/* Loop manipulation code for GNU compiler.
- Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc.
+ Copyright (C) 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
This file is part of GCC.
#include "tm.h"
#include "rtl.h"
#include "hard-reg-set.h"
+#include "obstack.h"
#include "basic-block.h"
#include "cfgloop.h"
#include "cfglayout.h"
+#include "cfghooks.h"
#include "output.h"
static void duplicate_subloops (struct loops *, struct loop *, struct loop *);
static void fix_bb_placements (struct loops *, basic_block);
static void place_new_loop (struct loops *, struct loop *);
static void scale_loop_frequencies (struct loop *, int, int);
-static void scale_bbs_frequencies (basic_block *, int, int, int);
static basic_block create_preheader (struct loop *, int);
static void fix_irreducible_loops (basic_block);
+static void unloop (struct loops *, struct loop *);
#define RDIV(X,Y) (((X) + (Y) / 2) / (Y))
int stack_top;
sbitmap on_stack;
edge *edges, e;
- unsigned n_edges, i;
+ unsigned num_edges, i;
if (!(from->flags & BB_IRREDUCIBLE_LOOP))
return;
bb->flags &= ~BB_IRREDUCIBLE_LOOP;
if (bb->loop_father->header == bb)
- edges = get_loop_exit_edges (bb->loop_father, &n_edges);
+ edges = get_loop_exit_edges (bb->loop_father, &num_edges);
else
{
- n_edges = EDGE_COUNT (bb->succs);
- edges = xmalloc (n_edges * sizeof (edge));
+ num_edges = EDGE_COUNT (bb->succs);
+ edges = xmalloc (num_edges * sizeof (edge));
FOR_EACH_EDGE (e, ei, bb->succs)
edges[ei.index] = e;
}
- for (i = 0; i < n_edges; i++)
+ for (i = 0; i < num_edges; i++)
{
e = edges[i];
e, but we only have basic block dominators. This is easy to
fix -- when e->dest has exactly one predecessor, this corresponds
to blocks dominated by e->dest, if not, split the edge. */
- if (EDGE_COUNT (e->dest->preds) > 1)
- e = EDGE_PRED (loop_split_edge_with (e, NULL_RTX), 0);
+ if (!single_pred_p (e->dest))
+ e = single_pred_edge (loop_split_edge_with (e, NULL_RTX));
/* It may happen that by removing path we remove one or more loops
we belong to. In this case first unloop the loops, then proceed
free (bbs);
}
-/* Multiply all frequencies of basic blocks in array BBS of length NBBS
- by NUM/DEN. */
-static void
-scale_bbs_frequencies (basic_block *bbs, int nbbs, int num, int den)
-{
- int i;
- edge e;
-
- for (i = 0; i < nbbs; i++)
- {
- edge_iterator ei;
- bbs[i]->frequency = (bbs[i]->frequency * num) / den;
- bbs[i]->count = RDIV (bbs[i]->count * num, den);
- FOR_EACH_EDGE (e, ei, bbs[i]->succs)
- e->count = (e->count * num) /den;
- }
-}
-
/* Multiply all frequencies in LOOP by NUM/DEN. */
static void
scale_loop_frequencies (struct loop *loop, int num, int den)
basic_block *bbs;
bbs = get_loop_body (loop);
- scale_bbs_frequencies (bbs, loop->num_nodes, num, den);
+ scale_bbs_frequencies_int (bbs, loop->num_nodes, num, den);
free (bbs);
}
/* Remove the latch edge of a LOOP and update LOOPS tree to indicate that
the LOOP was removed. After this function, original loop latch will
have no successor, which caller is expected to fix somehow. */
-void
+static void
unloop (struct loops *loops, struct loop *loop)
{
basic_block *body;
unsigned i, n;
basic_block latch = loop->latch;
edge *edges;
- unsigned n_edges;
+ unsigned num_edges;
/* This is relatively straightforward. The dominators are unchanged, as
loop header dominates loop latch, so the only thing we have to care of
its work. */
body = get_loop_body (loop);
- edges = get_loop_exit_edges (loop, &n_edges);
+ edges = get_loop_exit_edges (loop, &num_edges);
n = loop->num_nodes;
for (i = 0; i < n; i++)
if (body[i]->loop_father == loop)
loops->parray[loop->num] = NULL;
flow_loop_free (loop);
- remove_edge (EDGE_SUCC (latch, 0));
+ remove_edge (single_succ_edge (latch));
fix_bb_placements (loops, latch);
/* If the loop was inside an irreducible region, we would have to somehow
update the irreducible marks inside its body. While it is certainly
possible to do, it is a bit complicated and this situation should be
very rare, so we just remark all loops in this case. */
- for (i = 0; i < n_edges; i++)
+ for (i = 0; i < num_edges; i++)
if (edges[i]->flags & EDGE_IRREDUCIBLE_LOOP)
break;
- if (i != n_edges)
+ if (i != num_edges)
mark_irreducible_loops (loops);
free (edges);
}
if (!redirect_edge_and_branch (e, newdest))
return false;
- EDGE_SUCC (src, 0)->flags &= ~EDGE_IRREDUCIBLE_LOOP;
- EDGE_SUCC (src, 0)->flags |= irr;
+ single_succ_edge (src)->flags &= ~EDGE_IRREDUCIBLE_LOOP;
+ single_succ_edge (src)->flags |= irr;
return true;
}
/* The NBBS blocks in BBS will get duplicated and the copies will be placed
to LOOP. Update the single_exit information in superloops of LOOP. */
-void
+static void
update_single_exits_after_duplication (basic_block *bbs, unsigned nbbs,
struct loop *loop)
{
original LOOP body, the other copies are numbered in order given by control
flow through them) into TO_REMOVE array. Returns false if duplication is
impossible. */
-int
+bool
duplicate_loop_to_header_edge (struct loop *loop, edge e, struct loops *loops,
unsigned int ndupl, sbitmap wont_exit,
edge orig, edge *to_remove,
/* Set counts and frequencies. */
if (flags & DLTHE_FLAG_UPDATE_FREQ)
{
- scale_bbs_frequencies (new_bbs, n, scale_act, REG_BR_PROB_BASE);
+ scale_bbs_frequencies_int (new_bbs, n, scale_act, REG_BR_PROB_BASE);
scale_act = RDIV (scale_act * scale_step[j], REG_BR_PROB_BASE);
}
}
set_immediate_dominator (CDI_DOMINATORS, e->dest, e->src);
if (flags & DLTHE_FLAG_UPDATE_FREQ)
{
- scale_bbs_frequencies (bbs, n, scale_main, REG_BR_PROB_BASE);
+ scale_bbs_frequencies_int (bbs, n, scale_main, REG_BR_PROB_BASE);
free (scale_step);
}
static void
mfb_update_loops (basic_block jump)
{
- struct loop *loop = EDGE_SUCC (jump, 0)->dest->loop_father;
+ struct loop *loop = single_succ (jump)->loop_father;
if (dom_computed[CDI_DOMINATORS])
- set_immediate_dominator (CDI_DOMINATORS, jump, EDGE_PRED (jump, 0)->src);
+ set_immediate_dominator (CDI_DOMINATORS, jump, single_pred (jump));
add_bb_to_loop (jump, loop);
loop->latch = jump;
}
struct loop *cloop, *ploop;
int nentry = 0;
bool irred = false;
+ bool latch_edge_was_fallthru;
+ edge one_succ_pred = 0;
edge_iterator ei;
cloop = loop->outer;
continue;
irred |= (e->flags & EDGE_IRREDUCIBLE_LOOP) != 0;
nentry++;
+ if (single_succ_p (e->src))
+ one_succ_pred = e;
}
gcc_assert (nentry);
if (nentry == 1)
{
- FOR_EACH_EDGE (e, ei, loop->header->preds)
- if (e->src != loop->latch)
- break;
+ /* Get an edge that is different from the one from loop->latch
+ to loop->header. */
+ e = EDGE_PRED (loop->header,
+ EDGE_PRED (loop->header, 0)->src == loop->latch);
- if (!(flags & CP_SIMPLE_PREHEADERS) || EDGE_COUNT (e->src->succs) == 1)
+ if (!(flags & CP_SIMPLE_PREHEADERS) || single_succ_p (e->src))
return NULL;
}
mfb_kj_edge = loop_latch_edge (loop);
+ latch_edge_was_fallthru = (mfb_kj_edge->flags & EDGE_FALLTHRU) != 0;
fallthru = make_forwarder_block (loop->header, mfb_keep_just,
mfb_update_loops);
dummy = fallthru->src;
if (ploop->latch == dummy)
ploop->latch = fallthru->dest;
- /* Reorganize blocks so that the preheader is not stuck in the middle of the
- loop. */
- FOR_EACH_EDGE (e, ei, dummy->preds)
- if (e->src != loop->latch)
- break;
- move_block_after (dummy, e->src);
+ /* Try to be clever in placing the newly created preheader. The idea is to
+ avoid breaking any "fallthruness" relationship between blocks.
+
+ The preheader was created just before the header and all incoming edges
+ to the header were redirected to the preheader, except the latch edge.
+ So the only problematic case is when this latch edge was a fallthru
+ edge: it is not anymore after the preheader creation so we have broken
+ the fallthruness. We're therefore going to look for a better place. */
+ if (latch_edge_was_fallthru)
+ {
+ if (one_succ_pred)
+ e = one_succ_pred;
+ else
+ e = EDGE_PRED (dummy, 0);
+
+ move_block_after (dummy, e->src);
+ }
loop->header->loop_father = loop;
add_bb_to_loop (dummy, cloop);
if (irred)
{
dummy->flags |= BB_IRREDUCIBLE_LOOP;
- EDGE_SUCC (dummy, 0)->flags |= EDGE_IRREDUCIBLE_LOOP;
+ single_succ_edge (dummy)->flags |= EDGE_IRREDUCIBLE_LOOP;
}
if (dump_file)
for (i = 1; i < loops->num; i++)
{
- edge_iterator ei;
loop = loops->parray[i];
- if (loop->latch != loop->header && EDGE_COUNT (loop->latch->succs) == 1)
+ if (loop->latch != loop->header && single_succ_p (loop->latch))
continue;
- FOR_EACH_EDGE (e, ei, loop->header->preds)
- if (e->src == loop->latch)
- break;
+ e = find_edge (loop->latch, loop->header);
loop_split_edge_with (e, NULL_RTX);
}
NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_BEG);
#endif
- flow_loops_find (&loops, LOOP_TREE);
+ flow_loops_find (&loops);
free_dominance_info (CDI_DOMINATORS);
if (loops.num > 1)
{
&& onlyjump_p (insn))
{
pbb = BLOCK_FOR_INSN (insn);
- gcc_assert (pbb && EDGE_COUNT (pbb->succs) == 1);
+ gcc_assert (pbb && single_succ_p (pbb));
- if (!flow_bb_inside_loop_p (loop, EDGE_SUCC (pbb, 0)->dest))
+ if (!flow_bb_inside_loop_p (loop, single_succ (pbb)))
insn = BB_HEAD (first[loop->num]);
}
else
}
flow_loops_free (&loops);
}
+
+/* This function is called from loop_version. It splits the entry edge
+ of the loop we want to version, adds the versioning condition, and
+ adjust the edges to the two versions of the loop appropriately.
+ e is an incoming edge. Returns the basic block containing the
+ condition.
+
+ --- edge e ---- > [second_head]
+
+ Split it and insert new conditional expression and adjust edges.
+
+ --- edge e ---> [cond expr] ---> [first_head]
+ |
+ +---------> [second_head]
+*/
+
+static basic_block
+lv_adjust_loop_entry_edge (basic_block first_head,
+ basic_block second_head,
+ edge e,
+ tree cond_expr)
+{
+ basic_block new_head = NULL;
+ edge e1;
+
+ gcc_assert (e->dest == second_head);
+
+ /* Split edge 'e'. This will create a new basic block, where we can
+ insert conditional expr. */
+ new_head = split_edge (e);
+
+
+ lv_add_condition_to_bb (first_head, second_head, new_head,
+ cond_expr);
+
+ e1 = make_edge (new_head, first_head, EDGE_TRUE_VALUE);
+ set_immediate_dominator (CDI_DOMINATORS, first_head, new_head);
+ set_immediate_dominator (CDI_DOMINATORS, second_head, new_head);
+
+ /* Adjust loop header phi nodes. */
+ lv_adjust_loop_header_phi (first_head, second_head, new_head, e1);
+
+ return new_head;
+}
+
+/* Main entry point for Loop Versioning transformation.
+
+This transformation given a condition and a loop, creates
+-if (condition) { loop_copy1 } else { loop_copy2 },
+where loop_copy1 is the loop transformed in one way, and loop_copy2
+is the loop transformed in another way (or unchanged). 'condition'
+may be a run time test for things that were not resolved by static
+analysis (overlapping ranges (anti-aliasing), alignment, etc.). */
+
+struct loop *
+loop_version (struct loops *loops, struct loop * loop,
+ void *cond_expr, basic_block *condition_bb)
+{
+ basic_block first_head, second_head;
+ edge entry, latch_edge, exit, true_edge, false_edge;
+ int irred_flag;
+ struct loop *nloop;
+
+ /* CHECKME: Loop versioning does not handle nested loop at this point. */
+ if (loop->inner)
+ return NULL;
+
+ /* Record entry and latch edges for the loop */
+ entry = loop_preheader_edge (loop);
+ irred_flag = entry->flags & EDGE_IRREDUCIBLE_LOOP;
+ entry->flags &= ~EDGE_IRREDUCIBLE_LOOP;
+
+ /* Note down head of loop as first_head. */
+ first_head = entry->dest;
+
+ /* Duplicate loop. */
+ if (!cfg_hook_duplicate_loop_to_header_edge (loop, entry, loops, 1,
+ NULL, NULL, NULL, NULL, 0))
+ return NULL;
+
+ /* After duplication entry edge now points to new loop head block.
+ Note down new head as second_head. */
+ second_head = entry->dest;
+
+ /* Split loop entry edge and insert new block with cond expr. */
+ *condition_bb = lv_adjust_loop_entry_edge (first_head, second_head,
+ entry, cond_expr);
+ if (!*condition_bb)
+ {
+ entry->flags |= irred_flag;
+ return NULL;
+ }
+
+ latch_edge = single_succ_edge (loop->latch->rbi->copy);
+
+ extract_cond_bb_edges (*condition_bb, &true_edge, &false_edge);
+ nloop = loopify (loops,
+ latch_edge,
+ single_pred_edge (loop->header->rbi->copy),
+ *condition_bb, true_edge, false_edge,
+ false /* Do not redirect all edges. */);
+
+ exit = loop->single_exit;
+ if (exit)
+ nloop->single_exit = find_edge (exit->src->rbi->copy, exit->dest);
+
+ /* loopify redirected latch_edge. Update its PENDING_STMTS. */
+ lv_flush_pending_stmts (latch_edge);
+
+ /* loopify redirected condition_bb's succ edge. Update its PENDING_STMTS. */
+ extract_cond_bb_edges (*condition_bb, &true_edge, &false_edge);
+ lv_flush_pending_stmts (false_edge);
+ /* Adjust irreducible flag. */
+ if (irred_flag)
+ {
+ (*condition_bb)->flags |= BB_IRREDUCIBLE_LOOP;
+ loop_preheader_edge (loop)->flags |= EDGE_IRREDUCIBLE_LOOP;
+ loop_preheader_edge (nloop)->flags |= EDGE_IRREDUCIBLE_LOOP;
+ single_pred_edge ((*condition_bb))->flags |= EDGE_IRREDUCIBLE_LOOP;
+ }
+
+ /* At this point condition_bb is loop predheader with two successors,
+ first_head and second_head. Make sure that loop predheader has only
+ one successor. */
+ loop_split_edge_with (loop_preheader_edge (loop), NULL);
+ loop_split_edge_with (loop_preheader_edge (nloop), NULL);
+
+ return nloop;
+}
+
+/* The structure of LOOPS might have changed. Some loops might get removed
+ (and their headers and latches were set to NULL), loop exists might get
+ removed (thus the loop nesting may be wrong), and some blocks and edges
+ were changed (so the information about bb --> loop mapping does not have
+ to be correct). But still for the remaining loops the header dominates
+ the latch, and loops did not get new subloobs (new loops might possibly
+ get created, but we are not interested in them). Fix up the mess.
+
+ If CHANGED_BBS is not NULL, basic blocks whose loop has changed are
+ marked in it. */
+
+void
+fix_loop_structure (struct loops *loops, bitmap changed_bbs)
+{
+ basic_block bb;
+ struct loop *loop, *ploop;
+ unsigned i;
+
+ /* Remove the old bb -> loop mapping. */
+ FOR_EACH_BB (bb)
+ {
+ bb->aux = (void *) (size_t) bb->loop_father->depth;
+ bb->loop_father = loops->tree_root;
+ }
+
+ /* Remove the dead loops from structures. */
+ loops->tree_root->num_nodes = n_basic_blocks + 2;
+ for (i = 1; i < loops->num; i++)
+ {
+ loop = loops->parray[i];
+ if (!loop)
+ continue;
+
+ loop->num_nodes = 0;
+ if (loop->header)
+ continue;
+
+ while (loop->inner)
+ {
+ ploop = loop->inner;
+ flow_loop_tree_node_remove (ploop);
+ flow_loop_tree_node_add (loop->outer, ploop);
+ }
+
+ /* Remove the loop and free its data. */
+ flow_loop_tree_node_remove (loop);
+ loops->parray[loop->num] = NULL;
+ flow_loop_free (loop);
+ }
+
+ /* Rescan the bodies of loops, starting from the outermost. */
+ loop = loops->tree_root;
+ while (1)
+ {
+ if (loop->inner)
+ loop = loop->inner;
+ else
+ {
+ while (!loop->next
+ && loop != loops->tree_root)
+ loop = loop->outer;
+ if (loop == loops->tree_root)
+ break;
+
+ loop = loop->next;
+ }
+
+ loop->num_nodes = flow_loop_nodes_find (loop->header, loop);
+ }
+
+ /* Now fix the loop nesting. */
+ for (i = 1; i < loops->num; i++)
+ {
+ loop = loops->parray[i];
+ if (!loop)
+ continue;
+
+ bb = loop_preheader_edge (loop)->src;
+ if (bb->loop_father != loop->outer)
+ {
+ flow_loop_tree_node_remove (loop);
+ flow_loop_tree_node_add (bb->loop_father, loop);
+ }
+ }
+
+ /* Mark the blocks whose loop has changed. */
+ FOR_EACH_BB (bb)
+ {
+ if (changed_bbs
+ && (void *) (size_t) bb->loop_father->depth != bb->aux)
+ bitmap_set_bit (changed_bbs, bb->index);
+
+ bb->aux = NULL;
+ }
+
+ mark_single_exit_loops (loops);
+ mark_irreducible_loops (loops);
+}
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