[llvm] [IA]: Construct (de)interleave4 out of (de)interleave2 (PR #89276)

[Paul Walker via llvm-commits]

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@@ -17042,13 +17041,17 @@ bool AArch64TargetLowering::lowerDeinterleaveIntrinsicToLoad(
   VectorType *VTy = cast<VectorType>(DeinterleavedValues[0]->getType());
 
   bool UseScalable;
-  if (!isLegalInterleavedAccessType(VTy, DL, UseScalable))
+  if (!isLegalInterleavedAccessType(VTy, DL, UseScalable)) {
+    DeadInsts.clear();
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paulwalker-arm wrote:

This assumes `DeadInsts` will be empty when entering the function, which you shouldn't rely on in general. You likely need a local until you're ready to commit to the transformation and then update `DeadInsts` accordingly.

https://github.com/llvm/llvm-project/pull/89276