| Issue |
109888
|
| Summary |
[AVX2] `vpsllvq` builtin-semantics are not recognized by LLVM vectors
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
Validark
|
I wrote some Zig code trying to get the semantics of `vpsllvq`:
```zig
export fn foo(vec: @Vector(4, u64)) @Vector(4, u64) {
return @select(
u64,
vec < @as(@Vector(4, u64), @splat(64)),
@as(@Vector(4, u64), @splat(1)) << @truncate(vec),
@as(@Vector(4, u64), @splat(0))
);
}
```
Optimized LLVM:
```llvm
define dso_local range(i64 0, -9223372036854775807) <4 x i64> @foo(<4 x i64> %0) local_unnamed_addr {
Entry:
%1 = icmp ult <4 x i64> %0, <i64 64, i64 64, i64 64, i64 64>
%2 = and <4 x i64> %0, <i64 63, i64 63, i64 63, i64 63>
%3 = shl nuw <4 x i64> <i64 1, i64 1, i64 1, i64 1>, %2
%4 = select <4 x i1> %1, <4 x i64> %3, <4 x i64> zeroinitializer
ret <4 x i64> %4
}
```
Compiled for Zen 3:
```asm
.LCPI0_0:
.quad -9223372036854775808
.LCPI0_1:
.quad -9223372036854775745
.LCPI0_2:
.quad 63
.LCPI0_3:
.quad 1
foo:
vpbroadcastq ymm1, qword ptr [rip + .LCPI0_0]
vpbroadcastq ymm4, qword ptr [rip + .LCPI0_2]
vpbroadcastq ymm2, qword ptr [rip + .LCPI0_1]
vpbroadcastq ymm3, qword ptr [rip + .LCPI0_3]
vpxor ymm1, ymm0, ymm1
vpand ymm0, ymm0, ymm4
vpcmpgtq ymm1, ymm1, ymm2
vpsllvq ymm0, ymm3, ymm0
vpandn ymm0, ymm1, ymm0
ret
```
I was expecting just a `vpsllvq` instruction.
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