Questions about a constant array reference in the C++ front end

[Kazu Hirata <kazu at cs dot umass dot edu>]

Hi,

I have two questions about the C++ front end.

Consider a C++ program

static const int array[] = { 0, 0, 0, 1, 1, 1, 2, 2, 2 };

int
foo (int a)
{
  return array[7];
}

I am trying to fold array[7] into 2.  It turns out that if T is an
ARRAY_REF,

  TREE_READONLY (TREE_OPERAND (T, 0))

is 0.  Why?  This would be 1 if the program is fed into the C front
end, which is needed to safely fold a constant array reference.

Another question.  How is a RANGE_EXPR used in a C++'s array
constructor?  The CONSTRUCTOR section of tree.def says

   The TREE_PURPOSE of each node is the corresponding index.
   If the TREE_PURPOSE is a RANGE_EXPR, it is a short-hand for many nodes,
   one for each index in the range.  (If the corresponding TREE_VALUE
   has side-effects, they are evaluated once for each element.  Wrap the
   value in a SAVE_EXPR if you want to evaluate side effects only once.)

I created an array with more than one thousand elements.  I still did
not see a RANGE_EXPR in the array's CONSTRUCTOR.  How do I get a
RANGE_EXPR in a CONSTRUCTOR?

Kazu Hirata