On Tue, Aug 08, 2017 at 09:09:09AM +0900, Mike Hommey wrote: > On Tue, Aug 08, 2017 at 07:12:13AM +0900, Mike Hommey wrote: > > On Fri, Aug 04, 2017 at 08:45:14AM +0300, Henri Sivonen wrote: > > > I guess I buried my questions in too long a post, so extracting them: > > > > > > On Mon, Jul 31, 2017 at 1:02 PM, Henri Sivonen <hsivo...@hsivonen.fi> > > > wrote: > > > > Naïvely, one would think that it should be possible to do that with > > > > clang producing "object files" holding LLVM IR and rustc producing > > > > "object files" holding LLVM IR and the "link" step involving mashing > > > > those together, running LLVM optimizations again and then producing > > > > machine code from a massive collection of mashed-together LLVM IR. > > > ... > > > > If we were compiling C++ using clang on all platforms, how far off > > > > would such cross-language inlining be? > > > > > > > > If we could have the cross-language inlining benefit from compiling > > > > C++ using clang on all platforms, how far off would we be from being > > > > able to switch to clang on all platforms? > > > > Here's a bunch of data why "let's switch compilers" is not necessarily > > easy (I happen to have gathered that recently): > > > > Windows MSVC (PGO) vs. clang-cl: > > https://treeherder.mozilla.org/perf.html#/compare?originalProject=try&originalRevision=581eab2aa162&newProject=try&newRevision=c963d0cd6565&framework=1&showOnlyImportant=0 > > > > Windows MSVC (PGO) vs. clang-cl -O2 (the build system currently uses -O1 for > > msvc builds, which flags we use for clang-cl builds): > > https://treeherder.mozilla.org/perf.html#/compare?originalProject=try&originalRevision=581eab2aa162&newProject=try&newRevision=c963d0cd6565&framework=1&showOnlyImportant=0 > > It was pointed to me that both urls were the same. The second is > actually: > https://treeherder.mozilla.org/perf.html#/compare?originalProject=try&originalRevision=581eab2aa162&newProject=try&newRevision=232f977d9739&framework=1&showOnlyImportant=0
And now that the clang trunk bug that made it crash when building Firefox is fixed, here's another go at MSVC(PGO) vs. clang-cl -O2: https://treeherder.mozilla.org/perf.html#/compare?originalProject=try&originalRevision=f8ff2c492d2e&newProject=try&newRevision=868f0ef87a7d&framework=1&showOnlyImportant=0 (tl;dr: not much change from the version we were using before) Mike _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
