| Issue |
97783
|
| Summary |
[TBAA] "long long" type causes incorrect optimization in GVN
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
huhu233
|
There is a simple case, I get total different results with `long` type and `long long` type, as shown,
**long type**
```
#include <cstdio>
#include <arm_sve.h>
const int SIZE = 16;
int main()
{
int datas[SIZE];
#pragma clang loop vectorize(disable)
for (int i = 0; i < SIZE; i++) {
datas[i] = -i - i - 1;
}
long res2[SIZE];
svbool_t pa = svptrue_b32();
svint32_t v1 = svld1(pa, &datas[0]);
svint64_t v2 = svunpklo(v1);
svst1(pa, (long *)&res2[0], v2);
printf("--%dth-- %lld\n", 0, res2[0]);
printf("--%dth-- %lld\n", 1, res2[1]);
printf("\n");
return 0;
}
```
**output**
run with opensource `qemu`
```
--0th-- -1
--1th-- -3
```
```
#include <cstdio>
#include <arm_sve.h>
const int SIZE = 16;
int main()
{
int datas[SIZE];
#pragma clang loop vectorize(disable)
for (int i = 0; i < SIZE; i++) {
datas[i] = -i - i - 1;
}
long long res2[SIZE];
svbool_t pa = svptrue_b32();
svint32_t v1 = svld1(pa, &datas[0]);
svint64_t v2 = svunpklo(v1);
svst1(pa, (long *)&res2[0], v2);
printf("--%dth-- %lld\n", 0, res2[0]);
printf("--%dth-- %lld\n", 1, res2[1]);
printf("\n");
return 0;
}
```
**output**
run with opensource `qemu`
```
--0th-- -1
--1th-- -6484229677715469824
```
I did some preliminary analysis and found that the main difference was in the tbaa results。IR diverged after GVN pass and different tbaa caused different results,
**long type IR**
https://godbolt.org/
**long long type IR**
https://godbolt.org/
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