rjmccall added a comment. In D156539#4546834 <https://reviews.llvm.org/D156539#4546834>, @AlexVlx wrote:
> In D156539#4542836 <https://reviews.llvm.org/D156539#4542836>, @rjmccall > wrote: > >> We should probably write this code to work properly in case we add a target >> that makes `__builtin_alloca` return a pointer in the private address space. >> Could you recover the target AS from the type of the expression instead of >> assuming `LangAS::Default`? > > I believe it should work as written (it is possible that I misunderstand the > objection, case in which I do apologise). The issue is precisely that for > some targets (amdgcn being one) `alloca` returns a pointer to private, which > doesn't compose with the default AS being unspecified / nonexistent, for some > languages (e.g. HIP, C/C++ etc.). For the OCL case @arsenm mentions, I > believe that we make a choice based on `LangOpts.OpenCLGenericAddressSpace`, > and the code above would only be valid from the OCL language perspective iff > that is true. I've put together a short Godbolt that captures these (and the > bug the patch should fix, please see the bitcasts between ASes in the non-OCL > case): https://gcc.godbolt.org/z/sYGK76zqv. An address space conversion is required in IR if there is a difference between the address space of the pointer type formally returned by the call to `__builtin_alloca` and the address space produced by the `alloca` operation in IR. If Sema has set the type of `__builtin_alloca` to formally return something in the stack address space, no conversion is required. What I'm saying that I'd like you to not directly refer to `LangAS::Default` in this code, because you're assuming that `__builtin_alloca` is always returning a pointer that's formally in `LangAS::Default`. Please recover the target address space from the type of the expression. Additionally, in IRGen we allow the target to hook address-space conversions; please call `performAddrSpaceCast` instead of directly emitting an `addrspacecast` instruction. CHANGES SINCE LAST ACTION https://reviews.llvm.org/D156539/new/ https://reviews.llvm.org/D156539 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
