.file "calcnew.c"
.text
.globl calcnew
.type calcnew, @function
calcnew:
pushl %ebp
movl %esp, %ebp
movl 8(%ebp), %edx
movl 12(%ebp), %ecx
leal 0(,%ecx,8), %eax
subl %ecx, %eax
leal (%edx,%edx,2), %edx
addl %edx, %eax
imull $14, 16(%ebp), %edx
addl %edx, %eax
popl %ebp
ret
.size calcnew, .-calcnew
.ident "GCC: (Ubuntu 4.3.3-5ubuntu4) 4.3.3"
.section .note.GNU-stack,"",@progbits
我想删除此汇编代码中的所有leal
和imull
操作,并仅用sall
addl
和subl
操作替换它们的功能。这是我的尝试:
.file "calcnew.c"
.text
.globl calcnew
.type calcnew, @function
calcnew:
pushl %ebp
movl %esp, %ebp
movl 8(%ebp), %edx
movl 12(%ebp), %ecx
sall $3, %ecx
movl %ecx, %eax
;leal 0(,%ecx,8), %eax
subl %ecx, %eax
movl %edx, %ecx
sall $1, %edx
addl %ecx, %edx
;leal (%edx,%edx,2), %edx
addl %edx, %eax
movl 16(%ebp), %edx
movl %edx, %ecx
sall $4, %edx
sall $1, %ecx
subl %ecx, %edx
;imull $14, 16(%ebp), %edx
addl %edx, %eax
popl %ebp
ret
.size calcnew, .-calcnew
.ident "GCC: (Ubuntu 4.3.3-5ubuntu4) 4.3.3"
.section .note.GNU-stack,"",@progbits
使用新的程序集文件编译我的 c 代码时的输出应该与使用原始程序集文件编译(使用leal
和mull
操作)相同,但是,我的输出是错误的。我做错了什么?
下面是调用汇编文件的 C 代码:
#include <stdio.h>
int calcnew(int x, int y, int z);
int main()
{
int x = 2;
int y = 6;
int z = 11;
int result;
result = calcnew(x,y,z);
printf("x=%d, y=%d, z=%d, result=%d\n",x,y,z,result);
}