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re PR tree-optimization/68240 (compilation hangs on valid code at -O1 and above on x86_64-linux-gnu)

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2015-11-10  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/68240
	* tree-ssa-sccvn.c (cond_stmts_equal_p): Handle commutative compares
	properly.
	(visit_phi): For PHIs with just a single executable edge
	take its value directly.
	(expressions_equal_p): Handle VN_TOP properly.

	* gcc.dg/torture/pr68240.c: New testcase.

From-SVN: r230095
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Richard Biener 2015-11-10 10:14:02 +00:00 committed by Richard Biener
parent ef785d9f19
commit 94852c8ec4
4 changed files with 46 additions and 8 deletions
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9
gcc/ChangeLog
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@ -1,3 +1,12 @@
2015-11-10 Richard Biener <rguenther@suse.de>
PR tree-optimization/68240
* tree-ssa-sccvn.c (cond_stmts_equal_p): Handle commutative compares
properly.
(visit_phi): For PHIs with just a single executable edge
take its value directly.
(expressions_equal_p): Handle VN_TOP properly.
2015-11-10 Richard Biener <rguenther@suse.de>
* tree-vect-data-refs.c (vect_slp_analyze_node_dependences):

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2015-11-10 Richard Biener <rguenther@suse.de>
PR tree-optimization/68240
* gcc.dg/torture/pr68240.c: New testcase.
2015-11-10 Richard Biener <rguenther@suse.de>
PR tree-optimization/56118

12
gcc/testsuite/gcc.dg/torture/pr68240.c Normal file
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@ -0,0 +1,12 @@
/* { dg-do compile } */
int a, b, f;
void
fn1 ()
{
int c = 1, d, e = 1;
a = 1;
for (; f;)
b = (c && (d = (e && a)));
}

28
gcc/tree-ssa-sccvn.c
View File

@ -2760,11 +2760,15 @@ cond_stmts_equal_p (gcond *cond1, gcond *cond2, bool *inverted_p)
else
return false;
if (! expressions_equal_p (vn_valueize (lhs1), vn_valueize (lhs2))
|| ! expressions_equal_p (vn_valueize (rhs1), vn_valueize (rhs2)))
return false;
return true;
lhs1 = vn_valueize (lhs1);
rhs1 = vn_valueize (rhs1);
lhs2 = vn_valueize (lhs2);
rhs2 = vn_valueize (rhs2);
return ((expressions_equal_p (lhs1, lhs2)
&& expressions_equal_p (rhs1, rhs2))
|| (commutative_tree_code (code1)
&& expressions_equal_p (lhs1, rhs2)
&& expressions_equal_p (rhs1, lhs2)));
}
/* Compare two phi entries for equality, ignoring VN_TOP arguments. */
@ -3379,6 +3383,7 @@ visit_phi (gimple *phi)
tree result;
tree sameval = VN_TOP;
bool allsame = true;
unsigned n_executable = 0;
/* TODO: We could check for this in init_sccvn, and replace this
with a gcc_assert. */
@ -3394,6 +3399,7 @@ visit_phi (gimple *phi)
{
tree def = PHI_ARG_DEF_FROM_EDGE (phi, e);
++n_executable;
if (TREE_CODE (def) == SSA_NAME)
def = SSA_VAL (def);
if (def == VN_TOP)
@ -3408,9 +3414,11 @@ visit_phi (gimple *phi)
}
/* If none of the edges was executable or all incoming values are
undefined keep the value-number at VN_TOP. */
if (sameval == VN_TOP)
return set_ssa_val_to (PHI_RESULT (phi), VN_TOP);
undefined keep the value-number at VN_TOP. If only a single edge
is exectuable use its value. */
if (sameval == VN_TOP
|| n_executable == 1)
return set_ssa_val_to (PHI_RESULT (phi), sameval);
/* First see if it is equivalent to a phi node in this block. We prefer
this as it allows IV elimination - see PRs 66502 and 67167. */
@ -4610,6 +4618,10 @@ expressions_equal_p (tree e1, tree e2)
if (e1 == e2)
return true;
/* If either one is VN_TOP consider them equal. */
if (e1 == VN_TOP || e2 == VN_TOP)
return true;
/* If only one of them is null, they cannot be equal. */
if (!e1 || !e2)
return false;