| Issue |
144654
|
| Summary |
[VectorCombine] Recognise reduction patterns from extract+binop+shuffle chains
|
| Labels |
llvm:instcombine,
missed-optimization
|
| Assignees |
|
| Reporter |
RKSimon
|
```ll
define i16 @test_reduce_v8i16(<8 x i16> %a0) local_unnamed_addr #0 {
%1 = shufflevector <8 x i16> %a0, <8 x i16> poison, <8 x i32> <i32 4, i32 5, i32 6, i32 7, i32 poison, i32 poison, i32 poison, i32 poison>
%2 = tail call <8 x i16> @llvm.umin.v8i16(<8 x i16> %a0, <8 x i16> %1)
%3 = shufflevector <8 x i16> %2, <8 x i16> poison, <8 x i32> <i32 2, i32 3, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison>
%4 = tail call <8 x i16> @llvm.umin.v8i16(<8 x i16> %2, <8 x i16> %3)
%5 = shufflevector <8 x i16> %4, <8 x i16> poison, <8 x i32> <i32 1, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison>
%6 = tail call <8 x i16> @llvm.umin.v8i16(<8 x i16> %4, <8 x i16> %5)
%7 = extractelement <8 x i16> %6, i64 0
ret i16 %7
}
```
Recognise that patterns such as this can fold to a `llvm.vector.reduce.umin.v8i16(%a0)` intrinsic call (costs permitting)
Noticed when reviewing #144231
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