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re PR tree-optimization/60183 (phiprop creates invalid code)

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2014-02-15  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/60183
	* tree-ssa-phiprop.c (propagate_with_phi): Avoid speculating
	loads.
	(tree_ssa_phiprop): Calculate and free post-dominators.

	* gcc.dg/torture/pr60183.c: New testcase.

From-SVN: r207797
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Richard Biener 2014-02-15 09:54:52 +00:00 committed by Richard Biener
parent cd7734ca9e
commit a2b33cc36b
4 changed files with 59 additions and 0 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2014-02-15 Richard Biener <rguenther@suse.de>
PR tree-optimization/60183
* tree-ssa-phiprop.c (propagate_with_phi): Avoid speculating
loads.
(tree_ssa_phiprop): Calculate and free post-dominators.
2014-02-14 Jeff Law <law@redhat.com>
PR rtl-optimization/60131

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2014-02-15 Richard Biener <rguenther@suse.de>
PR tree-optimization/60183
* gcc.dg/torture/pr60183.c: New testcase.
2014-02-14 Jeff Law <law@redhat.com>
PR rtl-optimization/60131

38
gcc/testsuite/gcc.dg/torture/pr60183.c Normal file
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@ -0,0 +1,38 @@
/* { dg-do run } */
/* Large so an out-of-bound read will crash. */
unsigned char c[0x30001] = { 1 };
int j = 2;
static void
foo (unsigned long *x, unsigned char *y)
{
int i;
unsigned long w = x[0];
for (i = 0; i < j; i++)
{
w += *y;
y += 0x10000;
w += *y;
y += 0x10000;
}
x[1] = w;
}
__attribute__ ((noinline, noclone)) void
bar (unsigned long *x)
{
foo (x, c);
}
int
main ()
{
unsigned long a[2] = { 0, -1UL };
asm volatile (""::"r" (c):"memory");
c[0] = 0;
bar (a);
if (a[1] != 0)
__builtin_abort ();
return 0;
}

9
gcc/tree-ssa-phiprop.c
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@ -309,6 +309,12 @@ propagate_with_phi (basic_block bb, gimple phi, struct phiprop_d *phivn,
gimple def_stmt;
tree vuse;
/* Only replace loads in blocks that post-dominate the PHI node. That
makes sure we don't end up speculating loads. */
if (!dominated_by_p (CDI_POST_DOMINATORS,
bb, gimple_bb (use_stmt)))
continue;
/* Check whether this is a load of *ptr. */
if (!(is_gimple_assign (use_stmt)
&& TREE_CODE (gimple_assign_lhs (use_stmt)) == SSA_NAME
@ -380,6 +386,7 @@ tree_ssa_phiprop (void)
size_t n;
calculate_dominance_info (CDI_DOMINATORS);
calculate_dominance_info (CDI_POST_DOMINATORS);
n = num_ssa_names;
phivn = XCNEWVEC (struct phiprop_d, n);
@ -397,6 +404,8 @@ tree_ssa_phiprop (void)
bbs.release ();
free (phivn);
free_dominance_info (CDI_POST_DOMINATORS);
return 0;
}