https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121781
Bug ID: 121781
Summary: [Trunk] RISC-V rv64gcv: miscompile at -O1/O2
Product: gcc
Version: 16.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: xxs_chy at outlook dot com
Target Milestone: ---
GCC version: gcc version 16.0.0 20250903 (experimental) (gbda76b479)
Testcase:
#include <stdint.h>
#include <stdio.h>
typedef int16_t a;
typedef uint16_t b;
typedef b c __attribute__((vector_size(8)));
typedef a d __attribute__((vector_size(8)));
typedef b e __attribute__((vector_size(16)));
int f[10];
uint16_t g, l, k;
int32_t j;
int32_t m(uint32_t, const uint32_t *);
int32_t *n(uint64_t, uint8_t);
uint8_t o() {
int p = 7;
m(p, 0);
return 0;
}
int32_t m(uint32_t, const uint32_t *) {
int32_t q = l;
n(q, 0);
return k;
}
int32_t *n(uint64_t, uint8_t) {
c r = {1, 6, 8, 30};
d s = {};
e u;
int *t = &f[7];
for (j = 9; j; j--) {
*t ^= s[0];
r = __builtin_shufflevector(r * r, r, 2, 5, 7, 2);
for (g = 0; g != 1; g = g + 3)
s = (d)__builtin_shufflevector(
__builtin_shufflevector(u, (e){}, 3, 1, 1, 1), r, 4, 6, 0, 2);
}
return &j;
}
int main() {
o();
int BS_CHECKSUM = 5;
for (int i = 0; i < 10; i++)
BS_CHECKSUM ^= f[i];
printf("BackSmith Checksum = 0x%016llx\n", BS_CHECKSUM);
}
Commands:
> riscv64-unknown-elf-gcc -O0 -static -march=rv64gc reduced.c && qemu-riscv64
> a.out
> BackSmith Checksum = 0xffffffffffffced1
> riscv64-unknown-elf-gcc -O1 -static -march=rv64gc reduced.c && qemu-riscv64
> a.out
> BackSmith Checksum = 0x0000000000000005
> riscv64-unknown-elf-gcc -O2 -static -march=rv64gc reduced.c && qemu-riscv64
> a.out
> BackSmith Checksum = 0x0000000000000005
> riscv64-unknown-elf-gcc -O3 -static -march=rv64gc reduced.c && qemu-riscv64
> a.out
> BackSmith Checksum = 0xffffffffffffced1
