gdb/python: smarter symbol lookup for gdb.lookup_static_symbol

When using gdb.lookup_static_symbol I think that GDB should find
static symbols (global symbol with static linkage) from the current
object file ahead of static symbols from other object files.

This means that if we have two source files f1.c and f2.c, and both
files contains 'static int foo;', then when we are stopped in f1.c a
call to 'gdb.lookup_static_symbol ("foo")' will find f1.c::foo, and if
we are stopped in f2.c we would find 'f2.c::foo'.

Given that gdb.lookup_static_symbol always returns a single symbol,
but there can be multiple static symbols with the same name GDB is
always making a choice about which symbols to return.  I think that it
makes sense for the choice GDB makes in this case to match what a user
would get on the command line if they asked to 'print foo'.

gdb/testsuite/ChangeLog:

	* gdb.python/py-symbol.c: Declare and call function from new
	py-symbol-2.c file.
	* gdb.python/py-symbol.exp: Compile both source files, and add new
	tests for gdb.lookup_static_symbol.
	* gdb.python/py-symbol-2.c: New file.

gdb/doc/ChangeLog:

	* python.texi (Symbols In Python): Extend documentation for
	gdb.lookup_static_symbol.

gdb/ChangeLog:

	* python/py-symbol.c (gdbpy_lookup_static_symbol): Lookup in
	static block of current object file first.  Also fix typo in
	header comment.

Change-Id: Ie55dbeb8806f35577b46015deecde27a0ca2ab64

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 06e5423fbebe35d021907b719c9067384c72e2b7..ca0c0c366dcb1ec78dc2f2e1ea69d1bd3720d28c 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,9 @@
+2019-11-10  Andrew Burgess  <andrew.burgess@embecosm.com>
+
+       * python/py-symbol.c (gdbpy_lookup_static_symbol): Lookup in
+       static block of current object file first.  Also fix typo in
+       header comment.
+
 2019-11-10  Andrew Burgess  <andrew.burgess@embecosm.com>
 
        * stack.c (set_last_displayed_sal): Delete.

diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index ce89ee444ea157d800a525487d559b4d0c11cb2d..6db17b9c8ebb6bc0e16fe0a8073c6fbcca95c93c 100644 (file)
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,3 +1,8 @@
+2019-11-10  Andrew Burgess  <andrew.burgess@embecosm.com>
+
+       * python.texi (Symbols In Python): Extend documentation for
+       gdb.lookup_static_symbol.
+
 2019-10-31  Andrew Burgess  <andrew.burgess@embecosm.com>
 
        * gdb.texinfo (Symbols): Document new 'info module variables' and

diff --git a/gdb/doc/python.texi b/gdb/doc/python.texi
index 13191fc9ae8ef0378b7d302037f4cd25ee5ce464..9e227deba905566be1bafe479c84ff4b43d5a1f3 100644 (file)
--- a/gdb/doc/python.texi
+++ b/gdb/doc/python.texi
@@ -4872,6 +4872,15 @@ Note that this function will not find function-scoped static variables. To look
 up such variables, iterate over the variables of the function's
 @code{gdb.Block} and check that @code{block.addr_class} is
 @code{gdb.SYMBOL_LOC_STATIC}.
+
+There can be multiple global symbols with static linkage with the same
+name.  This function will only return the first matching symbol that
+it finds.  Which symbol is found depends on where @value{GDBN} is
+currently stopped, as @value{GDBN} will first search for matching
+symbols in the current object file, and then search all other object
+files.  If the application is not yet running then @value{GDBN} will
+search all object files in the order they appear in the debug
+information.
 @end defun
 
 A @code{gdb.Symbol} object has the following attributes:

diff --git a/gdb/python/py-symbol.c b/gdb/python/py-symbol.c
index 2b10e21d872a3ff36e29be68f3c05c637755aef9..4c88877bcbed5306f4d735b39cec579e20e742c4 100644 (file)
--- a/gdb/python/py-symbol.c
+++ b/gdb/python/py-symbol.c
@@ -472,7 +472,7 @@ gdbpy_lookup_global_symbol (PyObject *self, PyObject *args, PyObject *kw)
 }
 
 /* Implementation of
-   gdb.lookup_static_symbol (name [, domain) -> symbol or None.  */
+   gdb.lookup_static_symbol (name [, domain]) -> symbol or None.  */
 
 PyObject *
 gdbpy_lookup_static_symbol (PyObject *self, PyObject *args, PyObject *kw)
@@ -487,9 +487,32 @@ gdbpy_lookup_static_symbol (PyObject *self, PyObject *args, PyObject *kw)
                                        &domain))
     return NULL;
 
+  /* In order to find static symbols associated with the "current" object
+     file ahead of those from other object files, we first need to see if
+     we can acquire a current block.  If this fails however, then we still
+     want to search all static symbols, so don't throw an exception just
+     yet.  */
+  const struct block *block = NULL;
   try
     {
-      symbol = lookup_static_symbol (name, (domain_enum) domain).symbol;
+      struct frame_info *selected_frame
+       = get_selected_frame (_("No frame selected."));
+      block = get_frame_block (selected_frame, NULL);
+    }
+  catch (const gdb_exception &except)
+    {
+      /* Nothing.  */
+    }
+
+  try
+    {
+      if (block != nullptr)
+       symbol
+         = lookup_symbol_in_static_block (name, block,
+                                          (domain_enum) domain).symbol;
+
+      if (symbol == nullptr)
+       symbol = lookup_static_symbol (name, (domain_enum) domain).symbol;
     }
   catch (const gdb_exception &except)
     {

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 9b7bcf64478f6007a980bc78358c0dd1a9ecaf13..e170b7e7badb04513cf9cf84023e5bf7d2c7114a 100644 (file)
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2019-11-10  Andrew Burgess  <andrew.burgess@embecosm.com>
+
+       * gdb.python/py-symbol.c: Declare and call function from new
+       py-symbol-2.c file.
+       * gdb.python/py-symbol.exp: Compile both source files, and add new
+       tests for gdb.lookup_static_symbol.
+       * gdb.python/py-symbol-2.c: New file.
+
 2019-11-02  Tom de Vries  <tdevries@suse.de>
 
        * gdb.base/advance.exp: Drop superfluous 3rd argument to gdb_test.

diff --git a/gdb/testsuite/gdb.python/py-symbol-2.c b/gdb/testsuite/gdb.python/py-symbol-2.c
new file mode 100644 (file)
index 0000000..73ac986
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-symbol-2.c
@@ -0,0 +1,24 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2019 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/>.  */
+
+static int rr = 99;            /* line of other rr */
+
+void
+function_in_other_file (void)
+{
+  /* Nothing.  */
+}

diff --git a/gdb/testsuite/gdb.python/py-symbol.c b/gdb/testsuite/gdb.python/py-symbol.c
index 06a931bf5d951784f01f611be47f114f67c24be8..51325dcd450cc458a995a41d8fb0f3ab9beb7b8a 100644 (file)
--- a/gdb/testsuite/gdb.python/py-symbol.c
+++ b/gdb/testsuite/gdb.python/py-symbol.c
@@ -38,6 +38,10 @@ namespace {
 };
 #endif
 
+#ifdef USE_TWO_FILES
+extern void function_in_other_file (void);
+#endif
+
 int qq = 72;                   /* line of qq */
 static int rr = 42;            /* line of rr */
 
@@ -70,5 +74,10 @@ int main (int argc, char *argv[])
   sclass.seti (42);
   sclass.valueofi ();
 #endif
+
+#ifdef USE_TWO_FILES
+  function_in_other_file ();
+#endif
+
   return 0; /* Break at end.  */
 }

diff --git a/gdb/testsuite/gdb.python/py-symbol.exp b/gdb/testsuite/gdb.python/py-symbol.exp
index 5617f127e5bd9953808a2fcff2a14ae8efd9b413..61960075565b6de37422b2e9bb9ee17bd2fc0dec 100644 (file)
--- a/gdb/testsuite/gdb.python/py-symbol.exp
+++ b/gdb/testsuite/gdb.python/py-symbol.exp
@@ -18,9 +18,11 @@
 
 load_lib gdb-python.exp
 
-standard_testfile
+standard_testfile py-symbol.c py-symbol-2.c
 
-if {[prepare_for_testing "failed to prepare" $testfile $srcfile debug]} {
+set opts { debug additional_flags=-DUSE_TWO_FILES }
+if {[prepare_for_testing "failed to prepare" $testfile \
+        [list $srcfile $srcfile2] $opts]} {
     return -1
 }
 
@@ -48,6 +50,7 @@ gdb_test "python print (gdb.lookup_global_symbol('qq').needs_frame)" \
     "False" \
     "print whether qq needs a frame"
 
+# Similarly, test looking up a static symbol before we runto_main.
 set rr_line [gdb_get_line_number "line of rr"]
 gdb_test "python print (gdb.lookup_global_symbol ('rr') is None)" "True" \
     "lookup_global_symbol for static var"
@@ -100,10 +103,23 @@ gdb_test "python print (func.print_name)" "func" "test func.print_name"
 gdb_test "python print (func.linkage_name)" "func" "test func.linkage_name"
 gdb_test "python print (func.addr_class == gdb.SYMBOL_LOC_BLOCK)" "True" "test func.addr_class"
 
-gdb_breakpoint [gdb_get_line_number "Break at end."]
+# Stop in a second file and ensure we find its local static symbol.
+gdb_breakpoint "function_in_other_file"
+gdb_continue_to_breakpoint "function_in_other_file"
+gdb_test "python print (gdb.lookup_static_symbol ('rr').value ())" "99" \
+    "print value of rr from other file"
+
+# Now continue back to the first source file.
+set linenum [gdb_get_line_number "Break at end."]
+gdb_breakpoint "$srcfile:$linenum"
 gdb_continue_to_breakpoint "Break at end for variable a" ".*Break at end.*"
 gdb_py_test_silent_cmd "python frame = gdb.selected_frame()" "Get Frame" 0
 
+# Check that we find the static sybol local to this file over the
+# static symbol from the second source file.
+gdb_test "python print (gdb.lookup_static_symbol ('rr').value ())" "42" \
+    "print value of rr from main file"
+
 # Test is_variable attribute.
 gdb_py_test_silent_cmd "python a = gdb.lookup_symbol(\'a\')" "Get variable a" 0
 gdb_test "python print (a\[0\].is_variable)" "True" "test a.is_variable"
@@ -145,17 +161,12 @@ gdb_test "python print (t\[0\].symtab)" "${py_symbol_c}" "get symtab"
 
 # C++ tests
 # Recompile binary.
-if { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}-cxx" executable "debug c++"] != "" } {
-    untested "failed to compile in C++ mode"
+lappend opts c++
+if {[prepare_for_testing "failed to prepare" "${binfile}-cxx" \
+        [list $srcfile $srcfile2] $opts]} {
     return -1
 }
 
-# Start with a fresh gdb.
-gdb_exit
-gdb_start
-gdb_reinitialize_dir $srcdir/$subdir
-gdb_load ${binfile}-cxx
-
 gdb_test "python print (gdb.lookup_global_symbol ('(anonymous namespace)::anon') is None)" \
     "True" "anon is None"
 gdb_test "python print (gdb.lookup_static_symbol ('(anonymous namespace)::anon').value ())" \
@@ -189,7 +200,7 @@ gdb_test "python print (cplusfunc.addr_class == gdb.SYMBOL_LOC_BLOCK)" "True" "t
 # Test is_valid when the objfile is unloaded.  This must be the last
 # test as it unloads the object file in GDB.
 # Start with a fresh gdb.
-clean_restart ${testfile}
+clean_restart ${binfile}
 if ![runto_main] then {
     fail "cannot run to main."
     return 0