[Bug tree-optimization/118657] Missed optimization (unreachable branch could be pruned after taking into account the possible values of a constexpr lookup table)

[andi-gcc at firstfloor dot org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118657

--- Comment #6 from Andi Kleen <andi-gcc at firstfloor dot org> ---
The C test case needs to use constexpr too.

#define DATA_SIZE 1024
static constexpr int TO_DATA_INDEX[DATA_SIZE] = {};
bool foo(int* data, unsigned char first_idx)
{
  int second_idx = TO_DATA_INDEX[first_idx];
  if (second_idx >= DATA_SIZE)
    return false;
  data[second_idx] = 1;
  return true;
}