[llvm] [GlobalISel] Allow Legalizer to lower volatile memcpy family. (PR #145997)

[Pete Chou via llvm-commits]

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@@ -10099,8 +10100,8 @@ LegalizerHelper::lowerMemCpyFamily(MachineInstr &MI, unsigned MaxLen) {
   }
 
   bool IsVolatile = MemOp->isVolatile();
-  // Don't try to optimize volatile.
-  if (IsVolatile)
+  // Don't try to optimize volatile when not allowed.
+  if (SkipVolatile && IsVolatile)
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petechou wrote:

BTW, in 36527cb the `MaxLen` argument of the added LegalizerHelper lowerMemCpyFamily function could be a defualt argument.

`  LegalizeResult lowerMemCpyFamily(MachineInstr &MI, unsigned MaxLen = 0);`

It's probably for the same reason to support both legalizer and combiner users, I guess.

https://github.com/llvm/llvm-project/pull/145997