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EVEX Prefix
The EVEX prefix (enhanced vector extension) and corresponding coding scheme is an extension to the 32-bit x86 (IA-32) and 64-bit x86-64 (AMD64) instruction set architecture. EVEX is based on, but should not be confused with the MVEX prefix used by the Knights Corner processor. The EVEX scheme is a 4-byte extension to the VEX scheme which supports the AVX-512 instruction set and allows addressing new 512-bit ZMM registers and new 64-bit operand mask registers. With Advanced Performance Extensions, the Extended EVEX prefix redefines the semantics of several payload bits. Features EVEX coding can address 8 operand mask registers, 16 general-purpose registers and 32 vector registers in 64-bit mode (otherwise, 8 general-purpose and 8 vector), and can support up to 4 operands. Like the VEX coding scheme, the EVEX prefix unifies existing opcode prefixes and escape codes, memory addressing and operand length modifiers of the x86 instruction set. The following features are carried over ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X86-64
x86-64 (also known as x64, x86_64, AMD64, and Intel 64) is a 64-bit extension of the x86 instruction set architecture, instruction set. It was announced in 1999 and first available in the AMD Opteron family in 2003. It introduces two new operating modes: 64-bit mode and compatibility mode, along with a new four-level paging mechanism. In 64-bit mode, x86-64 supports significantly larger amounts of virtual memory and physical memory compared to its 32-bit computing, 32-bit predecessors, allowing programs to utilize more memory for data storage. The architecture expands the number of general-purpose registers from 8 to 16, all fully general-purpose, and extends their width to 64 bits. Floating-point arithmetic is supported through mandatory SSE2 instructions in 64-bit mode. While the older x87 FPU and MMX registers are still available, they are generally superseded by a set of sixteen 128-bit Processor register, vector registers (XMM registers). Each of these vector registers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Instruction Set Architecture
In computer science, an instruction set architecture (ISA) is an abstract model that generally defines how software controls the CPU in a computer or a family of computers. A device or program that executes instructions described by that ISA, such as a central processing unit (CPU), is called an ''implementation'' of that ISA. In general, an ISA defines the supported instructions, data types, registers, the hardware support for managing main memory, fundamental features (such as the memory consistency, addressing modes, virtual memory), and the input/output model of implementations of the ISA. An ISA specifies the behavior of machine code running on implementations of that ISA in a fashion that does not depend on the characteristics of that implementation, providing binary compatibility between implementations. This enables multiple implementations of an ISA that differ in characteristics such as performance, physical size, and monetary cost (among other things), but t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xeon Phi
Xeon Phi is a discontinued series of x86 manycore processors designed and made by Intel. It was intended for use in supercomputers, servers, and high-end workstations. Its architecture allowed use of standard programming languages and application programming interfaces (APIs) such as OpenMP. Xeon Phi launched in 2010. Since it was originally based on an earlier GPU design ( codenamed "Larrabee") by Intel that was cancelled in 2009, it shared application areas with GPUs. The main difference between Xeon Phi and a GPGPU like Nvidia Tesla was that Xeon Phi, with an x86-compatible core, could, with less modification, run software that was originally targeted to a standard x86 CPU. Initially in the form of PCI Express-based add-on cards, a second-generation product, codenamed ''Knights Landing'', was announced in June 2013. These second-generation chips could be used as a standalone CPU, rather than just as an add-in card. In June 2013, the Tianhe-2 supercomputer at the National S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
VEX Prefix
The VEX prefix (from "vector extensions") and VEX coding scheme are an extension to the IA-32 and x86-64 instruction set architecture for microprocessors from Intel, AMD and others. Features The VEX coding scheme allows the definition of new instructions and the extension or modification of previously existing instruction codes. This serves the following purposes: * The opcode map is extended to make space for future instructions. * It allows instruction codes to have up to four operands (plus immediate), where the original scheme allows only two operands (plus immediate). * It allows the size of SIMD vector registers to be extended from the 128- bit XMM registers to the 256-bit YMM registers. There is room for further extensions of the register size. * It allows existing two-operand instructions to be modified into non-destructive three-operand forms where the destination register is different from both source registers. For example, instead of (where register ''a'' is change ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AVX-512
AVX-512 are 512-bit extensions to the 256-bit Advanced Vector Extensions SIMD instructions for x86 instruction set architecture (ISA) proposed by Intel in July 2013, and first implemented in the 2016 Intel Xeon Phi x200 (Knights Landing), and then later in a number of AMD and other Intel CPUs ( see list below). AVX-512 consists of multiple extensions that may be implemented independently. This policy is a departure from the historical requirement of implementing the entire instruction block. Only the core extension AVX-512F (AVX-512 Foundation) is required by all AVX-512 implementations. Besides widening most 256-bit instructions, the extensions introduce various new operations, such as new data conversions, scatter operations, and permutations. The number of AVX registers is increased from 16 to 32, and eight new "mask registers" are added, which allow for variable selection and blending of the results of instructions. In CPUs with the vector length (VL) extension—included in m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SIMD
Single instruction, multiple data (SIMD) is a type of parallel computer, parallel processing in Flynn's taxonomy. SIMD describes computers with multiple processing elements that perform the same operation on multiple data points simultaneously. SIMD can be internal (part of the hardware design) and it can be directly accessible through an instruction set architecture (ISA), but it should not be confused with an ISA. Such machines exploit Data parallelism, data level parallelism, but not Concurrent computing, concurrency: there are simultaneous (parallel) computations, but each unit performs exactly the same instruction at any given moment (just with different data). A simple example is to add many pairs of numbers together, all of the SIMD units are performing an addition, but each one has different pairs of values to add. SIMD is particularly applicable to common tasks such as adjusting the contrast in a digital image or adjusting the volume of digital audio. Most modern Cen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Byte
The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit of memory in many computer architectures. To disambiguate arbitrarily sized bytes from the common 8-bit definition, network protocol documents such as the Internet Protocol () refer to an 8-bit byte as an octet. Those bits in an octet are usually counted with numbering from 0 to 7 or 7 to 0 depending on the bit endianness. The size of the byte has historically been hardware-dependent and no definitive standards existed that mandated the size. Sizes from 1 to 48 bits have been used. The six-bit character code was an often-used implementation in early encoding systems, and computers using six-bit and nine-bit bytes were common in the 1960s. These systems often had memory words of 12, 18, 24, 30, 36, 48, or 60 bits, corresponding t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ModR/M
The ModR/M byte is an important part of instruction encoding for the x86 instruction set. Description Opcodes in x86 are generally one-byte, though two-byte instructions and prefixes exist. ModR/M is a byte that, if required, follows the opcode and specifies zero, one, or two operands for the instruction. The format is: The "reg" field, if specifying an operand, encodes the three least-significant bits of a register index. Which register (general purpose, AVX, etc.) depends on the instruction being executed.register mapping (with various columns depending on type)? --> Instructions which take only one operand typically do not use this field, but instead repurpose the bits as an "opcode extension", allowing eight instructions to share a single opcode byte. In opcode listings, these are specified by following the opcode with a slash () and a digit 0-7. For example, the opcode for byte increment is , while for byte decrement it is . The "mod" field specifies the addressing mode ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X86 Instructions
The x86 instruction set refers to the set of instructions that x86-compatible microprocessors support. The instructions are usually part of an executable program, often stored as a computer file and executed on the processor. The x86 instruction set has been extended several times, introducing wider registers and datatypes as well as new functionality. x86 integer instructions Below is the full 8086/ 8088 instruction set of Intel (81 instructions total). These instructions are also available in 32-bit mode, in which they operate on 32-bit registers (eax, ebx, etc.) and values instead of their 16-bit (ax, bx, etc.) counterparts. The updated instruction set is grouped according to architecture ( i186, i286, i386, i486, i586/ i686) and is referred to as (32-bit) x86 and (64-bit) x86-64 (also known as AMD64). Original 8086/8088 instructions This is the original instruction set. In the 'Notes' column, ''r'' means ''register'', ''m'' means ''memory address'' and ''imm'' mean ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
