| Issue |
160348
|
| Summary |
[AVX-512] Replace static `vpermi2w` with `vpermi2b` on Intel
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
Validark
|
On many Intel targets, `vpermi2w` has higher latency than `vpermi2b`. Therefore, we should prefer to use `vpermi2b` where we can.
```llvm
define dso_local <64 x i8> @foo(<64 x i8> %0) local_unnamed_addr {
Entry:
%1 = shufflevector <64 x i8> %0, <64 x i8> poison, <64 x i32> <i32 0, i32 1, i32 8, i32 9, i32 16, i32 17, i32 24, i32 25, i32 32, i32 33, i32 40, i32 41, i32 48, i32 49, i32 56, i32 57, i32 2, i32 3, i32 10, i32 11, i32 18, i32 19, i32 26, i32 27, i32 34, i32 35, i32 42, i32 43, i32 50, i32 51, i32 58, i32 59, i32 4, i32 5, i32 12, i32 13, i32 20, i32 21, i32 28, i32 29, i32 36, i32 37, i32 44, i32 45, i32 52, i32 53, i32 60, i32 61, i32 6, i32 7, i32 14, i32 15, i32 22, i32 23, i32 30, i32 31, i32 38, i32 39, i32 46, i32 47, i32 54, i32 55, i32 62, i32 63>
ret <64 x i8> %1
}
```
Compiles to:
```asm
.LCPI0_1:
.byte 0
.byte 4
.byte 8
.byte 12
.byte 16
.byte 20
.byte 24
.byte 28
.byte 1
.byte 5
.byte 9
.byte 13
.byte 17
.byte 21
.byte 25
.byte 29
.byte 2
.byte 6
.byte 10
.byte 14
.byte 18
.byte 22
.byte 26
.byte 30
.byte 3
.byte 7
.byte 11
.byte 15
.byte 19
.byte 23
.byte 27
.byte 31
foo:
vpmovsxbw zmm1, ymmword ptr [rip + .LCPI0_1]
vpermw zmm0, zmm1, zmm0
ret
```
Should be:
```asm
.LCPI0_0:
.byte 0
.byte 1
.byte 8
.byte 9
.byte 16
.byte 17
.byte 24
.byte 25
.byte 32
.byte 33
.byte 40
.byte 41
.byte 48
.byte 49
.byte 56
.byte 57
.byte 2
.byte 3
.byte 10
.byte 11
.byte 18
.byte 19
.byte 26
.byte 27
.byte 34
.byte 35
.byte 42
.byte 43
.byte 50
.byte 51
.byte 58
.byte 59
.byte 4
.byte 5
.byte 12
.byte 13
.byte 20
.byte 21
.byte 28
.byte 29
.byte 36
.byte 37
.byte 44
.byte 45
.byte 52
.byte 53
.byte 60
.byte 61
.byte 6
.byte 7
.byte 14
.byte 15
.byte 22
.byte 23
.byte 30
.byte 31
.byte 38
.byte 39
.byte 46
.byte 47
.byte 54
.byte 55
.byte 62
.byte 63
sh:
vmovdqa64 zmm1, zmmword ptr [rip + .LCPI0_0]
vpermb zmm0, zmm1, zmm0
ret
```
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