432bf48 [profile] Fix file contention causing dropped counts on Windows under -fprofile-generate

4 files Authored by Hans Wennborg 4 years ago, Committed by tstellar 4 years ago,
    [profile] Fix file contention causing dropped counts on Windows under -fprofile-generate
    
    See PR43425:
    https://bugs.llvm.org/show_bug.cgi?id=43425
    
    When writing profile data on Windows we were opening profile file with
    exclusive read/write access.
    
    In case we are trying to write to the file from multiple processes
    simultaneously, subsequent calls to CreateFileA would return
    INVALID_HANDLE_VALUE.
    
    To fix this, I changed to open without exclusive access and then take a
    lock.
    
    Patch by Michael Holman!
    
    Differential revision: https://reviews.llvm.org/D70330
    
    (cherry picked from commit 900d8a9a3b4efeefddd310e92219741d98e7270b)