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fix Windows breakage

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Fixing typo revealed that _BitScanReverse is BSR, which behaves
differently than LZCNT.  What we want here is LZCNT so we have to
emulate.
This commit is contained in:
卜部昌平 2020-01-10 19:24:59 +09:00
parent db0398dc04
commit 7fed7eb50b
Notes: git 2020-01-10 21:17:38 +09:00 
Merged: https://github.com/ruby/ruby/pull/2824
1 changed files with 2 additions and 2 deletions
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4
internal/bits.h
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@ -215,7 +215,7 @@ nlz_int32(uint32_t x)
#elif defined(_MSC_VER) && defined(_WIN64) /* &&! defined(__AVX2__) */ #elif defined(_MSC_VER) && defined(_WIN64) /* &&! defined(__AVX2__) */
unsigned long r; unsigned long r;
return _BitScanReverse(&r, x) ? (int)r : 32; return _BitScanReverse(&r, x) ? (31 - (int)r) : 32;
#elif __has_builtin(__builtin_clz) #elif __has_builtin(__builtin_clz)
STATIC_ASSERT(sizeof_int, sizeof(int) * CHAR_BIT == 32); STATIC_ASSERT(sizeof_int, sizeof(int) * CHAR_BIT == 32);
@ -244,7 +244,7 @@ nlz_int64(uint64_t x)
#elif defined(_MSC_VER) && defined(_WIN64) /* &&! defined(__AVX2__) */ #elif defined(_MSC_VER) && defined(_WIN64) /* &&! defined(__AVX2__) */
unsigned long r; unsigned long r;
return _BitScanReverse64(&r, x) ? (unsigned int)r : 64; return _BitScanReverse64(&r, x) ? (63u - (unsigned int)r) : 64;
#elif __has_builtin(__builtin_clzl) #elif __has_builtin(__builtin_clzl)
if (x == 0) { if (x == 0) {