id = 2248
title = "qemu-aarch64: wrong execution result when executing the code"
state = "closed"
created_at = "2024-03-26T04:50:35.585Z"
closed_at = "2024-03-31T15:41:51.586Z"
labels = ["Closed::Fixed", "accel: TCG", "kind::Bug", "target: arm"]
url = "https://gitlab.com/qemu-project/qemu/-/issues/2248"
host-os = "Ubuntu 22.04.4 LTS"
host-arch = "x86_64"
qemu-version = "8.2.1, 8.2.2, 9.0.0-rc0, latest commit 6a4180af9686830d88c387baab6d79563ce42a15"
guest-os = "n/a"
guest-arch = "n/a"
description = """The following aarch64 code results in the wrong execution result `4611686018427387903`, which is `0x3fffffffffffffff`. (The correct result is `-1`) The bug seems to be introduced in between v8.1.5 and v8.2.1 since the results are correct in v8.1.5.

```c
// foo.c
#include <stdio.h>
#include <stdint.h>

int64_t callme(size_t _1, size_t _2, int64_t a, int64_t b, int64_t c);

int main() {
    int64_t ret = callme(0, 0, 0, 1, 2);
    printf("%ld\\n", ret);
    return 0;
}
```

```s
// foo.S
.global callme
callme:
  cmp   x2, x3
  cset  x12, lt
  and   w11, w12, #0xff
  cmp   w11, #0x0
  csetm x14, ne
  lsr   x13, x14, x4
  sxtb  x0, w13
  ret
```"""
reproduce = """1. Build the code with `aarch64-linux-gnu-gcc foo.c foo.S -o foo` (`aarch64-linux-gnu-gcc (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0`)
2. Run the code with `qemu-aarch64 -L /usr/aarch64-linux-gnu -E LD_LIBRARY_PATH=/usr/aarch64-linux-gnu/lib foo` and see the result"""
additional = """- Original discussion is held in [this wasmtime issue](https://github.com/bytecodealliance/wasmtime/issues/8233). Thanks to Alex Crichton for clarifying this bug."""