[PATCH] D151977: [X86][NFC]Use ref instead copy in for loop for SDValue::op_values()

[Wang, Xin via Phabricator via llvm-commits]

XinWang10 added a comment.

In D151977#4390071 <https://reviews.llvm.org/D151977#4390071>, @craig.topper wrote:

> We pass SDValue by value all over the SelectionD
> AG code. And it looks pretty easy for a compiler to see the unsigned field is unused. Does this change really make a difference?

I don't know about if compiler will do this opt to ignore the unused field for a class obj. Previously I mistook the enumerated element with SDUse which has more fields, but now the SDValue only has two fields, I also think this will make big difference. And if compiler would do the opt you said, maybe the program will go worse.


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