[llvm] [AMDGPU] Handle lowering addrspace casts from LDS to FLAT address in amdgpu-sw-lower-lds. (PR #121214)

[Matt Arsenault via llvm-commits]

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@@ -655,6 +655,10 @@ void AMDGPUSwLowerLDS::getLDSMemoryInstructions(
       } else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(&Inst)) {
         if (XCHG->getPointerAddressSpace() == AMDGPUAS::LOCAL_ADDRESS)
           LDSInstructions.insert(&Inst);
+      } else if (AddrSpaceCastInst *AscI = dyn_cast<AddrSpaceCastInst>(&Inst)) {
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arsenm wrote:

This approach doesn't feel very sound and is looking for very specific patterns instead of what is structurally possible. 

https://github.com/llvm/llvm-project/pull/121214