emilio added a comment. The relevant discussion is here <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92821#c2>. From the "Parameter Passing" section in https://github.com/hjl-tools/x86-psABI/wiki/x86-64-psABI-1.0.pdf, there's no mention of sign-extension requirements for arguments.
> The only related thing is > "When a value of type _Bool is returned or passed in a register or on the > stack, > bit 0 contains the truth value and bits 1 to 7 shall be zero." > with a footnote: > "Other bits are left unspecified, hence the consumer side of those values > can rely on it being 0 or 1 when truncated to 8 bit." which says that _Bool has only significant low 8 bits and the rest is unspecified. Then Michael Matz (one of the editors of that document) clarifies below: > Yes, we (intentionally) haven't required any extensions to happen for > arguments or return values smaller than 64bit (e.g. we haven't even specified that arguments <= 32bit would be zero-extended in the high bits, as would have been natural with the instruction set). If LLVM relies on that it would be a bug. There's more information on that bug and related ones, but I think the above should be enough :) Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D72742/new/ https://reviews.llvm.org/D72742 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
