精华内容
下载资源
问答
  • ARMv8 NEON寄存器

    2019-11-27 21:42:20
    ARMv8 NEON寄存器 在看OPENBLAS源码时,看了它的kernel汇编代码,在代码中出现了一个寄存器的表达形式:V0.4S,而且只有对其的使用,没有对其的赋值,在此之前只有对Q寄存器的赋值,怀疑这两个寄存器结构应该有包含...

    ARMv8 NEON寄存器

    在看OPENBLAS源码时,看了它的kernel汇编代码,在代码中出现了一个寄存器的表达形式:V0.4S,而且只有对其的使用,没有对其的赋值,在此之前只有对Q寄存器的赋值,怀疑这两个寄存器结构应该有包含关系。
    找了一些资料,才发现这个叫做NEON寄存器,且对于ARMv7和ARMv8两种有不同的形式。

    具体参考:
    https://blog.csdn.net/SoaringLee_fighting/article/details/82800919

    也可以直接查看ARM的manual:
    https://developer.arm.com/docs/den0024/latest/armv8-registers/neon-and-floating-point-registers/floating-point-register-organization-in-aarch64

    Name Shape
    Vn.8B 8 lanes, each containing an 8-bit element
    Vn.16B 16 lanes, each containing an 8-bit element
    Vn.4H 4 lanes, each containing a 16-bit element
    Vn.8H 8 lanes, each containing a 16-bit element
    Vn.2S 2 lanes, each containing a 32-bit element
    Vn.4S 4 lanes, each containing a 32-bit element
    Vn.1D 1 lane containing a 64-bit element
    Vn.2D 2 lanes, each containing a 64-bit element

    Q寄存器 V寄存器结构

    展开全文
  • AARCH64 ARMV8 NEON的变动

    2019-09-14 15:53:56
    32个NEON的v寄存器,全长都是128bits,从以前的16个翻了一番。因此,之前的4×32=2×64=128的组合不适用了。它们都是单独存在的。例如S0 S1的S1就不再是D0的一半了。 Unaligned addresses are permitted for ...



    • Access to a larger general-purpose register file with 31 unbanked registers (0-30), with each register extended to 64 bits.

      31个通用寄存器,外加一个r31作为zero register。

    • Floating point and Advanced SIMD processing share a register file, in a similar manner to AArch32, but extended to thirty-two 128-bit registers. Smaller registers are no longer packed into larger registers, but are mapped one-to-one to the low-order bits of the 128-bit register

      32个NEON的v寄存器,全长都是128bits,从以前的16个翻了一番。因此,之前的4×32=2×64=128的组合不适用了。它们都是单独存在的。例如S0 S1的S1就不再是D0的一半了。

    • Unaligned addresses are permitted for most loads and stores, including paired register accesses, floating point and SIMD registers, with the exception of exclusive and ordered accesses

      引入对成对的寄存器的非对齐访问

    • There are no multiple register LDM, STM, PUSH and POP instructions, but load-store of a non-contiguous pair of registers is available.

    • The A64 instruction set does not include the concept of predicated or conditional execution. Benchmarking shows that modern branch predictors work well enough that predicated execution of instructions does not offer sufficient benefit to justify its significant use of opcode space, and its implementation cost in advanced implementations.

      由于分支预测器已经足够好,不会再有分支预测或者条件执行指令了。很奇怪,条件分支跳转指令不是依然有吗?这里不太理解。

    • The first eight registers, r0-r7, are used to pass argument values into a subroutine and to return result values from a function. They may also be used to hold intermediate values within a routine (but, in general, only between subroutine calls)

      通用寄存器传参由以前的4个增加到7个。

    • The first eight registers, v0-v7, are used to pass argument values into a subroutine and to return result values from a function. They may also be used to hold intermediate values within a routine (but, in general, only between subroutine calls).

      向量寄存器传参也有7个了。
      Registers v8-v15 must be preserved by a callee across subroutine calls; the remaining registers (v0-v7, v16-v31) do not need to be preserved (or should be preserved by the caller). Additionally, only the bottom 64-bits of each value stored in v8-v15 need to be preserved; it is the responsibility of the caller to preserve larger values.

      v8-v15在子函数调用时必须要保留,但是只保留低64bits。

    • Floating point support is similar to AArch32 VFP but with some extensions.


    offical标准文档

    【1】:Procedure Call Standard for the ARM 64-bit Architecture http://infocenter.arm.com/help/topic/com.arm.doc.ihi0055b/IHI0055B_aapcs64.pdf

    如果你需要port汇编程序,可以参考一下这个

    【2】:http://www.slideshare.net/linaroorg/lce13-gwggfxonarmv8



    转载于:https://my.oschina.net/rinehart/blog/354523

    展开全文
  • Introducing Neon for Armv8-A

    2021-01-03 23:04:04
    Introducing Neon for Armv8-A 1. Overview 2. Before you begin 3. Data processing methodologies 4. Fundamentals of Armv8 Neon technology 5. Check your knowledge 6. Related information 7. Next steps ...

    Introducing Neon for Armv8-A

    1. Overview

    2. Before you begin

    3. Data processing methodologies

    4. Fundamentals of Armv8 Neon technology

    Armv8-A includes both 32-bit and 64-bit Execution states, each with their own instruction sets:
    Armv8-A 包括 32-bit and 64-bit 执行状态,每个状态都有自己的指令集:

    • AArch64 is the name used to describe the 64-bit Execution state of the Armv8-A architecture.
      In AArch64 state, the processor executes the A64 instruction set, which contains Neon instructions (also referred to as SIMD instructions). GNU and Linux documentation sometimes refers to AArch64 as ARM64.
    • AArch32 describes the 32-bit Execution state of the Armv8-A architecture, which is almost identical to Armv7.
      In AArch32 state, the processor can execute either the A32 (called ARM in earlier versions of the architecture) or the T32 (Thumb) instruction set. The A32 and T32 instruction sets are backwards compatible with Armv7, including Neon instructions.

    This guide will focus on Neon programming using A64 instructions for the AArch64 Execution state of the Armv8-A architecture.
    本指南将重点介绍针对 Armv8-A 架构的 AArch64 执行状态使用 A64 指令进行 Neon 编程。

    If you want to write Neon code to run in the AArch32 Execution state of the Armv8-A architecture, you should refer to version 1.0 of the Neon Programmer's Guide.
    如果要编写 Neon 代码以在 Armv8-A 架构的 AArch32 执行状态下运行,则应参考 Neon Programmer’s Guide 的 1.0 版。

    5. Check your knowledge

    6. Related information

    7. Next steps

    single page - multiple pages
    

    References

    Introducing Neon for Armv8-A - single page
    https://developer.arm.com/architectures/instruction-sets/simd-isas/neon/neon-programmers-guide-for-armv8-a/introducing-neon-for-armv8-a/single-page

    展开全文
  • ARMv8 浮点及NEON指令集

    千次阅读 2019-10-23 15:26:51
    通常,每个NEON指令都会导致n个指令并行执行! 向量寄存器 32个128位寄存器 32个64位寄存器 所有的寄存器都可以在任意时间被访问,且访问者不需要显式地在两种表示之间切换,指令会说明是使用64位还是128位寄存器...

    在这里插入图片描述
    通常,每个NEON指令都会导致n个指令并行执行!

    向量寄存器

    32个128位寄存器
    在这里插入图片描述
    32个64位寄存器
    在这里插入图片描述
    所有的寄存器都可以在任意时间被访问,且访问者不需要显式地在两种表示之间切换,指令会说明是使用64位还是128位寄存器形式。

    浮点寄存器

    在这里插入图片描述

    标量与NEON

    标量就相当于是向量中的某一个lane,通过index获取。
    在这里插入图片描述
    在这里插入图片描述
    MOV V0.B[3], W0
    只会把w0的第一个字节拷到v0寄存器的第四个lane:
    在这里插入图片描述
    乘法指令只允许16-bit和32-bit标量,而且只能使用前128个标量。即16-bit只能使用0~15号寄存器,32-bit可以使用所有寄存器(因为32个32位刚好是128个)
    在这里插入图片描述

    浮点参数

    在这里插入图片描述
    在这里插入图片描述

    AArch64 NEON指令形式

    主要是通过和ARMv7 NEON对比来说明ARMv8 NEON的形式

    V前缀被移除

    ARMv8 NEON指令具有完全统一的形式,不管是整数、浮点数还是向量。具体执行操作也是完全根据每个指令的不同和不同。
    在这里插入图片描述
    第一个是32位整数的加法指令;第二个是64位整数加法;第三个是浮点标量加法;最后是向量加法指令。

    S U F P 四个前缀可以被添加用来说明是有符号、无符号、浮点数、多项式中的某一种数据类型

    SADD x0, x0, x1
    UADD x0, x0, x1
    FADD D0, D0, D1
    PADD v0.16B, v0.16B, v1.16B
    

    向量的组织(元素size和数量)都是用向量寄存器的描述来区分的

    ADD Vd.T, Vn.T, Vm.T
    其中Vd Vn Vm都是寄存器的名字,T是寄存器的组织形式,可以是8B,16B,8H,4H,4S,2S,2D,D等。

    如果是要对2个double进行向量加法:
    ADD V0.2D, V0.2D, V1.2D

    正常、长、宽、窄、饱和指令

    • Normal指令,对相同类型的数据进行操作,返回结果的数据类型与源类型相同

    • 长指令,使用L作为后缀,结果数据的位数是源数据位数的两倍
      SADDL V0.4S, V1.4H, V2.4H
      [外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-7cG65WCq-1571815608835)(evernotecid://5DED79A6-B252-4516-B4D6-B8E679192EB1/appyinxiangcom/22266324/ENResource/p543)]

    • Wide宽指令,对一个双字数据和一个单字数据进行操作,结果将都是双字数据,使用W作为后缀
      SADDW V0.4S, V1.4H, V2.4S
      [外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-XUoGLF9X-1571815608835)(evernotecid://5DED79A6-B252-4516-B4D6-B8E679192EB1/appyinxiangcom/22266324/ENResource/p544)]

    • Narrow指令,操作两个四字向量,得到双字向量,结果数据是源数据的一半长,使用N作为后缀
      SUBHN V0.4H, V1.4S, V2.4S
      在这里插入图片描述

    • 有符号和无符号的饱和运算(SQ 和 UQ),比如加法 SQADD 和 UQADD分别表示有符号饱和加以及无符号饱和加,如果结构数据超过了最大最小界限,饱和运算会使得结果不过超过最大或最小
      SQADD V0.16B, V0.16B, V1.16B
      在这里插入图片描述

    后缀P,表示分对操作

    比如ADDP V0.4S, V1.4S, V2.4S
    在这里插入图片描述

    后缀V,表示跨所有lane的操作

    比如 ADDV S0, V1.4S
    在这里插入图片描述

    后缀2,表示对高位的那一半进行操作,可以用在Wide Narrow Lengthing等指令后

    • 宽指令
      在这里插入图片描述
    • narrow 指令
      在这里插入图片描述
    • Lengthing 指令
      在这里插入图片描述
    展开全文
  • Armv8 Android compile error

    2020-11-28 04:37:59
    <div><p>When I compile Armv...It seems that Armv8 neon only define float32x4_t and float32x2_t. <p>Does anyone know how to fix this? Thanks.</p><p>该提问来源于开源项目:Maratyszcza/NNPACK</p></div>
  • <div><p>MWE: <pre><code>rust #![feature(stdsimd,target_feature)] extern crate stdsimd;...armv7-unknown-linux-gnueabihf</code>.</p><p>该提问来源于开源项目:rust-lang/stdarch</p></div>
  • Armv8上不弃不离的NEON/FPU

    千次阅读 2019-01-28 15:11:25
    熟悉arm processor的朋友应该知道arm的Cortex-A是带有FPU和NEON的,FPU用来做浮点数运算的,而NEON是SIMD指令做并行运算的。在现有Cortex-A的设计里,NEON和FPU是不可分的,也就是不能单独只有NEON或是FPU。在比较高...
  • void xnet_f32_igemm_ukernel_4x8__neon_lane_ld128( size_t mr, size_t nc, size_t kc, size_t ks, const float** a, const float* w, float* c, size_t cm_stride, size_t cn_stride, size_t a_offset, ...
  • 与浮点计算一样,依旧是4x8的分块,为防止饱和将uint8塞进int16进行计算,这样一个寄存器装载8个数,本篇主要关注指令集。 指令集总结: vld1_dup_u8(const uint8_t*):广播broadcast uint8_t到8x8 vld1_u8(const...
  • Neon 指令集 ARMv7/v8 对比

    千次阅读 2016-03-10 15:49:52
    原文:http://community.arm.com/groups/android-community/blog/2015/03/27/arm-neon-programming-quick-reference ...ARM NEON programming quick reference 1 Introduction This article aims to intr
  • <p>The issue that I am having with xmrig-amd starts after 87%, The error is related to the SSE2NEON.h file and calls to stdinth. The images below give more detail on what is happening during the ...
  • <div><p>On a ODROID-XU4 ARM v7l machine, using the VOLK <code>neon_hardfp_orc</code> machine profile, I'm getting SIGBUS exceptions with certain neonasm kernels. These seem to be occurring because...
  • <div><p>I am cross-compiling a program on Ubuntu 18.04 x86_64 that uses ArmNN to ... Can ArmNN provide speedups with NEON acceleration only?</p><p>该提问来源于开源项目:ARM-software/armnn</p></div>
  • <ul><li>ARMv4 (<code>armv4t, 3-stage pipeline, Thumb, ARMv4 first to drop legacy ARM 26-bit addressing),</li><li>ARMv5 (<code>armv5te, Thumb, enhanced DSP instructions, caches), and</li><li>ARMv8 ...
  • NEON_4

    2020-03-13 10:49:05
    Armv8 Neon技术的基本原理 Armv8-A包括32位和64位执行状态,每种状态都有自己的指令集: AArch64是用于描述Armv8-A体系结构的64位执行状态的名称。 在AArch64状态下,处理器执行A64指令集,其中包含Neon指令(也...
  • ARMV8 kernels added

    2020-12-08 20:21:20
    s work (https://github.com/gnuradio/volk/commit/e98e9277409cd658f1a5b65ffaa0caab842bebce) support for ARMV8 kernels is available: - <code>volk_32u_reverse_32u</code> and <code>volk_64u_byteswappuppet_...
  • Add ARMv8-A AES support

    2021-01-12 01:24:09
    ARMv8 can be further improved with better use of NEON. <p>Also tweak ARMv7 multiplier <p>Someone please test ARMv7 with asm before merging this, thanks.</p><p>该提问来源于开源项目:monero-...
  • /usr/lib/gcc/armv7l-unknown-linux-gnueabihf/6.1.1/include/arm_neon.h:6169:1: error: inlining failed in call to always_inline 'vcombine_f32': target specific option mismatch vcombine_f32 ...
  • 如何编写ARM64 NEON之二

    千次阅读 2014-12-07 21:47:15
    花了大半个月的时间重写小波变换的NEON汇编,由于是在ARM32位NEON(ARMV7 NEON)的基础上,重写并且优化ARM64(ARMV8 NEON),由于种种原因,遇到很多困难,这里把一些遇到的问题记录下来: (1 )ARMV8指令集取消了在...
  • <p>NB ARMv8 has the FPU and NEON SIMD 'always on' which is why -mfpu and -mfloat options cease compilation</p><p>该提问来源于开源项目:monero-project/monero</p></div>
  • <div><p>I'...<p>When we searched online how to compile for the Raspberry Pi 3, people suggested to use <code>armv8</code>.</p><p>该提问来源于开源项目:agherzan/meta-raspberrypi</p></div>
  • Hardware verification engineers often run bare-metal tests to verify core-related function in a System on Chip (SoC). However, it can be challenging to ... They also apply to other ARMv8-A processors.
  • return (uint8x16_t)__builtin_neon_vld1v16qi ((const __builtin_neon_qi *) __a); 5900: f96e 0a0f vld1.8 {d16-d17}, [lr] } static inline void loadchunk(uint8_t const *s, chunk_t *chunk) { *chunk =...
  • <ul><li>ComputeLibrary: Latest version (v18.11)</li><li>Host OS: Ubuntu 18.04 on Intel i7</li><li>Compiler: armv8l-linux-gnueabihf-g++ downloaded from ...
  • <div><p>Compiling master branch fails on my armv8 machine running debian stretch. It seems to be a problem with volk, however compiling volk standalone works on the same system. <pre><code> [ 1%] ...
  • <p>the result show that running using OpenCL is much slower than NEON. about 10times slower. <p>is that right? <p>thanks.</p><p>该提问来源于开源项目:ARM-software/ComputeLibrary</p></div>
  • model name : ARMv8 Processor rev 2 (v8l) BogoMIPS : 100.00 Features : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt lpae evtstrm aes pmull sha1 sha2 crc32 CPU implementer : 0x41 CPU ...
  • module (which should only be compiled for x86) is being built (and failing).</li><li>I also wonder if other ARM specific optimizations and choices are not being set up correctly (like using NEON)</li>...

空空如也

空空如也

1 2 3 4 5 ... 20
收藏数 471
精华内容 188
关键字:

armv8neon