fold-const.c (fold_binary): Optimize A / A to 1.0 if we don't care about NaNs or Infinities.

        * fold-const.c (fold_binary) <RDIV_EXPR>: Optimize A / A to 1.0 
        if we don't care about NaNs or Infinities.

testsuite:

        * gcc.dg/fold-div-2.c: New test.

From-SVN: r107282

gcc/ChangeLog

+2005-11-21  Uros Bizjak  <uros@kss-loka.si>
+
+	* fold-const.c (fold_binary) <RDIV_EXPR>: Optimize A / A to 1.0 
+	if we don't care about NaNs or Infinities.
+
 2005-11-20  Ian Lance Taylor  <ian@airs.com>
 
 	PR rtl-optimization/24883

gcc/fold-const.c

@@ -8227,6 +8227,17 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1)
 	  && real_zerop (arg1))
 	return NULL_TREE;
 
+      /* Optimize A / A to 1.0 if we don't care about
+	 NaNs or Infinities.  */
+      if (! HONOR_NANS (TYPE_MODE (TREE_TYPE (arg0)))
+	  && ! HONOR_INFINITIES (TYPE_MODE (TREE_TYPE (arg0)))
+	  && operand_equal_p (arg0, arg1, 0))
+	{
+	  tree r = build_real (TREE_TYPE (arg0), dconst1);
+
+	  return omit_two_operands (type, r, arg0, arg1);
+	}
+
       /* (-A) / (-B) -> A / B  */
       if (TREE_CODE (arg0) == NEGATE_EXPR && negate_expr_p (arg1))
 	return fold_build2 (RDIV_EXPR, type,

gcc/testsuite/ChangeLog

+2005-11-21  Uros Bizjak  <uros@kss-loka.si>
+
+	* gcc.dg/fold-div-2.c: New test.
+	
 2005-11-20  Ian Lance Taylor  <ian@airs.com>
 
 	PR rtl-optimization/24883

gcc/testsuite/gcc.dg/fold-div-2.c

+/* { dg-do compile } */
+/* { dg-options "-ffinite-math-only -fdump-tree-gimple" } */
+
+double f(double x)
+{
+  return x / x;
+}
+
+/* Division should be turned into 1.0.  */
+
+/* { dg-final { scan-tree-dump-not " / " "gimple" } } */
+/* { dg-final { cleanup-tree-dump "gimple" } } */
+