Speedbuilding LLVM/Clang in 3 minutes on Power10 | Frederic Cambus

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2024-03-28 19:30:28

This post is the Power10 counterpart of my "Speedbuilding LLVM/Clang in 5 minutes" and "Speedbuilding LLVM/Clang in 2 minutes on ARM" articles.

The system I'm using for this experiment is an IBM POWER10 9043-MRX (E1050) server with a total of 24 cores and 192 threads, and 2 TB of RAM.

For all the following runs, I'm building from the Git repository main branch commit d7975c9d93fb4a69c0bd79d7d5b3f6be77a25c73. The build directory is of course fully erased between each run.

By default, CMake generates Makefiles. As documented in the "Getting Started with the LLVM System" tutorial, most LLVM developers use Ninja.

Using GNU gold instead of GNU ld results in slightly faster builds, and switching to LLD and then Mold shaves a few more seconds from the build. For the remaining of the article, I will stick to using LLD as linker.

Contrary to the previous builds done in 2021 on X86 and ARM, disabling optimizations by building with the "-O0" flag results in consistently slower build times on this server.

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