[PATCH] D23561: [RISCV 4/10] Add basic RISCV{InstrFormats, InstrInfo, RegisterInfo, }.td

[Tobias Grosser via llvm-commits]

> >>
> >> jyknight added inline comments.
> >>
> >> ================
> >> Comment at: lib/Target/RISCV/RISCVRegisterInfo.td:27
> >> @@ +26,3 @@
> >> +// Integer registers
> >> +let RegAltNameIndices = [ABIRegAltName] in {
> >> +  def X0    : Ri<0, "x0", ["zero"]>, DwarfRegNum<[0]>;
> >> ----------------
> >> Are the risc-v dwarf register numbers documented anywhere? (I assume not,
> >> just like the relocation types, but thought I'd ask anyways. Maybe you can
> >> start a list of Things That Ought To Be Documented...)
> >>
> >> ================
> >> Comment at: lib/Target/RISCV/RISCVRegisterInfo.td:63
> >> @@ +62,3 @@
> >> +def GPR : RegisterClass<"RISCV", [i64], 64, (add
> >> +  (sequence "X%u", 0, 31)
> >> +)>;
> >> ----------------
> >> May want to use a different register allocation sequence.
> >
> > Wait, this also controls register allocation order preference?  Hm, would
> > not have guessed that from the bit of backend code I'd read. With that in
> > mind, I'd prefer we submit with a simple structure and then land a separate
> > change with clear comments changing the allocation order.
> 
> Yes, given the MC-first approach I'm taking I decided to ignore
> register allocation preference at this stage. As you suggest, I'd
> rather introduce codegen concerns later. A comment to this effect
> would seem to make sense though. Would you be happy with that James?
> 
> [Sidenote: these email responses don't seem to be making it to
> phabricator - they should do, right?]

Phabricator only track top-post comments. The dirty solution I use is to
drop the beginning of citations "On ..." when replying. This makes the
emails generally appear in phabricator.

Best,
Tobias