[all-commits] [llvm/llvm-project] 08c085: [InstCombine] cttz(sext(x)) -> cttz(zext(x))

[Dávid Bolvanský via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 08c08577f94fd7efd2a670d0e5c3c6f72882fa0a
      https://github.com/llvm/llvm-project/commit/08c08577f94fd7efd2a670d0e5c3c6f72882fa0a
  Author: Dávid Bolvanský <david.bolvansky at gmail.com>
  Date:   2021-05-03 (Mon, 03 May 2021)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
    M llvm/test/Transforms/InstCombine/cttz.ll

  Log Message:
  -----------
  [InstCombine] cttz(sext(x)) -> cttz(zext(x))

```

----------------------------------------
define i32 @src(i16 %x, i1 %b) {
%0:
  %z = sext i16 %x to i32
  %p = cttz i32 %z, %b
  ret i32 %p
}
=>
define i32 @tgt(i16 %x, i1 %b) {
%0:
  %z = zext i16 %x to i32
  %p = cttz i32 %z, %b
  ret i32 %p
}
Transformation seems to be correct!
```

https://alive2.llvm.org/ce/z/evomeg

Reviewed By: spatel

Differential Revision: https://reviews.llvm.org/D101764