[llvm-dev] (Thin)LTO llvm build (original) (raw)

Mehdi Amini via llvm-dev llvm-dev at lists.llvm.org
Fri Sep 16 17:00:48 PDT 2016

On Sep 16, 2016, at 4:59 PM, Mehdi Amini via llvm-dev <llvm-dev at lists.llvm.org> wrote:

On Sep 16, 2016, at 4:46 PM, Carsten Mattner <carstenmattner at gmail.com <mailto:carstenmattner at gmail.com>> wrote: On Sat, Sep 17, 2016 at 12:48 AM, Teresa Johnson <tejohnson at google.com <mailto:tejohnson at google.com>> wrote:

On Fri, Sep 16, 2016 at 2:54 PM, Carsten Mattner via llvm-dev <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote:

On Fri, Sep 16, 2016 at 11:28 PM, Mehdi Amini <mehdi.amini at apple.com <mailto:mehdi.amini at apple.com>> wrote:

You probably missed -DLLVMBINUTILSINCDIR.

See: http://llvm.org/docs/GoldPlugin.html <http://llvm.org/docs/GoldPlugin.html> plugin-api.h is in /usr/include, so I'd expect it to be found, but I can explicitly set BINUTILSINCDIR and re-bootstrap with gcc 6.2.1. I have ld.gold, but I'm not sure if /usr/bin/ld uses it, though I'd expect it to since it's been in for a couple releases now. $ ld -v GNU ld (GNU Binutils) 2.27 $ ld.bfd -v GNU ld (GNU Binutils) 2.27 $ ld.gold -v GNU gold (GNU Binutils 2.27) 1.12 Looks like your default ld is GNU ld.bfd not ld.gold. You can either change your /usr/bin/ld (which probably is a link to /usr/bin/ld.bfd) to point instead to /usr/bin/ld.gold, or if you prefer, set your PATH before the stage1 compile to a location that has ld linked to ld.gold. I can look into and check why Arch Linux has it configured like that. In the meantime, Mehdi's suggestion to explicitly pass BINUTILSINCDIR restored the previous configure behavior, and the new llvm build has lib/LLVMgold.so. Thanks to both of you for pointing out the missing cmake flag. I've checked the configure step and it didn't fail as it did before, but before I try to build in ThinLTO mode: since the configure step checks for the gold plugin, is it safe to assume that I don't have to change the default system ld to gold and ThinLTO will work, or is that a build requirement for bootstrapping llvm in ThinLTO mode? Try to build llvm-tblgen, you’ll know quite quickly :)

Also, you should limit the number of parallel link jobs: cmake -DLLVM_PARALLEL_LINK_JOBS=1 And use ninja if you don’t already: cmake -GNinja

— Mehdi

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