diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index b3cc6305578124cc7d03f83c7e6a1fe49b0bfbde..ef945b1d3fbe9633101b4ba1280d3a5dc3fb8c48 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,11 @@
 2016-12-01  Jakub Jelinek  <jakub@redhat.com>
 
+	PR debug/78587
+	* dwarf2out.c (loc_descr_plus_const): For negative offset use
+	uint_loc_descriptor instead of int_loc_descriptor and perform negation
+	in unsigned HOST_WIDE_INT type.
+	(scompare_loc_descriptor): Shift UINTVAL left instead of INTVAL.
+
 	PR target/78614
 	* config/rs6000/rs6000.c (rs6000_frame_related): Call
 	set_used_flags (pat) before any simplifications.  Clear used flag on
diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index 66a4919187db718954c995dcb6b21c3b28e6aa33..bc328ab2ec6526330a4066cf2950d955d204627e 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -1514,7 +1514,8 @@ loc_descr_plus_const (dw_loc_descr_ref *list_head, HOST_WIDE_INT offset)
 
   else
     {
-      loc->dw_loc_next = int_loc_descriptor (-offset);
+      loc->dw_loc_next
+	= uint_loc_descriptor (-(unsigned HOST_WIDE_INT) offset);
       add_loc_descr (&loc->dw_loc_next, new_loc_descr (DW_OP_minus, 0, 0));
     }
 }
@@ -13837,7 +13838,7 @@ scompare_loc_descriptor (enum dwarf_location_atom op, rtx rtl,
       if (CONST_INT_P (XEXP (rtl, 1))
 	  && GET_MODE_BITSIZE (op_mode) < HOST_BITS_PER_WIDE_INT
 	  && (size_of_int_loc_descriptor (shift) + 1
-	      + size_of_int_loc_descriptor (INTVAL (XEXP (rtl, 1)) << shift)
+	      + size_of_int_loc_descriptor (UINTVAL (XEXP (rtl, 1)) << shift)
 	      >= size_of_int_loc_descriptor (GET_MODE_MASK (op_mode)) + 1
 		 + size_of_int_loc_descriptor (INTVAL (XEXP (rtl, 1))
 					       & GET_MODE_MASK (op_mode))))
@@ -13852,7 +13853,7 @@ scompare_loc_descriptor (enum dwarf_location_atom op, rtx rtl,
   add_loc_descr (&op0, int_loc_descriptor (shift));
   add_loc_descr (&op0, new_loc_descr (DW_OP_shl, 0, 0));
   if (CONST_INT_P (XEXP (rtl, 1)))
-    op1 = int_loc_descriptor (INTVAL (XEXP (rtl, 1)) << shift);
+    op1 = int_loc_descriptor (UINTVAL (XEXP (rtl, 1)) << shift);
   else
     {
       add_loc_descr (&op1, int_loc_descriptor (shift));
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index bf4bd8ac218086bcd22eddf041bd612adb2c7617..2d1c182f14a4936e191961f10126bc0efff9a819 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2016-12-01  Jakub Jelinek  <jakub@redhat.com>
+
+	PR debug/78587
+	* gcc.dg/debug/pr78587.c: New test.
+
 2016-12-01  Segher Boessenkool  <segher@kernel.crashing.org>
 
 	PR rtl-optimization/78607
diff --git a/gcc/testsuite/gcc.dg/debug/pr78587.c b/gcc/testsuite/gcc.dg/debug/pr78587.c
new file mode 100644
index 0000000000000000000000000000000000000000..b368a2ad71cdb8372f6a15c8cf9259606cf208ba
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/debug/pr78587.c
@@ -0,0 +1,23 @@
+/* PR debug/78587 */
+/* { dg-do compile } */
+/* { dg-additional-options "-w" } */
+
+extern void bar (void);
+
+void
+foo (long long x)
+{
+  x ^= 9223372036854775808ULL;
+  bar ();
+}
+
+struct S { int w[4]; } a[1], b;
+
+void
+baz ()
+{
+  int e = (int) baz;
+  if (e <= -80)
+    e = 0;
+  b = a[e];
+}