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fix mi_clz and mi_ctz having undefined behavior due to uninitialized variable

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fixes:
- issues while compiled with /os(like frozen program at startup)
- sometimes mi_bchunk_try_clearNX or mi_bchunk_try_find_and_clearNX fails even if it's compiled without /os while program is running
This commit is contained in:
_ClearEdge 2025-05-02 09:52:45 +09:00 • committed by 0x-FADED
parent 61f3ffd2a6
commit ab4ecac1ec
1 changed files with 7 additions and 5 deletions
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12
include/mimalloc/bits.h
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@ -236,8 +236,9 @@ static inline size_t mi_ctz(size_t x) {
#elif defined(_MSC_VER) && MI_ARCH_X64 && defined(__BMI1__) #elif defined(_MSC_VER) && MI_ARCH_X64 && defined(__BMI1__)
return (x!=0 ? _tzcnt_u64(x) : MI_SIZE_BITS); // ensure it still works on non-BMI1 cpu's as well return (x!=0 ? _tzcnt_u64(x) : MI_SIZE_BITS); // ensure it still works on non-BMI1 cpu's as well
#elif defined(_MSC_VER) && (MI_ARCH_X64 || MI_ARCH_X86 || MI_ARCH_ARM64 || MI_ARCH_ARM32) #elif defined(_MSC_VER) && (MI_ARCH_X64 || MI_ARCH_X86 || MI_ARCH_ARM64 || MI_ARCH_ARM32)
unsigned long idx; unsigned long idx = MI_SIZE_BITS;
return (mi_msc_builtinz(_BitScanForward)(&idx, x) ? (size_t)idx : MI_SIZE_BITS); if (x != 0) { mi_msc_builtinz(_BitScanForward)(&idx, x); return (size_t)idx; }
return MI_SIZE_BITS;
#elif defined(__GNUC__) && MI_ARCH_X86 #elif defined(__GNUC__) && MI_ARCH_X86
size_t r = MI_SIZE_BITS; size_t r = MI_SIZE_BITS;
__asm ("bsf\t%1, %0" : "+r"(r) : "r"(x) : "cc"); __asm ("bsf\t%1, %0" : "+r"(r) : "r"(x) : "cc");
@ -260,8 +261,9 @@ static inline size_t mi_clz(size_t x) {
#elif mi_has_builtinz(clz) #elif mi_has_builtinz(clz)
return (x!=0 ? (size_t)mi_builtinz(clz)(x) : MI_SIZE_BITS); return (x!=0 ? (size_t)mi_builtinz(clz)(x) : MI_SIZE_BITS);
#elif defined(_MSC_VER) && (MI_ARCH_X64 || MI_ARCH_X86 || MI_ARCH_ARM64 || MI_ARCH_ARM32) #elif defined(_MSC_VER) && (MI_ARCH_X64 || MI_ARCH_X86 || MI_ARCH_ARM64 || MI_ARCH_ARM32)
unsigned long idx; unsigned long idx = MI_SIZE_BITS;
return (mi_msc_builtinz(_BitScanReverse)(&idx, x) ? MI_SIZE_BITS - 1 - (size_t)idx : MI_SIZE_BITS); if (x != 0) { mi_msc_builtinz(_BitScanReverse)(&idx, x); return (size_t)(MI_SIZE_BITS - 1 - idx);}
return MI_SIZE_BITS;
#elif defined(__GNUC__) && (MI_ARCH_X64 || MI_ARCH_X86) #elif defined(__GNUC__) && (MI_ARCH_X64 || MI_ARCH_X86)
if (x==0) return MI_SIZE_BITS; if (x==0) return MI_SIZE_BITS;
size_t r; size_t r;
@ -363,4 +365,4 @@ static inline uint32_t mi_rotl32(uint32_t x, uint32_t r) {
} }
#endif // MI_BITS_H #endif // MI_BITS_H