re PR tree-optimization/34027 (-Os code size nearly doubled)

2007-11-12  Richard Guenther  <rguenther@suse.de>

	PR middle-end/34027
	* fold-const.c (fold_binary): Fold n - (n / m) * m to n % m.
	(fold_binary): Fold unsinged FLOOR_DIV_EXPR to TRUNC_DIV_EXPR.

	* gcc.dg/pr34027-1.c: New testcase.
	* gcc.dg/pr34027-2.c: Likewise.

From-SVN: r130097

gcc/ChangeLog

+2007-11-12  Richard Guenther  <rguenther@suse.de>
+
+	PR middle-end/34027
+	* fold-const.c (fold_binary): Fold n - (n / m) * m to n % m.
+	(fold_binary): Fold unsinged FLOOR_DIV_EXPR to TRUNC_DIV_EXPR.
+
+	* gcc.dg/pr34027-1.c: New testcase.
+	* gcc.dg/pr34027-2.c: Likewise.
+
 2007-11-12  Ira Rosen  <irar@il.ibm.com>
 
 	PR tree-optimization/33953

gcc/fold-const.c

@@ -9653,6 +9653,21 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1)
 		  return omit_one_operand (type, t1, arg0);
 		}
 	    }
+
+	  /* X + (X / CST) * -CST is X % CST.  */
+	  if (TREE_CODE (arg1) == MULT_EXPR
+	      && TREE_CODE (TREE_OPERAND (arg1, 0)) == TRUNC_DIV_EXPR
+	      && operand_equal_p (arg0,
+				  TREE_OPERAND (TREE_OPERAND (arg1, 0), 0), 0))
+	    {
+	      tree cst0 = TREE_OPERAND (TREE_OPERAND (arg1, 0), 1);
+	      tree cst1 = TREE_OPERAND (arg1, 1);
+	      tree sum = fold_binary (PLUS_EXPR, TREE_TYPE (cst1), cst1, cst0);
+	      if (sum && integer_zerop (sum))
+		return fold_convert (type,
+				     fold_build2 (TRUNC_MOD_EXPR,
+						  TREE_TYPE (arg0), arg0, cst0));
+	    }
 	}
 
       /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
@@ -10061,6 +10076,19 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1)
 	  && integer_all_onesp (arg0))
 	return fold_build1 (BIT_NOT_EXPR, type, op1);
 
+
+      /* X - (X / CST) * CST is X % CST.  */
+      if (INTEGRAL_TYPE_P (type)
+	  && TREE_CODE (arg1) == MULT_EXPR
+	  && TREE_CODE (TREE_OPERAND (arg1, 0)) == TRUNC_DIV_EXPR
+	  && operand_equal_p (arg0,
+			      TREE_OPERAND (TREE_OPERAND (arg1, 0), 0), 0)
+	  && operand_equal_p (TREE_OPERAND (TREE_OPERAND (arg1, 0), 1),
+			      TREE_OPERAND (arg1, 1), 0))
+	return fold_convert (type,
+			     fold_build2 (TRUNC_MOD_EXPR, TREE_TYPE (arg0),
+					  arg0, TREE_OPERAND (arg1, 1)));
+
       if (! FLOAT_TYPE_P (type))
 	{
 	  if (integer_zerop (arg0))
@@ -11221,6 +11249,14 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1)
 				  fold_convert (type, arg0), sh_cnt);
 	    }
 	}
+
+      /* For unsigned integral types, FLOOR_DIV_EXPR is the same as
+	 TRUNC_DIV_EXPR.  Rewrite into the latter in this case.  */
+      if (INTEGRAL_TYPE_P (type)
+	  && TYPE_UNSIGNED (type)
+	  && code == FLOOR_DIV_EXPR)
+	return fold_build2 (TRUNC_DIV_EXPR, type, op0, op1);
+
       /* Fall thru */
 
     case ROUND_DIV_EXPR:

gcc/testsuite/ChangeLog

+2007-11-12  Richard Guenther  <rguenther@suse.de>
+
+	PR middle-end/34027
+	* gcc.dg/pr34027-1.c: New testcase.
+	* gcc.dg/pr34027-2.c: Likewise.
+
 2007-11-12  Ira Rosen  <irar@il.ibm.com>
 
 	PR tree-optimization/33953

gcc/testsuite/gcc.dg/pr34027-1.c

+/* { dg-do compile } */
+/* { dg-options "-Os -fdump-tree-optimized" } */
+
+unsigned long foobar(unsigned long ns)
+{
+  while(ns >= 10000L)
+    ns -= 10000L;
+  return ns;
+}
+
+/* { dg-final { scan-tree-dump "ns % 10000" "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */

gcc/testsuite/gcc.dg/pr34027-2.c

+/* { dg-do compile } */
+/* { dg-options "-fdump-tree-gimple" } */
+
+long foo(long n, long m)
+{
+  return n - (n / m) * m;
+}
+
+/* { dg-final { scan-tree-dump "n % m" "gimple" } } */
+/* { dg-final { cleanup-tree-dump "gimple" } } */