https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112736
Bug ID: 112736
Summary: vectorizer is introducing out of bounds memory access
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: kristerw at gcc dot gnu.org
Target Milestone: ---
The following function (from gcc.dg/torture/pr68379.c)
int a, b[3], c[3][5];
void
fn1 ()
{
int e;
for (a = 2; a >= 0; a--)
for (e = 0; e < 4; e++)
c[a][e] = b[a];
}
generates out of bound memory access (where the three movdqu instructions read
1, 2, and 3 elements before b) when compiled as -O3 for x86_64:
fn1:
movdqu b-4(%rip), %xmm1
movdqu b-8(%rip), %xmm2
movl $-1, a(%rip)
movdqu b-12(%rip), %xmm3
pshufd $255, %xmm1, %xmm0
movups %xmm0, c+40(%rip)
pshufd $255, %xmm2, %xmm0
movups %xmm0, c+20(%rip)
pshufd $255, %xmm3, %xmm0
movaps %xmm0, c(%rip)
ret
The vector operations were introduced by the "vect" pass.
