[llvm-commits] List concatenation in tblgen

[James Molloy]

Hi,

I've been working on a processor itinerary with a lot of InstrStages - too
many to really put in each instruction itinerary definition. I wanted to
create a proper class hierarchy, but that would involve concatenating lists
of InstrStages and tablegen doesn't have that functionality.

I've created a patch to add a !listconcat(x, y) function along the same
lines as !strconcat. Before I push for internal approval to send this patch,
would there be any complaints to my applying it? It allows you to do, for
example:

// 2-cycle issue pipeline stage, 2-wide.
Def Issue00 : FuncUnit;
Def Issue01 : FuncUnit;
Def Issue10 : FuncUnit;
Def Issue11 : FuncUnit;

Class IssueStage<InstrItinClass Class, list<InstrStage> stages,
                 list<int> operandcycles = [], list<Bypass> bypasses = []>
  : InstrItinData<Class,
                  !listconcat([InstrStage<1, [Issue00,Issue01], 0>,
                               InstrStage<1, [Issue10,Issue11], 0>],
stages),
                  Operandcycles, bypasses>;

In this example, other classes (such as AddStage, MulStaget, LSStage) could
inherit from IssueStage to make it clearer that all itinerary descriptions
have a 2-wide, 2-cycle fetch/decode/issue stage at the beginning.

!listconcat is an obviously missing piece of functionality, imho.

Thoughts?

Cheers,

James