gchatelet added a comment. In D61634#1498376 <https://reviews.llvm.org/D61634#1498376>, @efriedma wrote:
> I still think there are really two things you're trying to accomplish here, > which should be handled separately. > > 1. Add a function attribute that works like -fno-builtin-memcpy currently > does, to prevent the compiler from synthesizing calls to memcpy. > 2. Provide a convenient way to write a small, fixed-length "memcpy", in C and > in LLVM IR, that is always expanded to optimal straight-line code (without > any calls or loops). > > These correspond to proposals (1) and (2) from your RFC; I think we need > both to arrive at a reasonable final state. > > (The "rep; movs" is a third thing, which I think should also be handled > separately, but it sounds like you don't think that's very important.) Thank you for taking the time to comment, your feedback is highly appreciated. I understand that your main concern is about conflating two orthogonal requirements (namely 1. and 2.) in a single attribute. Is that correct? From my point of view, the RFC (and this Patch) really is about 1. - because 2. can already be achieved with builtins `__builtin_memcpy(dst, src, <compile time size>)`. My secondary goals in decreasing priority order are: - do not change the semantic of current builtins, - create a relatively straightforward LLVM patch that does not touch too much code and that is easy review, - do not add more confusion around `-fno-builtin-*` meaning, - do not add more builtins or IR intrinsics. What is the main blocker on your end? What would you suggest so we can move forward? Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D61634/new/ https://reviews.llvm.org/D61634 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
