[all-commits] [llvm/llvm-project] ba3bc2: [mac/arm] Deflake 3 check-llvm tests

[Nico Weber via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: ba3bc2fd41b8428904fc779e353d3769074d8982
      https://github.com/llvm/llvm-project/commit/ba3bc2fd41b8428904fc779e353d3769074d8982
  Author: Nico Weber <thakis at chromium.org>
  Date:   2020-12-12 (Sat, 12 Dec 2020)

  Changed paths:
    M llvm/test/tools/llvm-isel-fuzzer/aarch64-execname-options.ll
    M llvm/test/tools/llvm-isel-fuzzer/execname-options.ll
    M llvm/test/tools/llvm-opt-fuzzer/exec-options.ll

  Log Message:
  -----------
  [mac/arm] Deflake 3 check-llvm tests

On macOS/arm, signature verification has kill semantics by default.
Signature verification is cached with a file's inode (actually, vnode),
and if a new executable is copied over an existing file (which reuses
the inode), the cache isn't invalidated. So when the new executable
is executed, the kernel still has the old content's signature cached
and the kills the executable because the old signatue doesn't match
the new contents (https://openradar.appspot.com/FB8914243).

As workaround, rm the desitnation files first, to ensure they have
a fresh vnode (and hence no stale cached signature) after the copy.

Part of PR46647. See also e0e334a9c1ac for a similar change.