Compiler Optimization problem/bug

Hi, we have spot a compiler optimization (software pipeline ) bug.

The bug can be reproduced on c6678 EVM with the following code.

please verify this compiler optimization problem, and fix this problem.

Thanks!

#include "stdlib.h"
#include "stdio.h"

//  This is the function that have problem.
//  if uncomment line 21, then the result will be correct.
void foo(double **a, int n, int *indx, double b[])
{
  int   i, ip, j;
  int ii = -1;
  double sum, tmp;

  for (i = 0; i<n; i++)
  {
    ip = indx[i];
    sum = b[ip];
    b[ip] = b[i];
    if (ii >= 0)
    {
      for (j = ii; j < i; j++)
      {
        // asm(" ");
        sum -= a[i][j] * b[j];
      }
    }
    else if (sum)
      ii = i;
    b[i] = sum;
  }
}

void allocdim2(double***a, int dim)
{
  int i;
  *a = (double**)malloc(dim*sizeof(double*));
  for (i = 0; i < dim; ++i)
  {
    (*a)[i] = (double*)malloc(dim*sizeof(double));
  }
}

void freedim2(double** a, int dim)
{
  int i;
  for (i = 0; i < dim; ++i)
  {
    free(a[i]);
  }
  free(a);
}

void initlizeMat(double ** a, int dim)
{
  int i, j;
  for (i = 0; i < dim; ++i)
  for (j = 0; j < dim; ++j)
  {
    a[i][j] = rand() % 32 / (0.41 + rand() % 1234);
  }
}



int isEqual(double*a, double *b, int dim)
{
  int i;
  int count = 0;
  for (i = 0; i < dim; ++i)
  {
    if (a[i] != b[i])
    {
      printf("diff: %lf\n", a[i]-b[i]);
      count++;
    }
  }
  return count==0;
}

void VerifyPipeLineError(int dim)
{
  double **a, *res1, *res2;
  int i;
  int *index;

  allocdim2(&a, dim);
  initlizeMat(a, dim);

  res1 = (double*)malloc(dim*sizeof(double));
  res2 = (double*)malloc(dim*sizeof(double));
  index = (int*)malloc(dim*sizeof(int));

  for (i = 0; i < dim; ++i)
  {
    res1[i] = rand() % 23 / (0.41 + rand() % 1231);
    res2[i] = res1[i];
    index[i] = rand() % dim;
  }
  
  foo(a,  dim,  index, res1);
  foo(a,  dim,  index, res2);

  if (!isEqual(res1, res2, dim))
    printf("BAD!!!!!!!\n");
  else
    printf("good!\n");
  freedim2(a, dim);
  free(res1);
  free(res2);
  free(index);
}

void main()
{
  int i;
  srand(13);
  for (i = 100; i < 200; i+=4)
  {
    printf("Dim :%d, ", i);
    VerifyPipeLineError(i);
  }
}