In this example (cut down from povray):

-------------------
struct foo {
  int Y;
  char X[100];
} F;

int test(char *Y) {
   return Y - F.X;
} 
-------------------

llvmgcc is emitting the following invalid constantexpr:

%tmp.5 = add int %tmp.1, sub (int cast (%struct.foo* sub (%struct.foo* null,
                                                          %struct.foo* %F)
                                        to int),
                              int 4)

The problem is the pointer subtract operation, which is not a kosher constant
expr (subtract only works for integral and fp types).

-Chris

Fixed.  Patch here:
http://mail.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20041122/021363.html

Testcase here:
http://mail.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20041122/021362.html

-Chris