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

[Matt Arsenault via llvm-commits]

================
@@ -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)) {
+        if ((AscI->getSrcAddressSpace() == AMDGPUAS::LOCAL_ADDRESS) &&
+            (AscI->getDestAddressSpace() == AMDGPUAS::FLAT_ADDRESS))
----------------
arsenm wrote:

```suggestion
        if (AscI->getSrcAddressSpace() == AMDGPUAS::LOCAL_ADDRESS &&
            AscI->getDestAddressSpace() == AMDGPUAS::FLAT_ADDRESS)
```

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