fold-const.c (split_tree): Don't assume a constant isn't splittable.

        * fold-const.c (split_tree): Don't assume a constant isn't splittable.
        (fold): Don't assume a constant isn't foldable.
        * tree.c (build): Set TREE_CONSTANT for an expression with no
        side-effects and constant operands.
        (build1): Likewise.

From-SVN: r39585

1 files changed, 18 insertions, 0 deletions

diff --git a/gcc/tree.c b/gcc/tree.c
index 6e8a32e..b45dc19 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -2323,6 +2323,7 @@ build VPARAMS ((enum tree_code code, tree tt, ...))
   register int length;
   register int i;
   int fro;
+  int constant;
 
   VA_START (p, tt);
 
@@ -2341,6 +2342,13 @@ build VPARAMS ((enum tree_code code, tree tt, ...))
      to do this.  */
   fro = first_rtl_op (code);
 
+  /* Expressions without side effects may be constant if their
+     arguments are as well.  */
+  constant = (TREE_CODE_CLASS (code) == '<'
+	      || TREE_CODE_CLASS (code) == '1'
+	      || TREE_CODE_CLASS (code) == '2'
+	      || TREE_CODE_CLASS (code) == 'c');
+
   if (length == 2)
     {
       /* This is equivalent to the loop below, but faster.  */
@@ -2356,6 +2364,8 @@ build VPARAMS ((enum tree_code code, tree tt, ...))
 	    TREE_SIDE_EFFECTS (t) = 1;
 	  if (!TREE_READONLY (arg0))
 	    TREE_READONLY (t) = 0;
+	  if (!TREE_CONSTANT (arg0))
+	    constant = 0;
 	}
 
       if (arg1 && fro > 1)
@@ -2364,6 +2374,8 @@ build VPARAMS ((enum tree_code code, tree tt, ...))
 	    TREE_SIDE_EFFECTS (t) = 1;
 	  if (!TREE_READONLY (arg1))
 	    TREE_READONLY (t) = 0;
+	  if (!TREE_CONSTANT (arg1))
+	    constant = 0;
 	}
     }
   else if (length == 1)
@@ -2390,10 +2402,14 @@ build VPARAMS ((enum tree_code code, tree tt, ...))
 	    {
 	      if (TREE_SIDE_EFFECTS (operand))
 		TREE_SIDE_EFFECTS (t) = 1;
+	      if (!TREE_CONSTANT (operand))
+		constant = 0;
 	    }
 	}
     }
   va_end (p);
+
+  TREE_CONSTANT (t) = constant;
   return t;
 }
 
@@ -2466,6 +2482,8 @@ build1 (code, type, node)
       break;
 
     default:
+      if (TREE_CODE_CLASS (code) == '1' && TREE_CONSTANT (node))
+	TREE_CONSTANT (t) = 1;
       break;
     }