[all-commits] [llvm/llvm-project] c662a9: [InstCombine] recognize missed i128 split optimiza...

[Muhammad Bassiouni via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: c662a9d303a9579c6b71b8abaf0068bee73de5ba
      https://github.com/llvm/llvm-project/commit/c662a9d303a9579c6b71b8abaf0068bee73de5ba
  Author: Muhammad Bassiouni <60100307+bassiounix at users.noreply.github.com>
  Date:   2025-03-06 (Thu, 06 Mar 2025)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
    A llvm/test/Transforms/InstCombine/iX-ext-split.ll

  Log Message:
  -----------
  [InstCombine] recognize missed i128 split optimization (#129363)

This pr fixes #126056, recognising a split i128 extension optimization.

Proof for working optimization:

```llvm
define i128 @src(i32 noundef %x) {
entry:
  %coerce.sroa.0.0.extract.trunc = sext i32 %x to i64
  %0 = ashr i32 %x, 31
  %coerce.sroa.2.0.extract.trunc = sext i32 %0 to i64
  %x.sroa.2.0.insert.ext.i = zext i64 %coerce.sroa.2.0.extract.trunc to i128
  %x.sroa.2.0.insert.shift.i = shl nuw i128 %x.sroa.2.0.insert.ext.i, 64
  %x.sroa.0.0.insert.ext.i = zext i64 %coerce.sroa.0.0.extract.trunc to i128
  %x.sroa.0.0.insert.insert.i = or disjoint i128 %x.sroa.2.0.insert.shift.i, %x.sroa.0.0.insert.ext.i
  ret i128 %x.sroa.0.0.insert.insert.i
}

define i128 @tgt(i32 noundef %x)  {
  %x.sroa.0.0.insert.insert.i = sext i32 %x to i128
  ret i128 %x.sroa.0.0.insert.insert.i
}
```



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