A little bit more about the compiler's different levels of optimization

Experimental Purpose

In a programming language, you can compare code writing in different programming styles, or generate assembly code from a compiler by using different compilers and compilation optimization parameters, and statically analyze the efficiency of the generated assembly code. experimental platform, tools

Under the Windows platform, use the VC6.0 tool.

Experimental design

Optimized comparison of redundant code by the same compiler at different levels of optimization.

int main ()

{

int a=0;

int b=1;

int c=2;

int d=3;

int e=4;

C=a+b;

return C;

}

The following is a compilation and code integration without optimized generation

_main PROC near; Comdat

; 4: {

Pushebp

MOVEBP, ESP

SUBESP, 84; 00000054H

Pushebx

Pushesi

Pushedi

Leaedi, DWORD PTR [ebp-84]

MOVECX, 21; 00000015H

Moveax,-858993460; Cccccccch

Rep STOSD

; 5:int a=0;

Movdword PTR _A$[EBP], 0

; 6:int b=1;

Movdword PTR _B$[EBP], 1

; 7:int c=2;

Movdword PTR _C$[EBP], 2

; 8:int d=3;

Movdword PTR _D$[EBP], 3

; 9:int e=4;

Movdword PTR _E$[EBP], 4

; 10:c=a+b;

Moveax, DWORD PTR _A$[EBP]

Addeax, DWORD PTR _B$[EBP]

Movdword PTR _C$[EBP], eax

; 11:return C;

Moveax, DWORD PTR _C$[EBP]

; 12:

; 13:}

Pop EDI

Pop esi

Pop ebx

mov esp, EBP

Pop EBP

RET 0

_main ENDP

}

The following is the release optimization level of code and compilation

_main PROC near; Comdat

; 5:int a=0;

; 6:int b=1;

; 7:int c=2;

; 8:int d=3;

; 9:int e=4;

; 10:c=a+b;

; 11:return C;

Moveax, 1

; 12:

; 13:}

RET 0

_main ENDP