[instcombine] Delete dead transform for rev(binop splat, rev(x))

preames · preames · commit 95d8a50d20ca · 2025-06-12T13:44:17.000-07:00
We canonicalize splats to RHS, so this transform should be dead code.
diff --git 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)))))) {

Original file line number	Diff line number	Diff line change
`@@ -3565,12 +3565,6 @@ Instruction *InstCombinerImpl::visitCallInst(CallInst &CI) {`
`3565`	`3565`	`OldBinOp, OldBinOp->getName(),`
`3566`	`3566`	`II->getIterator()));`
`3567`	`3567`	`}`
`3568`		`- // rev(binop BO0Splat, rev(Y)) --> binop BO0Splat, Y`
`3569`		`- if (match(BO1, m_VecReverse(m_Value(Y))) && isSplatValue(BO0))`
`3570`		`- return replaceInstUsesWith(CI,`
`3571`		`- BinaryOperator::CreateWithCopiedFlags(`
`3572`		`- OldBinOp->getOpcode(), BO0, Y, OldBinOp,`
`3573`		`- OldBinOp->getName(), II->getIterator()));`
`3574`	`3568`	`}`
`3575`	`3569`	`// rev(unop rev(X)) --> unop X`
`3576`	`3570`	`if (match(Vec, m_OneUse(m_UnOp(m_VecReverse(m_Value(X)))))) {`