c-typeck.c (build_c_cast): Try using a shared constant...

2005-11-07  Paolo Bonzini  <bonzini@gnu.org>

        * c-typeck.c (build_c_cast): Try using a shared constant, and see
        if TREE_OVERFLOW or TREE_CONSTANT_OVERFLOW really changed.

testsuite:
2005-11-07  Paolo Bonzini  <bonzini@gnu.org>

        * gcc.dg/overflow-2.c: New testcase.

From-SVN: r106587

gcc/ChangeLog

+2005-11-07  Paolo Bonzini  <bonzini@gnu.org>
+
+        * c-typeck.c (build_c_cast): Try using a shared constant, and see
+        if TREE_OVERFLOW or TREE_CONSTANT_OVERFLOW really changed.
+
 2005-11-07  Jakub Jelinek  <jakub@redhat.com>
 
 	PR rtl-optimization/23567

gcc/c-typeck.c

@@ -3500,16 +3500,19 @@ build_c_cast (tree type, tree expr)
       /* Ignore any integer overflow caused by the cast.  */
       if (TREE_CODE (value) == INTEGER_CST)
 	{
-	  /* If OVALUE had overflow set, then so will VALUE, so it
-	     is safe to overwrite.  */
-	  if (CONSTANT_CLASS_P (ovalue))
+	  if (CONSTANT_CLASS_P (ovalue)
+	      && (TREE_OVERFLOW (ovalue) || TREE_CONSTANT_OVERFLOW (ovalue)))
 	    {
+	      /* Avoid clobbering a shared constant.  */
+	      value = copy_node (value);
 	      TREE_OVERFLOW (value) = TREE_OVERFLOW (ovalue);
-	      /* Similarly, constant_overflow cannot have become cleared.  */
 	      TREE_CONSTANT_OVERFLOW (value) = TREE_CONSTANT_OVERFLOW (ovalue);
 	    }
-	  else
-	    TREE_OVERFLOW (value) = 0;
+	  else if (TREE_OVERFLOW (value) || TREE_CONSTANT_OVERFLOW (value))
+	    /* Reset VALUE's overflow flags, ensuring constant sharing.  */
+	    value = build_int_cst_wide (TREE_TYPE (value),
+					TREE_INT_CST_LOW (value),
+					TREE_INT_CST_HIGH (value));
 	}
     }
 

gcc/testsuite/ChangeLog

+2005-11-07  Paolo Bonzini  <bonzini@gnu.org>
+
+        * gcc.dg/overflow-2.c: New testcase.
+
 2005-11-07  Jakub Jelinek  <jakub@redhat.com>
 
 	PR rtl-optimization/23567

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

+/* { dg-do compile } */
+/* { dg-options "-std=c99 -pedantic-errors" } */
+
+/* PR c/24599 */
+
+int
+main (void)
+{
+  if ((_Bool)(__INT_MAX__ + 1)) /* { dg-warning "overflow in expression" } */
+    return 1;
+  else
+    return 0;
+}