[PATCH] D86883: [X86] Add support for using fast short rep mov for memcpy lowering.

[Hiroshi Yamauchi via Phabricator via llvm-commits]

yamauchi added inline comments.


================
Comment at: llvm/lib/Target/X86/X86SelectionDAGInfo.cpp:198
   SDValue InFlag;
-  Chain = DAG.getCopyToReg(Chain, dl, CX, Size, InFlag);
+  Chain = DAG.getCopyToReg(
+      Chain, dl, CX,
----------------
craig.topper wrote:
> Is this needed because we're no longer calling this with just constants we fixed the size of?
Do you mean, "is the getCopyToReg call needed"? The size needs to be loaded into the RCX/ECX register for the rep movs instruction and the callers aren't doing that. So, it seems yes. Did you mean in a different way?


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  https://reviews.llvm.org/D86883/new/

https://reviews.llvm.org/D86883