[all-commits] [llvm/llvm-project] 6ffc44: [PGO][AIX] Disable multi-process continuous mode t...

[Wael Yehia via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 6ffc4451037bbae26cce51fb80418f8e9ed2ac84
      https://github.com/llvm/llvm-project/commit/6ffc4451037bbae26cce51fb80418f8e9ed2ac84
  Author: Wael Yehia <wyehia at ca.ibm.com>
  Date:   2025-01-15 (Wed, 15 Jan 2025)

  Changed paths:
    M compiler-rt/test/profile/ContinuousSyncMode/online-merging.c

  Log Message:
  -----------
  [PGO][AIX] Disable multi-process continuous mode test in 32-bit

In PGO continuous mode, we mmap the profile file into shared memory, which
allows multiple processes to be updating the same memory.

The -fprofile-update=atomic option forces the counter increments to be atomic,
but the counter size is always 64-bit (in -m32 and -m64), so in 32-bit mode the
atomic operations are function calls to libatomic.a and these function calls use
locks.

The lock based libatomic.a functions are per-process, so two processes will race
on the same shared memory because each will acquire their own lock.



To unsubscribe from these emails, change your notification settings at https://github.com/llvm/llvm-project/settings/notifications