https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98196
Bug ID: 98196
Summary: [11 Regression] aarch64: Wrong code at -O3
-march=armv8.2-a+sve -msve-vector-bits=256
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: acoplan at gcc dot gnu.org
Target Milestone: ---
AArch64 GCC miscompiles the following testcase:
static unsigned long long a;
static long b;
static signed char c[17][11];
static signed char (*d)[11] = c;
static void e(unsigned long long *f, int h) { *f ^= h; }
int main() {
for (long g = 0; g < 17; ++g)
for (long i = 0; i < 1; ++i)
c[g][i] = 2;
for (int g = 0; g < 16; g += 4)
for (short i = 0; i < 10; i += 10)
b = d[g][i];
e(&a, b);
if (a != 2)
__builtin_abort();
}
at -O3 -march=armv8.2-a+sve -msve-vector-bits=256 -fvect-cost-model=unlimited
since r11-3705-gdae673abd37d400408959497e50fe1f3fbef5533.
The broken code is below. It seems that we load a without first storing to it,
so we just load 0 (instead of 2) and make the call to abort.
main:
adrp x2, .LANCHOR0
add x0, x2, :lo12:.LANCHOR0
mov w1, 2
strb w1, [x2, #:lo12:.LANCHOR0] // c[0][0] = 2
ldr x2, [x0, 200] // x2 <- a (= 0)
strb w1, [x0, 11]
strb w1, [x0, 22]
strb w1, [x0, 33]
strb w1, [x0, 44]
strb w1, [x0, 55]
strb w1, [x0, 66]
strb w1, [x0, 77]
strb w1, [x0, 88]
strb w1, [x0, 99]
strb w1, [x0, 110]
strb w1, [x0, 121]
strb w1, [x0, 132]
strb w1, [x0, 143]
strb w1, [x0, 154]
strb w1, [x0, 165]
strb w1, [x0, 176]
str xzr, [x0, 192] // b = 0
cmp x2, 2
bne .L7
mov w0, 0
ret
.L7:
stp x29, x30, [sp, -16]!
mov x29, sp
bl abort
.size main, .-main
.bss
.align 4
.set .LANCHOR0,. + 0
.type c, %object
.size c, 187
c:
.zero 187
.zero 5
.type b, %object
.size b, 8
b:
.zero 8
.type a, %object
.size a, 8
a:
.zero 8
.ident "GCC: (unknown) 11.0.0 20201207 (experimental)"
