Should gcc-4.0 apply mathematical associative rules for addition or multiplication

[Andrew Pinski]

On Oct 4, 2004, at 7:07 PM, Andrew Pinski wrote:

>
> On Oct 4, 2004, at 6:56 PM, Fariborz Jahanian wrote:
>> /* test */
>> static const double C = 0x1.0p1023;
>>
>> double foo(double x)
>> {
>>         return ( ( (x * C) * C ) * C );
>> }
>>
>> This is done in routine: simplify_rhs_and_lookup_avail_expr(...) 
>> which is preceded with this comment:
>>
>>  /* If we have z = (x OP C1), see if we earlier had x = y OP C2.
>>      If OP is associative, create and fold (y OP C2) OP C1 which
>>      should result in (y OP C3), use that as the RHS for the
>>      assignment.  Add minus to this, as we handle it specially below. 
>>  */
>
> This patch should work:

Obviously I mean:
Index: tree-ssa-dom.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/tree-ssa-dom.c,v
retrieving revision 2.58
diff -u -p -r2.58 tree-ssa-dom.c
--- tree-ssa-dom.c	4 Oct 2004 13:19:20 -0000	2.58
+++ tree-ssa-dom.c	4 Oct 2004 23:19:07 -0000
@@ -1598,7 +1598,9 @@ simplify_rhs_and_lookup_avail_expr (stru
       assignment.  Add minus to this, as we handle it specially below.  
*/
    if ((associative_tree_code (rhs_code) || rhs_code == MINUS_EXPR)
        && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
-      && is_gimple_min_invariant (TREE_OPERAND (rhs, 1)))
+      && is_gimple_min_invariant (TREE_OPERAND (rhs, 1))
+      && (!FLOAT_TYPE_P (TREE_TYPE (rhs))
+	  || flag_unsafe_math_optimizations))
      {
        tree rhs_def_stmt = SSA_NAME_DEF_STMT (TREE_OPERAND (rhs, 0));