[PATCH] D120476: [LoongArch] Add basic support to AsmParser

[Lu Weining via Phabricator via llvm-commits]

SixWeining added inline comments.


================
Comment at: llvm/lib/Target/LoongArch/LoongArchInstrInfo.td:65
+
+def simm12 : Operand<GRLenVT>, ImmLeaf<GRLenVT, [{return isInt<12>(Imm);}]> {
+  let ParserMatchClass = SImmAsmOperand<12>;
----------------
xen0n wrote:
> SixWeining wrote:
> > xen0n wrote:
> > > I may have missed this in the previous patches, but why does only this kind of imm get the `ImmLeaf` treatment? I briefly looked at the other targets and they seem to mark most of their commonly used immediate kinds as such.
> > The `ImmLeaf` is used in instruction selection stage to match the immediate. Yes, all immediate kinds that could be used in instruction selection should be defined with `ImmLeaf`. They will added when we implement the `codegen`.
> > 
> > The reason why only `simm12` is defined with `ImmLeaf` is that in line 491 we defined a few instruction selection `Pat`s: 
> > ```
> > ...
> > def : PatGprImm<add, ADDI_W, simm12>;
> > ...
> > ```
> > 
> > These `Pat`s here are just to demonstrate layout of this `.td` file and the way to define `Pat`. Of course, more `Pat`s will be defined later to support `codegen`.
> > 
> > Sorry for the confusion. I hope I make it clear now.
> Okay, understood. It's generally better to only add things when absolutely needed though, this way you don't have to explain every time that these are "to be used later".
Yes, thanks.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D120476/new/

https://reviews.llvm.org/D120476