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.
That's a bug, or, rather, a place where the C++ front-end is failing to give full information to the optimizer. It should be TREE_READONLY. There are some tricky bits, in that if we're doing a dynamic initialization, we presently cannot mark it TREE_READONLY, but this is a static initialization, so it should be fine. Isn't TREE_OPERAND (T, 0) the VAR_DECL for array itself? If so, waht's probably going wrong is that it's not being marked TREE_READONLY because we're afraid of the dynamic initialization case. We're missing a call to c_apply_quals_to_decl (sp?) somewhere.
-- Mark Mitchell CodeSourcery, LLC [EMAIL PROTECTED] (916) 791-8304
