[PATCH] D47374: [RFC][patch 3/3] Add support for variant scheduling classes in llvm-mca.

Andrea Di Biagio via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Sun May 27 12:41:42 PDT 2018

andreadb added inline comments.

Comment at: lib/Target/X86/X86ScheduleBtVer2.td:560
+def JPackedIntXOR : CheckOpcode<[PXORrr, VPXORrr]>;
RKSimon wrote:
> Just to be clear, can this work for GPR zero-idioms as well (XOR32rr/XOR64rr etc)?
Yes. `JZeroIdiomPredicate` can be used to describe XOR32rr and XOR64rr zero-idioms too.

You would still need a fall-back strategy for when the XOR is not a zero idiom.
That means, you would need to add the following case to `JWriteZeroIdiom`:
`SchedVar<MCSchedPredicate<JIntXOR>, [WriteALU]>`

where JIntXOR is defined as a `CheckOpcode<[XOR32rr, XOR64rr]>`.


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