https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123285
Bug ID: 123285
Summary: [Trunk] AArch64: Miscompile at -O3
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 16.0.0 20251220 (experimental)
Testcase:
#include <stdint.h>
#include <stdio.h>
#include <arm_neon.h>
#define BS_VEC(type, num) type __attribute__((vector_size(num * sizeof(type))))
#define BARRIER_u8() vqadd_u64((uint64x1_t){}, (uint64x1_t){})[0]
uint64_t BS_CHECKSUM;
uint16_t g_16;
int32_t g_35;
int64_t func_25(uint16_t *, uint16_t *);
uint16_t *func_28(int16_t, uint32_t);
int32_t *func_41(const int32_t *);
uint64_t func_1()
{
int8_t l_14 = 0;
uint16_t *l_31 = &g_16;
func_25(func_28(l_14, l_14), l_31);
return 0;
}
int64_t func_25(uint16_t *, uint16_t *)
{
int32_t l_2088 = 0;
func_41(&g_35);
return l_2088;
}
uint16_t *func_28(int16_t, uint32_t) { return &g_16; }
int32_t *func_41(const int32_t *)
{
BS_VEC(uint8_t, 32) BS_VAR_1[44] = {};
uint64_t LOCAL_CHECKSUM = 0;
int32_t l_58 = 10;
for (g_35 = 4; g_35; g_35 -= 1)
{
__asm("" ::: "v30");
BS_VAR_1[BS_VAR_1[6][9] < 4 ? BARRIER_u8() : 0] -=
(BS_VEC(uint8_t, 32)){ l_58, l_58, l_58, l_58, l_58, l_58,
l_58,
l_58, l_58, l_58, l_58, l_58, l_58,
l_58,
l_58, l_58, l_58 };
}
for (uint32_t BS_TEMP_398 = 0; BS_TEMP_398 < 44; BS_TEMP_398++)
for (uint32_t BS_TEMP_399 = 0; BS_TEMP_399 < 2; BS_TEMP_399++)
LOCAL_CHECKSUM ^=
BS_VAR_1[BS_TEMP_398][BS_TEMP_399] + LOCAL_CHECKSUM >> 2;
BS_CHECKSUM += LOCAL_CHECKSUM;
return 0;
}
int main()
{
func_1();
printf("BackSmith Checksum = 0x%016llx\n", BS_CHECKSUM);
}
Commands:
> aarch64-unknown-linux-musl-gcc -O2 -static a.c
> qemu-aarch64 ./a.out
BackSmith Checksum = 0x0000000000000072
> aarch64-unknown-linux-musl-gcc -O3 -static a.c
> qemu-aarch64 ./a.out
BackSmith Checksum = 0x0000000000000075
