re PR c/50565 (initializer element is not computable at load time)

	PR c/50565
	* convert.c (convert_to_integer): Do not narrow operands of
	pointer subtraction.

testsuite:
	* gcc.c-torture/compile/pr50565-1.c,
	gcc.c-torture/compile/pr50565-2.c: New tests.

From-SVN: r179845

gcc/ChangeLog

+2011-10-12  Joseph Myers  <joseph@codesourcery.com>
+
+	PR c/50565
+	* convert.c (convert_to_integer): Do not narrow operands of
+	pointer subtraction.
+
 2011-10-12  Nick Clifton  <nickc@redhat.com>
 
 	* config/arm/arm.h (EMIT_EABI_ATTRIBUTE): New macro.  Used to

gcc/convert.c

@@ -745,6 +745,15 @@ convert_to_integer (tree type, tree expr)
 	    tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
 	    tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
 
+	    /* Do not try to narrow operands of pointer subtraction;
+	       that will interfere with other folding.  */
+	    if (ex_form == MINUS_EXPR
+		&& CONVERT_EXPR_P (arg0)
+		&& CONVERT_EXPR_P (arg1)
+		&& POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (arg0, 0)))
+		&& POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (arg1, 0))))
+	      break;
+
 	    if (outprec >= BITS_PER_WORD
 		|| TRULY_NOOP_TRUNCATION (outprec, inprec)
 		|| inprec > TYPE_PRECISION (TREE_TYPE (arg0))

gcc/testsuite/ChangeLog

+2011-10-12  Joseph Myers  <joseph@codesourcery.com>
+
+	PR c/50565
+	* gcc.c-torture/compile/pr50565-1.c,
+	gcc.c-torture/compile/pr50565-2.c: New tests.
+
 2011-10-11  Jason Merrill  <jason@redhat.com>
 
 	PR c++/49855

gcc/testsuite/gcc.c-torture/compile/pr50565-1.c

+struct s { char p[2]; };
+static struct s v;
+const int o0 = (int) ((void *) &v.p[0] - (void *) &v) + 0U;
+const int o1 = (int) ((void *) &v.p[0] - (void *) &v) + 1U;

gcc/testsuite/gcc.c-torture/compile/pr50565-2.c

+struct s { char p[2]; };
+static struct s v;
+const int o0 = (int) ((void *) &v.p[0] - (void *) &v) + 0;
+const int o1 = (int) ((void *) &v.p[0] - (void *) &v) + 1;