OpenE2K
/
gcc
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

fold-const: Optimize &"foo"[0] == "foo" [PR89074] 

This is a non-C++ related part from the PR89074 address_compare changes.
For "foo" == "foo" we already optimize this from the (cmp @0 @0)
simplification, because we use operand_equal_p in that case
and operand_equal_p also compares the STRING_CSTs bytes rather than
just addresses.

2022-01-19  Jakub Jelinek  <jakub@redhat.com>

	PR c++/89074
	* fold-const.cc (address_compare): Consider different STRING_CSTs
	with the same lengths that memcmp the same as equal, not different.

	* gcc.dg/tree-ssa/pr89074.c: New test.
This commit is contained in:
Jakub Jelinek 2022-01-19 09:26:13 +01:00
parent 29a6db635f
commit b834435c8f
2 changed files with 21 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
gcc/fold-const.cc
View File

@ -16587,6 +16587,15 @@ address_compare (tree_code code, tree type, tree op0, tree op1,
|| TREE_CODE (base1) == SSA_NAME
|| TREE_CODE (base1) == STRING_CST))
equal = (base0 == base1);
/* Assume different STRING_CSTs with the same content will be
merged. */
if (equal == 0
&& TREE_CODE (base0) == STRING_CST
&& TREE_CODE (base1) == STRING_CST
&& TREE_STRING_LENGTH (base0) == TREE_STRING_LENGTH (base1)
&& memcmp (TREE_STRING_POINTER (base0), TREE_STRING_POINTER (base1),
TREE_STRING_LENGTH (base0)) == 0)
equal = 1;
if (equal == 1)
{
if (code == EQ_EXPR

12
gcc/testsuite/gcc.dg/tree-ssa/pr89074.c Normal file
View File

@ -0,0 +1,12 @@
/* PR c++/89074 */
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-optimized" } */
/* { dg-final { scan-tree-dump "return 1;" "optimized" } } */
int
foo (void)
{
const char *a = &"foo"[0];
const char *b = "foo";
return a == b;
}