sse2

I need to shift a __m128i variable, (say v), by m bits, in such a way that bits move through all of the variable (So, the resulting variable represents v*2^m). What is the best way to do this?! Note that _mm_slli_epi64 shifts v0 and v1 seperately: r0 := v0 << count r1 := v1 << count so the last bits of v0 missed, but I want to move those bits to r1. Edit: I looking for a code, faster than this (m<64): r0 = v0 << m; r1 = v0 >> (64-m); r1 ^= v1 << m; r2 = v1 >> (64-m); For compile-time constant shift counts, you can get fairly good results. Otherwise not really. This is just an SSE

I have many function which use the same constant __m128i values. For example: const __m128i K8 = _mm_setr_epi8(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16); const __m128i K16 = _mm_setr_epi16(1, 2, 3, 4, 5, 6, 7, 8); const __m128i K32 = _mm_setr_epi32(1, 2, 3, 4); So I want to store all these constants in an one place. But there is a problem: I perform checking of existed CPU extension in run time. If the CPU doesn't support for example SSE (or AVX) than will be a program crash during constants initialization. So is it possible to initialize these constants without using of SSE?

Actually I have 2 questions: Is SSE2 Compatibility a CPU issue or Compiler issue? How to check if your CPU or Compiler support SSE2? I am using GCC Version: gcc (GCC) 4.5.1 When I tried to compile a code it give me this error: $ gcc -O3 -msse2 -fno-strict-aliasing -DHAVE_SSE2=1 -DMEXP=19937 -o test-sse2-M19937 test.c cc1: error: unrecognized command line option "-msse2" And cpuinfo showed this: processor : 0 vendor : GenuineIntel arch : IA-64 family : 32 model : 1 model name : Dual-Core Intel(R) Itanium(R) Processor 9140M revision : 1 archrev : 0 features : branchlong, 16-byte atomic ops cpu

I'm trying to break into SSE2 and tried the following example program : #include "stdafx.h" #include <emmintrin.h> int main(int argc, char* argv[]) { __declspec(align(16)) long mul; // multiply variable __declspec(align(16)) int t1[100000]; // temporary variable __declspec(align(16)) int t2[100000]; // temporary variable __m128i mul1, mul2; for (int j = 0; j < 100000; j++) { t1[j] = j; t2[j] = j+1; } // set temporary variables to random values _asm { mov eax, 0 label: movdqa xmm0, xmmword ptr [t1+eax] movdqa xmm1, xmmword ptr [t2+eax] pmuludq xmm0, xmm1 movdqa mul1, xmm0 movdqa xmm0, xmmword

A and B are vectors or length N, where N could be in the range 20 to 200 say. I want to calculate the square of the distance between these vectors, i.e. d^2 = ||A-B||^2. So far I have: float* a = ...; float* b = ...; float d2 = 0; for(int k = 0; k < N; ++k) { float d = a[k] - b[k]; d2 += d * d; } That seems to work fine, except that I have profiled my code and this is the bottleneck (more than 50% of time is spent just doing this). I am using Visual Studio 2012, on Win 7, with these optimization options: /O2 /Oi /Ot /Oy- . My understanding is that VS2012 should auto-vectorize that loop (using