| Issue |
167079
|
| Summary |
Missed Optimization: Rewrite sub(x, select(x<1 ? -1 : 1)) == 0 → (x == -1) || (x == 1)
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
Leo0506
|
```
define i1 @src(i32 %arg0) {
%v0 = icmp slt i32 %arg0, 1
%v1 = select i1 %v0, i32 -1, i32 1
%v2 = sub nsw i32 %arg0, %v1
%v3 = icmp eq i32 %v2, 0
ret i1 %v3
}
define i1 @tgt(i32 %arg0) {
%v0 = icmp eq i32 %arg0, -1
%v1 = icmp eq i32 %arg0, 1
%v2 = or i1 %v0, %v1
ret i1 %v2
}
```
alive2: https://alive2.llvm.org/ce/z/c-_auN
godbolt: https://godbolt.org/z/17b7bh598
Pattern found in: https://github.com/dtcxzyw/llvm-opt-benchmark/blob/main/bench/ffmpeg/optimized/pvq.ll
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