jhuber6 wrote: > > Interesting, though reading through that I didn't see any mentions of > > implicit casts. It's simply stating that they can do casting if the target > > lists them as a subset. > > That matches my understanding -- implicit or explicit casts require a subset > relationship, as best I understand.
Okay, my generous interpretation is that it's fine for the compiler to use the target's information to determine if this is legal. So I updated the patch to use target information when making the decision. > > Also it's worth noting that in the documentation it has stuff like __X char > > x, y, z which is a warning in clang due to how type level attributes work > > https://godbolt.org/z/Pfv36nEdq. > > This is because the TR was written before we had attributes. AIUI, the TR is > written with the idea that address spaces are specified via qualifiers (so > more like `__global__`, for example). But the important bit is that the > address space is a property of the type (and for `[[]]` attributes, there's > specific syntactic requirements for where the attribute has to be written to > apply to the type). `__global__` is just `__attribute__((global))`, which works becuase `[[clang::global]] int x` also works, it just emits a warning because apparently that behavior was "deprecated" but not removed yet. > > Maybe someone who reads better standardese than me can help with this. My > > ultimate goal is to make this legal when targeting NVPTX or AMDGPU, which > > is easily done by stating that DefaultAS is a superset of these other AS's. > > Let me know if making this target dependent is a good idea. > > ``` > > void *foo(void [[clang::addrspace(3) *p) { return p; } > > ``` > > Making sure I understand your example, you want a pointer in the generic > address space to an object in address space three? As opposed to `void * > [[clang::address_space(3)]] p` which would be a pointer in address space > three to an object in the generic address space? For AMDGPU and NVPTX, pointers are allowed to drop their address spaces transparently. So, `void AS(3) *` can convert to `void *`. Languages like CUDA and SYCL and HIP use these 'language' address spaces to describe exactly this, but my assertion is that it's more of a function of the target. I'm sure @arsenm could explain the underlying implementation more deeply. https://github.com/llvm/llvm-project/pull/115777 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
