re PR tree-optimization/57521 (wrong code for expressions in loop at -O3)

2013-08-27  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/57521
	* tree-if-conv.c (if_convertible_bb_p): Verify that at least
	one edge is non-critical.
	(find_phi_replacement_condition): Make sure to use a non-critical
	edge.  Cleanup and remove old bug workarounds.
	(bb_postdominates_preds): Remove.
	(if_convertible_loop_p_1): Do not compute post-dominators.
	(combine_blocks): Do not free post-dominators.
	(main_tree_if_conversion): Likewise.
	(pass_data_if_conversion): Add TODO_verify_ssa.

	* gcc.dg/torture/pr57521.c: New testcase.

From-SVN: r202019
This commit is contained in:
Richard Biener 2013-08-27 10:10:34 +00:00 committed by Richard Biener
parent d15774b631
commit 4ded82768a
4 changed files with 95 additions and 62 deletions

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@ -1,3 +1,16 @@
2013-08-27 Richard Biener <rguenther@suse.de>
PR tree-optimization/57521
* tree-if-conv.c (if_convertible_bb_p): Verify that at least
one edge is non-critical.
(find_phi_replacement_condition): Make sure to use a non-critical
edge. Cleanup and remove old bug workarounds.
(bb_postdominates_preds): Remove.
(if_convertible_loop_p_1): Do not compute post-dominators.
(combine_blocks): Do not free post-dominators.
(main_tree_if_conversion): Likewise.
(pass_data_if_conversion): Add TODO_verify_ssa.
2013-08-27 DJ Delorie <dj@redhat.com>
* config/i386/djgpp.h (ASM_DECLARE_FUNCTION_NAME): New.

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@ -1,3 +1,8 @@
2013-08-27 Richard Biener <rguenther@suse.de>
PR tree-optimization/57521
* gcc.dg/torture/pr57521.c: New testcase.
2013-08-27 Jakub Jelinek <jakub@redhat.com>
PR rtl-optimization/57860

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@ -0,0 +1,51 @@
/* { dg-do run } */
/* { dg-options "-ftree-loop-if-convert" } */
void abort (void);
int a, b, c, d, o = 1, p;
short e;
int
fn1 (int * p1)
{
int f, g, h, j = 0, k = 0, l = 0;
unsigned int i;
int *m[1] = { &l };
for (; b >= 0; b--)
{
if (*p1)
if (j >= 0)
{
int n = 1;
e = 1;
h = a ? a : 1 % n;
g = h > 0 ? 0 : h + 1;
k = c + g;
}
else
continue;
else
{
f = d > 0 ? 0 : d + 1;
i = f;
j = 1 + i;
}
l++;
}
return k;
}
int
main ()
{
for (;; p++)
{
fn1 (&o);
break;
}
if (e != 1)
abort ();
return 0;
}

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@ -797,20 +797,6 @@ if_convertible_stmt_p (gimple stmt, vec<data_reference_p> refs)
return true;
}
/* Return true when BB post-dominates all its predecessors. */
static bool
bb_postdominates_preds (basic_block bb)
{
unsigned i;
for (i = 0; i < EDGE_COUNT (bb->preds); i++)
if (!dominated_by_p (CDI_POST_DOMINATORS, EDGE_PRED (bb, i)->src, bb))
return false;
return true;
}
/* Return true when BB is if-convertible. This routine does not check
basic block's statements and phis.
@ -868,10 +854,23 @@ if_convertible_bb_p (struct loop *loop, basic_block bb, basic_block exit_bb)
return false;
}
if (EDGE_COUNT (bb->preds) == 2
&& bb != loop->header
&& !bb_postdominates_preds (bb))
return false;
/* At least one incoming edge has to be non-critical as otherwise edge
predicates are not equal to basic-block predicates of the edge
source. */
if (EDGE_COUNT (bb->preds) > 1
&& bb != loop->header)
{
bool found = false;
FOR_EACH_EDGE (e, ei, bb->preds)
if (EDGE_COUNT (e->src->succs) == 1)
found = true;
if (!found)
{
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "only critical predecessors\n");
return false;
}
}
return true;
}
@ -1084,7 +1083,6 @@ if_convertible_loop_p_1 (struct loop *loop,
return false;
calculate_dominance_info (CDI_DOMINATORS);
calculate_dominance_info (CDI_POST_DOMINATORS);
/* Allow statements that can be handled during if-conversion. */
ifc_bbs = get_loop_body_in_if_conv_order (loop);
@ -1220,8 +1218,7 @@ if_convertible_loop_p (struct loop *loop)
if-conversion. */
static basic_block
find_phi_replacement_condition (struct loop *loop,
basic_block bb, tree *cond,
find_phi_replacement_condition (basic_block bb, tree *cond,
gimple_stmt_iterator *gsi)
{
edge first_edge, second_edge;
@ -1231,34 +1228,10 @@ find_phi_replacement_condition (struct loop *loop,
first_edge = EDGE_PRED (bb, 0);
second_edge = EDGE_PRED (bb, 1);
/* Use condition based on following criteria:
1)
S1: x = !c ? a : b;
S2: x = c ? b : a;
S2 is preferred over S1. Make 'b' first_bb and use its condition.
2) Do not make loop header first_bb.
3)
S1: x = !(c == d)? a : b;
S21: t1 = c == d;
S22: x = t1 ? b : a;
S3: x = (c == d) ? b : a;
S3 is preferred over S1 and S2*, Make 'b' first_bb and use
its condition.
4) If pred B is dominated by pred A then use pred B's condition.
See PR23115. */
/* Select condition that is not TRUTH_NOT_EXPR. */
/* Prefer an edge with a not negated predicate.
??? That's a very weak cost model. */
tmp_cond = bb_predicate (first_edge->src);
gcc_assert (tmp_cond);
if (TREE_CODE (tmp_cond) == TRUTH_NOT_EXPR)
{
edge tmp_edge;
@ -1268,11 +1241,9 @@ find_phi_replacement_condition (struct loop *loop,
second_edge = tmp_edge;
}
/* Check if FIRST_BB is loop header or not and make sure that
FIRST_BB does not dominate SECOND_BB. */
if (first_edge->src == loop->header
|| dominated_by_p (CDI_DOMINATORS,
second_edge->src, first_edge->src))
/* Check if the edge we take the condition from is not critical.
We know that at least one non-critical edge exists. */
if (EDGE_COUNT (first_edge->src->succs) > 1)
{
*cond = bb_predicate (second_edge->src);
@ -1347,9 +1318,6 @@ predicate_scalar_phi (gimple phi, tree cond,
arg_1 = gimple_phi_arg_def (phi, 1);
}
gcc_checking_assert (bb == bb->loop_father->header
|| bb_postdominates_preds (bb));
/* Build new RHS using selected condition and arguments. */
rhs = fold_build_cond_expr (TREE_TYPE (res), unshare_expr (cond),
arg_0, arg_1);
@ -1395,7 +1363,7 @@ predicate_all_scalar_phis (struct loop *loop)
/* BB has two predecessors. Using predecessor's aux field, set
appropriate condition for the PHI node replacement. */
gsi = gsi_after_labels (bb);
true_bb = find_phi_replacement_condition (loop, bb, &cond, &gsi);
true_bb = find_phi_replacement_condition (bb, &cond, &gsi);
while (!gsi_end_p (phi_gsi))
{
@ -1765,9 +1733,6 @@ combine_blocks (struct loop *loop)
free (ifc_bbs);
ifc_bbs = NULL;
/* Post-dominators are corrupt now. */
free_dominance_info (CDI_POST_DOMINATORS);
}
/* If-convert LOOP when it is legal. For the moment this pass has no
@ -1830,8 +1795,6 @@ main_tree_if_conversion (void)
if (changed && flag_tree_loop_if_convert_stores)
todo |= TODO_update_ssa_only_virtuals;
free_dominance_info (CDI_POST_DOMINATORS);
#ifdef ENABLE_CHECKING
{
basic_block bb;
@ -1867,7 +1830,8 @@ const pass_data pass_data_if_conversion =
0, /* properties_provided */
0, /* properties_destroyed */
0, /* todo_flags_start */
( TODO_verify_stmts | TODO_verify_flow ), /* todo_flags_finish */
( TODO_verify_stmts | TODO_verify_flow
| TODO_verify_ssa ), /* todo_flags_finish */
};
class pass_if_conversion : public gimple_opt_pass