| Issue |
178215
|
| Summary |
[X86] Add i512 shift expansion on AVX512 targets
|
| Labels |
backend:X86
|
| Assignees |
|
| Reporter |
RKSimon
|
These haven't been fully tested, but should efficiently handle `_BitInt(512)` shifts when AVX512F is available:
```cpp
__m512i shlv(__m512i x, unsigned a) {
__m512i lo = _mm512_maskz_expand_epi64(-1U << (a / 64), x);
__m512i hi = _mm512_alignr_epi64(lo, _mm512_setzero_epi32(), 7);
return __builtin_elementwise_fshl(lo, hi, _mm512_set1_epi64(a % 64));
}
__m512i srlv(__m512i x, unsigned a) {
__m512i hi = _mm512_maskz_compress_epi64(-1U << (a / 64), x);
__m512i lo = _mm512_alignr_epi64(_mm512_setzero_epi32(), hi, 1);
return __builtin_elementwise_fshr(lo, hi, _mm512_set1_epi64(a % 64));
}
__m512i srav(__m512i x, unsigned a) {
__m512i sign = __builtin_shufflevector(_mm512_srai_epi64(x, 63), _mm512_setzero_epi32(), 7, 7, 7, 7, 7, 7, 7, 7);
__m512i hi = _mm512_mask_compress_epi64(sign, -1U << (a / 64), x);
__m512i lo = _mm512_alignr_epi64(sign, hi, 1);
return __builtin_elementwise_fshr(lo, hi, _mm512_set1_epi64(a % 64));
}
```
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