https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90025
Bug ID: 90025
Summary: [9 Regression] botan2 miscompilation on s390x-linux
since r268957
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: jakub at gcc dot gnu.org
Target Milestone: ---
The following testcase is miscompiled e.g. with -O2 -march=zEC12 -mtune=z13 on
s390x-linux:
__attribute__((noipa)) void
bar (char *p)
{
int i;
for (i = 0; i < 6; i++)
if (p[i] != "foobar"[i])
__builtin_abort ();
for (; i < 32; i++)
if (p[i] != '\0')
__builtin_abort ();
}
__attribute__((noipa)) void
foo (unsigned int x)
{
char s[32] = { 'f', 'o', 'o', 'b', 'a', 'r', 0 };
((unsigned int *) s)[2] = __builtin_bswap32 (x);
bar (s);
}
int
main ()
{
foo (0);
return 0;
}
The problem is that since that change we emit a store_by_pieces (8 bytes)
followed by clear_storage (24 bytes), but the object we pass to the latter
actually has S1, so DSE2 then happily removes it when it sees a further store
of 4 bytes to s+8.
