Make exception handling more efficient

This makes exception handling more efficient in a few spots, through
the use of const- and rvalue-references.

I wrote this patch by commenting out the gdb_exception copy
constructor and then examining the resulting error messages one by
one, introducing the use of std::move where appropriate.

gdb/ChangeLog
2019-04-25  Tom Tromey  <tromey@adacore.com>

	* xml-support.c (struct gdb_xml_parser) <set_error>: Take an
	rvalue reference.
	(gdb_xml_start_element_wrapper, gdb_xml_end_element_wrapper)
	(gdb_xml_parser::parse): Use std::move.
	* python/python-internal.h (gdbpy_convert_exception): Take a const
	reference.
	* python/py-value.c (valpy_getitem, valpy_nonzero): Use
	std::move.
	* python/py-utils.c (gdbpy_convert_exception): Take a const
	reference.
	* python/py-inferior.c (infpy_write_memory, infpy_search_memory):
	Use std::move.
	* python/py-breakpoint.c (bppy_set_condition, bppy_set_commands):
	Use std::move.
	* mi/mi-main.c (mi_print_exception): Take a const reference.
	* main.c (handle_command_errors): Take a const reference.
	* linespec.c (parse_linespec): Use std::move.
	* infcall.c (run_inferior_call): Use std::move.
	(call_function_by_hand_dummy): Use std::move.
	* exec.c (try_open_exec_file): Use std::move.
	* exceptions.h (exception_print, exception_fprintf)
	(exception_print_same): Update.
	* exceptions.c (print_exception, exception_print)
	(exception_fprintf, exception_print_same): Change parameters to
	const reference.
	* event-top.c (gdb_rl_callback_read_char_wrapper): Update.
	* common/new-op.c: Use std::move.
	* common/common-exceptions.h (struct gdb_exception): Add move
	constructor.
	(struct gdb_exception_error, struct gdb_exception_quit, struct
	gdb_quit_bad_alloc): Change constructor to move constructor.
	(throw_exception): Change parameter to rvalue reference.
	* common/common-exceptions.c (throw_exception): Take rvalue
	reference.
	* cli/cli-interp.c (safe_execute_command): Use std::move.
	* breakpoint.c (insert_bp_location, location_to_sals): Use
	std::move.

1 files changed, 7 insertions, 7 deletions

diff --git a/gdb/xml-support.c b/gdb/xml-support.c
index d4cd89c..ae727da 100644
--- a/gdb/xml-support.c
+++ b/gdb/xml-support.c
@@ -113,9 +113,9 @@ struct gdb_xml_parser
   { m_is_xinclude = is_xinclude; }
 
   /* A thrown error, if any.  */
-  void set_error (gdb_exception error)
+  void set_error (gdb_exception &&error)
   {
-    m_error = error;
+    m_error = std::move (error);
 #ifdef HAVE_XML_STOPPARSER
     XML_StopParser (m_expat_parser, XML_FALSE);
 #endif
@@ -387,9 +387,9 @@ gdb_xml_start_element_wrapper (void *data, const XML_Char *name,
     {
       parser->start_element (name, attrs);
     }
-  catch (const gdb_exception &ex)
+  catch (gdb_exception &ex)
     {
-      parser->set_error (ex);
+      parser->set_error (std::move (ex));
     }
 }
 
@@ -459,9 +459,9 @@ gdb_xml_end_element_wrapper (void *data, const XML_Char *name)
     {
       parser->end_element (name);
     }
-  catch (const gdb_exception &ex)
+  catch (gdb_exception &ex)
     {
-      parser->set_error (ex);
+      parser->set_error (std::move (ex));
     }
 }
 
@@ -603,7 +603,7 @@ gdb_xml_parser::parse (const char *buffer)
   else
     {
       gdb_assert (m_error.reason < 0);
-      throw_exception (m_error);
+      throw_exception (std::move (m_error));
     }
 
   if (m_last_line != 0)