[PATCH] D126771: [fastalloc] Support allocate specific register class in fastalloc.

[Xiang Zhang via Phabricator via llvm-commits]

xiangzhangllvm added inline comments.


================
Comment at: llvm/lib/CodeGen/RegAllocFast.cpp:1146
     MachineOperand &MO = MI.getOperand(I);
     if (MO.isReg()) {
       Register Reg = MO.getReg();
----------------
I just take a look on this pass.
Seem this patch mainly to insert the condition where will allocated the virtual regs.

This check seems a little duplicated with MO.isReg().
Because we need to first make sure the MO is reg before we try to allocated for it.
(The only exception I find is handleDebugValue, it directly get reg for MI.getUsedDebugRegs() not MO.  In fact, it also can be unified with MO)

I think we just need to replace all the "MO.isReg()" with a function which do the check of ShouldAllocateRegister

Some like:

```
ShouldAllocateForMO(MO){
  return MO.isReg() && ShouldAllocateRegister(MO.getReg());   
}
```

and keep your change in handleDebugValue (or unify the code with MO)


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D126771/new/

https://reviews.llvm.org/D126771