[llvm] [LLVM][SelectionDAG] Don't assume masked loads access all lanes in memory. (PR #192706)

[Matt Arsenault via llvm-commits]

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@@ -5122,7 +5122,7 @@ void SelectionDAGBuilder::visitMaskedLoad(const CallInst &I, bool IsExpanding) {
 
   MachineMemOperand *MMO = DAG.getMachineFunction().getMachineMemOperand(
       MachinePointerInfo(PtrOperand), MMOFlags,
-      VT.getStoreSize(), Alignment, AAInfo, Ranges);
+      LocationSize::beforeOrAfterPointer(), Alignment, AAInfo, Ranges);
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arsenm wrote:

What is the problem here? This should report the maximum possible size read, it doesn't matter if it reads less

https://github.com/llvm/llvm-project/pull/192706