[llvm] [AMDGPU] Infer amdgpu-no-flat-scratch-init attribute in AMDGPUAttributor (PR #94647)

[Matt Arsenault via llvm-commits]

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@@ -433,6 +433,13 @@ struct AAAMDAttributesFunction : public AAAMDAttributes {
       indicatePessimisticFixpoint();
       return;
     }
+
+    for (Instruction &I : instructions(F)) {
+      if (isa<AllocaInst>(I) || isa<AddrSpaceCastInst>(I)) {
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arsenm wrote:

only addrspacecasts from address space 5 require flat_scr. Just an alloca does not imply flat_scr is required, only if the alloca is ever cast to flat. 


I suppose for robustness you could double check the alloca address space is correct 

https://github.com/llvm/llvm-project/pull/94647