AT&T GNU X86-64,I386 汇编语法简述

1

Purposeand Caveats

 

 

 

 

•       This guide should give you enough background to read andunderstand (most) of the 64bit x86 assembly that gcc is likely to produce.

 

•       x86 is apoorly-designed ISA. It’s a mess, but it is the most widely used ISA in theworld today.

 

•         Itbreaks almost every rule of good ISA design

•         Justbecause it is popular does not mean it’s good

•       Inteland AMD have managed to engineer (at considerable cost) their CPUs so that thisugliness has relatively little impact on their processors’ design (more on thislater)

 

•        There’sa nice example here

•        http://en.wikibooks.org/wiki/X86_Assembly/GAS_Syntax

 

 

2

Registers

 

 

16bit		32bit		64bit	Description	Notes
AX		EAX		RAX	The accumulator register
BX		EBX		RBX	The base register
CX		ECX		RCX	The counter
DX		EDX		RDX	The data register	These can be used
SP		ESP		RSP	Stack pointer	more or less
						interchangeably
BP		EBP		RBP	Points to the base of the stack frame
		Rn		RnD	(n = 8...15) General purpose registers
SI		ESI		RSI	Source index for string operations
DI		EDI		RDI	Destination index for string operations
IP		EIP		RIP	Instruction Pointer
	FLAGS				Condition codes

 

Differentnames (e.g. ax vs. eax vs. rax) refer to different parts of the same register