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BAssert.h: use __builtin_trap for BCRASH on clang-cl #316

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BAssert.h: use __builtin_trap for BCRASH on clang-cl #316

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10 changes: 8 additions & 2 deletions Source/bmalloc/bmalloc/BAssert.h
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Original file line number Diff line number Diff line change
Expand Up @@ -60,7 +60,13 @@
#define BCRASH() __builtin_trap()
#else

#if defined(__GNUC__) // GCC or Clang
// clang-cl defines __clang__ but not __GNUC__. With only defined(__GNUC__),
// clang-cl fell into the #else and compiled BCRASH() as ((void(*)())0)(),
// which clang treats as unconditional UB and uses to prove the surrounding
// branch unreachable. Every RELEASE_BASSERT(x) in bmalloc compiled to nothing
// at -O2, so e.g. fastCompactMalloc became a bare `jmp mi_malloc` with the
// OOM null check deleted. https://bun.com/issues/sentry/BUN-2Z94.
#if defined(__GNUC__) || defined(__clang__)
#define BCRASH() do { \
BIGNORE_CLANG_STATIC_ANALYZER_WARNINGS_ATTRIBUTE("core.FixedAddressDereference") *(int*)0xbbadbeef = 0; \
__builtin_trap(); \
Expand All @@ -70,7 +76,7 @@
BIGNORE_CLANG_STATIC_ANALYZER_WARNINGS_ATTRIBUTE("core.FixedAddressDereference") *(int*)0xbbadbeef = 0; \
((void(*)())0)(); \
} while (0)
#endif // defined(__GNUC__)
#endif // defined(__GNUC__) || defined(__clang__)
#endif // BASAN_ENABLED

#endif // defined(NDEBUG) && (BOS(DARWIN) || BPLATFORM(PLAYSTATION))
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