(fold): Handle EQ_EXPR and NE_EXPR where both args are comparisons or

BIT_AND_EXPR with constant 1.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@5186 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 9d5aecc..a859f6d 100644 (file)
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -3167,9 +3167,11 @@ fold (expr)
      one of the operands is a comparison and the other is either a comparison
      or a BIT_AND_EXPR with the constant 1.  In that case, the code below
      would make the expression more complex.  Change it to a
-     TRUTH_{AND,OR}_EXPR.  */
+     TRUTH_{AND,OR}_EXPR.  Likewise, convert a similar NE_EXPR to 
+     TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR.  */
 
-  if ((code == BIT_AND_EXPR || code == BIT_IOR_EXPR)
+  if ((code == BIT_AND_EXPR || code == BIT_IOR_EXPR
+       || code == EQ_EXPR || code == NE_EXPR)
       && ((TREE_CODE_CLASS (TREE_CODE (arg0)) == '<'
           && (TREE_CODE_CLASS (TREE_CODE (arg1)) == '<'
               || (TREE_CODE (arg1) == BIT_AND_EXPR
@@ -3178,8 +3180,17 @@ fold (expr)
              && (TREE_CODE_CLASS (TREE_CODE (arg0)) == '<'
                  || (TREE_CODE (arg0) == BIT_AND_EXPR
                      && integer_onep (TREE_OPERAND (arg0, 1)))))))
-    return fold (build (code == BIT_AND_EXPR ? TRUTH_AND_EXPR : TRUTH_OR_EXPR,
-                       type, arg0, arg1));
+    {
+      t = fold (build (code == BIT_AND_EXPR ? TRUTH_AND_EXPR
+                      : code == BIT_IOR_EXPR ? TRUTH_OR_EXPR
+                      : TRUTH_XOR_EXPR,
+                      type, arg0, arg1));
+
+      if (code == EQ_EXPR)
+       t = invert_truthvalue (t);
+
+      return t;
+    }
 
   if (TREE_CODE_CLASS (code) == '1')
     {