[PATCH] Put all constants last in tree_swap_operands_p, remove odd -Os check

[Richard Biener]

The following makes tree_swap_operands_p put all constants 2nd place,
also looks through sign-changes when considering further canonicalzations
and removes the odd -Os guard for those.  That was put in with
https://gcc.gnu.org/ml/gcc-patches/2003-10/msg01208.html just
motivated by CSiBE numbers - but rather than disabling canonicalization
this should have disabled the actual harmful transforms.

Bootstrap and regtest ongoing on x86_64-unknown-linux-gnu.

Richard.

2014-08-15  Richard Biener  <rguent...@suse.de>

        * fold-const.c (tree_swap_operands_p): Put all constants
        last, also strip sign-changing NOPs when considering further
        canonicalization.  Canonicalize also when optimizing for size.

Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c    (revision 214007)
+++ gcc/fold-const.c    (working copy)
@@ -6642,37 +6650,19 @@ reorder_operands_p (const_tree arg0, con
 bool
 tree_swap_operands_p (const_tree arg0, const_tree arg1, bool reorder)
 {
-  STRIP_SIGN_NOPS (arg0);
-  STRIP_SIGN_NOPS (arg1);
-
-  if (TREE_CODE (arg1) == INTEGER_CST)
+  if (CONSTANT_CLASS_P (arg1) == INTEGER_CST)
     return 0;
-  if (TREE_CODE (arg0) == INTEGER_CST)
+  if (CONSTANT_CLASS_P (arg0) == INTEGER_CST)
     return 1;
 
-  if (TREE_CODE (arg1) == REAL_CST)
-    return 0;
-  if (TREE_CODE (arg0) == REAL_CST)
-    return 1;
-
-  if (TREE_CODE (arg1) == FIXED_CST)
-    return 0;
-  if (TREE_CODE (arg0) == FIXED_CST)
-    return 1;
-
-  if (TREE_CODE (arg1) == COMPLEX_CST)
-    return 0;
-  if (TREE_CODE (arg0) == COMPLEX_CST)
-    return 1;
+  STRIP_NOPS (arg0);
+  STRIP_NOPS (arg1);
 
   if (TREE_CONSTANT (arg1))
     return 0;
   if (TREE_CONSTANT (arg0))
     return 1;
 
-  if (optimize_function_for_size_p (cfun))
-    return 0;
-
   if (reorder && flag_evaluation_order
       && (TREE_SIDE_EFFECTS (arg0) || TREE_SIDE_EFFECTS (arg1)))
     return 0;