我正在努力学习使用SSE,我正在制作的程序之一需要使用模数除法,因此我写了这样做(抱歉它被过度评价):
__m128i SSEModDiv(__m128i input, __m128i divisors) { //Error Checking (div by zero) /*__m128i zeros = _mm_set1_epi32(0); __m128i error = _mm_set1_epi32(-1); __m128i zerocheck = _mm_cmpeq_epi32(zeros, divisors); if (_mm_extract_epi16(zerocheck, 0) != 0) return error; if (_mm_extract_epi16(zerocheck, 2) != 0) return error; if (_mm_extract_epi16(zerocheck, 4) != 0) return error; if (_mm_extract_epi16(zerocheck, 6) != 0) return error;*/ //Now for the real work __m128 inputf = _mm_cvtepi32_ps(input); __m128 divisorsf = _mm_cvtepi32_ps(divisors); /*__m128 recip = _mm_rcp_ps(divisorsf); //Takes reciprocal __m128 divided = _mm_mul_ps(inputf, recip); //multiplies by reciprical values*/ __m128 divided = _mm_div_ps(inputf, divisorsf); __m128i intermediateint = _mm_cvttps_epi32(divided); //makes an integer version truncated __m128 intermediate = _mm_cvtepi32_ps(intermediateint); __m128 multiplied = _mm_mul_ps(intermediate, divisorsf); //multiplies the intermediate with the divisors __m128 mods = _mm_sub_ps(inputf, multiplied); //subtracts to get moduli return _mm_cvtps_epi32(mods); }
问题是,这与在释放时单独取四个32位整数的每个元素的模数一样快,在调试中大约慢10倍(通过分析找到).
任何人都可以给我任何关于如何更快地使这个功能的指针?
- 我不能使用SVML因为我正在使用Visual Studio-