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Rewrite mulh64/umulh64

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Use __int128_t/__uint128_t idioms on GCC/Clang.
May result in better codegen by avoiding inline asm.
This commit is contained in:
Nekotekina 2019-03-13 00:06:12 +03:00
parent 688aabc6c9
commit eae5b9e049
1 changed files with 8 additions and 8 deletions
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16
Utilities/asm.h
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@ -157,18 +157,18 @@ namespace utils
#endif #endif
} }
inline u64 umulh64(u64 a, u64 b) constexpr u64 umulh64(u64 a, u64 b)
{ {
u64 result; const __uint128_t x = a;
__asm__("mulq %[b]" : "=d"(result) : [a] "a"(a), [b] "rm"(b)); const __uint128_t y = b;
return result; return (x * y) >> 64;
} }
inline s64 mulh64(s64 a, s64 b) constexpr s64 mulh64(s64 a, s64 b)
{ {
s64 result; const __int128_t x = a;
__asm__("imulq %[b]" : "=d"(result) : [a] "a"(a), [b] "rm"(b)); const __int128_t y = b;
return result; return (x * y) >> 64;
} }
#elif defined(_MSC_VER) #elif defined(_MSC_VER)