On 13 September 2010 23:41, Ian Lance Taylor <i...@google.com> wrote: > Manuel López-Ibáñez <lopeziba...@gmail.com> writes: > >> On 13 September 2010 22:04, Ian Lance Taylor <i...@google.com> wrote: >>> Manuel López-Ibáñez <lopeziba...@gmail.com> writes: >>> >>>> From a user-perspective, there are benefits on both clang->gcc and >>>> gcc->llvm. However, from what I know about the GCC project, I don't >>>> see yet how GCC developers can consider either more beneficial than >>>> the other. >>> >>> It seems to me that at the present moment LLVM's frontends are better >>> than GCC's, and GCC's backends are better than LLVM's. By this I mean >>> specifically that LLVM's frontends generate better diagnostics, whereas >>> GCC's backends generate code that has better runtime performance. (LLVM >>> also appears to run faster, which is a good feature but not in my mind a >>> determining one.) Therefore, I see a clear benefit to clang->gcc, but I >>> do not see a clear benefit to gcc->llvm. This comment is of course >>> entirely independent of the licensing issues. >> >> I think you are again talking about user benefits. > > I'm not sure I understand the distinction you are drawing. What is the > difference between a benefit to users of gcc and a benefit to gcc > itself? > >> You don't see a >> (user) benefit in gcc->llvm because you perhaps do not use the >> features that LLVM has and GCC doesn't. But users of gcc->llvm surely >> see a large benefit if people have spent so much effort working on it, >> first as a patched gcc and now as a plugin. > > I understand the benefit that existed before clang. And my general > understanding is that clang C++ support is not yet complete, so there is > a benefit there, but only a temporary one. I don't see a real benefit > going forward.
Access to all the other GCC front-ends that the LLVM project has not (yet) reimplemented? Someone provided above a real user-case for gcc->llvm involving Fortran. I don't think dragon-egg development is stalled at all. >> But I am talking about benefits to GCC. Do you see any >> benefit/downside on adding code to GCC to enable a plugin that >> implements clang->gcc? > > Since for me benefits to users of gcc are pretty much the same as > benefits to gcc, yes, I see a benefit. By that rule, it is clearly beneficial for some gcc users to compile Fortran using dragon-egg to take advantage of OpenCL. Ergo, dragon-egg is beneficial to GCC. Anyway, I don't see anyone implementing clang->gcc soon, but it is good to know it would be welcome. Thanks for answering, Manuel.
