[LLVMdev] Using thin archives when building llvm (original) (raw)

Pete Cooper peter_cooper at apple.com
Fri Jul 17 09:54:28 PDT 2015

On Jul 17, 2015, at 7:49 AM, Rafael Espíndola <rafael.espindola at gmail.com> wrote:

On 17 July 2015 at 07:19, Brad King <brad.king at kitware.com> wrote: On 07/15/2015 09:00 PM, Rafael Espíndola wrote:

I have just committed support to llvm-ar for creating thin archives. The idea of thin archives is that they contain just the symbol table and the path to find the original .o files.

Neat! Is this expected to be used only for non-installed archives? Yes, the idea is to speed up a regular development build. Is there any way to do that with cmake without having to have a hacked llvm-ar? All that is needed is for cmake to run

.../llvm-ar cqT foo.a .... instead of .../llvm-ar cq foo.a .... CMake has undocumented variables set by the Modules/Platform/* files to specify the rules for creating archives. These are: CMAKEARCHIVE{CREATE,APPEND,FINISH} I went with this one on my run-cmake script, thanks. FWIW, i’d more than welcome a patch to get this in to cmake.

Chris added a flag (LLVM_OPTIMIZED_TBLGEN) to build an optimized tblgen and use that in the regular build. I’d be happy to see a similar flag used to have that step build an llvm-ar used by the rest of compilation to use thin archives. At least until we start shipping this.

I’m happy to propose a patch or help test one if you have one in future.

Cheers, Pete

Cheers, Rafael

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