re PR rtl-optimization/45728 (ICE: in gen_lowpart_general, at rtlhooks.c:59 at -O1 when comparing union members)

PR rtl-optimization/45728
	* expr.c (expand_expr_real_1): If op0 isn't REG or MEM, try
	gen_lowpart_common first and if that fails, force_reg first
	before calling gen_lowpart.

	* gcc.c-torture/compile/pr45728.c: New test.

From-SVN: r164456

gcc/ChangeLog

@@ -1,5 +1,10 @@
 2010-09-20  Jakub Jelinek  <jakub@redhat.com>
 
+	PR rtl-optimization/45728
+	* expr.c (expand_expr_real_1): If op0 isn't REG or MEM, try
+	gen_lowpart_common first and if that fails, force_reg first
+	before calling gen_lowpart.
+
 	PR middle-end/45678
 	* cfgexpand.c (expand_one_stack_var_at): Use
 	crtl->max_used_stack_slot_alignment as max_align, instead

gcc/expr.c

@@ -9381,7 +9381,15 @@ expand_expr_real_1 (tree exp, rtx target, enum machine_mode tmode,
 	{
 	  if (GET_CODE (op0) == SUBREG)
 	    op0 = force_reg (GET_MODE (op0), op0);
-	  op0 = gen_lowpart (mode, op0);
+	  temp = gen_lowpart_common (mode, op0);
+	  if (temp)
+	    op0 = temp;
+	  else
+	    {
+	      if (!REG_P (op0) && !MEM_P (op0))
+		op0 = force_reg (GET_MODE (op0), op0);
+	      op0 = gen_lowpart (mode, op0);
+	    }
 	}
       /* If both types are integral, convert from one mode to the other.  */
       else if (INTEGRAL_TYPE_P (type) && INTEGRAL_TYPE_P (TREE_TYPE (treeop0)))

gcc/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2010-09-20  Jakub Jelinek  <jakub@redhat.com>
+
+	PR rtl-optimization/45728
+	* gcc.c-torture/compile/pr45728.c: New test.
+
 2010-09-20  Paul Thomas  <pault@gcc.gnu.org>
 
 	PR fortran/45081

gcc/testsuite/gcc.c-torture/compile/pr45728.c

@@ -0,0 +1,17 @@
+/* PR rtl-optimization/45728 */
+
+union U
+{
+  int *m;
+  double d;
+};
+
+int i;
+union U u;
+
+int
+foo (void)
+{
+  union U v = { &i };
+  return u.d == v.d;
+}