intrinsics

What is meant by “fixing up” floats?

由 自闭症网瘾萝莉.ら 提交于 2019-12-01 04:43:27
I was looking through the instruction set in AVX-512 and noticed a set of fixup instructions. Some examples : _mm512_fixupimm_pd, _mm512_mask_fixupimm_pd, _mm512_maskz_fixupimm_pd _mm512_fixupimm_round_pd, _mm512_mask_fixupimm_round_pd, _mm512_maskz_fixupimm_round_pd What is meant here by "fixing up"? That's a great question. Intel's answer (my bold) is here: This instruction is specifically intended for use in fixing up the results of arithmetic calculations involving one source so that they match the spec, although it is generally useful for fixing up the results of multiple-instruction

Intel AVX intrinsics: any compatibility library out?

由 大憨熊 提交于 2019-12-01 04:11:12
Are there any Intel AVX intrinsics library out? I'm looking for something similar as 'sse2mmx.h' header which fall-backs to MMX intrinsics if SSE2 integer intrinsics are not available on compile time. Thus if I had similar library for AVX I could write optimized code for new hardware which would have almost optimal speed in case AVX extension isn't available. Googling didn't help much so far :( Intel provides a AVX emulation header . I haven't tried it, but quoting the linked article "The AVX emulation header file uses intrinsics for the prior Intel instruction set extensions up to Intel SSE4

Issue with __m256 type of intel intrinsics

由 独自空忆成欢 提交于 2019-12-01 04:06:42
问题 I'm trying to test some of the Intel Intrinsics to see how they work. So, i created a function to do that for me and this is the code: void test_intel_256() { __m256 res,vec1,vec2; __M256_MM_SET_PS(vec1, 7.0, 7.0, 7.0, 7.0, 7.0, 7.0, 7.0, 7.0); __M256_MM_SET_PS(vec1, 2.0, 2.0, 2.0, 2.0, 2.0, 2.0, 2.0, 2.0); __M256_MM_ADD_PS(res,vec1,vec2); if (res[0] ==9 && res[1] ==9 && res[2] ==9 && res[3] ==9 && res[4] ==9 && res[5] ==9 && res[6] ==9 && res[7] ==9 ) printf("Addition : OK!\n"); else printf(

Fallback implementation for conflict detection in AVX2

由 喜你入骨 提交于 2019-12-01 03:31:29
AVX512CD contains the intrinsic _mm512_conflict_epi32(__m512i a) it returns a vector where for every element in a a bit is set if it has the same value. Is there a way to do something similar in AVX2? I'm not interested in the extact bits I just need to know which elements are duplicates of the elements to their left (or right). I simply need to know if a scatter would conflict. Basically I need an AVX2 equivalent for __mm256i detect_conflict(__mm256i a) { __mm256i cd = _mm256_conflict_epi32(a); return _mm256_cmpgt_epi32(cd, _mm256_set1_epi32(0)); } The only way I could think of is to use

Intel AVX intrinsics: any compatibility library out?

由 对着背影说爱祢 提交于 2019-12-01 02:22:01
问题 Are there any Intel AVX intrinsics library out? I'm looking for something similar as 'sse2mmx.h' header which fall-backs to MMX intrinsics if SSE2 integer intrinsics are not available on compile time. Thus if I had similar library for AVX I could write optimized code for new hardware which would have almost optimal speed in case AVX extension isn't available. Googling didn't help much so far :( 回答1: Intel provides a AVX emulation header. I haven't tried it, but quoting the linked article "The

Fallback implementation for conflict detection in AVX2

由 你说的曾经没有我的故事 提交于 2019-11-30 23:20:04
问题 AVX512CD contains the intrinsic _mm512_conflict_epi32(__m512i a) it returns a vector where for every element in a a bit is set if it has the same value. Is there a way to do something similar in AVX2? I'm not interested in the extact bits I just need to know which elements are duplicates of the elements to their left (or right). I simply need to know if a scatter would conflict. Basically I need an AVX2 equivalent for __mm256i detect_conflict(__mm256i a) { __mm256i cd = _mm256_conflict_epi32

How to use NEON comparison (greater than or equal to) instruction?

由 不羁岁月 提交于 2019-11-30 22:26:32
How to use the NEON comparison instructions in general? Here is a case, I want to use, Greater-than-or-equal-to instruction? Currently I have a, int x; ... ... ... if(x >= 0) { .... } In NEON, I would like to use x in the same way, just that x this time is a vector. int32x4_t x; ... ... ... if(vcgeq_s32(x, vdupq_n_s32(0))) // Whats the best way to achieve this effect? { .... } With SIMD it's not straightforward to go from a single scalar if/then to a test on multiple elements. Usually you want to test if any element is greater than or if all elements are greater than, and there will usually be

How to use NEON comparison (greater than or equal to) instruction?

由 荒凉一梦 提交于 2019-11-30 18:02:23
问题 How to use the NEON comparison instructions in general? Here is a case, I want to use, Greater-than-or-equal-to instruction? Currently I have a, int x; ... ... ... if(x >= 0) { .... } In NEON, I would like to use x in the same way, just that x this time is a vector. int32x4_t x; ... ... ... if(vcgeq_s32(x, vdupq_n_s32(0))) // Whats the best way to achieve this effect? { .... } 回答1: With SIMD it's not straightforward to go from a single scalar if/then to a test on multiple elements. Usually

Horizontal add with __m512 (AVX512)

由 泪湿孤枕 提交于 2019-11-30 17:23:33
问题 How does one efficiently perform horizontal addition with floats in a 512-bit AVX register (ie add the items from a single vector together)? For 128 and 256 bit registers this can be done using _mm_hadd_ps and _mm256_hadd_ps but there is no _mm512_hadd_ps. The Intel intrinsics guide documents _mm512_reduce_add_ps. It doesn't actually correspond to a single instruction but its existence suggests there is an optimal method, but it doesn't appear to be defined in the header files that come with

Data type compatibility with NEON intrinsics

由 时光怂恿深爱的人放手 提交于 2019-11-30 15:54:33
问题 I am working on ARM optimizations using the NEON intrinsics, from C++ code. I understand and master most of the typing issues, but I am stuck on this one: The instruction vzip_u8 returns a uint8x8x2_t value (in fact an array of two uint8x8_t ). I want to assign the returned value to a plain uint16x8_t . I see no appropriate vreinterpretq intrinsic to achieve that, and simple casts are rejected. 回答1: Some definitions to answer clearly... NEON has 32 registers, 64-bits wide (dual view as 16
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