[clang] Replace llvm.memcpy et al's i1 isVolatile with i8 VolFlags (PR #65748)

[Simon Pilgrim via cfe-commits]

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@@ -24790,8 +24790,8 @@ static SDValue LowerVACOPY(SDValue Op, const X86Subtarget &Subtarget,
   return DAG.getMemcpy(
       Chain, DL, DstPtr, SrcPtr,
       DAG.getIntPtrConstant(Subtarget.isTarget64BitLP64() ? 24 : 16, DL),
-      Align(Subtarget.isTarget64BitLP64() ? 8 : 4), /*isVolatile*/ false, false,
-      false, MachinePointerInfo(DstSV), MachinePointerInfo(SrcSV));
+      Align(Subtarget.isTarget64BitLP64() ? 8 : 4), /*Vol=*/{false, false},
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RKSimon wrote:

For understandability, should we use a MemTransferVolatility builder helper instead of embedding implicit values like this?

https://github.com/llvm/llvm-project/pull/65748