[all-commits] [llvm/llvm-project] d5ee72: [GlobalISel] Implement identity transforms for x o...

[Jessica Paquette via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: d5ee72065b9e5d28f89b1200133e80ce60cb99a0
      https://github.com/llvm/llvm-project/commit/d5ee72065b9e5d28f89b1200133e80ce60cb99a0
  Author: Jessica Paquette <jpaquette at apple.com>
  Date:   2020-03-30 (Mon, 30 Mar 2020)

  Changed paths:
    M llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h
    M llvm/include/llvm/Target/GlobalISel/Combine.td
    M llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
    M llvm/test/CodeGen/AArch64/GlobalISel/arm64-fallback.ll
    A llvm/test/CodeGen/AArch64/GlobalISel/prelegalizercombiner-binop-same-val.mir

  Log Message:
  -----------
  [GlobalISel] Implement identity transforms for x op x -> x

When we have

```
a = G_OR x, x
```

or

```
b = G_AND y, y
```

We can drop the G_OR/G_AND and just use x/y respectively.

Also update arm64-fallback.ll because there was an or in there which hits this
transformation.

Differential Revision: https://reviews.llvm.org/D77105