user: 下面的汇编指令对应的C源代码是什么:

```asm
<mutstep>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  push   %r15
  mov    %ecx,%r15d
  push   %r14
  push   %r13
  push   %r12
  push   %rbx
  sub    $0x48,%rsp
  mov    %rsi,-0x58(%rbp)
  mov    %edx,-0x50(%rbp)
  movslq %edx,%rdx
  mov    %rsp,%rsi
  mov    %rdi,-0x68(%rbp)
  mov    %fs:0x28,%rax
  mov    %rax,-0x38(%rbp)
  xor    %eax,%eax
  movslq %ecx,%rax
  lea    0x0(,%rax,8),%r9
  imul   %rdx,%rax
  lea    0xf(,%rax,8),%rdx
  mov    %rdx,%rax
  and    $0xfffffffffffff000,%rdx
  sub    %rdx,%rsi
  and    $0xfffffffffffffff0,%rax
  cmp    %rsi,%rsp
  je     L59
L74:
  sub    $0x1000,%rsp
  orq    $0x0,0xff8(%rsp)
  cmp    %rsi,%rsp
  jne    L74
L59:
  and    $0xfff,%eax
  sub    %rax,%rsp
  test   %rax,%rax
  jne    L31
L113:
  mov    -0x50(%rbp),%edx
  mov    %rsp,%rax
  mov    %rax,-0x70(%rbp)
  test   %edx,%edx
  jle    L91
  test   %r15d,%r15d
  jle    L91
  mov    %r15d,%r14d
  mov    %rax,%rdi
  xor    %r13d,%r13d
  mov    -0x68(%rbp),%rbx
  lea    0x0(,%r14,8),%rcx
  mov    %r15d,%r14d
  add    %rcx,%rax
  and    $0xfffffffe,%r14d
  mov    %rcx,-0x60(%rbp)
  mov    %r15d,%ecx
  mov    %rax,%r10
  mov    %r15d,%eax
  mov    %r14d,%r15d
  mov    %r13d,%r14d
  shr    %eax
  mov    %r9,%r13
  lea    -0x1(%rax),%r12d
  add    $0x1,%r12
  shl    $0x4,%r12
  nopl   0x0(%rax)
L51:
  mov    -0x60(%rbp),%rdx
  xor    %esi,%esi
  mov    %ecx,-0x4c(%rbp)
  mov    %r10,-0x48(%rbp)
  call   <memset@plt>
  mov    -0x58(%rbp),%rdx
  mov    -0x4c(%rbp),%ecx
  pxor   %xmm3,%xmm3
  mov    -0x48(%rbp),%r10
  mov    %rax,%rdi
  mov    %rax,%rsi
  nopw   0x0(%rax,%rax,1)
L60:
  cmp    $0x1,%ecx
  je     L24
  xor    %eax,%eax
  movapd %xmm3,%xmm0
  nop
L118:
  movupd (%rdx,%rax,1),%xmm2
  movupd (%rbx,%rax,1),%xmm4
  add    $0x10,%rax
  mulpd  %xmm4,%xmm2
  addsd  %xmm2,%xmm0
  unpckhpd %xmm2,%xmm2
  addsd  %xmm2,%xmm0
  cmp    %r12,%rax
  jne    L118
  movslq %r15d,%rax
  cmp    %ecx,%r15d
  je     L124
L2:
  movsd  (%rbx,%rax,8),%xmm1
  mulsd  (%rdx,%rax,8),%xmm1
  addsd  %xmm1,%xmm0
L124:
  movsd  %xmm0,(%rsi)
  add    $0x8,%rsi
  add    %r13,%rdx
  cmp    %r10,%rsi
  jne    L60
  add    $0x1,%r14d
  add    %r13,%rdi
  add    %r13,%r10
  add    %r13,%rbx
  cmp    %r14d,-0x50(%rbp)
  jne    L51
  mov    %ecx,%r15d
L91:
  mov    -0x50(%rbp),%edx
  mov    -0x70(%rbp),%rsi
  mov    -0x68(%rbp),%rdi
  imul   %r15d,%edx
  shl    $0x3,%edx
  call   <memcpy@plt>
  mov    -0x38(%rbp),%rax
  sub    %fs:0x28,%rax
  jne    L72
  lea    -0x28(%rbp),%rsp
  pop    %rbx
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  pop    %rbp
  ret
  nopl   0x0(%rax,%rax,1)
L24:
  movapd %xmm3,%xmm0
  xor    %eax,%eax
  jmp    L2
L31:
  orq    $0x0,-0x8(%rsp,%rax,1)
  jmp    L113
L72:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
void mutstep(double *vec, const double *mut, const int nislands, const int nhap) {
  int i, j, k;
  double vec2[nislands][nhap];
  for (i = 0; i < nislands; i++)
    for (j = 0; j < nhap; j++) {
      vec2[i][j] = 0;
      for (k = 0; k < nhap; k++)
        vec2[i][j] += ((double(*)[nhap])mut)[j][k] * ((double(*)[nhap])vec)[i][k];
    }
  memcpy(vec, (double *)vec2, sizeof(double) * nislands * nhap);
  return;
}
```