[llvm] [instcombine] Delete dead transform for rev(binop splat, rev(x)) (PR #143967)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-transforms

Author: Philip Reames (preames)

<details>
<summary>Changes</summary>

We canonicalize splats to RHS, so this transform should be dead code.

---
Full diff: https://github.com/llvm/llvm-project/pull/143967.diff


1 Files Affected:

- (modified) llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp (-6) 


``````````diff
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index c169ab25b2106..d5738520715b0 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -3565,12 +3565,6 @@ Instruction *InstCombinerImpl::visitCallInst(CallInst &CI) {
                                              OldBinOp, OldBinOp->getName(),
                                              II->getIterator()));
       }
-      // rev(binop BO0Splat, rev(Y)) --> binop BO0Splat, Y
-      if (match(BO1, m_VecReverse(m_Value(Y))) && isSplatValue(BO0))
-        return replaceInstUsesWith(CI,
-                                   BinaryOperator::CreateWithCopiedFlags(
-                                       OldBinOp->getOpcode(), BO0, Y, OldBinOp,
-                                       OldBinOp->getName(), II->getIterator()));
     }
     // rev(unop rev(X)) --> unop X
     if (match(Vec, m_OneUse(m_UnOp(m_VecReverse(m_Value(X)))))) {

``````````

</details>


https://github.com/llvm/llvm-project/pull/143967