vector-processing | 易学教程

Fastest way to do horizontal vector sum with AVX instructions [duplicate]

阅读更多关于 Fastest way to do horizontal vector sum with AVX instructions [duplicate]

问题 This question already has answers here : Get sum of values stored in __m256d with SSE/AVX (2 answers) Closed 11 months ago . I have a packed vector of four 64-bit floating-point values. I would like to get the sum of the vector's elements. With SSE (and using 32-bit floats) I could just do the following: v_sum = _mm_hadd_ps(v_sum, v_sum); v_sum = _mm_hadd_ps(v_sum, v_sum); Unfortunately, even though AVX features a _mm256_hadd_pd instruction, it differs in the result from the SSE version. I

What compilers besides gcc can vectorize code?

阅读更多关于 What compilers besides gcc can vectorize code?

问题 GCC can vectorize loops automatically when certain options are specified and given the right conditions. Are there other compilers widely available that can do the same? 回答1: ICC 回答2: llvm can also do it and vector pascal too and one that is not free VectorC. These are just some I remember. 回答3: Also PGI's compilers. 回答4: The Mono project, the Open Source alternative to Microsoft's Silverlight project, has added objects that use SIMD instructions. While not a compiler, the Mono CLR is the

How to find the horizontal maximum in a 256-bit AVX vector

阅读更多关于 How to find the horizontal maximum in a 256-bit AVX vector

I have a __m256d vector packed with four 64-bit floating-point values. I need to find the horizontal maximum of the vector's elements and store the result in a double-precision scalar value; My attempts all ended up using a lot of shuffling of the vector elements, making the code not very elegant nor efficient. Also, I found it impossible to stay only in the AVX domain. At some point I had to use SSE 128-bit instructions to extract the final 64-bit value. However, I would like to be proved wrong on this last statement. So the ideal solution will: 1) only use only AVX instructions. 2) minimize

How to vectorize with gcc?

阅读更多关于 How to vectorize with gcc?

The v4 series of the gcc compiler can automatically vectorize loops using the SIMD processor on some modern CPUs, such as the AMD Athlon or Intel Pentium/Core chips. How is this done? casualcoder The original page offers details on getting gcc to automatically vectorize loops, including a few examples: http://gcc.gnu.org/projects/tree-ssa/vectorization.html While the examples are great, it turns out the syntax for calling those options with latest GCC seems to have changed a bit, see now: https://gcc.gnu.org/onlinedocs/gcc/Developer-Options.html#index-fopt-info In summary, the following

How to find the horizontal maximum in a 256-bit AVX vector

阅读更多关于 How to find the horizontal maximum in a 256-bit AVX vector

问题 I have a __m256d vector packed with four 64-bit floating-point values. I need to find the horizontal maximum of the vector's elements and store the result in a double-precision scalar value; My attempts all ended up using a lot of shuffling of the vector elements, making the code not very elegant nor efficient. Also, I found it impossible to stay only in the AVX domain. At some point I had to use SSE 128-bit instructions to extract the final 64-bit value. However, I would like to be proved

How to vectorize with gcc?

阅读更多关于 How to vectorize with gcc?

问题 The v4 series of the gcc compiler can automatically vectorize loops using the SIMD processor on some modern CPUs, such as the AMD Athlon or Intel Pentium/Core chips. How is this done? 回答1: The original page offers details on getting gcc to automatically vectorize loops, including a few examples: http://gcc.gnu.org/projects/tree-ssa/vectorization.html While the examples are great, it turns out the syntax for calling those options with latest GCC seems to have changed a bit, see now: https:/