Tolerate flaky LLD tests on NetBSD

[krytarowski]

Summary

For unknown reasons LLD tests are flaky on the NetBSD buildbot,
but not on local machines of developers.

Unless the linker will be fully functional on this target,
allow to pass flaky tests with optional retry.

[lebedev.ri]

'tests'?
check-lld, ELF/relocatable-build-id.s is flaky on http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-fast too.
@ruiu is that test ever going to be addressed? Super frustrating.

[krytarowski]

http://lab.llvm.org:8011/builders/lldb-amd64-ninja-netbsd8/builds/17766

FAIL: lld::weak.ll
FAIL: lld::strip-debug.test

http://lab.llvm.org:8011/builders/lldb-amd64-ninja-netbsd8/builds/17765

FAIL: lld::parallel.ll

etc

[krytarowski]

I would happily debug lld with TSan.. but we need to raise our (The NetBSD Foundation) resources to be able to continue & speedup our work post New Year.

[mgorny]

test/lit.cfg.py

50 ↗

(On Diff #179430)

Could you make it in ['NetBSD'], so that it'd be easier to add more platforms if necessary?

[krytarowski]

• apply comment from review

[mgorny]

Looks good, thanks.

[ruiu]

Many (all?) lld tests actually are flaky on http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-fast. Filed https://bugs.llvm.org/show_bug.cgi?id=40162 to track that issue.

lld/trunk/test/lit.cfg.py

 
 tool_patterns = [
     'llc', 'llvm-as', 'llvm-mc', 'llvm-nm', 'llvm-objdump', 'llvm-pdbutil',
     'llvm-dwarfdump', 'llvm-readelf', 'llvm-readobj', 'obj2yaml', 'yaml2obj',
     'opt', 'llvm-dis']
 
 llvm_config.add_tool_substitutions(tool_patterns)
 
+# LLD tests tend to be flaky on NetBSD, so add some retries.
+# We don't do this on other platforms because it's slower.
+if platform.system() in ['NetBSD']:
+    config.test_retry_attempts = 2
+
 # When running under valgrind, we mangle '-vg' onto the end of the triple so we
 # can check it with XFAIL and XTARGET.
 if lit_config.useValgrind:
     config.target_triple += '-vg'
 
 # Running on ELF based *nix
 if platform.system() in ['FreeBSD', 'Linux']:
     config.available_features.add('system-linker-elf')