[all-commits] [llvm/llvm-project] 5502bd: [profile] Remove useless msync when dumping gcda f...

[calixteman via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 5502bd66bb97f7cf3888a869b73091c51fdbba4c
      https://github.com/llvm/llvm-project/commit/5502bd66bb97f7cf3888a869b73091c51fdbba4c
  Author: Calixte Denizet <calixte.denizet at gmail.com>
  Date:   2020-10-14 (Wed, 14 Oct 2020)

  Changed paths:
    M compiler-rt/lib/profile/GCDAProfiling.c

  Log Message:
  -----------
  [profile] Remove useless msync when dumping gcda files

Summary:
According the mmap man page (https://man7.org/linux/man-pages/man2/mmap.2.html) is only required to precisely control updates, so we can safely remove it.
Since gcda files are dumped just before to call exec** functions, dump need to be fast.
On my computer, Firefox built with --coverage needs ~1min40 to display something and in removing msync it needs ~8s.

Reviewers: void

Subscribers: #sanitizers, marco-c, sylvestre.ledru

Tags: #sanitizers

Differential Revision: https://reviews.llvm.org/D81060