diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index d9238215dfad..7a64192a6d7a 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2010-12-16  Jakub Jelinek  <jakub@redhat.com>
+
+	PR debug/46893
+	* cfgexpand.c (expand_debug_expr): If GET_MODE (op0) is VOIDmode,
+	use TYPE_MODE (TREE_TYPE (tem)) instead of mode1.
+
 2010-12-16  Chung-Lin Tang  <cltang@codesourcery.com>
 
 	PR target/46883
diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index 6cc5d01912fc..a3940d01775f 100644
--- a/gcc/cfgexpand.c
+++ b/gcc/cfgexpand.c
@@ -2703,7 +2703,7 @@ expand_debug_expr (tree exp)
 	    enum machine_mode opmode = GET_MODE (op0);
 
 	    if (opmode == VOIDmode)
-	      opmode = mode1;
+	      opmode = TYPE_MODE (TREE_TYPE (tem));
 
 	    /* This condition may hold if we're expanding the address
 	       right past the end of an array that turned out not to
@@ -2724,7 +2724,8 @@ expand_debug_expr (tree exp)
 				     ? SIGN_EXTRACT
 				     : ZERO_EXTRACT, mode,
 				     GET_MODE (op0) != VOIDmode
-				     ? GET_MODE (op0) : mode1,
+				     ? GET_MODE (op0)
+				     : TYPE_MODE (TREE_TYPE (tem)),
 				     op0, GEN_INT (bitsize), GEN_INT (bitpos));
       }
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 8645df9e4b2f..df48e936b24e 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2010-12-16  Jakub Jelinek  <jakub@redhat.com>
+
+	PR debug/46893
+	* gcc.dg/pr46893.c: New test.
+
 2010-12-16  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR lto/46976
diff --git a/gcc/testsuite/gcc.dg/pr46893.c b/gcc/testsuite/gcc.dg/pr46893.c
new file mode 100644
index 000000000000..ef97e2edfd2a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr46893.c
@@ -0,0 +1,13 @@
+/* PR debug/46893 */
+/* { dg-do compile } */
+/* { dg-options "-O -g" } */
+
+void
+foo (void)
+{
+  union { unsigned long long l; double d; } u = { 0x7ff0000000000000ULL };
+  double v = 0, w = -u.d;
+
+  if (w)
+    w = v;
+}