How to represent a fallthrough condtion (with no else) in "Match and Simplify"?

[Hanke Zhang <hkzhang455@gmail.com>]

Hi,

I'm trying to study "Match and Simplify" recently, and I had this sample code:

int main() {
  int n = 1000;
  int *a = malloc (sizeof(int) * n);
  int *b = malloc (sizeof(int) * n);
  int *c = malloc (sizeof(int) * n);
  for (int i = 0; i < n; i++) {
    if (a[i] & b[i]) {
      a[i] ^= c[i];
    }
  }
}

But this code cannot be vectorized very well. I hope it can become like this:

int main() {
  int n = 1000;
  int *a = malloc (sizeof(int) * n);
  int *b = malloc (sizeof(int) * n);
  int *c = malloc (sizeof(int) * n);
  for (int i = 0; i < n; i++) {
    int cond = ((a[i] & b[i]) == 1);
    unsigned int mask = cond ? -1 : 0;
    a[i] ^= (c[i] & mask);
  }
}


This can finally result in concise and efficient vectorized
instructions. But I want to know if this can be achieved through
"Match and Simplify"? Because when I tried to write the pattern, I
found that the condtional statement here seemed not to be matched
well, as there is not an else block.

Or is this not possible with "Match and Simplify"? Is it possible to
implement it in if-conversion?

Thanks
Hanke Zhang