mirror of
https://github.com/GerbilSoft/zlib-ng.git
synced 2025-06-18 19:45:37 -04:00
17331431e0
Added debug assert check for value = 0. Added more details to the comment to avoid future confusion. Added fallback logic for older MSVC versions, just in case.
94 lines
3.2 KiB
C
94 lines
3.2 KiB
C
#ifndef FALLBACK_BUILTINS_H
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#define FALLBACK_BUILTINS_H
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#if defined(_MSC_VER) && !defined(__clang__)
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#if defined(_M_IX86) || defined(_M_AMD64) || defined(_M_IA64) || defined(_M_ARM) || defined(_M_ARM64)
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#include <intrin.h>
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#ifdef X86_FEATURES
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# include "arch/x86/x86_features.h"
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#endif
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/* This is not a general purpose replacement for __builtin_ctz. The function expects that value is != 0.
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* Because of that assumption trailing_zero is not initialized and the return value is not checked.
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* Tzcnt and bsf give identical results except when input value is 0, therefore this can not be allowed.
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* If tzcnt instruction is not supported, the cpu will itself execute bsf instead.
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* Performance tzcnt/bsf is identical on Intel cpu, tzcnt is faster than bsf on AMD cpu.
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*/
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static __forceinline int __builtin_ctz(unsigned int value) {
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Assert(value != 0, "Invalid input value: 0");
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# if defined(X86_FEATURES) && !(_MSC_VER < 1700)
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return (int)_tzcnt_u32(value);
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# else
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unsigned long trailing_zero;
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_BitScanForward(&trailing_zero, value);
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return (int)trailing_zero;
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# endif
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}
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#define HAVE_BUILTIN_CTZ
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#ifdef _M_AMD64
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/* This is not a general purpose replacement for __builtin_ctzll. The function expects that value is != 0.
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* Because of that assumption trailing_zero is not initialized and the return value is not checked.
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*/
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static __forceinline int __builtin_ctzll(unsigned long long value) {
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Assert(value != 0, "Invalid input value: 0");
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# if defined(X86_FEATURES) && !(_MSC_VER < 1700)
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return (int)_tzcnt_u64(value);
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# else
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unsigned long trailing_zero;
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_BitScanForward64(&trailing_zero, value);
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return (int)trailing_zero;
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# endif
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}
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#define HAVE_BUILTIN_CTZLL
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#endif // Microsoft AMD64
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#endif // Microsoft AMD64/IA64/x86/ARM/ARM64 test
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#endif // _MSC_VER & !clang
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/* Unfortunately GCC didn't support these things until version 10.
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* Similarly, AppleClang didn't support them in Xcode 9.2 but did in 9.3.
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*/
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#ifdef __AVX2__
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#include <immintrin.h>
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#if (!defined(__clang__) && defined(__GNUC__) && __GNUC__ < 10) \
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|| (defined(__apple_build_version__) && __apple_build_version__ < 9020039)
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static inline __m256i _mm256_zextsi128_si256(__m128i a) {
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__m128i r;
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__asm__ volatile ("vmovdqa %1,%0" : "=x" (r) : "x" (a));
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return _mm256_castsi128_si256(r);
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}
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#ifdef __AVX512F__
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static inline __m512i _mm512_zextsi128_si512(__m128i a) {
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__m128i r;
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__asm__ volatile ("vmovdqa %1,%0" : "=x" (r) : "x" (a));
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return _mm512_castsi128_si512(r);
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}
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#endif // __AVX512F__
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#endif // gcc/AppleClang version test
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#endif // __AVX2__
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/* Missing zero-extension AVX and AVX512 intrinsics.
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* Fixed in Microsoft Visual Studio 2017 version 15.7
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* https://developercommunity.visualstudio.com/t/missing-zero-extension-avx-and-avx512-intrinsics/175737
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*/
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#if defined(_MSC_VER) && _MSC_VER < 1914
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#ifdef __AVX2__
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static inline __m256i _mm256_zextsi128_si256(__m128i a) {
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return _mm256_inserti128_si256(_mm256_setzero_si256(), a, 0);
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}
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#endif // __AVX2__
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#ifdef __AVX512F__
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static inline __m512i _mm512_zextsi128_si512(__m128i a) {
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return _mm512_inserti32x4(_mm512_setzero_si512(), a, 0);
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}
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#endif // __AVX512F__
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#endif // defined(_MSC_VER) && _MSC_VER < 1914
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#endif // include guard FALLBACK_BUILTINS_H
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