| Issue |
177553
|
| Summary |
[clang] Wrong code at -O1/Os with PGO on x86_64-gnu_linux
|
| Labels |
clang
|
| Assignees |
|
| Reporter |
zxt5
|
small.c:
```
#include <stdint.h>
#include <stdio.h>
int32_t j, k, l, m = 2, n;
int8_t o;
int32_t *p;
static int32_t **q = &p;
static uint32_t *r = &l;
uint64_t s[1];
int8_t(c)(int8_t d, int8_t e) { return d; }
uint8_t(f)(uint8_t g, int right) { return g; }
int a(int b) { return 3 * b / 2; }
static int16_t func_27(int64_t, uint16_t, uint64_t, int8_t);
int64_t aa(uint32_t, int64_t);
int32_t *ab(int8_t *, int8_t *);
static uint32_t func_1() {
(0 == 0 == func_27(aa(n = c((0 < 0) < 5, 0) > 0, 0), 0, 0, 0)) >= 1 && 0;
return *r;
}
int16_t func_27(int64_t af, uint16_t ag, uint64_t ah, int8_t ai) {
for (k = 0; k <= 1; ++k) {
int16_t aj = 0;
uint64_t *ak = &s[0];
&k != (m || f(af, 5) && (*ak = *r != aj), &k);
}
return 0;
}
int64_t aa(uint32_t al, int64_t am) {
int8_t *an = &o;
*q = ab(an, an);
for (n = 0;;)
return a(al + 5) - 5;
}
int32_t *ab(int8_t *ao, int8_t *ap) {
uint16_t aq[41];
int i;
for (i = 0; i < 4; i++)
aq[i] = 9;
for (n = 0;;) {
if (aq[n])
break;
for (j = 0;;)
;
}
return 0;
}
int main() {
func_1();
printf("%d\n", n);
}
```
Clang at -O1/Os with PGO produces the wrong code.
Steps to reproduce:
1. Generate the profile using [profile.txt](https://github.com/user-attachments/files/24817579/profile.txt)
```
llvm-profdata merge -o test.profdata profile.txt
```
2. Compile with PGO:
```
$ clang-trunk -O1 -fprofile-instr-use=test.profdata small.c && ./a.out
1
$ clang-trunk -Os -fprofile-instr-use=test.profdata small.c && ./a.out
1
$ clang-trunk -O1 small.c && ./a.out
0
$ clang-trunk -Os small.c && ./a.out
0
```
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