[all-commits] [llvm/llvm-project] 2e6004: [InstCombine] Fold zext(X) + C2 pred C -> X + C3 p...

[Yingwei Zheng via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 2e60048641e86b7a414aec51d920bc4e1e3fbeb6
      https://github.com/llvm/llvm-project/commit/2e60048641e86b7a414aec51d920bc4e1e3fbeb6
  Author: Yingwei Zheng <dtcxzyw2333 at gmail.com>
  Date:   2024-11-21 (Thu, 21 Nov 2024)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
    M llvm/test/Transforms/InstCombine/icmp-add.ll

  Log Message:
  -----------
  [InstCombine] Fold zext(X) + C2 pred C -> X + C3 pred C4 (#110511)

Motivating case from
https://github.com/torvalds/linux/blob/9852d85ec9d492ebef56dc5f229416c925758edc/drivers/gpu/drm/drm_edid.c#L5238-L5240:
```
define i1 @src(i8 noundef %v13) {
entry:
  %conv1 = zext i8 %v13 to i32
  %add = add nsw i32 %conv1, -4
  %cmp = icmp ult i32 %add, 3
  %cmp4 = icmp slt i8 %v13, 4
  %cond = select i1 %cmp4, i1 true, i1 %cmp
  ret i1 %cond
}

define i1 @tgt(i8 noundef %v13) {
entry:
  %cmp4 = icmp slt i8 %v13, 7
  ret i1 %cmp4
}
```



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