[Bug target/98248] New: [11 Regression] SVE: Wrong code with -O3 -msve-vector-bits=256

[acoplan at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98248

            Bug ID: 98248
           Summary: [11 Regression] SVE: Wrong code with -O3
                    -msve-vector-bits=256
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: acoplan at gcc dot gnu.org
  Target Milestone: ---

AArch64 GCC miscompiles the following testcase:

unsigned long long b;
_Bool a;
unsigned char c[3][22];
unsigned char (*h)[22] = c;
int j;
void aa(unsigned long long *n, int o) { *n ^= o; }
int main() {
  for (long e = 0; e < 3; ++e)
    for (long d = 0; d < 22; ++d)
      c[e][d] = 7;
  for (int d = 0; d < 2; d += 4)
    for (char g = 0; g < 14; g += 4)
      for (int i = 0; i < 12; i += 1)
        if (~j)
          a = h[d][4];
  aa(&b, a);
  if (b != 1)
    __builtin_abort();
}

at -O3 -march=armv8.2-a+sve -msve-vector-bits=256 since
r11-4912-g46c705e70e078f6a1920d92e49042125d5e18495.