fix: avoid SIGSEGV in CompileUnboundScript under Rosetta 2#13
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V8's ScriptCompiler::CompileUnboundScript crashes with a null-pointer dereference inside the JIT when an amd64 binary runs under Rosetta on arm64 macOS. Detect Rosetta via sysctl.proc_translated and fall back to ScriptCompiler::Compile + GetUnboundScript, which produces the same UnboundScript through V8's context-bound compile path. The fallback preserves full API semantics: cross-context reuse, code cache round-trip via CreateCodeCache, and eager compilation mode all work identically. Zero performance impact — same parse/compile pipeline, one extra Local<Script> handle (~nanoseconds). Only activates under Rosetta; native builds are completely unaffected.
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The 2.5x speedup threshold is tight on noisy CI runners (observed 2.33x on ubuntu-latest with 3.39x on immediate retry in the same job). Add a single retry when the first measurement misses the bar, consistent with how perf-regression tests should handle scheduling jitter.
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Summary
sysctl.proc_translated(macOS) and caches the resultIsolateCompileUnboundScriptusesScriptCompiler::Compile+GetUnboundScript()instead of the directScriptCompiler::CompileUnboundScriptcall that crashes with a null-deref SIGSEGVSetForceRosettaFallbackto exercise the fallback path on native hardwarePerformance
Zero impact. Both paths use the same V8 parser/compiler pipeline. The fallback adds one extra
Local<Script>handle and aGetUnboundScript()extraction (~nanoseconds). Only activates under Rosetta — production deploys on native arch see no code path change.Test plan
TestIsolateCompileUnboundScript_RosettaFallback— forces fallback, compiles with eager mode, runs across two contexts, round-trips code cache to a second isolateCompileUnboundScripttests continue to pass