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AMD64 (also variously referred to by AMD in their literature and documentation as “AMD 64-bit Technology” and “AMD x86-64 Architecture”) was created as an alternative to the radically different IA-64 architecture designed by Intel and Hewlett-Packard, which was backward-incompatible with IA-32, the 32-bit version of the x86 architecture.
The term 64-bit also describes a generation of computers in which 64-bit processors are the norm. 64 bits is a word size that defines certain classes of computer architecture, buses, memory, and CPUs and, by extension, the software that runs on them. 64-bit CPUs have been used in supercomputers since the 1970s (Cray-1, 1975) and in reduced ...
PUSHFQ/POPFQ (introduced with the x86-64 architecture) transfer the 64-bit quadword register RFLAGS. In 64-bit mode, PUSHF/POPF and PUSHFQ/POPFQ are available but PUSHFD/POPFD are not. [8]: 4–349, 4–432 The lower 8 bits of the FLAGS register is also open to direct load/store manipulation by SAHF and LAHF (load/store AH into flags).
Released in 2011, the ARMv8-A architecture added support for a 64-bit address space and 64-bit arithmetic with its new 32-bit fixed-length instruction set. [13] Arm Holdings has also released a series of additional instruction sets for different rules; the "Thumb" extension adds both 32- and 16-bit instructions for improved code density , while ...
The instructions constituting a program are rarely specified using their internal, numeric form (machine code); they may be specified by programmers using an assembly language or, more commonly, may be generated from high-level programming languages by compilers. [17]
Below is the full 8086/8088 instruction set of Intel (81 instructions total). [2] 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.
LLVM targets many platforms, however its main focus is not machine-dependent code generation; instead a more high-level typed assembly-like intermediate representation is used. Nevertheless for the most common targets the LLVM MC (machine code) project provides an assembler both as an integrated component of the compilers and as an external tool.
An instruction set architecture (ISA) is an abstract model of a computer, also referred to as computer architecture.A realization of an ISA is called an implementation.An ISA permits multiple implementations that may vary in performance, physical size, and monetary cost (among other things); because the ISA serves as the interface between software and hardware.