"lea eax，[ebx + eax]"和"lea eax，[ebx + eax]"之间的区别是什么?和“添加eax，ebx"在x86-32组装中? [英] What is the difference between "lea eax, [ebx + eax]" and "add eax, ebx" in x86-32 assembly?

问题描述

GCC为我提供了一些汇编代码，并在其中添加了以下语句:

GCC made me some assembly code, and inside theres this statement:

lea eax, [ebx+eax]

(英特尔语法) 只是好奇，两者之间有什么区别?

(Intel Syntax) Just curious, what would the difference between that, and:

add eax, ebx

是吗?

eax和ebx包含函数的返回值:)

eax, and ebx contains return values from functions :)

mov eax, DWORD PTR [ebp+8]
mov DWORD PTR [esp], eax 
call CALC1
mov ebx, eax.
mov eax, DWORD PTR [ebp+8]
mov DWORD PTR [esp], eax
call CALC2
lea eax, [ebx+eax]

推荐答案

您可以将结果放入EAX以外的其他寄存器中，例如lea edx, eax + ebx. add无法做到.

You can put the result into another register than EAX, such as lea edx, eax + ebx. add cannot do it.

lea也可以有一个附加的第三操作数，例如lea eax, ebp + esi + 12，这使它成为add指令的替代品.

lea can also have an additional third operand such as lea eax, ebp + esi + 12 which makes it a handier alternative to add instruction.

您还可以将某些(单词大小的)乘法运算与之结合使用，例如lea eax, ebp + eax * 8.

You can also combine certain (word-sized) multiplication operations with it, such as lea eax, ebp + eax * 8.

更不用说它更好地描述了意图:)

Not to mention that it describes the intent better :)

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