re PR target/69071 (ICE: in decompose, at rtl.h:2107 with -g)

	PR target/69071
	* lra-eliminations.c (move_plus_up): Only move plus up
	if subreg of the constant can be simplified into constant
	and use the simplified subreg of the constant instead of
	the original constant.

	* gcc.dg/pr69071.c: New test.

From-SVN: r232241

gcc/ChangeLog

 2016-01-11  Jakub Jelinek  <jakub@redhat.com>
 
+	PR target/69071
+	* lra-eliminations.c (move_plus_up): Only move plus up
+	if subreg of the constant can be simplified into constant
+	and use the simplified subreg of the constant instead of
+	the original constant.
+
 	* fold-const.c (fold_convertible_p): Don't return true
 	for conversion of VECTOR_TYPE to same sized integral type.
 	(fold_convert_loc): Fix up formatting.  Fold conversion of

gcc/lra-eliminations.c

@@ -296,9 +296,14 @@ move_plus_up (rtx x)
   if (GET_CODE (x) == SUBREG && GET_CODE (subreg_reg) == PLUS
       && GET_MODE_SIZE (x_mode) <= GET_MODE_SIZE (subreg_reg_mode)
       && CONSTANT_P (XEXP (subreg_reg, 1)))
-    return gen_rtx_PLUS (x_mode, lowpart_subreg (x_mode, subreg_reg,
-						 subreg_reg_mode),
-			 XEXP (subreg_reg, 1));
+    {
+      rtx cst = simplify_subreg (x_mode, XEXP (subreg_reg, 1), subreg_reg_mode,
+				 subreg_lowpart_offset (x_mode,
+							subreg_reg_mode));
+      if (cst && CONSTANT_P (cst))
+	return gen_rtx_PLUS (x_mode, lowpart_subreg (x_mode, subreg_reg,
+						     subreg_reg_mode), cst);
+    }
   return x;
 }
 

gcc/testsuite/ChangeLog

 2016-01-11  Jakub Jelinek  <jakub@redhat.com>
 
+	PR target/69071
+	* gcc.dg/pr69071.c: New test.
+
 	PR c++/69211
 	* g++.dg/opt/pr69211.C: New test.
 

gcc/testsuite/gcc.dg/pr69071.c

+/* PR target/69071 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -g" } */
+
+void *bar (void *);
+
+void
+foo (int c)
+{
+  unsigned char bf[65400];
+  unsigned char *p2 = bar (bf);
+  unsigned char *p3 = bar (bf);
+  for (; *p2; p2++, c++)
+    {
+      if (c)
+	{
+	  short of = p2 - bf - 6;
+	  unsigned ofu = of;
+	  __builtin_memcpy (p3, &ofu, sizeof (ofu));
+	}
+    }
+}