user: 提供的汇编代码用C语言表示会是什么样子:

```asm
<smatvec>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  mov    %edi,-0x24(%rsp)
  mov    %esi,-0x18(%rsp)
  mov    %edx,-0x28(%rsp)
  mov    %rcx,%r13
  mov    %r8,-0x20(%rsp)
  cmp    $0x7,%edx
  jle    L115
  mov    %edx,%ebx
  movslq %edi,%rax
  lea    0x0(,%rdi,8),%edx
  movslq %edx,%rdx
  lea    0x0(,%rdx,4),%rdi
  mov    %rdi,-0x48(%rsp)
  mov    %r8,%rcx
  lea    0x0(%r13,%rax,4),%r15
  lea    -0x8(%rbx),%edx
  shr    $0x3,%edx
  mov    %edx,-0x14(%rsp)
  mov    %edx,%ebx
  mov    %rbx,-0x10(%rsp)
  mov    %rbx,%rdx
  shl    $0x5,%rdx
  lea    0x20(%r8,%rdx,1),%rbx
  mov    %rbx,-0x40(%rsp)
  lea    0x0(,%rax,8),%r14
  mov    %rax,%rbx
  shl    $0x4,%rbx
  mov    %rbx,-0x38(%rsp)
  lea    (%rax,%rax,2),%rax
  shl    $0x3,%rax
  mov    %rax,-0x30(%rsp)
  mov    %r13,%rdx
  mov    %esi,%r12d
  mov    %r13,-0x8(%rsp)
  mov    %esi,%r13d
L81:
  mov    %r15,%r8
  lea    (%r14,%rdx,1),%r10
  lea    (%r15,%r14,1),%rsi
  mov    -0x38(%rsp),%rax
  lea    (%rdx,%rax,1),%r11
  lea    (%r14,%rsi,1),%rdi
  mov    -0x30(%rsp),%rax
  lea    (%rdx,%rax,1),%rbx
  lea    (%r14,%rdi,1),%rbp
  movss  (%rcx),%xmm1
  movss  0x4(%rcx),%xmm2
  movss  0x8(%rcx),%xmm3
  movss  0xc(%rcx),%xmm4
  movss  0x10(%rcx),%xmm5
  movss  0x14(%rcx),%xmm6
  movss  0x18(%rcx),%xmm7
  movss  0x1c(%rcx),%xmm8
  test   %r13d,%r13d
  jle    L48
  mov    $0x0,%eax
L47:
  movaps %xmm1,%xmm0
  mulss  (%rdx,%rax,4),%xmm0
  movaps %xmm2,%xmm9
  mulss  (%r8,%rax,4),%xmm9
  addss  %xmm9,%xmm0
  movaps %xmm3,%xmm9
  mulss  (%r10,%rax,4),%xmm9
  addss  %xmm9,%xmm0
  movaps %xmm4,%xmm9
  mulss  (%rsi,%rax,4),%xmm9
  addss  %xmm9,%xmm0
  movaps %xmm5,%xmm9
  mulss  (%r11,%rax,4),%xmm9
  addss  %xmm9,%xmm0
  movaps %xmm6,%xmm9
  mulss  (%rdi,%rax,4),%xmm9
  addss  %xmm9,%xmm0
  movaps %xmm7,%xmm9
  mulss  (%rbx,%rax,4),%xmm9
  addss  %xmm9,%xmm0
  movaps %xmm8,%xmm9
  mulss  0x0(%rbp,%rax,4),%xmm9
  addss  %xmm9,%xmm0
  addss  (%r9,%rax,4),%xmm0
  movss  %xmm0,(%r9,%rax,4)
  add    $0x1,%rax
  cmp    %r12,%rax
  jne    L47
L48:
  mov    -0x48(%rsp),%rax
  add    %rax,%rdx
  add    $0x20,%rcx
  add    %rax,%r15
  cmp    -0x40(%rsp),%rcx
  jne    L81
  mov    -0x8(%rsp),%r13
  mov    -0x14(%rsp),%eax
  lea    0x8(,%rax,8),%r11d
  mov    -0x10(%rsp),%rax
  add    $0x1,%rax
  imul   -0x48(%rsp),%rax
  add    %rax,%r13
L90:
  mov    -0x28(%rsp),%ebx
  lea    -0x3(%rbx),%eax
  cmp    %r11d,%eax
  jle    L36
  movslq -0x24(%rsp),%rax
  lea    0x0(,%rax,4),%r14
  mov    %rax,%r15
  shl    $0x4,%r15
  movslq %r11d,%rcx
  mov    -0x20(%rsp),%rsi
  lea    (%rsi,%rcx,4),%r10
  lea    -0x4(%rbx),%edx
  sub    %r11d,%edx
  shr    $0x2,%edx
  mov    %edx,-0x48(%rsp)
  mov    %edx,%ebx
  mov    %rbx,-0x40(%rsp)
  lea    (%rcx,%rbx,4),%rdx
  lea    0x10(%rsi,%rdx,4),%r12
  lea    0x0(,%rax,8),%rbp
  lea    (%rax,%rax,2),%rbx
  shl    $0x2,%rbx
  mov    %r13,%rdx
  mov    -0x18(%rsp),%eax
  mov    %eax,%r8d
  mov    %r11d,-0x38(%rsp)
  mov    %eax,%r11d
L104:
  lea    (%r14,%rdx,1),%rcx
  lea    (%rdx,%rbp,1),%rsi
  lea    (%rdx,%rbx,1),%rdi
  movss  (%r10),%xmm2
  movss  0x4(%r10),%xmm3
  movss  0x8(%r10),%xmm4
  movss  0xc(%r10),%xmm5
  test   %r11d,%r11d
  jle    L30
  mov    $0x0,%eax
L3:
  movaps %xmm2,%xmm0
  mulss  (%rdx,%rax,4),%xmm0
  movaps %xmm3,%xmm1
  mulss  (%rcx,%rax,4),%xmm1
  addss  %xmm1,%xmm0
  movaps %xmm4,%xmm1
  mulss  (%rsi,%rax,4),%xmm1
  addss  %xmm1,%xmm0
  movaps %xmm5,%xmm1
  mulss  (%rdi,%rax,4),%xmm1
  addss  %xmm1,%xmm0
  addss  (%r9,%rax,4),%xmm0
  movss  %xmm0,(%r9,%rax,4)
  add    $0x1,%rax
  cmp    %rax,%r8
  jne    L3
L30:
  add    %r15,%rdx
  add    $0x10,%r10
  cmp    %r12,%r10
  jne    L104
  mov    -0x38(%rsp),%r11d
  mov    -0x48(%rsp),%eax
  lea    0x4(%r11,%rax,4),%r11d
  mov    -0x40(%rsp),%rax
  add    $0x1,%rax
  imul   %r15,%rax
  add    %rax,%r13
L36:
  mov    -0x28(%rsp),%edi
  cmp    %r11d,%edi
  jle    L116
  movslq -0x24(%rsp),%rcx
  shl    $0x2,%rcx
  movslq %r11d,%r11
  mov    -0x18(%rsp),%esi
  mov    %esi,%edx
  mov    -0x20(%rsp),%r8
L121:
  movss  (%r8,%r11,4),%xmm1
  test   %esi,%esi
  jle    L50
  mov    $0x0,%eax
L95:
  movaps %xmm1,%xmm0
  mulss  0x0(%r13,%rax,4),%xmm0
  addss  (%r9,%rax,4),%xmm0
  movss  %xmm0,(%r9,%rax,4)
  add    $0x1,%rax
  cmp    %rax,%rdx
  jne    L95
L50:
  add    %rcx,%r13
  add    $0x1,%r11
  cmp    %r11d,%edi
  jg     L121
L116:
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L115:
  mov    $0x0,%r11d
  jmp    L90
```

assistant: ```c
void smatvec(ldm, nrow, ncol, M, vec, Mxvec) int ldm;
int nrow;
int ncol;
float *M;
float *vec;
float *Mxvec;
{
  float vi0, vi1, vi2, vi3, vi4, vi5, vi6, vi7;
  float *M0;
  register float *Mki0, *Mki1, *Mki2, *Mki3, *Mki4, *Mki5, *Mki6, *Mki7;
  register int firstcol = 0;
  int k;
  M0 = &M[0];
  while (firstcol < ncol - 7) {
    Mki0 = M0;
    Mki1 = Mki0 + ldm;
    Mki2 = Mki1 + ldm;
    Mki3 = Mki2 + ldm;
    Mki4 = Mki3 + ldm;
    Mki5 = Mki4 + ldm;
    Mki6 = Mki5 + ldm;
    Mki7 = Mki6 + ldm;
    vi0 = vec[firstcol++];
    vi1 = vec[firstcol++];
    vi2 = vec[firstcol++];
    vi3 = vec[firstcol++];
    vi4 = vec[firstcol++];
    vi5 = vec[firstcol++];
    vi6 = vec[firstcol++];
    vi7 = vec[firstcol++];
    for (k = 0; k < nrow; k++)
      Mxvec[k] += vi0 * *Mki0++ + vi1 * *Mki1++ + vi2 * *Mki2++ + vi3 * *Mki3++ + vi4 * *Mki4++ + vi5 * *Mki5++ + vi6 * *Mki6++ + vi7 * *Mki7++;
    M0 += 8 * ldm;
  }
  while (firstcol < ncol - 3) {
    Mki0 = M0;
    Mki1 = Mki0 + ldm;
    Mki2 = Mki1 + ldm;
    Mki3 = Mki2 + ldm;
    vi0 = vec[firstcol++];
    vi1 = vec[firstcol++];
    vi2 = vec[firstcol++];
    vi3 = vec[firstcol++];
    for (k = 0; k < nrow; k++)
      Mxvec[k] += vi0 * *Mki0++ + vi1 * *Mki1++ + vi2 * *Mki2++ + vi3 * *Mki3++;
    M0 += 4 * ldm;
  }
  while (firstcol < ncol) {
    Mki0 = M0;
    vi0 = vec[firstcol++];
    for (k = 0; k < nrow; k++)
      Mxvec[k] += vi0 * *Mki0++;
    M0 += ldm;
  }
}
```