[llvm-dev] LLVM AsmMatcher / AsmParser question - register number with dot modifier

[Przemyslaw Ossowski via llvm-dev]

Thank you Jason,
that was very helpful!

Przemek


On Fri, Feb 12, 2021 at 2:22 AM Jason Eckhardt <jeckhardt at nvidia.com> wrote:

>
> What approach should I take?
>
> One way is to custom parse your operands-- take a look at AsmOperandClass
> and the related machinery in
> include/llvm/Target/Target.td.
>
> Is there any example of such a case in any Target?
>
> A number of targets need similar sorts of handling, but AArch64 seems to
> be the closest example to your case.
> In particular, the Neon vector register handling might be a good place to
> start. E.g., the VectorReg64AsmOperand+V64
> definitions in AArchRegisterInfo.td (and users) and the corresponding
> parse code in AArch64AsmParser::tryParseNeonVectorRegister.
>
> ------------------------------
> *From:* llvm-dev <llvm-dev-bounces at lists.llvm.org> on behalf of
> Przemyslaw Ossowski via llvm-dev <llvm-dev at lists.llvm.org>
> *Sent:* Thursday, February 11, 2021 11:30 AM
> *To:* llvm-dev <llvm-dev at lists.llvm.org>
> *Subject:* [llvm-dev] LLVM AsmMatcher / AsmParser question - register
> number with dot modifier
>
> *External email: Use caution opening links or attachments*
>
> Hi,
>
>
>
> I am trying to implement support for asm matching for instruction which
> uses three registers (operands).
>
> And sometimes the register could have a suffix like .M.
>
>
>
> For example:
>
> add x1, x2, x3
>
> and sometimes:
>
> add x1.M, x.2, x.3
>
>
>
> For the second case I’ve defined instruction as follows:
>
>  (outs REGCLASS:$x1),
>
>  (ins REGCLASS:$x2, REGCLASS:$x3),
>
> “add\t\t${x1}.M, ${x2}, ${x3}"
>
>
>
> But AsmParser doesn’t recognize the case with .M returning "invalid
> operand for instruction".
>
>
>
> Should I define .M as separate operand for example:
>
> (outs REGCLASS:$x1),
>
> (ins REGCLASS:$x2, REGCLASS:$x3, REGMOD:$MOD)
>
> “add\t\t${x1}.${MOD}, ${x2}, ${x3}"
>
>
>
> But in such case it still doesn’t recognize “x1.M”, because as I
> understand it separates operands just with “,” (comma).
>
>
>
> What approach should I take?
>
> Is there any example of such a case in any Target?
>
>
>
> Thanks,
>
> Przemek
>
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