[all-commits] [llvm/llvm-project] 6522b7: [clang] Add option to clear AST memory before runn...

[aeubanks via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 6522b7cc3240626952ebc271d8714043a805911d
      https://github.com/llvm/llvm-project/commit/6522b7cc3240626952ebc271d8714043a805911d
  Author: Arthur Eubanks <aeubanks at google.com>
  Date:   2021-10-06 (Wed, 06 Oct 2021)

  Changed paths:
    M clang/include/clang/Basic/CodeGenOptions.def
    M clang/include/clang/Driver/Options.td
    M clang/lib/CodeGen/CodeGenAction.cpp
    A clang/test/Misc/clear-ast-before-backend.c

  Log Message:
  -----------
  [clang] Add option to clear AST memory before running LLVM passes

This is to save memory for Clang compiles.
Measuring building PassBuilder.cpp under /usr/bin/time, max rss goes from 0.93GB to 0.7GB.

This does not turn it by default yet.

I've turned on the option locally and run it over a good amount of files without any issues.

For more background, see
https://lists.llvm.org/pipermail/cfe-dev/2021-September/068930.html.

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D111105