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zig.h: replace _InterlockedExchangeAdd with a plain volatile load

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This was causing zig2.exe to crash during bootstrap, because there was an atomic
load of read-only memory, and the attempt to write to it as part of the (idempotent)
atomic exchange was invalid.

Aligned reads (of u32 / u64) are atomic on x86 / x64, so this is replaced with an
optimization-proof load (`__iso_volatile_load8*`) and a reordering barrier.
This commit is contained in:
kcbanner 2024-07-13 17:46:24 -04:00
parent 11534aa34d
commit bc28454b43
2 changed files with 30 additions and 26 deletions
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24
lib/zig.h
View file

@ -3670,7 +3670,7 @@ typedef int zig_memory_order;
/* TODO: zig_msvc_atomic_load should load 32 bit without interlocked on x86, and load 64 bit without interlocked on x64 */
#define zig_msvc_atomics(ZigType, Type, SigType, suffix) \
#define zig_msvc_atomics(ZigType, Type, SigType, suffix, iso_suffix) \
static inline bool zig_msvc_cmpxchg_##ZigType(Type volatile* obj, Type* expected, Type desired) { \
Type comparand = *expected; \
Type initial = _InterlockedCompareExchange##suffix((SigType volatile*)obj, (SigType)desired, (SigType)comparand); \
@ -3741,21 +3741,23 @@ typedef int zig_memory_order;
} \
static inline void zig_msvc_atomic_store_##ZigType(Type volatile* obj, Type value) { \
(void)_InterlockedExchange##suffix((SigType volatile*)obj, (SigType)value); \
} \
} \
static inline Type zig_msvc_atomic_load_##ZigType(Type volatile* obj) { \
return _InterlockedExchangeAdd##suffix((SigType volatile*)obj, (SigType)0); \
Type val = __iso_volatile_load##iso_suffix((SigType volatile*)obj); \
_ReadWriteBarrier(); \
return val; \
}
zig_msvc_atomics( u8, uint8_t, char, 8)
zig_msvc_atomics( i8, int8_t, char, 8)
zig_msvc_atomics(u16, uint16_t, short, 16)
zig_msvc_atomics(i16, int16_t, short, 16)
zig_msvc_atomics(u32, uint32_t, long, )
zig_msvc_atomics(i32, int32_t, long, )
zig_msvc_atomics( u8, uint8_t, char, 8, 8)
zig_msvc_atomics( i8, int8_t, char, 8, 8)
zig_msvc_atomics(u16, uint16_t, short, 16, 16)
zig_msvc_atomics(i16, int16_t, short, 16, 16)
zig_msvc_atomics(u32, uint32_t, long, , 32)
zig_msvc_atomics(i32, int32_t, long, , 32)
#if _M_X64
zig_msvc_atomics(u64, uint64_t, __int64, 64)
zig_msvc_atomics(i64, int64_t, __int64, 64)
zig_msvc_atomics(u64, uint64_t, __int64, 64, 64)
zig_msvc_atomics(i64, int64_t, __int64, 64, 64)
#endif
#define zig_msvc_flt_atomics(Type, SigType, suffix) \

32
stage1/zig.h
View file

@ -207,16 +207,16 @@ typedef char bool;
__asm(zig_mangle_c(name) " = " zig_mangle_c(symbol))
#endif
#define zig_mangled_tentative zig_mangled
#define zig_mangled_final zig_mangled
#if _MSC_VER
#define zig_mangled_tentative(mangled, unmangled)
#define zig_mangled_final(mangled, unmangled) ; \
#define zig_mangled(mangled, unmangled) ; \
zig_export(#mangled, unmangled)
#define zig_mangled_export(mangled, unmangled, symbol) \
zig_export(unmangled, #mangled) \
zig_export(symbol, unmangled)
#else /* _MSC_VER */
#define zig_mangled_tentative(mangled, unmangled) __asm(zig_mangle_c(unmangled))
#define zig_mangled_final(mangled, unmangled) zig_mangled_tentative(mangled, unmangled)
#define zig_mangled(mangled, unmangled) __asm(zig_mangle_c(unmangled))
#define zig_mangled_export(mangled, unmangled, symbol) \
zig_mangled_final(mangled, unmangled) \
zig_export(symbol, unmangled)
@ -3670,7 +3670,7 @@ typedef int zig_memory_order;
/* TODO: zig_msvc_atomic_load should load 32 bit without interlocked on x86, and load 64 bit without interlocked on x64 */
#define zig_msvc_atomics(ZigType, Type, SigType, suffix) \
#define zig_msvc_atomics(ZigType, Type, SigType, suffix, iso_suffix) \
static inline bool zig_msvc_cmpxchg_##ZigType(Type volatile* obj, Type* expected, Type desired) { \
Type comparand = *expected; \
Type initial = _InterlockedCompareExchange##suffix((SigType volatile*)obj, (SigType)desired, (SigType)comparand); \
@ -3741,21 +3741,23 @@ typedef int zig_memory_order;
} \
static inline void zig_msvc_atomic_store_##ZigType(Type volatile* obj, Type value) { \
(void)_InterlockedExchange##suffix((SigType volatile*)obj, (SigType)value); \
} \
} \
static inline Type zig_msvc_atomic_load_##ZigType(Type volatile* obj) { \
return _InterlockedExchangeAdd##suffix((SigType volatile*)obj, (SigType)0); \
Type val = __iso_volatile_load##iso_suffix((SigType volatile*)obj); \
_ReadWriteBarrier(); \
return val; \
}
zig_msvc_atomics( u8, uint8_t, char, 8)
zig_msvc_atomics( i8, int8_t, char, 8)
zig_msvc_atomics(u16, uint16_t, short, 16)
zig_msvc_atomics(i16, int16_t, short, 16)
zig_msvc_atomics(u32, uint32_t, long, )
zig_msvc_atomics(i32, int32_t, long, )
zig_msvc_atomics( u8, uint8_t, char, 8, 8)
zig_msvc_atomics( i8, int8_t, char, 8, 8)
zig_msvc_atomics(u16, uint16_t, short, 16, 16)
zig_msvc_atomics(i16, int16_t, short, 16, 16)
zig_msvc_atomics(u32, uint32_t, long, , 32)
zig_msvc_atomics(i32, int32_t, long, , 32)
#if _M_X64
zig_msvc_atomics(u64, uint64_t, __int64, 64)
zig_msvc_atomics(i64, int64_t, __int64, 64)
zig_msvc_atomics(u64, uint64_t, __int64, 64, 64)
zig_msvc_atomics(i64, int64_t, __int64, 64, 64)
#endif
#define zig_msvc_flt_atomics(Type, SigType, suffix) \