[llvm] [RISCV][GlobalISel] Legalize G_ADD, G_SUB, G_AND, G_OR, G_XOR on RISC-V Vector Extension (PR #71400)
Craig Topper via llvm-commits
llvm-commits at lists.llvm.org
Tue Nov 14 09:27:10 PST 2023
topperc wrote:
> > Given different conditions
> > > nxv1s64, nxv2s64, nxv4s64, nxv8s64 require hasVInstructionsI64 instead of hasVInstructions
> >
> >
> > > nxv1s8, nxv1s16, nxv1s32 require Subtarget.getELen() == 64
> >
> >
> > I have this literal implementation locally:
> > ```c++
> > getActionDefinitionsBuilder({G_ADD, G_SUB, G_AND, G_OR, G_XOR})
> > .legalFor({s32, sXLen})
> > .legalFor(ST.hasVInstructions()
> > ? std::initializer_list<LLT>{nxv2s8, nxv4s8, nxv8s8,
> > nxv16s8, nxv32s8, nxv64s8,
> > nxv2s16, nxv4s16, nxv8s16,
> > nxv16s16, nxv32s16, nxv2s32,
> > nxv4s32, nxv8s32, nxv16s32}
> > : std::initializer_list<LLT>())
> > .legalFor(
> > ST.hasVInstructionsI64()
> > ? std::initializer_list<LLT>{nxv1s64, nxv2s64, nxv4s64, nxv8s64}
> > : std::initializer_list<LLT>())
> > .legalFor(ST.getELen() == 64
> > ? std::initializer_list<LLT>{nxv1s8, nxv1s16, nxv1s32}
> > : std::initializer_list<LLT>())
> > .widenScalarToNextPow2(0)
> > .clampScalar(0, s32, sXLen);
> > ```
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > Please point out any issue this code snippet has.
>
> This LGTM.
>
> > In addition, it has to have fragments of `AllVecTys`, so I was wondering, as per @michaelmaitland 's review:
> > > In any case, I'd like to have AllVecTys exist so it can be reused by future patches.
> >
> >
> > Shall we still be declaring `AllVecTys`? It's good to declare it because it's likely to be reused, what if future patches also need the aforementioned condition checking so it won't be reused as a whole, is it still worth it?
>
> Since we are not using AllVecTys, I think we should not include this variable. The compiler would emit a warning for an unused variable, and we don't want that. I think you should make this change and bring this PR out of draft, marking it ready for review!
Something like this could work.
```
.legalFor([=, &ST](const LegalityQuery &Query) {
return Subtarget.hasVInstruction() && typeInSet(0, AllVecTys)(Query) &&
(Query.Types[0].getScalarSize() != 64 || Subtarget.hasVInstruction64()) &&
(Query.Types[0].getElementCount().getKnownMinValue() != 1 || Subtarget.getELEN() == 64));
}
```
https://github.com/llvm/llvm-project/pull/71400
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