[V2] PR varobj/18564 regression in showing __thread so extern variable

diff --git a/gdb/findvar.c b/gdb/findvar.c
index 1c077f7..fd1b9d7 100644
--- a/gdb/findvar.c
+++ b/gdb/findvar.c
@@ -739,14 +739,17 @@  default_read_var_value (struct symbol *var, const struct block *var_block,
 
 	if (msym == NULL)
 	  error (_("No global symbol \"%s\"."), SYMBOL_LINKAGE_NAME (var));
-	if (overlay_debugging)
-	  addr = symbol_overlayed_address (BMSYMBOL_VALUE_ADDRESS (lookup_data.result),
-					   MSYMBOL_OBJ_SECTION (lookup_data.result.objfile,
-								msym));
-	else
-	  addr = BMSYMBOL_VALUE_ADDRESS (lookup_data.result);
-
 	obj_section = MSYMBOL_OBJ_SECTION (lookup_data.result.objfile, msym);
+	/* Relocate address, unless there is no section or the variable is
+	   a TLS variable. */
+	if (obj_section == NULL
+	    || (obj_section->the_bfd_section->flags & SEC_THREAD_LOCAL) != 0)
+	   addr = MSYMBOL_VALUE_RAW_ADDRESS (msym);
+	else
+	   addr = BMSYMBOL_VALUE_ADDRESS (lookup_data.result);
+	if (overlay_debugging)
+	  addr = symbol_overlayed_address (addr, obj_section);
+	/* Determine address of TLS variable. */
 	if (obj_section
 	    && (obj_section->the_bfd_section->flags & SEC_THREAD_LOCAL) != 0)
 	  addr = target_translate_tls_address (obj_section->objfile, addr);
diff --git a/gdb/printcmd.c b/gdb/printcmd.c
index 5729b24..823f27b 100644
--- a/gdb/printcmd.c
+++ b/gdb/printcmd.c
@@ -1376,16 +1376,19 @@  address_info (char *exp, int from_tty)
 	else
 	  {
 	    section = MSYMBOL_OBJ_SECTION (msym.objfile, msym.minsym);
-	    load_addr = BMSYMBOL_VALUE_ADDRESS (msym);
 
 	    if (section
 		&& (section->the_bfd_section->flags & SEC_THREAD_LOCAL) != 0)
-	      printf_filtered (_("a thread-local variable at offset %s "
-				 "in the thread-local storage for `%s'"),
-			       paddress (gdbarch, load_addr),
-			       objfile_name (section->objfile));
+	      {
+		load_addr = MSYMBOL_VALUE_RAW_ADDRESS (msym.minsym);
+		printf_filtered (_("a thread-local variable at offset %s "
+				   "in the thread-local storage for `%s'"),
+				 paddress (gdbarch, load_addr),
+				 objfile_name (section->objfile));
+	      }
 	    else
 	      {
+		load_addr = BMSYMBOL_VALUE_ADDRESS (msym);
 		printf_filtered (_("static storage at address "));
 		fputs_filtered (paddress (gdbarch, load_addr), gdb_stdout);
 		if (section_is_overlay (section))
diff --git a/gdb/symtab.h b/gdb/symtab.h
index c6f26e7..d4a8e5f 100644
--- a/gdb/symtab.h
+++ b/gdb/symtab.h
@@ -584,7 +584,13 @@  enum address_class
      not find it in the full symbol table.  But a reference to an external
      symbol in a local block shadowing other definition requires full symbol
      without possibly having its address available for LOC_STATIC.  Testcase
-     is provided as `gdb.dwarf2/dw2-unresolved.exp'.  */
+     is provided as `gdb.dwarf2/dw2-unresolved.exp'.
+
+     This is also used for thread local storage (TLS) variables.  In this case,
+     the address of the TLS variable must be determined when the variable is
+     referenced, from the MSYMBOL_VALUE_RAW_ADDRESS, which is the offset
+     of the TLS variable in the thread local storage of the shared
+     library/object.  */
 
   LOC_UNRESOLVED,
 
diff --git a/gdb/testsuite/gdb.threads/tls-so_extern.c b/gdb/testsuite/gdb.threads/tls-so_extern.c
new file mode 100644
index 0000000..03febeb
--- /dev/null
+++ b/gdb/testsuite/gdb.threads/tls-so_extern.c
@@ -0,0 +1,19 @@ 
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2015 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/>.  */
+
+__thread void *so_extern;
+__thread void *so_extern2;
diff --git a/gdb/testsuite/gdb.threads/tls-so_extern.exp b/gdb/testsuite/gdb.threads/tls-so_extern.exp
new file mode 100644
index 0000000..35a55f0
--- /dev/null
+++ b/gdb/testsuite/gdb.threads/tls-so_extern.exp
@@ -0,0 +1,81 @@ 
+# Copyright 2003-2015 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/>.  */
+
+# tls-so_extern.exp -- Expect script to test thread local storage in gdb, with
+# a variable defined in a shared library.
+
+standard_testfile tls-so_extern_main.c
+set libfile tls-so_extern
+set srcfile_lib ${libfile}.c
+set binfile_lib [standard_output_file ${libfile}.so]
+
+
+# get the value of gcc_compiled
+if [get_compiler_info] {
+    return -1
+}
+
+
+if { [gdb_compile_shlib_pthreads ${srcdir}/${subdir}/${srcfile_lib} ${binfile_lib} {debug}] != ""
+     || [gdb_compile_pthreads ${srcdir}/${subdir}/${srcfile} ${binfile} executable [list debug shlib=${binfile_lib}]] != ""} {
+    return -1
+}
+
+
+clean_restart ${binfile}
+gdb_load_shlibs ${binfile_lib}
+
+if ![runto_main] then {
+    fail "Can't run to main"
+    return 0
+}
+
+gdb_test "print so_extern" "0x0" "print thread local storage variable"
+
+gdb_test "ptype so_extern" "void \\*" "ptype of thread local storage variable"
+
+gdb_test "info address so_extern" \
+	"Symbol \\\"so_extern\\\" is a thread-local variable at offset 0x0 in the thread-local storage for .*tls-so_extern.*" \
+	"print storage info for thread local storage variable"
+
+set line_number [gdb_get_line_number "break here to check result"]
+
+gdb_test "break $line_number" \
+	"Breakpoint.*at.*file.*tls-so_extern_main.c.*line ${line_number}." \
+	"break in thread function"
+gdb_test "continue" \
+	"tls_ptr .* at .*:.*break here to check result.*" \
+        "continue to break in tls_ptr called by main"
+gdb_test "print so_extern == &so_extern" \
+         " = 1" \
+        "check so_extern address in main"
+gdb_test "continue" \
+	"tls_ptr .* at .*:.*break here to check result.*" \
+        "continue to break in a thread"
+gdb_test "print so_extern == &so_extern" \
+         " = 1" \
+        "check so_extern address"
+gdb_test "continue" \
+	"tls_ptr .* at .*:.*break here to check result.*" \
+        "continue to break in the other thread"
+gdb_test "print so_extern == &so_extern" \
+         " = 1" \
+        "check so_extern address in other thread"
+gdb_test "continue" \
+	"tls_ptr .* at .*:.*break here to check result.*" \
+        "continue to break in tls_ptr called at end of main"
+gdb_test "print so_extern == &so_extern" \
+         " = 1" \
+        "check so_extern address at end of main"
diff --git a/gdb/testsuite/gdb.threads/tls-so_extern_main.c b/gdb/testsuite/gdb.threads/tls-so_extern_main.c
new file mode 100644
index 0000000..ab70faf
--- /dev/null
+++ b/gdb/testsuite/gdb.threads/tls-so_extern_main.c
@@ -0,0 +1,47 @@ 
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2015 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/>.  */
+
+#include <pthread.h>
+
+extern __thread void *so_extern;
+extern __thread void *so_extern2;
+
+static void *
+tls_ptr (void *p)
+{
+   so_extern = &so_extern;
+   so_extern2 = &so_extern2; /* break here to check result */
+}
+
+int
+main (void)
+{
+   pthread_t threads[2];
+
+   tls_ptr (NULL);
+
+   pthread_create (&threads[0], NULL, tls_ptr, NULL);
+   pthread_create (&threads[1], NULL, tls_ptr, NULL);
+
+   pthread_join (threads[0], NULL);
+   pthread_join (threads[1], NULL);
+
+   tls_ptr (NULL);
+
+   return 0;
+}
+