[RFA] Fix size check in dwarf2_evaluate_loc_desc_full

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index fd52229..e331f4a 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@ 
+2017-05-29  Tom Tromey  <tom@tromey.com>
+
+	* dwarf2loc.c (dwarf2_evaluate_loc_desc_full): Reverse size
+	check and apply to outer type.
+
 2017-05-26  Alan Hayward  <alan.hayward@arm.com>
 
 	* defs.h (copy_integer_to_size): New declaration.
diff --git a/gdb/dwarf2loc.c b/gdb/dwarf2loc.c
index 127167d..9ffe197 100644
--- a/gdb/dwarf2loc.c
+++ b/gdb/dwarf2loc.c
@@ -2407,7 +2407,9 @@  dwarf2_evaluate_loc_desc_full (struct type *type, struct frame_info *frame,
 
       for (i = 0; i < ctx.num_pieces; ++i)
 	bit_size += ctx.pieces[i].size;
-      if (8 * (subobj_byte_offset + TYPE_LENGTH (subobj_type)) > bit_size)
+      /* Complain if the expression is larger than the size of the
+	 outer type.  */
+      if (bit_size > 8 * TYPE_LENGTH (type))
 	invalid_synthetic_pointer ();
 
       c = allocate_piece_closure (per_cu, ctx.num_pieces, ctx.pieces,
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index c16f201..d31679a 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,7 @@ 
+2017-05-29  Tom Tromey  <tom@tromey.com>
+
+	* gdb.dwarf2/shortpiece.exp: New file.
+
 2017-05-21  Tom Tromey  <tom@tromey.com>
 
 	PR rust/21466:
diff --git a/gdb/testsuite/gdb.dwarf2/shortpiece.exp b/gdb/testsuite/gdb.dwarf2/shortpiece.exp
new file mode 100644
index 0000000..8526a70
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/shortpiece.exp
@@ -0,0 +1,100 @@ 
+# Copyright 2017 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+load_lib dwarf.exp
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+if {![dwarf2_support]} {
+    return 0
+}
+
+standard_testfile main.c shortpiece-dw.S
+
+# Make some DWARF for the test.
+set asm_file [standard_output_file $srcfile2]
+Dwarf::assemble $asm_file {
+    global pair
+
+    cu { addr_size 4 } {
+	compile_unit {} {
+	    declare_labels int_label ushort_label struct_label
+
+	    int_label: DW_TAG_base_type {
+		{DW_AT_byte_size 4 DW_FORM_udata}
+		{DW_AT_encoding @DW_ATE_unsigned}
+		{DW_AT_name "myint"}
+	    }
+	    ushort_label: DW_TAG_base_type {
+		{DW_AT_byte_size 2 DW_FORM_udata}
+		{DW_AT_encoding @DW_ATE_unsigned}
+		{DW_AT_name "myushort"}
+	    }
+
+	    struct_label: DW_TAG_structure_type {
+		{DW_AT_name "S"}
+		{DW_AT_byte_size 8 DW_FORM_udata}
+	    } {
+		DW_TAG_member {
+		    {DW_AT_name "a"}
+		    {DW_AT_type :${int_label}}
+		    {DW_AT_data_member_location 0 DW_FORM_udata}
+		}
+
+		DW_TAG_member {
+		    {DW_AT_name "b"}
+		    {DW_AT_type :${ushort_label}}
+		    {DW_AT_data_member_location 4 DW_FORM_udata}
+		}
+	    }
+
+	    DW_TAG_variable {
+		{DW_AT_name "s1"}
+		{DW_AT_type :${struct_label}}
+		{DW_AT_external 1 DW_FORM_flag}
+		{DW_AT_location {
+		    DW_OP_constu 1
+		    DW_OP_stack_value
+		    DW_OP_piece 4
+		    DW_OP_constu 0
+		    DW_OP_stack_value
+		    DW_OP_piece 2
+		} SPECIAL_expr}
+	    }
+
+	    DW_TAG_variable {
+		{DW_AT_name "s2"}
+		{DW_AT_type :${struct_label}}
+		{DW_AT_external 1 DW_FORM_flag}
+		{DW_AT_location {
+		    DW_OP_constu 1
+		    DW_OP_stack_value
+		    DW_OP_piece 4
+		    DW_OP_constu 0
+		    DW_OP_stack_value
+		    DW_OP_piece 8
+		} SPECIAL_expr}
+	    }
+	}
+    }
+}
+
+if { [prepare_for_testing "failed to prepare" ${testfile} \
+			  [list $srcfile $asm_file] {nodebug}] } {
+    return -1
+}
+
+gdb_test "p s1" " = {a = 1, b = 0}"
+gdb_test "p s2" \
+    "access outside bounds of object referenced via synthetic pointer"