| #ifndef FALLBACK_BUILTINS_H |
| #define FALLBACK_BUILTINS_H |
| |
| #if defined(_MSC_VER) && !defined(__clang__) |
| #if defined(_M_IX86) || defined(_M_AMD64) || defined(_M_IA64) || defined(_M_ARM) || defined(_M_ARM64) || defined(_M_ARM64EC) |
| |
| #include <intrin.h> |
| #ifdef X86_FEATURES |
| # include "arch/x86/x86_features.h" |
| #endif |
| |
| /* This is not a general purpose replacement for __builtin_ctz. The function expects that value is != 0. |
| * Because of that assumption trailing_zero is not initialized and the return value is not checked. |
| * Tzcnt and bsf give identical results except when input value is 0, therefore this can not be allowed. |
| * If tzcnt instruction is not supported, the cpu will itself execute bsf instead. |
| * Performance tzcnt/bsf is identical on Intel cpu, tzcnt is faster than bsf on AMD cpu. |
| */ |
| static __forceinline int __builtin_ctz(unsigned int value) { |
| Assert(value != 0, "Invalid input value: 0"); |
| # if defined(X86_FEATURES) && !(_MSC_VER < 1700) |
| return (int)_tzcnt_u32(value); |
| # else |
| unsigned long trailing_zero; |
| _BitScanForward(&trailing_zero, value); |
| return (int)trailing_zero; |
| # endif |
| } |
| #define HAVE_BUILTIN_CTZ |
| |
| #ifdef _M_AMD64 |
| /* This is not a general purpose replacement for __builtin_ctzll. The function expects that value is != 0. |
| * Because of that assumption trailing_zero is not initialized and the return value is not checked. |
| */ |
| static __forceinline int __builtin_ctzll(unsigned long long value) { |
| Assert(value != 0, "Invalid input value: 0"); |
| # if defined(X86_FEATURES) && !(_MSC_VER < 1700) |
| return (int)_tzcnt_u64(value); |
| # else |
| unsigned long trailing_zero; |
| _BitScanForward64(&trailing_zero, value); |
| return (int)trailing_zero; |
| # endif |
| } |
| #define HAVE_BUILTIN_CTZLL |
| #endif // Microsoft AMD64 |
| |
| #endif // Microsoft AMD64/IA64/x86/ARM/ARM64 test |
| #endif // _MSC_VER & !clang |
| |
| #endif // include guard FALLBACK_BUILTINS_H |