[SDAG] Fix CSE for ADDRSPACECAST nodes

Author: AlexMaclean

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

@@ -954,6 +954,12 @@ static void AddNodeIDCustom(FoldingSetNodeID &ID, const SDNode *N) {
       ID.AddInteger(M);
     break;
   }
+  case ISD::ADDRSPACECAST: {
+    const AddrSpaceCastSDNode *ASC = cast<AddrSpaceCastSDNode>(N);
+    ID.AddInteger(ASC->getSrcAddressSpace());
+    ID.AddInteger(ASC->getDestAddressSpace());
+    break;
+  }
   case ISD::TargetBlockAddress:
   case ISD::BlockAddress: {
     const BlockAddressSDNode *BA = cast<BlockAddressSDNode>(N);

llvm/test/CodeGen/NVPTX/addrspacecast-cse.ll

@@ -0,0 +1,19 @@
+; RUN: llc < %s -mcpu=sm_80 -mattr=+ptx73 -debug-only=isel -o /dev/null 2>&1 | FileCheck %s
+
+; REQUIRES: asserts
+
+target triple = "nvptx64-nvidia-cuda"
+
+;; Selection DAG CSE is hard to test since we run CSE/GVN on the IR before and
+;; after selection DAG ISel so most cases will be handled by one of these.
+define void @foo(ptr %p) {
+; CHECK-LABEL: Optimized legalized selection DAG: %bb.0 'foo:'
+; CHECK:       addrspacecast[0 -> 5]
+; CHECK-NOT:   addrspacecast[0 -> 5]
+; CHECK-LABEL: ===== Instruction selection begins
+;
+  %a1 = addrspacecast ptr %p to ptr addrspace(5)
+  call void @llvm.stackrestore(ptr %p)
+  store ptr %p, ptr addrspace(5) %a1
+  ret void
+}