erichkeane wrote: > This change adds two semi-magical builtins for AMDGPU: > > * `__builtin_amdgcn_processor_is`, which is similar in observable > behaviour with `__builtin_cpu_is`, except that it is never "evaluated" at run > time; > > * `__builtin_amdgcn_is_invocable`, which is behaviourally similar with > `__has_builtin`, except that it is not a macro (i.e. not evaluated at > preprocessing time). > > > Neither of these are `constexpr`, even though when compiling for concrete > (i.e. `gfxXXX` / `gfxXXX-generic`) targets they get evaluated in Clang, so > they shouldn't tear the AST too badly / at all for multi-pass compilation > cases like HIP. They can only be used in specific contexts (as args to > control structures). > > The motivation for adding these is two-fold: > > * as a nice to have, it provides an AST-visible way to incorporate > architecture specific code, rather than having to rely on macros and the > preprocessor, which burn in the choice quite early; > > * as a must have, it allows featureful AMDGCN flavoured SPIR-V to be > produced, where target specific capability is guarded and chosen or discarded > when finalising compilation for a concrete target. > > > I've tried to keep the overall footprint of the change small. The changes to > Sema are a bit unpleasant, but there was a strong desire to have Clang > validate these, and to constrain their uses, and this was the most compact > solution I could come up with (suggestions welcome). > > In the end, I will note there is nothing that is actually AMDGPU specific > here, so it is possible that in the future, assuming interests from other > targets / users, we'd just promote them to generic intrinsics.
First read through this, I find myself wondering WHY these aren't constexpr. They seem exactly the sort of thing that folks would like to use `if constexpr` for. https://github.com/llvm/llvm-project/pull/134016 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
