Static Array Bound Checks

bool
ArrayBoundsCheckLocal::runOnFunction(Function & F) {
  //
  // Get required analysis passes.
  //
  TD = &F.getParent()->getDataLayout();
  SE = &getAnalysis<ScalarEvolution>();

  //
  // Look for all GEPs in the function and try to prove that they're safe.
  //
  visit (F);

  //
  // We modify nothing; return false.
  //
  return false;
}

//
  // If the offset is less than zero, then we know that we are indexing
  // backwards from the beginning of the object.  We know that this is illegal;
  // declare it unsafe.
  //
  if ((SE->getSMaxExpr(offset, zero) == zero) && (offset != zero)) {
    ++unsafeGEPs;
    return;
  }

  //
  // Otherwise, we are indexing zero or more bytes forward.  Determine whether
  // we will index past the end of the object.
  //
  if ((SE->getSMaxExpr(diff, zero) == diff) && (diff != zero)) {
    ++safeGEPs;
    SafeGEPs.insert (&GEP);
    return;
  }
  //
  // We cannot statically prove that the GEP is safe.
  //
  return;