[llvm] [LV] Reverse mask up front, not when creating vector pointer. (PR #72163)

[via llvm-commits]

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@@ -9562,8 +9562,12 @@ void VPWidenMemoryInstructionRecipe::execute(VPTransformState &State) {
   InnerLoopVectorizer::VectorParts BlockInMaskParts(State.UF);
   bool isMaskRequired = getMask();
   if (isMaskRequired)
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ayalz wrote:

nit: worth retaining the comment below, perhaps here, that reversal is restricted to required masks because `// Reverse of a null all-one mask is a null mask.`

https://github.com/llvm/llvm-project/pull/72163