On Mon, 27 Sep 2021, sunil.k.pandey wrote:
> On Linux/x86_64,
>
> d06dc8a2c73735e9496f434787ba4c93ceee5eea is the first bad commit
> commit d06dc8a2c73735e9496f434787ba4c93ceee5eea
> Author: Richard Biener <rguent...@suse.de>
> Date: Mon Sep 27 13:36:12 2021 +0200
>
> middle-end/102450 - avoid type_for_size for non-existing modes
>
> caused
>
> FAIL: gcc.dg/out-of-bounds-1.c (test for warnings, line 12)
> FAIL: gcc.dg/pr78408-1.c scan-tree-dump-times fab1 "after previous" 17
> FAIL: gcc.dg/strlenopt-13.c scan-tree-dump-times strlen1 "memcpy \\(" 7
After the change the new memcpy inlining limit using MOVE_MAX * MOVE_RATIO
comes into play and ends up using an OImode move which previously was
disregarded as there's no __int256 standard type in the frontend
(but now we build such type anyway after verifying the mode exists and
it has move support).
For example gcc.dg/out-of-bounds-1.c which looks like
void ProjectOverlay(const float localTextureAxis[2], char *lump)
{
const void *d = &localTextureAxis;
int size = sizeof(float)*8 ;
__builtin_memcpy( &lump[ 0 ], d, size ); /* { dg-warning "reading" }
*/
}
gets turned into
movq %rdi, -8(%rsp)
vmovdqu64 -8(%rsp), %ymm31
vmovdqu64 %ymm31, (%rsi)
which I guess is good but then the diagnostic is no longer emitted
because -Wstringop-overread only applies to the builtin. Usually
we avoid the folding in such a case but
/* Detect out-of-bounds accesses without issuing warnings.
Avoid folding out-of-bounds copies but to avoid false
positives for unreachable code defer warning until after
DCE has worked its magic.
-Wrestrict is still diagnosed. */
if (int warning = check_bounds_or_overlap (as_a <gcall
*>(stmt),
dest, src, len,
len,
false, false))
if (warning != OPT_Wrestrict)
return false;
does not seem to trigger here. Changing the testcase to
void ProjectOverlay(const float localTextureAxis[2], char *lump)
{
const void *d = &localTextureAxis;
int size = sizeof(float)*4 ;
__builtin_memcpy( &lump[ 0 ], d, size ); /* { dg-warning "reading" }
*/
}
also fails to warn.
Richard.
