[llvm] [LowerMemIntrinsics] Lower llvm.memmove to wide memory accesses (PR #100122)

[Matt Arsenault via llvm-commits]

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@@ -434,18 +455,8 @@ static void createMemMoveLoopUnknownSize(Instruction *InsertBefore,
   // If the pointers are in different address spaces, they need to be converted
   // to a compatible one. Cases where memory ranges in the different address
   // spaces cannot overlap are lowered as memcpy and not handled here.
-  Value *CmpSrcAddr = SrcAddr;
-  Value *CmpDstAddr = DstAddr;
-  if ((SrcAS != DstAS)) {
-    if (TTI.isValidAddrSpaceCast(DstAS, SrcAS)) {
-      CmpDstAddr = PLBuilder.CreateAddrSpaceCast(DstAddr, SrcAddr->getType());
-    } else if (TTI.isValidAddrSpaceCast(SrcAS, DstAS)) {
-      CmpSrcAddr = PLBuilder.CreateAddrSpaceCast(SrcAddr, DstAddr->getType());
-    } else {
-      llvm_unreachable("Can only lower memmove between address spaces if they "
-                       "support addrspacecast");
-    }
-  }
+  auto [CmpSrcAddr, CmpDstAddr] =
+      tryInsertCastToCommonAddrSpace(PLBuilder, SrcAddr, DstAddr, TTI);
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arsenm wrote:

I don't see how this bails out if the cast isn't possible. It will go ahead to create the invalid compare with different pointer types? 

https://github.com/llvm/llvm-project/pull/100122