intrinsics

Here's the code I'm trying to convert to SSE2: double *pA = a; double *pB = b[voiceIndex]; double *pC = c[voiceIndex]; double *left = audioLeft; double *right = audioRight; double phase = 0.0; double bp0 = mNoteFrequency * mHostPitch; for (int sampleIndex = 0; sampleIndex < blockSize; sampleIndex++) { // some other code (that will use phase) phase += std::clamp(mRadiansPerSample * (bp0 * pB[sampleIndex] + pC[sampleIndex]), 0.0, PI); while (phase >= TWOPI) { phase -= TWOPI; } } Here's what I've achieved: double *pA = a; double *pB = b[voiceIndex]; double *pC = c[voiceIndex]; double *left =

I understand that operations across SIMD lanes should generally be avoided. However, sometimes it has to be done. I am using AVX2 intrinsics, and have 8 floating point values in an __m256. I want to know the lowest value in this vector, and to complicate matters: also in which slot this was. My current solution makes a round trip to memory, which I don't like: float closestvals[8]; _mm256_store_ps( closestvals, closest8 ); float closest = closestvals[0]; int closestidx = 0; for ( int k=1; k<8; ++k ) { if ( closestvals[k] < closest ) { closest = closestvals[ k ]; closestidx = k; } } What would

The title is in lack of a better name, and I am not sure I managed to explain myself clearly enough. I am looking for a way to access a "data type" via an index, but not force the compiler to keep it in an array. The problem occurs in writing a low-level code based on SSE/AVX intrinsics. For ease of programming I would like to write code as the following, with fixed-length loops over "registers" (data type __m512 ): inline void load(__m512 *vector, const float *in) { for(int i=0; i<24; i++) vector[i] = _mm512_load_ps((in + i*SIMD_WIDTH)); } // similarely: inline add(...) and inline store(...)

How do I find max element in array of 8 bytes, 8 shorts or 8 ints? I may need just the position of the max element, value of the max element, or both of them. For example : unsigned FindMax8(const uint32_t src[8]) // returns position of max element { unsigned ret = 0; for (unsigned i=0; i<8; ++i) { if (src[i] > src[ret]) ret = i; } return ret; } At -O2 clang unrolls the loop but it does not use neon, which should give decent perf boost (because it eliminates many data dependent branches?) For 8 bytes and 8 shorts approach should be simpler as entire array can be loaded into a single q-register

I'm working on some code that uses the LLVM C API. How do I use intrinsics, such as llvm.cos.f64 or llvm.sadd.with.overflow.i32 ? Whenever I try to do it by generating a global with LLVMAddGlobal (with the correct type signature), I just get this error message during the JIT linking stage: LLVM ERROR: Could not resolve external global address: llvm.cos.f64 I'm not using the LLVM C++ interface , so the advice in LLVM insert intrinsic function Cos does not seem to apply. I presume I need something like Intrinsic::getDeclaration , but I can't seem to find it. Am I missing something obvious? No

Im making some intrinsic optimized matrix-wrapper in java(with help of JNI). Needing affirmation of this, can you give some hints about matrix optimizations? What Im going to implement is: Matrix can be represented as four set of buffers/arrays, one for horizontal accessing, one for vertical accessing, one for diagonal access and a command buffer to compute elements of matrix only when needed. Here is an illustration. Matrix signature: 0 1 2 3 4 5 6 7 8 9 1 3 3 5 2 9 First(hroizontal) set: horSet[0]={0,1,2,3} horSet[1]={4,5,6,7} horSet[2]={8,9,1,3} horSet[3]={3,5,2,9} Second(vertical) set:

I can see various built-in functions (like __builtin_popount, __builtin_clz, etc) in the Xcode auto-completion pop-up. I'm not sure where these are getting picked up from though. Command clicking doesn't lead to a swift definition or any documentation. Are any __builtin_* or equivalent intrinsic functions available in Swift 3 and if so, what modules do I need to include and how can I call them? 来源： https://stackoverflow.com/questions/41353482/are-built-in-intrinsic-functions-available-in-swift-3

Suppose we have an std::vector , or any other sequence container (sometimes it will be a deque), which store uint64_t elements. Now, let's see this vector as a sequence of size() * 64 contiguous bits. I need to find the word formed by the bits in a given [begin, end) range, given that end - begin <= 64 so it fits in a word. The solution I have right now finds the two words whose parts will form the result, and separately masks and combines them. Since I need this to be as efficient as possible, I've tried to code everything without any if branch to not cause branch mispredictions, so for

I'm working on an SHA-256 implementation using Power8 built-ins . The performance is off a bit. I estimate it is off by about 2 cycles per byte (cpb). The C/C++ code to perform SHA on a block looks like so: // Schedule 64-byte message SHA256_SCHEDULE(W, data); uint32x4_p8 a = abcd, e = efgh; uint32x4_p8 b = VectorShiftLeft<4>(a); uint32x4_p8 f = VectorShiftLeft<4>(e); uint32x4_p8 c = VectorShiftLeft<4>(b); uint32x4_p8 g = VectorShiftLeft<4>(f); uint32x4_p8 d = VectorShiftLeft<4>(c); uint32x4_p8 h = VectorShiftLeft<4>(g); for (unsigned int i=0; i<64; i+=4) { const uint32x4_p8 k =