[PATCH] D62565: [PowerPC] Exploiting to use mtvsrdd instruction when save called-saved GPR register to VSR registers

[Qiu Chaofan via Phabricator via llvm-commits]

qiucf added inline comments.


================
Comment at: llvm/lib/Target/PowerPC/PPCFrameLowering.h:33
+  // TODO: Use local table in methods to avoid this mutable member.
+  mutable DenseMap<unsigned, SmallVector<Register, 2>> VSRToGPRs;
+
----------------
nemanjai wrote:
> I am curious why this maps from `unsigned`. Why not from `Register`?
> Also, I think it makes sense to map to `std::pair` since there will be (at most) two GPR's.
> 
> Finally, I think the name is confusing. I understand that it is mapping a VSR to GPRs, but since this optimization is moving stuff between registers, it can easily be misunderstood to mean that we are moving a VSR to GPRs. I think a better name would be something like `VSRContainsGPRs`.
Ah, I just used `unsigned` to align with class `CalleeSavedInfo` definition:

```
class CalleeSavedInfo {
  Register Reg;
  union {
    int FrameIdx;
    unsigned DstReg;
  };
  //...
};


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