/* Natural loop discovery code for GNU compiler.
- Copyright (C) 2000, 2001 Free Software Foundation, Inc.
+ Copyright (C) 2000, 2001, 2003, 2004, 2005, 2006, 2007
+ Free Software Foundation, Inc.
This file is part of GCC.
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. */
+Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301, USA. */
#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 *);
\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 (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;
+ }
- if (! loops->num)
- abort ();
+ ggc_free (loop->exits);
+ ggc_free (loop);
+}
+
+/* Free all the memory allocated for LOOPS. */
+
+void
+flow_loops_free (struct loops *loops)
+{
+ if (loops->larray)
+ {
+ unsigned i;
+ loop_p loop;
/* Free the loop descriptors. */
- for (i = 0; i < loops->num; i++)
+ for (i = 0; VEC_iterate (loop_p, loops->larray, i, loop); i++)
+ {
+ if (!loop)
+ continue;
+
+ flow_loop_free (loop);
+ }
+
+ VEC_free (loop_p, gc, loops->larray);
+ }
+}
+
+/* Find the nodes contained within the LOOP with header HEADER.
+ Return the number of nodes within the loop. */
+
+int
+flow_loop_nodes_find (basic_block header, struct loop *loop)
+{
+ VEC (basic_block, heap) *stack = NULL;
+ int num_nodes = 1;
+ edge latch;
+ edge_iterator latch_ei;
+ unsigned depth = loop_depth (loop);
+
+ header->loop_father = loop;
+ header->loop_depth = depth;
+
+ FOR_EACH_EDGE (latch, latch_ei, loop->header->preds)
+ {
+ if (latch->src->loop_father == loop
+ || !dominated_by_p (CDI_DOMINATORS, latch->src, loop->header))
+ continue;
+
+ num_nodes++;
+ VEC_safe_push (basic_block, heap, stack, latch->src);
+ latch->src->loop_father = loop;
+ latch->src->loop_depth = depth;
+
+ while (!VEC_empty (basic_block, stack))
{
- 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);
+ basic_block node;
+ edge e;
+ edge_iterator ei;
+
+ node = VEC_pop (basic_block, stack);
+
+ FOR_EACH_EDGE (e, ei, node->preds)
+ {
+ basic_block ancestor = e->src;
+
+ if (ancestor->loop_father != loop)
+ {
+ ancestor->loop_father = loop;
+ ancestor->loop_depth = depth;
+ num_nodes++;
+ VEC_safe_push (basic_block, heap, stack, ancestor);
+ }
+ }
}
+ }
+ VEC_free (basic_block, heap, stack);
+
+ return num_nodes;
+}
+
+/* Records the vector of superloops of the loop LOOP, whose immediate
+ superloop is FATHER. */
+
+static void
+establish_preds (struct loop *loop, struct loop *father)
+{
+ loop_p ploop;
+ unsigned depth = loop_depth (father) + 1;
+ unsigned i;
+
+ VEC_truncate (loop_p, loop->superloops, 0);
+ VEC_reserve (loop_p, gc, loop->superloops, depth);
+ for (i = 0; VEC_iterate (loop_p, father->superloops, i, ploop); i++)
+ VEC_quick_push (loop_p, loop->superloops, ploop);
+ VEC_quick_push (loop_p, loop->superloops, father);
+
+ for (ploop = loop->inner; ploop; ploop = ploop->next)
+ establish_preds (ploop, loop);
+}
+
+/* Add LOOP to the loop hierarchy tree where FATHER is father of the
+ added loop. If LOOP has some children, take care of that their
+ pred field will be initialized correctly. */
+
+void
+flow_loop_tree_node_add (struct loop *father, struct loop *loop)
+{
+ loop->next = father->inner;
+ father->inner = loop;
- free (loops->array);
- loops->array = NULL;
+ establish_preds (loop, father);
+}
- if (loops->cfg.dom)
- sbitmap_vector_free (loops->cfg.dom);
+/* Remove LOOP from the loop hierarchy tree. */
- if (loops->cfg.dfs_order)
- free (loops->cfg.dfs_order);
+void
+flow_loop_tree_node_remove (struct loop *loop)
+{
+ struct loop *prev, *father;
- if (loops->shared_headers)
- sbitmap_free (loops->shared_headers);
+ 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;
+}
+
+/* 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;
+ struct loop *root;
+
+ memset (loops, 0, sizeof *loops);
+
+ /* Taking care of this degenerate case makes the rest of
+ this code simpler. */
+ if (n_basic_blocks == NUM_FIXED_BLOCKS)
+ return 0;
+
+ dfs_order = NULL;
+ rc_order = NULL;
+
+ /* Ensure that the dominators are computed. */
+ calculate_dominance_info (CDI_DOMINATORS);
- *entry_edges = NULL;
+ /* Count the number of loop headers. This should be the
+ same as the number of natural loops. */
+ headers = sbitmap_alloc (last_basic_block);
+ sbitmap_zero (headers);
- num_entries = 0;
- for (e = header->pred; e; e = e->pred_next)
+ num_loops = 0;
+ FOR_EACH_BB (header)
{
- basic_block src = e->src;
+ 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));
- if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index))
- num_entries++;
+ /* 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. */
+ loops->larray = VEC_alloc (loop_p, gc, num_loops + 1);
+
+ /* 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 and record information about all the natural loops
+ in the CFG. */
+ FOR_EACH_BB (bb)
+ bb->loop_father = loops->tree_root;
+
+ if (num_loops)
+ {
+ /* Compute depth first search order of the CFG so that outer
+ natural loops will be found before inner natural loops. */
+ dfs_order = XNEWVEC (int, n_basic_blocks);
+ rc_order = XNEWVEC (int, n_basic_blocks);
+ pre_and_rev_post_order_compute (dfs_order, rc_order, false);
+
+ num_loops = 1;
+
+ for (b = 0; b < n_basic_blocks - NUM_FIXED_BLOCKS; b++)
+ {
+ struct loop *loop;
+ edge_iterator ei;
+
+ /* Search the nodes of the CFG in reverse completion order
+ so that we can find outer loops first. */
+ if (!TEST_BIT (headers, rc_order[b]))
+ continue;
+
+ header = BASIC_BLOCK (rc_order[b]);
+
+ loop = alloc_loop ();
+ VEC_quick_push (loop_p, loops->larray, loop);
+
+ loop->header = header;
+ loop->num = num_loops;
+ num_loops++;
+
+ flow_loop_tree_node_add (header->loop_father, loop);
+ loop->num_nodes = flow_loop_nodes_find (loop->header, loop);
+
+ /* Look for the latch for this header block, if it has just a
+ single one. */
+ FOR_EACH_EDGE (e, ei, header->preds)
+ {
+ basic_block latch = e->src;
+
+ if (flow_bb_inside_loop_p (loop, latch))
+ {
+ if (loop->latch != NULL)
+ {
+ /* More than one latch edge. */
+ loop->latch = NULL;
+ break;
+ }
+ loop->latch = latch;
+ }
+ }
+ }
+
+ free (dfs_order);
+ free (rc_order);
+ }
+
+ sbitmap_free (headers);
+
+ loops->exits = NULL;
+ loops->state = 0;
+ return VEC_length (loop_p, loops->larray);
+}
+
+/* Ratio of frequencies of edges so that one of more latch edges is
+ considered to belong to inner loop with same header. */
+#define HEAVY_EDGE_RATIO 8
+
+/* Minimum number of samples for that we apply
+ find_subloop_latch_edge_by_profile heuristics. */
+#define HEAVY_EDGE_MIN_SAMPLES 10
+
+/* If the profile info is available, finds an edge in LATCHES that much more
+ frequent than the remaining edges. Returns such an edge, or NULL if we do
+ not find one.
+
+ We do not use guessed profile here, only the measured one. The guessed
+ profile is usually too flat and unreliable for this (and it is mostly based
+ on the loop structure of the program, so it does not make much sense to
+ derive the loop structure from it). */
+
+static edge
+find_subloop_latch_edge_by_profile (VEC (edge, heap) *latches)
+{
+ unsigned i;
+ edge e, me = NULL;
+ gcov_type mcount = 0, tcount = 0;
+
+ for (i = 0; VEC_iterate (edge, latches, i, e); i++)
+ {
+ if (e->count > mcount)
+ {
+ me = e;
+ mcount = e->count;
+ }
+ tcount += e->count;
}
- if (! num_entries)
- abort ();
+ 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.
- *entry_edges = (edge *) xmalloc (num_entries * sizeof (edge *));
+ 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. */
- num_entries = 0;
- for (e = header->pred; e; e = e->pred_next)
+static edge
+find_subloop_latch_edge_by_ivs (struct loop *loop, VEC (edge, heap) *latches)
+{
+ edge e, latch = VEC_index (edge, latches, 0);
+ unsigned i;
+ tree phi, 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 (phi = phi_nodes (loop->header); phi; phi = PHI_CHAIN (phi))
{
- basic_block src = e->src;
+ 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 = bb_for_stmt (SSA_NAME_DEF_STMT (lop));
+ if (!bb || !flow_bb_inside_loop_p (loop, bb))
+ continue;
+
+ for (i = 0; VEC_iterate (edge, latches, i, e); i++)
+ if (e != latch
+ && PHI_ARG_DEF_FROM_EDGE (phi, e) == lop)
+ return NULL;
+ }
+
+ if (dump_file)
+ fprintf (dump_file,
+ "Found latch edge %d -> %d using iv structure.\n",
+ latch->src->index, latch->dest->index);
+ return latch;
+}
- if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index))
- (*entry_edges)[num_entries++] = e;
+/* If we can determine that one of the several latch edges of LOOP behaves
+ as a latch edge of a separate subloop, returns this edge. Otherwise
+ returns NULL. */
+
+static edge
+find_subloop_latch_edge (struct loop *loop)
+{
+ VEC (edge, heap) *latches = get_loop_latch_edges (loop);
+ edge latch = NULL;
+
+ if (VEC_length (edge, latches) > 1)
+ {
+ latch = find_subloop_latch_edge_by_profile (latches);
+
+ if (!latch
+ /* We consider ivs to guess the latch edge only in SSA. Perhaps we
+ should use cfghook for this, but it is hard to imagine it would
+ be useful elsewhere. */
+ && current_ir_type () == IR_GIMPLE)
+ latch = find_subloop_latch_edge_by_ivs (loop, latches);
}
- return num_entries;
+ VEC_free (edge, heap, latches);
+ 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. */
+/* Callback for make_forwarder_block. Returns true if the edge E is marked
+ in the set MFB_REIS_SET. */
-static int
-flow_loop_exit_edges_find (nodes, exit_edges)
- const sbitmap nodes;
- edge **exit_edges;
+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 (basic_block bb, void *glb_loop)
+{
+ struct loop *loop = (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, (void *) 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;
+}
+
+/* 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;
- while (sp)
+ 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. */
+/* Get body of a LOOP in breadth first sort order. */
-static basic_block
-flow_loop_pre_header_find (header, dom)
- basic_block header;
- const sbitmap *dom;
+basic_block *
+get_loop_body_in_bfs_order (const struct loop *loop)
{
- basic_block pre_header;
- edge e;
+ 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)
+{
+ struct loop_exit *exit = (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)
+{
+ struct loop_exit *exit = (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;
- num_loops = loops->num;
- if (! num_loops)
+ if ((current_loops->state & LOOPS_HAVE_RECORDED_EXITS) == 0)
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;
+ 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;
- /* 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]);
+ exit->next = aloop->exits->next;
+ exit->prev = aloop->exits;
+ exit->next->prev = exit;
+ exit->prev->next = exit;
+
+ exit->next_e = exits;
+ exits = exit;
+ }
+ }
+
+ if (!exits && new_edge)
+ return;
+
+ slot = htab_find_slot_with_hash (current_loops->exits, e,
+ htab_hash_pointer (e),
+ exits ? INSERT : NO_INSERT);
+ if (!slot)
+ return;
+
+ if (exits)
+ {
+ if (*slot)
+ loop_exit_free (*slot);
+ *slot = exits;
+ }
+ else
+ htab_clear_slot (current_loops->exits, slot);
}
-/* 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 (current_loops->state & LOOPS_HAVE_RECORDED_EXITS)
+ return;
+ current_loops->state |= 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 (current_loops->state & LOOPS_HAVE_RECORDED_EXITS);
+ htab_delete (current_loops->exits);
+ current_loops->exits = NULL;
+ current_loops->state &= ~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 (current_loops->state & 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;
+}
+
+/* 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;
- /* 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]);
+ 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++;
- /* The header of a natural loop must dominate
- all exits. */
- if (! TEST_BIT (loop->exits_doms, loop->header->index))
- abort ();
+ 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);
+ }
+}
+
+/* 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;
- /* Find the blocks within the extended basic block of
- the loop pre-header. */
- flow_loop_pre_header_scan (loop);
+ 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 (e = header->pred; e; e = e->pred_next)
+ FOR_EACH_LOOP (li, loop, LI_INCLUDE_ROOT)
+ {
+ i = loop->num;
+
+ 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);
- if (latch != ENTRY_BLOCK_PTR && TEST_BIT (dom[latch->index], b))
- num_loops++;
+ 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 ((current_loops->state & LOOPS_HAVE_PREHEADERS)
+ && EDGE_COUNT (loop->header->preds) != 2)
+ {
+ error ("loop %d's header does not have exactly 2 entries", i);
+ err = 1;
+ }
+ if (current_loops->state & 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 ((current_loops->state & 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 (current_loops->state & 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 ();
+
+ /* Compare. */
+ FOR_EACH_BB (bb)
+ {
+ edge_iterator ei;
- /* Allocate loop structures. */
- loops->array
- = (struct loop *) xcalloc (num_loops, sizeof (struct loop));
+ 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);
+ }
- headers = sbitmap_alloc (n_basic_blocks);
- sbitmap_zero (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;
+ }
- loops->shared_headers = sbitmap_alloc (n_basic_blocks);
- sbitmap_zero (loops->shared_headers);
+ 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 ((current_loops->state & LOOPS_HAVE_RECORDED_EXITS) == 0)
{
- 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 (current_loops->state & 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 ((current_loops->state & LOOPS_HAVE_PREHEADERS) != 0);
- /* 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, 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_loops_find (loops, flags);
+ return (flow_bb_inside_loop_p (loop, e->src)
+ && !flow_bb_inside_loop_p (loop, e->dest));
}
-/* Return non-zero if edge E enters header of LOOP from outside of LOOP. */
+/* 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. */
-int
-flow_loop_outside_edge_p (loop, e)
- const struct loop *loop;
- edge e;
+edge
+single_exit (const struct loop *loop)
{
- if (e->dest != loop->header)
- abort ();
+ struct loop_exit *exit = loop->exits->next;
+
+ if ((current_loops->state & LOOPS_HAVE_RECORDED_EXITS) == 0)
+ return NULL;
- return (e->src == ENTRY_BLOCK_PTR)
- || ! TEST_BIT (loop->nodes, e->src->index);
+ if (exit->e && exit->next == loop->exits)
+ return exit->e;
+ else
+ return NULL;
}