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tree-ssa-sccvn.c (visit_phi): Compare invariant addresses as base and offset.

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2018-08-01  Richard Biener  <rguenther@suse.de>

	* tree-ssa-sccvn.c (visit_phi): Compare invariant addresses
	as base and offset.

	* gcc.dg/tree-ssa/ssa-fre-68.c: New testcase.

From-SVN: r263206
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Richard Biener 2018-08-01 12:03:29 +00:00 • committed by Richard Biener
parent 42c4ccce72
commit e4837aa9fb
4 changed files with 56 additions and 0 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
2018-08-01 Richard Biener <rguenther@suse.de>
* tree-ssa-sccvn.c (visit_phi): Compare invariant addresses
as base and offset.
2018-08-01 Martin Liska <mliska@suse.cz>
* value-prof.c (gimple_divmod_fixed_value_transform): Unify

4
gcc/testsuite/ChangeLog
View file

@ -1,3 +1,7 @@
2018-08-01 Richard Biener <rguenther@suse.de>
* gcc.dg/tree-ssa/ssa-fre-68.c: New testcase.
2018-08-01 Uros Bizjak <ubizjak@gmail.com>
* gcc.dg/plugin/poly-int-07_plugin.c (dg-options): Use -O0.

28
gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-68.c Normal file
View file

@ -0,0 +1,28 @@
/* { dg-do compile } */
/* { dg-options "-O -fdump-tree-fre1" } */
struct S { char a[3]; char b[5]; } s = { "abc", "defg" };
__SIZE_TYPE__
foo (struct S s, int a, int b)
{
char *p = (char *) &s.a[0];
if (a)
p = (char *) &s.a;
else if (b)
p = (char *) &s;
return __builtin_strlen (p);
}
__SIZE_TYPE__
bar (int a, int b)
{
char *p = (char *) &s.a[0];
if (a)
p = (char *) &s.a;
else if (b)
p = (char *) &s;
return __builtin_strlen (p);
}
/* { dg-final { scan-tree-dump-times "strlen \\\(&s" 2 "fre1" } } */

19
gcc/tree-ssa-sccvn.c
View file

@ -3941,6 +3941,8 @@ static bool
visit_phi (gimple *phi)
{
tree result, sameval = VN_TOP, seen_undef = NULL_TREE;
tree sameval_base = NULL_TREE;
poly_int64 soff, doff;
unsigned n_executable = 0;
bool allsame = true;
edge_iterator ei;
@ -3971,6 +3973,23 @@ visit_phi (gimple *phi)
sameval = def;
else if (!expressions_equal_p (def, sameval))
{
/* We know we're arriving only with invariant addresses here,
try harder comparing them. We can do some caching here
which we cannot do in expressions_equal_p. */
if (TREE_CODE (def) == ADDR_EXPR
&& TREE_CODE (sameval) == ADDR_EXPR
&& sameval_base != (void *)-1)
{
if (!sameval_base)
sameval_base = get_addr_base_and_unit_offset
(TREE_OPERAND (sameval, 0), &soff);
if (!sameval_base)
sameval_base = (tree)(void *)-1;
else if ((get_addr_base_and_unit_offset
(TREE_OPERAND (def, 0), &doff) == sameval_base)
&& known_eq (soff, doff))
continue;
}
allsame = false;
break;
}