sse

This is a simpler view of my Problem, I want to convert a float value into defined type v4si (I want to use SIMD Operation for optimization.) Please help to convert float/double value to a defined type. #include<stdio.h> typedef double v4si __attribute__ ((vector_size (16))); int main() { double stoptime=36000; float x =0.5*stoptime; float * temp = &x; v4si a = ((v4si)x); // Error: Incompatible data types v4si b; v4si *c; c = ((v4si*)&temp); // Copies address of temp, b = *(c); printf("%f\n" , b); // but printing (*c) crashes program } You don't need to define a custom SIMD vector type ( v4si

I try to work with SSE and i faced with some strange behaviour. I write simple code for comparing two strings with SSE Intrinsics, run it and it work. But later i understand, that in my code one of pointer still not aligned, but i use _mm_load_si128 instruction, which requires pointer aligned on a 16-byte boundary. //Compare two different, not overlapping piece of memory __attribute((target("avx"))) int is_equal(const void* src_1, const void* src_2, size_t size) { //Skip tail for right alignment of pointer [head_1] const char* head_1 = (const char*)src_1; const char* head_2 = (const char*)src

par2 has a small and fairly clean C++ codebase, which I think builds fine on GNU/Linux, OS X, and Windows (with MSVC++). I'd like to incorporate an x86-64 asm version of the one function that takes nearly all the CPU time. ( mailing list posts with more details . My implementation/benchmark here .) Intrinsics would be the obvious solution, but gcc doesn't generate good enough code for getting one byte at a time from a 64bit register for use as an index into a LUT. I might also take the time to schedule instructions so each uop cache line holds a multiple of 4 uops, since uop throughput is the

If I have an AVX register with 4 doubles in them and I want to store the reverse of this in another register, is it possible to do this with a single intrinsic command? For example: If I had 4 floats in a SSE register, I could use: _mm_shuffle_ps(A,A,_MM_SHUFFLE(0,1,2,3)); Can I do this using, maybe _mm256_permute2f128_pd() ? I don't think you can address each individual double using the above intrinsic. You actually need 2 permutes to do this: _mm256_permute2f128_pd() only permutes in 128-bit chunks. _mm256_permute_pd() does not permute across 128-bit boundaries. So you need to use both:

Let's say you have values in rax and rdx you want to load into an xmm register. One way would be: movq xmm0, rax pinsrq xmm0, rdx, 1 It's pretty slow though! Is there a better way? You're not going to do better for latency or uop count on recent Intel or AMD (I mostly looked at Agner Fog's tables for Ryzen / Skylake). movq+movq+punpcklqdq is also 3 uops, for the same port(s). On Intel / AMD, storing the GP registers to a temporary location and reloading them with a 16-byte read may be worth considering for throughput if surrounding code bottlenecks on the ALU port for integer->vector, which is

How many clock cycles does cost AVX/SSE exponentiation on modern x86_64 CPU? I am about: pow(x, y) = exp(y*log(x)) I.e. do both exp() and log() AVX x86_64 instructions require certain known number of cycles? exp(): _mm256_exp_ps() log(): _mm256_log_ps() Or the number of cycles may vary depending on the exponential degree, is there the maximum number of cycles can cost exponentiation? The x86 SIMD instruction set (i.e. not x87), at least up to AVX2, does not include SIMD exp , log , or pow with the exception of pow(x,0.5) which is the square root. There are SIMD math libraries however which are

As we know from from C11-memory_order: http://en.cppreference.com/w/c/atomic/memory_order And the same from C++11-std::memory_order: http://en.cppreference.com/w/cpp/atomic/memory_order On strongly-ordered systems ( x86 , SPARC, IBM mainframe), release-acquire ordering is automatic. No additional CPU instructions are issued for this synchronization mode , only certain compiler optimizations are affected (e.g. the compiler is prohibited from moving non-atomic stores past the atomic store-release or perform non-atomic loads earlier than the atomic load-acquire) But is this true for x86-SSE

I'm trying to get my code to auto vectorize, but it isn't working. int _tmain(int argc, _TCHAR* argv[]) { const int N = 4096; float x[N]; float y[N]; float sum = 0; //create random values for x and y for (int i = 0; i < N; i++) { x[i] = rand() >> 1; y[i] = rand() >> 1; } for (int i = 0; i < N; i++){ sum += x[i] * y[i]; } } Neither loop vectorizes here, but I'm really only interested in the second loop. I'm using visual studio express 2013 and am compiling with the /O2 and /Qvec-report:2 (To report whether or not the loop was vectorized) options. When I compile, I get the following message: ---

I was looking at the tutorials in DirectX SDK. Tutorial 5 works fine, but after I have copied and separated the code to my own classes, I got strange error during launching my application. The line is: g_World1 = XMMatrixIdentity(); Because of it, I got error in xnamathmatrix.int operator= which looks like that: XMFINLINE _XMMATRIX& _XMMATRIX::operator= ( CONST _XMMATRIX& M ) { r[0] = M.r[0]; r[1] = M.r[1]; r[2] = M.r[2]; r[3] = M.r[3]; return *this; } And the error message is: Access violation reading location 0xffffffff I have read somewhere that it could be caused by something connected to