C段錯誤的匯編功能

Question

我正在嘗試使用SSE和FPU進行並行計算的匯編函數。 不幸的是，我收到segmentation fault(core dumped)錯誤（調試時，匯編功能中未顯示該錯誤）。 我也不能退出匯編功能。 Gdb顯示：

Warning:
Cannot insert breakpoint 0.
Cannot access memory at address 0x2bffff

在ret語句之后。 我沒有任何想法可能導致這種行為。 也許有些人看不到我的東西？ 干杯。

Integrals.s

#float intgr_vert(float x)
#{
#   return pow(x, 2) - 4*x + 6;
#}

s_precision = 0x007f

.bss
    .lcomm holder, 4
    .lcomm  rect_size_vec, 16
    .lcomm  x_vec, 16
    .lcomm  result, 16

.data
four:
    .float 4.0, 4.0, 4.0, 4.0
six:
    .float 6.0, 6.0, 6.0, 6.0

.globl four_intgr_strips

.type four_intgr_strips, @function
four_intgr_strips:

pushl %eax
pushl %ecx
pushl %edx
pushl %ebp
movl  %esp, %ebp

subl $2, %esp  

movl $0, %edi
movl 20(%ebp),  %eax    #x position
movl 24(%ebp), %ebx #rectangle size
movw $s_precision, -2(%ebp)

finit

fldcw -2(%ebp)

pool:
movl %eax, x_vec(, %edi, 4)
movl %ebx, rect_size_vec(, %edi, 4)

movl %eax, holder
flds holder
movl %ebx, holder
flds holder     #adding size of rectangle to calculate different x
fadd %st(1), %st(0)
fstps holder
movl holder, %eax

inc %edi
cmp $4, %edi
je pool_dne
jmp pool

pool_dne:


ret ###########################can't go further

.type sumAreas, @function
sumAreas:
movl $0, %edi

flds result(, %edi, 4)
inc %edi

loop:
flds result(, %edi, 4)
fadd %st(1), %st(0)
inc %edi
cmp $4, %edi
je end_loop
jmp loop

end_loop:


ret

.type calcAreas, @function
calcAreas:

movaps rect_size_vec, %xmm1
mulps %xmm1, %xmm0
movaps %xmm0, result

ret

.type calcVertical, @function
calcVertical:

movaps x_vec, %xmm0
mulps %xmm0, %xmm0
movaps x_vec, %xmm1
movups four, %xmm2
mulps %xmm1, %xmm2
subps %xmm2, %xmm0
movups six, %xmm1
addps %xmm1, %xmm0

ret

main.c中

#include <stdio.h>
#include <math.h>

// x^2 - 4x + 6 integral

float four_intgr_strips(float, float);


float calc_intgr_in_as(int a, int n, float rect_size)
{
    float sum = 0;
    float four_rect_area;
    float last_rect_l_corner = a;

for(int i = 0; i != n/4; i++)
{
        four_rect_area = four_intgr_strips(last_rect_l_corner, rect_size);
        sum = sum + four_rect_area;
        last_rect_l_corner = last_rect_l_corner + 4*rect_size;
    }


return sum;
}

int main()
{
    int a, b, n;
    float rect_size;
    float sum;

    printf("\nType integral lower bound:");
    scanf("%d", &a);
    printf("\nType integral upper bound:");

 scanf("%d", &b);
    do
    {
        printf("\nType rectangles number(must be multiple of 4):");
        scanf("%d", &n);
    }
    while(n % 4 != 0);

    rect_size = (float)(b - a)/n;

    sum = calc_intgr_in_as(a, n, rect_size);
    printf("\nArea under function is: %f with SSE", sum);
}

Answer 1

您忘記了清理堆棧。 在序言中，您有：

pushl %eax
pushl %ecx
pushl %edx
pushl %ebp
movl  %esp, %ebp

您顯然需要撤消操作，然后再ret ，例如：

movl %ebp, %esp
popl %ebp
popl %edx
popl %ecx
popl %eax
ret

PS：我已經告訴過您，取消堆棧對齊是個壞主意，遲早會咬住您。 另外，下次您提問題時，請提及您使用了什么輸入以及期望了什么輸出。