Viewing file:  calloc-4.c (1.09 KB) -rw-r--r--
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/* PR tree-optimization/83821 - local aggregate initialization defeats
strlen optimization
Verify that a memset() call to zero out a subregion of memory
allocated by calloc() is eliminated even if a zero byte is written
into it in between the two calls. See the calloc-2.c test that
verifies that the memset() calls isn't eliminated if the written
value is non-zero.
{ dg-do compile }
{ dg-options "-O2 -fdump-tree-optimized" } */
void* elim_calloc_store_memset_1 (unsigned a, unsigned b)
{
char *p = __builtin_calloc (a, 1);
p[1] = '\0';
__builtin_memset (p, 0, b); // should be eliminated
return p;
}
void* elim_calloc_store_memset_2 (unsigned a, unsigned b, unsigned c)
{
char *p = __builtin_calloc (a, 1);
p[1] = '\0';
__builtin_memset (p, 0, b); // should be eliminated
p[3] = '\0';
__builtin_memset (p, 0, c); // should also be eliminated
return p;
}
/* { dg-final { scan-tree-dump-not "malloc" "optimized" } }
{ dg-final { scan-tree-dump-times "_calloc \\\(" 2 "optimized" } }
{ dg-final { scan-tree-dump-not "_memset \\\(" "optimized" } } */
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