build: do not build with code cache for core coverage collection

joyeecheung · targos · commit e862eecac9f0 · 2024-10-02T07:57:58.000+02:00
Disable code cache for built-ins when are building Node.js to collect test coverage of built-ins, as code caching makes the V8 coverage collection less precises (specifically, all the functions deserialized from the code cache will not have block-level coverage data). Data from local testing: Before: ---------|----------|---------|--------- % Stmts | % Branch | % Funcs | % Lines ---------|----------|---------|--------- 95.58 | 94.43 | 95.19 | 95.58 ---------|----------|---------|--------- After: ---------|----------|---------|--------- % Stmts | % Branch | % Funcs | % Lines ---------|----------|---------|--------- 95.93 | 94.77 | 96.03 | 95.93 ---------|----------|---------|--------- PR-URL: #54633 Reviewed-By: Chengzhong Wu <legendecas@gmail.com> Reviewed-By: Richard Lau <rlau@redhat.com> Reviewed-By: Luigi Pinca <luigipinca@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Daeyeon Jeong <daeyeon.dev@gmail.com>
diff --git a/configure.py b/configure.py
@@ -1389,7 +1389,9 @@ def configure_node(o):
     o['variables']['node_use_node_snapshot'] = b(
       not cross_compiling and not options.shared)
 
-  if options.without_node_code_cache or options.without_node_snapshot or options.node_builtin_modules_path:
+  # Do not use code cache when Node.js is built for collecting coverage of itself, this allows more
+  # precise coverage for the JS built-ins.
+  if options.without_node_code_cache or options.without_node_snapshot or options.node_builtin_modules_path or options.coverage:
     o['variables']['node_use_node_code_cache'] = 'false'
   else:
     # TODO(refack): fix this when implementing embedded code-cache when cross-compiling.
