[llvm] [DAG] Teach SelectionDAGBuilder to read parameter alignment of compressstore/expandload. (PR #83763)

[Matt Arsenault via llvm-commits]

================
@@ -4746,6 +4748,8 @@ void SelectionDAGBuilder::visitMaskedLoad(const CallInst &I, bool IsExpanding) {
     // @llvm.masked.expandload.*(Ptr, Mask, Src0)
     Ptr = I.getArgOperand(0);
     Alignment = std::nullopt;
+    if (MaybeAlign Align = I.getParamAlign(0))
+      Alignment = Align;
----------------
arsenm wrote:

MaybeAlign shouldn't exist. We should just make all of the contexts behave like getValueOr1

https://github.com/llvm/llvm-project/pull/83763