mirror of
https://github.com/llvm/llvm-project.git
synced 2025-04-17 08:56:43 +00:00
6ab034b828
Reland #120514 after 2f6e3df08a8b7cd29273980e47310cf09c6fdbd8 fixed iteration order issue and libstdc++/libc++ differences. --- Both options instruct the linker to optimize section layout with the following goals: * `--bp-compression-sort=[data|function|both]`: Improve Lempel-Ziv compression by grouping similar sections together, resulting in a smaller compressed app size. * `--bp-startup-sort=function --irpgo-profile=<file>`: Utilize a temporal profile file to reduce page faults during program startup. The linker determines the section order by considering three groups: * Function sections ordered according to the temporal profile (`--irpgo-profile=`), prioritizing early-accessed and frequently accessed functions. * Function sections. Sections containing similar functions are placed together, maximizing compression opportunities. * Data sections. Similar data sections are placed together. Within each group, the sections are ordered using the Balanced Partitioning algorithm. The linker constructs a bipartite graph with two sets of vertices: sections and utility vertices. * For profile-guided function sections: + The number of utility vertices is determined by the symbol order within the profile file. + If `--bp-compression-sort-startup-functions` is specified, extra utility vertices are allocated to prioritize nearby function similarity. * For sections ordered for compression: Utility vertices are determined by analyzing k-mers of the section content and relocations. The call graph profile is disabled during this optimization. When `--symbol-ordering-file=` is specified, sections described in that file are placed earlier. Co-authored-by: Pengying Xu <xpy66swsry@gmail.com>
See docs/NewLLD.rst