[llvm] [NVPTX][InferAS] assume alloca instructions are in local AS (PR #121710)

[Alex MacLean via llvm-commits]

================
@@ -562,4 +563,11 @@ Value *NVPTXTTIImpl::rewriteIntrinsicWithAddressSpace(IntrinsicInst *II,
   }
   }
   return nullptr;
-}
\ No newline at end of file
+}
+
+unsigned NVPTXTTIImpl::getAssumedAddrSpace(const Value *V) const {
+  if (isa<AllocaInst>(V))
+    return ADDRESS_SPACE_LOCAL;
+
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AlexMaclean wrote:

@arsenm would it be alright if I proceeded with this change despite your point about switching to specific-AS allocas? I agree this is worth investigating but it will take a fair bit of work I think, and this solution is small, shows immediate improvements, and won't hamper any efforts to handle specific-AS allocas in the future. 

https://github.com/llvm/llvm-project/pull/121710