For altivec targets, 32 bits, the spec2k-gap bmk does not build.  The
reason is that at some point the vectorizer creates an CONST_VECTOR
rtl, where the elements are SYMBOL_REFs.

Gcc ICE on simplify_immed_subreg, where it checks that CONST_VECTORS
can be only made of CONST_INT, CONST_DOUBLE, or CONST_FIXED.

I really don't understand what that function does, but since the
vectorizer will bailout later anyway, I think it is safe to treat
SYMBOL_REFs as CONST_INT. (NOT for FSF submission, as I really don't
have a clue)

This problem does not exists on gcc-4.5

This problem does not exists on 64 bits, since there is no altivec
type that can support 64bit elements.

Here is a simplified test case:

typedef void f_t (void);
extern f_t f;
extern f_t *A[12];
extern f_t *B[12];
void bad_vector ()
{                                                                                                                                                    
  int i;                                                                                                                                             
                                                                                                                                                     
  for (i = 0; i < 12; i++ ) {                                                                                                                        
    A[i] = f;                                                                                                                                        
    B[i] = f;                                                                                                                                        
  }                                                                                                                                                  
}                                                                                                                                                    

--- gcc-4.6.2/gcc/simplify-rtx.c~	2011-12-28 12:28:01.700039002 -0600
+++ gcc-4.6.2/gcc/simplify-rtx.c	2011-12-28 12:38:22.287039002 -0600
@@ -5001,6 +5001,7 @@
       switch (GET_CODE (el))
 	{
 	case CONST_INT:
+        case SYMBOL_REF:
 	  for (i = 0;
 	       i < HOST_BITS_PER_WIDE_INT && i < elem_bitsize;
 	       i += value_bit)