re PR middle-end/16790 (Integer down cast ignored in larger expression)

	PR middle-end/16790
	* fold-const.c (extract_muldiv_1) <NOP_EXPR>: Disallow local
	truncations, not just global truncations.

	* gcc.c-torture/execute/pr16790-1.c: New test case.

From-SVN: r85506

gcc/ChangeLog

+2004-08-03  Roger Sayle  <roger@eyesopen.com>
+
+	PR middle-end/16790
+	* fold-const.c (extract_muldiv_1) <NOP_EXPR>: Disallow local
+	truncations, not just global truncations.
+
 2004-08-03  Andrew Pinski  <apinski@apple.com>
 
 	PR bootstrap/16865

gcc/fold-const.c

@@ -5102,9 +5102,9 @@ extract_muldiv_1 (tree t, tree c, enum tree_code code, tree wide_type)
 		     && TYPE_IS_SIZETYPE (TREE_TYPE (op0)))
 	       && (GET_MODE_SIZE (TYPE_MODE (ctype))
 	           > GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (op0)))))
-	      /* ... or its type is larger than ctype,
-		 then we cannot pass through this truncation.  */
-	      || (GET_MODE_SIZE (TYPE_MODE (ctype))
+	      /* ... or this is a truncation (t is narrower than op0),
+		 then we cannot pass through this narrowing.  */
+	      || (GET_MODE_SIZE (TYPE_MODE (type))
 		  < GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (op0))))
 	      /* ... or signedness changes for division or modulus,
 		 then we cannot pass through this conversion.  */

gcc/testsuite/ChangeLog

+2004-08-03  Roger Sayle  <roger@eyesopen.com>
+
+	PR middle-end/16790
+	* gcc.c-torture/execute/pr16790-1.c: New test case.
+
 2004-08-03  Mark Mitchell  <mark@codesourcery.com>
 
 	* gcc.dg/symbian1.c: New test.

gcc/testsuite/gcc.c-torture/execute/pr16790-1.c

+/* PR middle-end/16790.  */
+
+extern void abort ();
+
+static void test1(unsigned int u1)
+{
+  unsigned int y_final_1;
+  signed short y_middle;
+  unsigned int y_final_2;
+
+  y_final_1 = (unsigned int)( (signed short)(u1 * 2) * 3 );
+  y_middle  =                 (signed short)(u1 * 2);
+  y_final_2 = (unsigned int)( y_middle * 3 );
+
+  if (y_final_1 != y_final_2)
+    abort ();
+}
+
+
+static void test2(unsigned int u1)
+{
+  unsigned int y_final_1;
+  signed short y_middle;
+  unsigned int y_final_2;
+
+  y_final_1 = (unsigned int)( (signed short)(u1 << 1) * 3 );
+  y_middle  =                 (signed short)(u1 << 1);
+  y_final_2 = (unsigned int)( y_middle * 3 );
+
+  if (y_final_1 != y_final_2)
+    abort ();
+}
+
+
+int main()
+{
+  test1(0x4000U);
+  test2(0x4000U);
+  return 0;
+}
+