llvm dev - May 2021 - how to set BaseOpcode when using multiclass for relation model in td file

Hi, 


I am trying to relate normal instructions with predicate instructions. I have
read the document How To Use Instruction Mappings — LLVM 12 documentation.
If normal instruction and the corresponding instruction are related, they should
have the same BaseOpcode.

The document covers class/def only. It doesn't cover multiclass/defm.
for example:
class VFORM<...> {...}
multiclass MFORM<...> {
def _aa: VFORM<...>;
def _bb: VFORM<...>;
}
defm MOV: MFORM<...>;
defm P_MOV: MFORM<...>;


P_MOV_aa and P_MOV_bb are the corresponding predicate instruction of MOV_aa and
MOV_bb.
when relating P_MOV_aa with MOV_aa and P_MOV_bb with MOV_bb, they should have
the same BaseOpcode.
I think the normal instruction definition name is the best option for
BaseOpcode, such as "MOV_aa" and "MOV_bb".
Could I get the instruction definition name automatically and assign it to
BaseOpcode in td file?
Or is there a convenint way to set BaseOpcode for normal/predicate instruction
when using multiclass/defm?

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I think that you for example should be able to do something like this:

multiclass MFORM<string BaseName, …> {
  let BaseOpcode = BaseName in {
    def BaseName#_aa : VFORM<…>;
    def BaseName#_bb : VFORM<…>;
  }
}
defm “” : MFORM<”MOV”, …>;
defm “” : MFORM<”P_MOV”, …>;

/Björn

From: llvm-dev <llvm-dev-bounces at lists.llvm.org> On Behalf Of ??? via
llvm-dev
Sent: den 24 maj 2021 17:03
To: llvm-dev at lists.llvm.org
Subject: [llvm-dev] how to set BaseOpcode when using multiclass for relation
model in td file

Hi,

I am trying to relate normal instructions with predicate instructions. I have
read the document How To Use Instruction Mappings — LLVM 12
documentation<https://protect2.fireeye.com/v1/url?k=93a78a7d-cc3cb330-93a7cae6-86b568293eb5-73720be28813bde3&q=1&e=3e653e85-9f00-4403-9d18-ece444e45ae9&u=https%3A%2F%2Fllvm.org%2Fdocs%2FHowToUseInstrMappings.html>.
If normal instruction and the corresponding instruction are related, they should
have the same BaseOpcode.
The document covers class/def only. It doesn't cover multiclass/defm.
for example:
class VFORM<...> {...}
multiclass MFORM<...> {
def _aa: VFORM<...>;
def _bb: VFORM<...>;
}
defm MOV: MFORM<...>;
defm P_MOV: MFORM<...>;

P_MOV_aa and P_MOV_bb are the corresponding predicate instruction of MOV_aa and
MOV_bb.
when relating P_MOV_aa with MOV_aa and P_MOV_bb with MOV_bb, they should have
the same BaseOpcode.
I think the normal instruction definition name is the best option for
BaseOpcode, such as "MOV_aa" and "MOV_bb".
Could I get the instruction definition name automatically and assign it to
BaseOpcode in td file?
Or is there a convenint way to set BaseOpcode for normal/predicate instruction
when using multiclass/defm?




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