汇编 for循环

Posted 2020-08-30 whzym111

知识点：
?for循环生成代码1
?for循环生成代码2
?inc指令

一、一般情况下的for循环汇编代码分析
     for (int i=1;i<=10;i++)
     {
         printf("%d,",i);
     }
//00401003  |.  51            PUSH ECX                                 ;  sub esp,4;int i;
//00401004  |.  C745 FC 01000>MOV DWORD PTR SS:[EBP-4],1               ;  i=1;
//0040100B  |.  EB 09         JMP SHORT for.00401016
//0040100D  |>  8B45 FC       /MOV EAX,DWORD PTR SS:[EBP-4]
//00401010  |.  83C0 01       |ADD EAX,1
//00401013  |.  8945 FC       |MOV DWORD PTR SS:[EBP-4],EAX            ;  i++;i=i+1;
//00401016  |>  837D FC 0A     CMP DWORD PTR SS:[EBP-4],0A
//0040101A  |.  7F 14         |JG SHORT for.00401030                   ;  i>10 跳出for循环
//0040101C  |.  8B4D FC       |MOV ECX,DWORD PTR SS:[EBP-4]            ;  ecx=i
//0040101F  |.  51            |PUSH ECX                                ; /<%d>
//00401020  |.  68 F4204000   |PUSH for.004020F4                       ; |format = "%d,"
//00401025  |.  FF15 A0204000 |CALL DWORD PTR DS:[<&MSVCR90.printf>]   ; \printf
//0040102B  |.  83C4 08       |ADD ESP,8                               ;  esp=esp+8
//0040102E  |.^ EB DD         \JMP SHORT for.0040100D
//00401030  |>  33C0          XOR EAX,EAX                              ;  return 0;

二、速度优化下的for循环汇编代码分析


//最小化优化
//00401000  /$  56            PUSH ESI
//00401001  |.  33F6          XOR ESI,ESI                              ;  i=0;
//00401003  |.  46            INC ESI                                  ;  i=1;
//00401004  |>  56            /PUSH ESI                                ; /<%d>
//00401005  |.  68 F4204000   |PUSH for.004020F4                       ; |format = "%d,"
//0040100A  |.  FF15 A0204000 |CALL DWORD PTR DS:[<&MSVCR90.printf>]   ; \printf
//00401010  |.  46            |INC ESI                                 ;  i++
//00401011  |.  83FE 0A       |CMP ESI,0A                              ;  if (i<=10) goto 401004
//00401014  |.  59            |POP ECX
//00401015  |.  59            |POP ECX
//00401016  |.^ 7E EC         \JLE SHORT for.00401004
//00401018  |.  33C0          XOR EAX,EAX
//0040101A  |.  5E            POP ESI
//0040101B  \.  C3            RETN                                     ;  33-1B

//最大化速度优化
//00401000  /$  56            PUSH ESI
//00401001  |.  57            PUSH EDI
//00401002  |.  8B3D A0204000 MOV EDI,DWORD PTR DS:[<&MSVCR90.printf>]     ;  MSVCR90.printf
//00401008  |.  BE 01000000   MOV ESI,1                                    ;  int i=1;
//0040100D  |.  8D49 00       LEA ECX,DWORD PTR DS:[ECX]                   ;  ecx=ecx
//00401010  |>  56            /PUSH ESI
//00401011  |.  68 F4204000   |PUSH for.004020F4                           ;  ASCII "%d,"
//00401016  |.  FFD7          |CALL EDI                                    ;  call dword ptr [printf]
//00401018  |.  46            |INC ESI                                     ;  i++;
//00401019  |.  83C4 08       |ADD ESP,8
//0040101C  |.  83FE 0A       |CMP ESI,0A                                  ;  0B
//0040101F  |.^ 7E EF         \JLE SHORT for.00401010                      ;  if (i<=10) 继续循环goto 401010
//00401021  |.  5F            POP EDI
//00401022  |.  33C0          XOR EAX,EAX
//00401024  |.  5E            POP ESI
//00401025  \.  C3            RETN