| Issue |
96463
|
| Summary |
x86 SSE4.2 suboptimal codegen: `_mm_cmpestrc` is not fused with `_mm_cmpestri` or `_mm_cmpestrm`
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
AlexGuteniev
|
The following C++ code:
```c++
#include <immintrin.h>
int test1(__m128i needle, __m128i haystack) {
if (_mm_cmpestrc(needle, 2, haystack, 8, _SIDD_CMP_EQUAL_ORDERED | _SIDD_BIT_MASK))
{
int bitmask = _mm_cmpestri(needle, 2, haystack, 8, _SIDD_CMP_EQUAL_ORDERED | _SIDD_BIT_MASK);
return bitmask;
}
else
{
return 0;
}
}
int test2(__m128i needle, __m128i haystack) {
if (_mm_cmpestrc(needle, 2, haystack, 8, _SIDD_CMP_EQUAL_ORDERED | _SIDD_BIT_MASK))
{
int bitmask = _mm_cvtsi128_si32(_mm_cmpestrm(needle, 2, haystack, 8, _SIDD_CMP_EQUAL_ORDERED | _SIDD_BIT_MASK));
return bitmask;
}
else
{
return 0;
}
}
```
Produces two `pcmpestri` instructions for `test1` and `pcmpestri` followed by `pcmpestrm` for test2`,
Demo: https://godbolt.org/z/GE783h8dz
I expect that `_mm_cmpestrc` is fused with the other intrinsic, so there's one `pcmpestri` in `test1` and one `pcmpestrm` for test2.
(MSVC does this susion for `test1`, and gcc does this fusion for both `test1` and `test2`)
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