llvm dev - Feb 2021 - LLVM AsmMatcher / AsmParser question - register number with dot modifier

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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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

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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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