[llvm] [AMDGPU] Restrict promote alloca on pointers across address spaces (PR #119762)

[Matt Arsenault via llvm-commits]

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@@ -796,6 +796,16 @@ bool AMDGPUPromoteAllocaImpl::tryPromoteAllocaToVector(AllocaInst &Alloca) {
       if (!IsSimple)
         return RejectUser(Inst, "not a simple load or store");
 
+      // If the access type is a pointer, reject the address spaces with
+      // different pointer sizes.
+      // store <2 x ptr> %arg, ptr addrspace(5) %alloca - Reject.
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arsenm wrote:

> %alloca is defined by addrcast, we can impart a reasonable conversion.

There are no conversions, and alloca is just the direct stack object reference. 

https://github.com/llvm/llvm-project/pull/119762