbitmap headers;
- dominance_info dom;
- int *dfs_order;
- int *rc_order;
- basic_block header;
+ edge e, latch = latches[0];
+ unsigned i;
+ gphi *phi;
+ gphi_iterator psi;
+ tree lop;
basic_block bb;
- /* 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 ();
+ /* 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;
- memset (loops, 0, sizeof *loops);
+ /* 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;
- /* Taking care of this degenerate case makes the rest of
- this code simpler. */
- if (n_basic_blocks == 0)
- return 0;
+ /* 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 = psi.phi ();
+ 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;
- dfs_order = NULL;
- rc_order = NULL;
+ FOR_EACH_VEC_ELT (latches, i, e)
+ if (e != latch
+ && PHI_ARG_DEF_FROM_EDGE (phi, e) == lop)
+ return NULL;
+ }
- /* Join loops with shared headers. */
- canonicalize_loop_headers ();
+ if (dump_file)
+ fprintf (dump_file,
+ "Found latch edge %d -> %d using iv structure.\n",
+ latch->src->index, latch->dest->index);
+ return latch;
+}
- /* Compute the dominators. */
- dom = loops->cfg.dom = calculate_dominance_info (CDI_DOMINATORS);
+/* 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. */
- /* 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);
+static edge
+find_subloop_latch_edge (struct loop *loop)
+{
+ vec<edge> latches = get_loop_latch_edges (loop);
+ edge latch = NULL;
- num_loops = 0;
- FOR_EACH_BB (header)
+ if (latches.length () > 1)
{
- int more_latches = 0;
-
- header->loop_depth = 0;
+ 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);
+ }
- for (e = header->pred; e; e = e->pred_next)
- {
- basic_block latch = e->src;
+ latches.release ();
+ return latch;
+}
- if (e->flags & EDGE_ABNORMAL)
- {
- if (more_latches)
- {
- RESET_BIT (headers, header->index);
- num_loops--;
- }
- break;
- }
+/* Callback for make_forwarder_block. Returns true if the edge E is marked
+ in the set MFB_REIS_SET. */
- /* 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 (dom, latch, header))
- {
- /* Shared headers should be eliminated by now. */
- if (more_latches)
- abort ();
- more_latches = 1;
- SET_BIT (headers, header->index);
- num_loops++;
- }
- }
- }
+static hash_set<edge> *mfb_reis_set;
+static bool
+mfb_redirect_edges_in_set (edge e)
+{
+ return mfb_reis_set->contains (e);
+}
- /* Allocate loop structures. */
- loops->parray = (struct loop **) xcalloc (num_loops + 1, sizeof (struct loop *));
+/* Creates a subloop of LOOP with latch edge LATCH. */
- /* Dummy loop containing whole function. */
- loops->parray[0] = xcalloc (1, sizeof (struct loop));
- loops->parray[0]->next = NULL;
- loops->parray[0]->inner = NULL;
- loops->parray[0]->outer = NULL;
- loops->parray[0]->depth = 0;
- loops->parray[0]->pred = NULL;
- loops->parray[0]->num_nodes = n_basic_blocks + 2;
- loops->parray[0]->latch = EXIT_BLOCK_PTR;
- loops->parray[0]->header = ENTRY_BLOCK_PTR;
- ENTRY_BLOCK_PTR->loop_father = loops->parray[0];
- EXIT_BLOCK_PTR->loop_father = loops->parray[0];
-
- loops->tree_root = loops->parray[0];
-
- /* Find and record information about all the natural loops
- in the CFG. */
- loops->num = 1;
- FOR_EACH_BB (bb)
- bb->loop_father = loops->tree_root;
-
- if (num_loops)
+static void
+form_subloop (struct loop *loop, edge latch)
+{
+ edge_iterator ei;
+ edge e, new_entry;
+ struct loop *new_loop;
+
+ mfb_reis_set = new hash_set<edge>;
+ FOR_EACH_EDGE (e, ei, loop->header->preds)
{
- /* 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);
+ if (e != latch)
+ mfb_reis_set->add (e);
+ }
+ new_entry = make_forwarder_block (loop->header, mfb_redirect_edges_in_set,
+ NULL);
+ delete 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);
+}
- /* Save CFG derived information to avoid recomputing it. */
- loops->cfg.dom = dom;
- loops->cfg.dfs_order = dfs_order;
- loops->cfg.rc_order = rc_order;
+/* Make all the latch edges of LOOP to go to a single forwarder block --
+ a new latch of LOOP. */
- num_loops = 1;
+static void
+merge_latch_edges (struct loop *loop)
+{
+ vec<edge> latches = get_loop_latch_edges (loop);
+ edge latch, e;
+ unsigned i;
- for (b = 0; b < n_basic_blocks; b++)
- {
- struct loop *loop;
+ gcc_assert (latches.length () > 0);
- /* 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;
+ 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 = new hash_set<edge>;
+ FOR_EACH_VEC_ELT (latches, i, e)
+ mfb_reis_set->add (e);
+ latch = make_forwarder_block (loop->header, mfb_redirect_edges_in_set,
+ NULL);
+ delete mfb_reis_set;
+
+ loop->header = latch->dest;
+ loop->latch = latch->src;
+ }
- header = BASIC_BLOCK (rc_order[b]);
-
- loop = loops->parray[num_loops] = xcalloc (1, sizeof (struct loop));
+ latches.release ();
+}
- loop->header = header;
- loop->num = num_loops;
- num_loops++;
+/* LOOP may have several latch edges. Transform it into (possibly several)
+ loops with single latch edge. */
- /* Look for the latch for this header block. */
- for (e = header->pred; e; e = e->pred_next)
- {
- basic_block latch = e->src;
+static void
+disambiguate_multiple_latches (struct loop *loop)
+{
+ edge e;
- if (latch != ENTRY_BLOCK_PTR
- && dominated_by_p (dom, latch, header))
- {
- loop->latch = latch;
- break;
- }
- }
+ /* 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_FOR_FN (cfun), loop->header);
+ if (e)
+ split_edge (e);
+
+ while (1)
+ {
+ e = find_subloop_latch_edge (loop);
+ if (!e)
+ break;
- flow_loop_tree_node_add (header->loop_father, loop);
- loop->num_nodes = flow_loop_nodes_find (loop->header, loop);
- }
+ form_subloop (loop, e);
+ }
+
+ merge_latch_edges (loop);
+}
+
+/* Split loops with multiple latch edges. */
+
+void
+disambiguate_loops_with_multiple_latches (void)
+{
+ struct loop *loop;
+
+ FOR_EACH_LOOP (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_FOR_FN (cfun)
+ || bb == EXIT_BLOCK_PTR_FOR_FN (cfun))
+ 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);
+}
- sbitmap_free (headers);
+/* 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;
- /* Assign the loop nesting depth and enclosed loop level for each
- loop. */
- loops->levels = flow_loops_level_compute (loops);
+ gcc_assert (loop->num_nodes);
- /* Scan the loops. */
- for (i = 1; i < num_loops; i++)
- flow_loop_scan (loops, loops->parray[i], flags);
+ body = XNEWVEC (basic_block, loop->num_nodes);
- loops->num = num_loops;
+ if (loop->latch == EXIT_BLOCK_PTR_FOR_FN (cfun))
+ {
+ /* 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_for_fn (cfun));
+ body[tv++] = loop->header;
+ body[tv++] = EXIT_BLOCK_PTR_FOR_FN (cfun);
+ FOR_EACH_BB_FN (bb, cfun)
+ 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))
{
- loops->cfg.dom = NULL;
- free_dominance_info (dom);
+ 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);
}
-#ifdef ENABLE_CHECKING
- verify_flow_info ();
- verify_loop_structure (loops, 0);
-#endif
- return loops->num;
+ if (postpone)
+ fill_sons_in_loop (loop, postpone, tovisit, tv);
}
-/* Update the information regarding the loops in the CFG
- specified by LOOPS. */
+/* 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. */
-int
-flow_loops_update (loops, flags)
- struct loops *loops;
- int flags;
+basic_block *
+get_loop_body_in_dom_order (const struct loop *loop)
{
- /* 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->parray)
- flow_loops_free (loops);
+ basic_block *tovisit;
+ int tv;
+
+ gcc_assert (loop->num_nodes);
+
+ tovisit = XNEWVEC (basic_block, loop->num_nodes);
+
+ gcc_assert (loop->latch != EXIT_BLOCK_PTR_FOR_FN (cfun));
+
+ tv = 0;
+ fill_sons_in_loop (loop, loop->header, tovisit, &tv);
- return flow_loops_find (loops, flags);
+ gcc_assert (tv == (int) loop->num_nodes);
+
+ return tovisit;
}
-/* Return nonzero if basic block BB belongs to LOOP. */
-bool
-flow_bb_inside_loop_p (loop, bb)
- const struct loop *loop;
- const basic_block bb;
+/* 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 *))
{
- struct loop *source_loop;
+ basic_block *bbs = get_loop_body (loop);
- if (bb == ENTRY_BLOCK_PTR || bb == EXIT_BLOCK_PTR)
- return 0;
+ qsort (bbs, loop->num_nodes, sizeof (basic_block), bb_comparator);
- source_loop = bb->loop_father;
- return loop == source_loop || flow_loop_nested_p (loop, source_loop);
+ 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;
+ unsigned int i = 1;
+ unsigned int vc = 0;
+
+ gcc_assert (loop->num_nodes);
+ gcc_assert (loop->latch != EXIT_BLOCK_PTR_FOR_FN (cfun));
+
+ blocks = XNEWVEC (basic_block, loop->num_nodes);
+ auto_bitmap visited;
+ blocks[0] = loop->header;
+ bitmap_set_bit (visited, loop->header->index);
+ while (i < loop->num_nodes)
+ {
+ edge e;
+ edge_iterator ei;
+ gcc_assert (i > vc);
+ bb = blocks[vc++];
+
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ {
+ if (flow_bb_inside_loop_p (loop, e->dest))
+ {
+ /* This bb is now visited. */
+ if (bitmap_set_bit (visited, e->dest->index))
+ blocks[i++] = e->dest;
+ }
+ }
+ }
+
+ return blocks;
+}
+
+/* Hash function for struct loop_exit. */
+
+hashval_t
+loop_exit_hasher::hash (loop_exit *exit)
+{
+ return htab_hash_pointer (exit->e);
}
-/* Return nonzero if edge E enters header of LOOP from outside of LOOP. */
+/* Equality function for struct loop_exit. Compares with edge. */
bool
-flow_loop_outside_edge_p (loop, e)
- const struct loop *loop;
- edge e;
+loop_exit_hasher::equal (loop_exit *exit, edge e)
{
- if (e->dest != loop->header)
- abort ();
- return !flow_bb_inside_loop_p (loop, e->src);
+ return exit->e == e;
}
-/* Enumeration predicate for get_loop_body. */
-static bool
-glb_enum_p (bb, glb_header)
- basic_block bb;
- void *glb_header;
+/* Frees the list of loop exit descriptions EX. */
+
+void
+loop_exit_hasher::remove (loop_exit *exit)
{
- return bb != (basic_block) glb_header;
+ loop_exit *next;
+ for (; exit; exit = next)
+ {
+ next = exit->next_e;
+
+ exit->next->prev = exit->prev;
+ exit->prev->next = exit->next;
+
+ ggc_free (exit);
+ }
}
-/* Gets basic blocks of a loop. */
-basic_block *
-get_loop_body (loop)
- const struct loop *loop;
+/* Returns the list of records for E as an exit of a loop. */
+
+static struct loop_exit *
+get_exit_descriptions (edge e)
{
- basic_block *tovisit, bb;
- int tv = 0;
+ return current_loops->exits->find_with_hash (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. */
- if (!loop->num_nodes)
- abort ();
+void
+rescan_loop_exit (edge e, bool new_edge, bool removed)
+{
+ struct loop_exit *exits = NULL, *exit;
+ struct loop *aloop, *cloop;
- tovisit = xcalloc (loop->num_nodes, sizeof (basic_block));
- tovisit[tv++] = loop->header;
+ if (!loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS))
+ return;
- if (loop->latch == EXIT_BLOCK_PTR)
+ if (!removed
+ && e->src->loop_father != NULL
+ && e->dest->loop_father != NULL
+ && !flow_bb_inside_loop_p (e->src->loop_father, e->dest))
{
- /* There may be blocks unreachable from EXIT_BLOCK. */
- if (loop->num_nodes != n_basic_blocks + 2)
- abort ();
- FOR_EACH_BB (bb)
- tovisit[tv++] = bb;
- tovisit[tv++] = EXIT_BLOCK_PTR;
+ 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;
+ }
}
- else if (loop->latch != loop->header)
+
+ if (!exits && new_edge)
+ return;
+
+ loop_exit **slot
+ = current_loops->exits->find_slot_with_hash (e, htab_hash_pointer (e),
+ exits ? INSERT : NO_INSERT);
+ if (!slot)
+ return;
+
+ if (exits)
{
- tv = dfs_enumerate_from (loop->latch, 1, glb_enum_p,
- tovisit + 1, loop->num_nodes - 1,
- loop->header) + 1;
+ if (*slot)
+ loop_exit_hasher::remove (*slot);
+ *slot = exits;
}
+ else
+ current_loops->exits->clear_slot (slot);
+}
- if (tv != loop->num_nodes)
- abort ();
- return tovisit;
+/* 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
+ = hash_table<loop_exit_hasher>::create_ggc (2 * number_of_loops (cfun));
+
+ FOR_EACH_BB_FN (bb, cfun)
+ {
+ 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. */
+
+int
+dump_recorded_exit (loop_exit **slot, FILE *file)
+{
+ struct loop_exit *exit = *slot;
+ unsigned n = 0;
+ edge e = exit->e;
+
+ for (; exit != NULL; exit = exit->next_e)
+ n++;
+
+ fprintf (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;
+ current_loops->exits->traverse<FILE *, dump_recorded_exit> (file);
+}
+
+/* Releases lists of loop exits. */
+
+void
+release_recorded_exits (function *fn)
+{
+ gcc_assert (loops_state_satisfies_p (fn, LOOPS_HAVE_RECORDED_EXITS));
+ loops_for_fn (fn)->exits->empty ();
+ loops_for_fn (fn)->exits = NULL;
+ loops_state_clear (fn, 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_FOR_FN (cfun));
+
+ /* 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_FOR_FN (cfun));
+
+ 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 (bb, loop)
- basic_block bb;
- struct loop *loop;
- {
- int i;
-
- bb->loop_father = loop;
- bb->loop_depth = loop->depth;
- loop->num_nodes++;
- for (i = 0; i < loop->depth; i++)
- loop->pred[i]->num_nodes++;
- }
+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 (bb)
- basic_block bb;
- {
- int i;
- struct loop *loop = bb->loop_father;
-
- loop->num_nodes--;
- for (i = 0; i < loop->depth; i++)
- loop->pred[i]->num_nodes--;
- bb->loop_father = NULL;
- bb->loop_depth = 0;
- }
+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 (loop_s, loop_d)
- struct loop *loop_s;
- struct loop *loop_d;
+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;
-
- if (loop_s->depth < loop_d->depth)
- loop_d = loop_d->pred[loop_s->depth];
- else if (loop_s->depth > loop_d->depth)
- loop_s = loop_s->pred[loop_d->depth];
+
+ 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_s->outer;
- loop_d = loop_d->outer;
+ loop_s = loop_outer (loop_s);
+ loop_d = loop_outer (loop_d);
}
return loop_s;
}
-/* Checks that LOOPS are allright:
- -- sizes of loops are allright
+/* 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
*/
-void
-verify_loop_structure (loops, flags)
- struct loops *loops;
- int flags;
+DEBUG_FUNCTION void
+verify_loop_structure (void)
{
- int *sizes, i, j;
- basic_block *bbs, bb;
+ unsigned *sizes, i, j;
+ basic_block bb, *bbs;
struct loop *loop;
int err = 0;
+ edge e;
+ unsigned num = number_of_loops (cfun);
+ struct loop_exit *exit, *mexit;
+ bool dom_available = dom_info_available_p (CDI_DOMINATORS);
+
+ if (loops_state_satisfies_p (LOOPS_NEED_FIXUP))
+ {
+ error ("loop verification on loop tree that needs fixup");
+ err = 1;
+ }
+
+ /* 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 = xcalloc (loops->num, sizeof (int));
- sizes[0] = 2;
+ /* Check the loop tree root. */
+ if (current_loops->tree_root->header != ENTRY_BLOCK_PTR_FOR_FN (cfun)
+ || current_loops->tree_root->latch != EXIT_BLOCK_PTR_FOR_FN (cfun)
+ || (current_loops->tree_root->num_nodes
+ != (unsigned) n_basic_blocks_for_fn (cfun)))
+ {
+ error ("corrupt loop tree root");
+ err = 1;
+ }
- FOR_EACH_BB (bb)
- for (loop = bb->loop_father; loop; loop = loop->outer)
- sizes[loop->num]++;
+ /* Check the headers. */
+ FOR_EACH_BB_FN (bb, cfun)
+ if (bb_loop_header_p (bb))
+ {
+ if (bb->loop_father->header == NULL)
+ {
+ error ("loop with header %d marked for removal", bb->index);
+ err = 1;
+ }
+ else if (bb->loop_father->header != bb)
+ {
+ error ("loop with header %d not in loop tree", bb->index);
+ err = 1;
+ }
+ }
+ else if (bb->loop_father->header == bb)
+ {
+ error ("non-loop with header %d not marked for removal", bb->index);
+ err = 1;
+ }
- for (i = 0; i < loops->num; i++)
+ /* Check the recorded loop father and sizes of loops. */
+ auto_sbitmap visited (last_basic_block_for_fn (cfun));
+ bitmap_clear (visited);
+ bbs = XNEWVEC (basic_block, n_basic_blocks_for_fn (cfun));
+ FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
{
- if (!loops->parray[i])
- continue;
+ unsigned n;
- if (loops->parray[i]->num_nodes != sizes[i])
+ if (loop->header == NULL)
{
- error ("Size of loop %d should be %d, not %d.",
- i, sizes[i], loops->parray[i]->num_nodes);
+ error ("removed loop %d in loop tree", loop->num);
err = 1;
+ continue;
}
- }
- free (sizes);
+ n = get_loop_body_with_size (loop, bbs, n_basic_blocks_for_fn (cfun));
+ if (loop->num_nodes != n)
+ {
+ error ("size of loop %d should be %d, not %d",
+ loop->num, n, loop->num_nodes);
+ err = 1;
+ }
- /* Check get_loop_body. */
- for (i = 1; i < loops->num; i++)
- {
- loop = loops->parray[i];
- if (!loop)
- continue;
- bbs = get_loop_body (loop);
+ for (j = 0; j < n; j++)
+ {
+ bb = bbs[j];
- 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, i);
- err = 1;
- }
- free (bbs);
+ 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);
/* Check headers and latches. */
- for (i = 1; i < loops->num; i++)
+ FOR_EACH_LOOP (loop, 0)
{
- loop = loops->parray[i];
- if (!loop)
+ i = loop->num;
+ if (loop->header == NULL)
continue;
-
- if ((flags & VLS_EXPECT_PREHEADERS)
- && (!loop->header->pred->pred_next
- || loop->header->pred->pred_next->pred_next))
+ if (!bb_loop_header_p (loop->header))
{
- error ("Loop %d's header does not have exactly 2 entries.", i);
+ error ("loop %d%'s header is not a loop header", i);
err = 1;
}
- if (flags & VLS_EXPECT_SIMPLE_LATCHES)
+ 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 (!loop->latch->succ
- || loop->latch->succ->succ_next)
+ if (!single_succ_p (loop->latch))
{
- error ("Loop %d's latch does not have exactly 1 successor.", i);
+ error ("loop %d%'s latch does not have exactly 1 successor", i);
err = 1;
}
- if (loop->latch->succ->dest != loop->header)
+ if (single_succ (loop->latch) != loop->header)
{
- error ("Loop %d's latch does not have header as successor.", i);
+ 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);
+ 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);
+ 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))
+ {
+ auto_edge_flag saved_irr_mask (cfun);
+ /* Record old info. */
+ auto_sbitmap irreds (last_basic_block_for_fn (cfun));
+ FOR_EACH_BB_FN (bb, cfun)
+ {
+ 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 |= saved_irr_mask;
+ }
+
+ /* Recount it. */
+ mark_irreducible_loops ();
+
+ /* Compare. */
+ FOR_EACH_BB_FN (bb, cfun)
+ {
+ 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 & saved_irr_mask))
+ {
+ 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 & saved_irr_mask))
+ {
+ error ("edge from %d to %d should not be marked irreducible",
+ e->src->index, e->dest->index);
+ err = 1;
+ }
+ e->flags &= ~saved_irr_mask;
+ }
+ }
+ }
+
+ /* Check the recorded loop exits. */
+ FOR_EACH_LOOP (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;
+
+ sizes = XCNEWVEC (unsigned, num);
+ memset (sizes, 0, sizeof (unsigned) * num);
+ FOR_EACH_BB_FN (bb, cfun)
+ {
+ 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 != current_loops->exits->elements ())
+ {
+ error ("too many loop exits recorded");
err = 1;
}
+
+ FOR_EACH_LOOP (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;
+ }
+ }
+
+ free (sizes);
}
- if (err)
- abort ();
+ gcc_assert (!err);
+
+ if (!dom_available)
+ free_dominance_info (CDI_DOMINATORS);
}
/* Returns latch edge of LOOP. */
edge
-loop_latch_edge (loop)
- struct loop *loop;
+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)
+ && ! loops_state_satisfies_p (LOOPS_MAY_HAVE_MULTIPLE_LATCHES));
- for (e = loop->header->pred; e->src != loop->latch; e = e->pred_next)
- continue;
+ FOR_EACH_EDGE (e, ei, loop->header->preds)
+ if (e->src != loop->latch)
+ break;
+
+ if (! e)
+ {
+ gcc_assert (! loop_outer (loop));
+ return single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun));
+ }
return e;
}
-/* Returns preheader edge of LOOP. */
+/* 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
-loop_preheader_edge (loop)
- struct loop *loop;
+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 (e = loop->header->pred; e->src == loop->latch; e = e->pred_next)
- continue;
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ if (loop_exit_edge_p (loop, e))
+ return true;
- return e;
+ 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. */
+
+dump_user_location_t
+get_loop_location (struct loop *loop)
+{
+ rtx_insn *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;
+ }
+ }
+ /* 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;
+ }
+ }
+ /* 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;
+ }
+ /* 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;
+ }
+ /* If all else fails, simply return the current function location. */
+ return dump_user_location_t::from_function_decl (current_function_decl);
+}
+
+/* Records that every statement in LOOP is executed I_BOUND times.
+ REALISTIC is true if I_BOUND is expected to be close to the real number
+ of iterations. UPPER is true if we are sure the loop iterates at most
+ I_BOUND times. */
+
+void
+record_niter_bound (struct loop *loop, const widest_int &i_bound,
+ bool realistic, bool upper)
+{
+ /* Update the bounds only when there is no previous estimation, or when the
+ current estimation is smaller. */
+ if (upper
+ && (!loop->any_upper_bound
+ || wi::ltu_p (i_bound, loop->nb_iterations_upper_bound)))
+ {
+ loop->any_upper_bound = true;
+ loop->nb_iterations_upper_bound = i_bound;
+ if (!loop->any_likely_upper_bound)
+ {
+ loop->any_likely_upper_bound = true;
+ loop->nb_iterations_likely_upper_bound = i_bound;
+ }
+ }
+ if (realistic
+ && (!loop->any_estimate
+ || wi::ltu_p (i_bound, loop->nb_iterations_estimate)))
+ {
+ loop->any_estimate = true;
+ loop->nb_iterations_estimate = i_bound;
+ }
+ if (!realistic
+ && (!loop->any_likely_upper_bound
+ || wi::ltu_p (i_bound, loop->nb_iterations_likely_upper_bound)))
+ {
+ loop->any_likely_upper_bound = true;
+ loop->nb_iterations_likely_upper_bound = i_bound;
+ }
+
+ /* If an upper bound is smaller than the realistic estimate of the
+ number of iterations, use the upper bound instead. */
+ if (loop->any_upper_bound
+ && loop->any_estimate
+ && wi::ltu_p (loop->nb_iterations_upper_bound,
+ loop->nb_iterations_estimate))
+ loop->nb_iterations_estimate = loop->nb_iterations_upper_bound;
+ if (loop->any_upper_bound
+ && loop->any_likely_upper_bound
+ && wi::ltu_p (loop->nb_iterations_upper_bound,
+ loop->nb_iterations_likely_upper_bound))
+ loop->nb_iterations_likely_upper_bound = loop->nb_iterations_upper_bound;
}
+/* Similar to get_estimated_loop_iterations, but returns the estimate only
+ if it fits to HOST_WIDE_INT. If this is not the case, or the estimate
+ on the number of iterations of LOOP could not be derived, returns -1. */
+
+HOST_WIDE_INT
+get_estimated_loop_iterations_int (struct loop *loop)
+{
+ widest_int nit;
+ HOST_WIDE_INT hwi_nit;
+
+ if (!get_estimated_loop_iterations (loop, &nit))
+ return -1;
+
+ if (!wi::fits_shwi_p (nit))
+ return -1;
+ hwi_nit = nit.to_shwi ();
+
+ return hwi_nit < 0 ? -1 : hwi_nit;
+}
+
+/* Returns an upper bound on the number of executions of statements
+ in the LOOP. For statements before the loop exit, this exceeds
+ the number of execution of the latch by one. */
+
+HOST_WIDE_INT
+max_stmt_executions_int (struct loop *loop)
+{
+ HOST_WIDE_INT nit = get_max_loop_iterations_int (loop);
+ HOST_WIDE_INT snit;
+
+ if (nit == -1)
+ return -1;
+
+ snit = (HOST_WIDE_INT) ((unsigned HOST_WIDE_INT) nit + 1);
+
+ /* If the computation overflows, return -1. */
+ return snit < 0 ? -1 : snit;
+}
+
+/* Returns an likely upper bound on the number of executions of statements
+ in the LOOP. For statements before the loop exit, this exceeds
+ the number of execution of the latch by one. */
+
+HOST_WIDE_INT
+likely_max_stmt_executions_int (struct loop *loop)
+{
+ HOST_WIDE_INT nit = get_likely_max_loop_iterations_int (loop);
+ HOST_WIDE_INT snit;
+
+ if (nit == -1)
+ return -1;
+
+ snit = (HOST_WIDE_INT) ((unsigned HOST_WIDE_INT) nit + 1);
+
+ /* If the computation overflows, return -1. */
+ return snit < 0 ? -1 : snit;
+}
+
+/* Sets NIT to the estimated number of executions of the latch of the
+ LOOP. If we have no reliable estimate, the function returns false, otherwise
+ returns true. */
+
+bool
+get_estimated_loop_iterations (struct loop *loop, widest_int *nit)
+{
+ /* Even if the bound is not recorded, possibly we can derrive one from
+ profile. */
+ if (!loop->any_estimate)
+ {
+ if (loop->header->count.reliable_p ())
+ {
+ *nit = gcov_type_to_wide_int
+ (expected_loop_iterations_unbounded (loop) + 1);
+ return true;
+ }
+ return false;
+ }
+
+ *nit = loop->nb_iterations_estimate;
+ return true;
+}
+
+/* Sets NIT to an upper bound for the maximum number of executions of the
+ latch of the LOOP. If we have no reliable estimate, the function returns
+ false, otherwise returns true. */
+
+bool
+get_max_loop_iterations (const struct loop *loop, widest_int *nit)
+{
+ if (!loop->any_upper_bound)
+ return false;
+
+ *nit = loop->nb_iterations_upper_bound;
+ return true;
+}
+
+/* Similar to get_max_loop_iterations, but returns the estimate only
+ if it fits to HOST_WIDE_INT. If this is not the case, or the estimate
+ on the number of iterations of LOOP could not be derived, returns -1. */
+
+HOST_WIDE_INT
+get_max_loop_iterations_int (const struct loop *loop)
+{
+ widest_int nit;
+ HOST_WIDE_INT hwi_nit;
+
+ if (!get_max_loop_iterations (loop, &nit))
+ return -1;
+
+ if (!wi::fits_shwi_p (nit))
+ return -1;
+ hwi_nit = nit.to_shwi ();
+
+ return hwi_nit < 0 ? -1 : hwi_nit;
+}
+
+/* Sets NIT to an upper bound for the maximum number of executions of the
+ latch of the LOOP. If we have no reliable estimate, the function returns
+ false, otherwise returns true. */
+
+bool
+get_likely_max_loop_iterations (struct loop *loop, widest_int *nit)
+{
+ if (!loop->any_likely_upper_bound)
+ return false;
+
+ *nit = loop->nb_iterations_likely_upper_bound;
+ return true;
+}
+
+/* Similar to get_max_loop_iterations, but returns the estimate only
+ if it fits to HOST_WIDE_INT. If this is not the case, or the estimate
+ on the number of iterations of LOOP could not be derived, returns -1. */
+
+HOST_WIDE_INT
+get_likely_max_loop_iterations_int (struct loop *loop)
+{
+ widest_int nit;
+ HOST_WIDE_INT hwi_nit;
+
+ if (!get_likely_max_loop_iterations (loop, &nit))
+ return -1;
+
+ if (!wi::fits_shwi_p (nit))
+ return -1;
+ hwi_nit = nit.to_shwi ();
+
+ return hwi_nit < 0 ? -1 : hwi_nit;
+}
+
+/* Returns the loop depth of the loop BB belongs to. */
+
+int
+bb_loop_depth (const_basic_block bb)
+{
+ return bb->loop_father ? loop_depth (bb->loop_father) : 0;
+}
+
+/* Marks LOOP for removal and sets LOOPS_NEED_FIXUP. */
+
+void
+mark_loop_for_removal (loop_p loop)
+{
+ if (loop->header == NULL)
+ return;
+ loop->former_header = loop->header;
+ loop->header = NULL;
+ loop->latch = NULL;
+ loops_state_set (LOOPS_NEED_FIXUP);
+}