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re PR c/61779 (gcc -Og fails with impossible constraint on legal C code)

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2014-07-14  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/61779
	* tree-ssa-copy.c (copy_prop_visit_cond_stmt): Always try
	simplifying a condition.

	* gcc.dg/tree-ssa/ssa-copyprop-2.c: New testcase.

From-SVN: r212521
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Richard Biener 2014-07-14 13:52:38 +00:00 committed by Richard Biener
parent 72602c6cb4
commit 236aff7251
4 changed files with 41 additions and 29 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2014-07-14 Richard Biener <rguenther@suse.de>
PR tree-optimization/61779
* tree-ssa-copy.c (copy_prop_visit_cond_stmt): Always try
simplifying a condition.
2014-07-14 Richard Biener <rguenther@suse.de>
* builtins.c (c_strlen): Make only_value == 2 really only

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2014-07-14 Richard Biener <rguenther@suse.de>
PR tree-optimization/61779
* gcc.dg/tree-ssa/ssa-copyprop-2.c: New testcase.
2014-07-14 Richard Biener <rguenther@suse.de>
PR tree-optimization/61786

13
gcc/testsuite/gcc.dg/tree-ssa/ssa-copyprop-2.c Normal file
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@ -0,0 +1,13 @@
/* { dg-do compile } */
/* { dg-options "-Og -fdump-tree-optimized" } */
extern long long __sdt_unsp;
void
f(void)
{
for (;;)
__asm__ ("%0" :: "i" (((!__extension__ (__builtin_constant_p ((((unsigned long long) (__typeof (__builtin_choose_expr (((__builtin_classify_type (0) + 3) & -4) == 4, (0), 0U))) __sdt_unsp) ) == 0) )) ? 1 : -1) ));
}
/* { dg-final { scan-tree-dump-not "PHI" "optimized" } } */
/* { dg-final { cleanup-tree-dump "optimized" } } */

46
gcc/tree-ssa-copy.c
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@ -237,38 +237,26 @@ copy_prop_visit_cond_stmt (gimple stmt, edge *taken_edge_p)
enum ssa_prop_result retval = SSA_PROP_VARYING;
location_t loc = gimple_location (stmt);
tree op0 = gimple_cond_lhs (stmt);
tree op1 = gimple_cond_rhs (stmt);
tree op0 = valueize_val (gimple_cond_lhs (stmt));
tree op1 = valueize_val (gimple_cond_rhs (stmt));
/* The only conditionals that we may be able to compute statically
are predicates involving two SSA_NAMEs. */
if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
/* See if we can determine the predicate's value. */
if (dump_file && (dump_flags & TDF_DETAILS))
{
op0 = valueize_val (op0);
op1 = valueize_val (op1);
fprintf (dump_file, "Trying to determine truth value of ");
fprintf (dump_file, "predicate ");
print_gimple_stmt (dump_file, stmt, 0, 0);
}
/* See if we can determine the predicate's value. */
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "Trying to determine truth value of ");
fprintf (dump_file, "predicate ");
print_gimple_stmt (dump_file, stmt, 0, 0);
}
/* We can fold COND and get a useful result only when we have
the same SSA_NAME on both sides of a comparison operator. */
if (op0 == op1)
{
tree folded_cond = fold_binary_loc (loc, gimple_cond_code (stmt),
boolean_type_node, op0, op1);
if (folded_cond)
{
basic_block bb = gimple_bb (stmt);
*taken_edge_p = find_taken_edge (bb, folded_cond);
if (*taken_edge_p)
retval = SSA_PROP_INTERESTING;
}
}
/* Fold COND and see whether we get a useful result. */
tree folded_cond = fold_binary_loc (loc, gimple_cond_code (stmt),
boolean_type_node, op0, op1);
if (folded_cond)
{
basic_block bb = gimple_bb (stmt);
*taken_edge_p = find_taken_edge (bb, folded_cond);
if (*taken_edge_p)
retval = SSA_PROP_INTERESTING;
}
if (dump_file && (dump_flags & TDF_DETAILS) && *taken_edge_p)