| Issue |
84025
|
| Summary |
InstCombine calculated a wrong `insertelement` instruction
|
| Labels |
miscompilation,
llvm:optimizations,
llvm:instcombine
|
| Assignees |
DianQK
|
| Reporter |
DianQK
|
I tried this IR:
```llvm
define <4 x i32> @src(i32 %arg) {
%i = zext i32 %arg to i64
%i1 = shl i64 %i, 32
%i2 = or i64 %i1, 65
%i3 = zext i64 %i2 to i128
%i4 = shl i128 %i3, 64
%i5 = bitcast i128 %i4 to <4 x i32>
ret <4 x i32> %i5
}
define <4 x i32> @tgt(i32 %arg) {
%i5 = insertelement <4 x i32> <i32 0, i32 0, i32 0, i32 poison>, i32 %arg, i64 3
ret <4 x i32> %i5
}
```
I expect `src` to be:
```llvm
define <4 x i32> @src(i32 %arg) {
%i5 = insertelement <4 x i32> <i32 0, i32 0, i32 65, i32 poison>, i32 %arg, i64 3
ret <4 x i32> %i5
}
```
But I'm getting the same instructions as `tgt`.
Godbolt: https://llvm.godbolt.org/z/KnMEY4rTq
Alive2: https://alive2.llvm.org/ce/z/7FIJNi
From: https://github.com/rust-lang/rust/issues/121996
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