[LLVMdev] Question on X86 backend

[Christoph Erhardt]

Hi Micah,

> In X86InstrInfo.td for Call Instructions, it mentions that Uses for
> argument registers are added manually. Can someone point me to the
> location where they are added as the comment doesn't reference a
> where or how?
the register uses are added by the function
X86TargetLowering::LowerCall() during the DAG Lowering phase. This is
the relevant code segment:

// Add argument registers to the end of the list so that they are known live
// into the call.
for (unsigned i = 0, e = RegsToPass.size(); i != e; ++i)
  Ops.push_back(DAG.getRegister(RegsToPass[i].first,
                                RegsToPass[i].second.getValueType()));

Regards,
Christoph