[all-commits] [llvm/llvm-project] c753a3: [scudo][standalone] Various improvements wrt RSS

[Kostya Kortchinsky via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: c753a306fd1ad4a7e5c61367225abce86ac29cd7
      https://github.com/llvm/llvm-project/commit/c753a306fd1ad4a7e5c61367225abce86ac29cd7
  Author: Kostya Kortchinsky <kostyak at google.com>
  Date:   2020-02-26 (Wed, 26 Feb 2020)

  Changed paths:
    M compiler-rt/lib/scudo/standalone/combined.h
    M compiler-rt/lib/scudo/standalone/local_cache.h
    M compiler-rt/lib/scudo/standalone/primary32.h
    M compiler-rt/lib/scudo/standalone/primary64.h
    M compiler-rt/lib/scudo/standalone/release.h
    M compiler-rt/lib/scudo/standalone/secondary.h
    M compiler-rt/lib/scudo/standalone/size_class_map.h
    M compiler-rt/lib/scudo/standalone/tests/release_test.cpp
    M compiler-rt/lib/scudo/standalone/tests/size_class_map_test.cpp

  Log Message:
  -----------
  [scudo][standalone] Various improvements wrt RSS

Summary:
This patch includes several changes to reduce the overall footprint
of the allocator:
- for realloc'd chunks: only keep the same chunk when lowering the size
  if the delta is within a page worth of bytes;
- when draining a cache: drain the beginning, not the end; we add pointers
  at the end, so that meant we were draining the most recently added
  pointers;
- change the release code to account for an freed up last page: when
  scanning the pages, we were looking for pages fully covered by blocks;
  in the event of the last page, if it's only partially covered, we
  wouldn't mark it as releasable - even what follows the last chunk is
  all 0s. So now mark the rest of the page as releasable, and adapt the
  test;
- add a missing `setReleaseToOsIntervalMs` to the cacheless secondary;
- adjust the Android classes based on more captures thanks to pcc@'s
  tool.

Reviewers: pcc, cferris, hctim, eugenis

Subscribers: #sanitizers, llvm-commits

Tags: #sanitizers, #llvm

Differential Revision: https://reviews.llvm.org/D75142