PR symtab/15885

* dwarf2read.c (dw2_dump): Print some minimal information indicating
	.gdb_index is in use.
	* symfile.c (reread_symbols): Reset objfile->sf.

	testsuite/
	* gdb.dwarf2/Makefile.in (EXECUTABLES): Add gdb-index.
	(clean): rm -f *.gdb-index *.with-index.
	* gdb.dwarf2/gdb-index.exp: New testcase.

gdb/ChangeLog

@@ -1,5 +1,10 @@
 2013-08-26  Doug Evans  <dje@google.com>
 
+	PR symtab/15885
+	* dwarf2read.c (dw2_dump): Print some minimal information indicating
+	.gdb_index is in use.
+	* symfile.c (reread_symbols): Reset objfile->sf.
+
 	* NEWS: Document "mt print objfiles" now takes optional regexp.
 	* symmisc.c (maintenance_print_objfiles): Argument is now an optional
 	regexp of objfiles to print.

gdb/dwarf2read.c

@@ -3357,10 +3357,25 @@ dw2_print_stats (struct objfile *objfile)
   printf_filtered (_("  Number of unread CUs: %d\n"), count);
 }
 
+/* This dumps minimal information about the index.
+   It is called via "mt print objfiles".
+   One use is to verify .gdb_index has been loaded by the
+   gdb.dwarf2/gdb-index.exp testcase.  */
+
 static void
 dw2_dump (struct objfile *objfile)
 {
-  /* Nothing worth printing.  */
+  dw2_setup (objfile);
+  gdb_assert (dwarf2_per_objfile->using_index);
+  printf_filtered (".gdb_index:");
+  if (dwarf2_per_objfile->index_table != NULL)
+    {
+      printf_filtered (" version %d\n",
+		       dwarf2_per_objfile->index_table->version);
+    }
+  else
+    printf_filtered (" faked for \"readnow\"\n");
+  printf_filtered ("\n");
 }
 
 static void

gdb/symfile.c

@@ -2504,6 +2504,12 @@ reread_symbols (void)
 	     empty.  We could use obstack_specify_allocation but
 	     gdb_obstack.h specifies the alloc/dealloc functions.  */
 	  obstack_init (&objfile->objfile_obstack);
+
+	  /* Reset the sym_fns pointer.  The ELF reader can change it
+	     based on whether .gdb_index is present, and we need it to
+	     start over.  PR symtab/15885  */
+	  objfile->sf = find_sym_fns (objfile->obfd);
+
 	  build_objfile_section_table (objfile);
 	  terminate_minimal_symbol_table (objfile);
 

gdb/testsuite/ChangeLog

@@ -1,5 +1,10 @@
 2013-08-26  Doug Evans  <dje@google.com>
 
+	PR symtab/15885
+	* gdb.dwarf2/Makefile.in (EXECUTABLES): Add gdb-index.
+	(clean): rm -f *.gdb-index *.with-index.
+	* gdb.dwarf2/gdb-index.exp: New testcase.
+
 	* lib/gdb.exp (run_on_host): Moved here from gnu-debugdata.exp.
 	* gdb.base/gnu-debugdata.exp (run): Moved to gdb.exp and renamed to
 	run_on_host.  All callers updated.

gdb/testsuite/gdb.dwarf2/Makefile.in

@@ -21,7 +21,7 @@ VPATH = @srcdir@
 srcdir = @srcdir@
 
 EXECUTABLES = *.x pr10770 dw2-cp-infcall-ref-static dw2-inline-param \
-	dw2-noloc dw2-ranges dw2-ref-missing-frame dw2-unresolved
+	dw2-noloc dw2-ranges dw2-ref-missing-frame dw2-unresolved gdb-index
 
 all info install-info dvi install uninstall installcheck check:
 	@echo "Nothing to be done for $@..."
@@ -31,6 +31,7 @@ clean mostlyclean:
 	-rm -f core core.coremaker coremaker.core corefile
 	-rm -f *.dwo *.dwp
 	-rm -f $(EXECUTABLES)
+	-rm -f *.gdb-index *.with-index
 
 distclean maintainer-clean realclean: clean
 	-rm -f *~ core

gdb/testsuite/gdb.dwarf2/gdb-index.exp

@@ -0,0 +1,101 @@
+# Copyright 2013 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.
+if {![dwarf2_support]} {
+    return 0
+}
+
+standard_testfile main.c
+
+if { [prepare_for_testing "${testfile}.exp" "${testfile}" \
+	  [list ${srcfile}]] } {
+    return -1
+}
+
+# Add a .gdb_index section to PROGRAM.
+# PROGRAM is assumed to be the output of standard_output_file.
+# Returns the path of the program or "" if there is a failure.
+# If there is a failure it will have already been logged.
+
+proc add_gdb_index { program } {
+    set index_file ${program}.gdb-index
+    verbose -log "index_file: ${index_file}"
+    remote_file host delete ${index_file}
+    gdb_test_no_output "save gdb-index [file dirname ${index_file}]"
+
+    # No point in continuing if generating the index failed.
+    # N.B.: There are times when gdb won't create an index, and it's not a
+    # failure.  However, in our case we need an index.  So if you find one
+    # not being generated, you'll either have to tweak the .c file or maybe
+    # add a flag to force an index to be generated.
+    if { [remote_file host exists ${index_file}] } {
+	pass "gdb-index file created"
+    } else {
+	fail "gdb-index file created"
+	return ""
+    }
+
+    set program_with_index ${program}.with-index
+    if {[run_on_host "objcopy" [transform objcopy] "--remove-section .gdb_index --add-section .gdb_index=$index_file --set-section-flags .gdb_index=readonly ${program} ${program_with_index}"]} {
+	return ""
+    }
+    return ${program_with_index}
+}
+
+# Build a copy of the program with .gdb_index.
+# But only if the toolchain didn't already create one: gdb doesn't support
+# building an index from a program already using one.
+
+set test "check if index present"
+gdb_test_multiple "mt print objfiles ${testfile}" $test {
+    -re "gdb_index.*${gdb_prompt} $" {
+	set binfile_with_index $binfile
+    }
+    -re "Psymtabs.*${gdb_prompt} $" {
+	set binfile_with_index [add_gdb_index $binfile]
+	if { ${binfile_with_index} == "" } {
+	    return -1
+	}
+    }
+}
+
+# Ok, we have a copy of $binfile with .gdb_index.
+# Restart gdb and verify the index was used.
+
+clean_restart ${binfile_with_index}
+gdb_test "mt print objfiles ${testfile}" \
+    "gdb_index.*" \
+    ".gdb_index used"
+
+# Make gdb re-read symbols and see if .gdb_index still gets used.
+# symtab/15885
+
+# There is gdb_touch_execfile, but it doesn't handle remote hosts.
+# Is touch portable enough?
+# First make sure enough time has passed, file mtime resolution is seconds.
+gdb_test_no_output "shell sleep 1"
+if {[run_on_host "touch binary" touch ${binfile_with_index}]} {
+    return -1
+}
+
+if ![runto_main] {
+    return -1
+}
+gdb_test "mt print objfiles ${testfile}" \
+    "gdb_index.*" \
+    ".gdb_index used after symbol reloading"