[clang] [llvm] [AMDGPU] Add alignment attr & propagate alignment through make.buffer.rsrc inst (PR #145278)

[Shilei Tian via cfe-commits]

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@@ -5500,7 +5504,34 @@ struct AAAlignCallSiteReturned final
   using Base = AACalleeToCallSite<AAAlign, AAAlignImpl>;
   AAAlignCallSiteReturned(const IRPosition &IRP, Attributor &A)
       : Base(IRP, A) {}
+  ChangeStatus updateImpl(Attributor &A) override {
+    SmallVector<AA::ValueAndContext> Values;
+    const auto &AligmentCBs = A.getAlignmentCallback(getIRPosition());
+
+    if (!AligmentCBs.empty()) {
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shiltian wrote:

since `lookup` will do a default construct, you don't need to check emptiness here.

https://github.com/llvm/llvm-project/pull/145278