x86指令集架构详解：兼容性与现代软件应用

3星 · 超过75%的资源需积分: 11 186 浏览量更新于2024-09-15 收藏 123KB PDF 举报

本文档是关于Intel X86指令集架构（ISA）的详细介绍，适用于计算机体系结构II课程（CS232）。该文档的目的是让读者对x86架构有深入理解，以便能够编写简单的程序并能轻松阅读汇编代码。由于篇幅限制，重点放在了简化的解释上，忽略了ISA的大部分细节，以保持内容的易懂性。首先，x86指令集架构与RISC（ Reduced Instruction Set Computing，精简指令集计算）和CISC（Complex Instruction Set Computing，复杂指令集计算）概念相关。尽管这些术语在过去的营销策略中有些模糊不清，但x86确实比MIPS等RISC架构更为复杂。然而，这种复杂性在很大程度上源于历史的向后兼容性问题，这对现代编程者来说并不太重要，因为他们的主要关注点在于编写高效的代码。文档的核心内容包括以下几个方面： 1. **基本概念**：涵盖了CPU中的寄存器、数据类型以及内存管理。x86架构拥有多达几十个通用寄存器，如eax、ebx、ecx、edx等，每个都有特定的功能，用于存储数据和操作结果。同时，它支持多种数据类型，如字节（byte）、字（word）、双字（dword）等，这在处理不同大小的数据时至关重要。 2. **指令集设计**：x86的指令集包含数千条指令，每一条可能执行复杂的算术运算、逻辑运算、控制转移等功能。这既体现了CISC的特点，即通过单条指令完成多个操作，但也导致了指令长度和复杂性的增加。相比之下，RISC架构通常更倾向于简洁的指令，每个指令执行单一任务。 3. **汇编语言**：文档使用GNU工具链中的汇编语言和调试器，如gas（GCC的汇编器）和gdb，来教学。学习者通过这些工具理解和编写汇编代码，这对于理解底层硬件工作原理和优化性能至关重要。 4. **面向现代软件开发**：尽管x86的复杂性对新手而言可能显得有些挑战，但随着技术发展，许多复杂性已经通过高级编程语言和库函数进行了抽象。因此，即使面对这样的架构，现代软件开发者也能编写出高效且可维护的代码。本资源为读者提供了一个深入了解Intel X86指令集架构的基础，帮助他们掌握编写和理解该架构下的程序能力，这对于从事软件开发或研究计算机体系结构的人来说是一项宝贵的知识。

The x86 Instruction Set Architecture

CS232: Computer Architecture II

This set of notes provides an overview of the x86 instruction set architecture and its use in modern software. The goal

is to familiarize you with the ISA to the point that you can code simple programs and can read disassembled binary

code comfortably. Substantial portions of the ISA are ignored completely for the sake of simplicity. The notes use the

assembly notation used by the GNU tools, including the assembler as (used by the compiler gcc) and the debugger

gdb. Other tools may deﬁne other notations, but such things are merely cosmetic so long as you pay attention to what

you are using at the time.

The Basics: Registers, Data Types, and Memory

You may have heard or seen the term “Reduced Instruction Set Computing,” or RISC, and its counterpart, “Complex

Instruction Set Computing,” or CISC. While these terms were never entirely clear and have been further muddied by

years of marketing, the x86 ISA is certainly vastly more complex than that of MIPS. On the other hand, much of

the complexity has to do with backwards compatibility, which is mostly irrelevant to someone writing code today.

Furthermore, we need use only a limited subset of the ISA in this class.

Modern ﬂavors of x86—also called IA32, or Intel Architecture 32—have eight 32-bit integer registers. The registers

are not entirely general-purpose, meaning that some instructions limit your choice of register operands to fewer than

eight. A couple of other special-purpose 32-bit registers are also available—namely the instruction pointer (program

counter) and the ﬂags (condition codes), and we shall ignore the ﬂoating-point and multimedia registers. Unlike most

RISC machines, the registers have names stemming from their historical special purposes, as described below.

%eax accumulator (for adding, multiplying, etc.)

%ebx base (address of array in memory)

%ecx count (of loop iterations)

%edx data (e.g., second operand for binary operations)

%esi source index (for string copy or array access)

%edi destination index (for string copy or array access)

%ebp base pointer (base of current stack frame)

%esp stack pointer (top of stack)

%eip instruction pointer (program counter)

%eflags ﬂags (condition codes and other things)

high

AH AL

EAX

8 016 15 7

8−bit

low

EAX

EBX

ECX

EDX

ESI

EDI

EBP

ESP

32−bit

16−bit

The character “%” is used to denote a register in assembly code and is not considered a part of the register name itself;

note also that register names are not case sensitive. The letter “E” in each name indicates that the “extended” version

of the register is desired (extended from 16 bits). Registers can also be used to store 16- and 8-bit values, which is

useful when writing smaller values to memory or I/O ports. As shown to the right above, the low 16 bits of a register

are accessed by dropping the “E” from the register name, e.g., %si. Finally, the two 8-bit halves of the low 16 bits of

the ﬁrst four registers can be used as 8-bit registers by replacing “X” with “H” (high) or “L” (low).

The x86 ISA supports both 2’s complement and unsigned integers in widths of 32, 16, and 8 bits, single and double-

precision IEEE ﬂoating-point, 80-bit Intel ﬂoating-point, ASCII strings, and binary-coded decimal (BCD). Most in-

structions are independent of data type, but some require that you select the proper instruction for the data types of the

operands. Try multiplying 32-bit representations of -1 and 1 to produce a 64-bit result, for example.

Use of memory is more ﬂexible in x86 than in MIPS: in addition to load and store operations, many x86 operations

accept memory locations as operands. For example, a single instruction serves to read the value in a memory location,

add a constant, and store the sum back to the memory location. With x86, memory is 8-bit (byte) addressable and uses

32-bit addresses, although few machines today fully populate this 4 GB address space.

One aspect of x86’s treatment of memory may confuse you: it is little endian. Little endian means that if you store a

32-bit register into memory and then look at the four bytes of memory one by one, you will ﬁnd the little end of the

32 bits ﬁrst, followed by the next eight bits, then the next, and ﬁnally the high eight bits of the stored value. Thus

0x12345678 becomes 0x78, 0x56, 0x34, 0x12 in consecutive memory locations. Obviously, values read from memory

下载后可阅读完整内容，剩余7页未读，立即下载

chinaldzs

粉丝: 0
资源: 2

x86指令集架构详解：兼容性与现代软件应用

Armv8-A Instruction Set Architecture.pdf

Intel Architecture Software Developer's Manual+Intel Fortran Libraries Reference

Instruction Set Reference_intel 64

intel x86 instruction set manual

xtensa instruction set architecture

Describe the execution of the JMP instruction if R3 contains x369C (refer to Example 4.5). (6 points)

show me detail performance data for 64bit multiply instruction, and 32bit multiply instruction on cortex-M0 thumb instruction set.

Write the assembly language program using the following instruction a) Set on less than instruction b) Set on less than immediate instruction c) Branch equal

7. Write the assembly language program using the following instruction a) Set on less than instruction b) Set on less than immediate instruction c) Branch equal PRINCIPLES OF COMPUTER ORGANISATION d) Branch if not equal

最新资源