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, 3 insertions, 3 deletions

diff --git a/gdb/linespec.c b/gdb/linespec.c
index 6d26638296e..f418e03b774 100644
--- a/gdb/linespec.c
+++ b/gdb/linespec.c
@@ -2613,9 +2613,9 @@ parse_linespec (linespec_parser *parser, const char *arg,
 	    = symtabs_from_filename (user_filename.get (),
 				     PARSER_STATE (parser)->search_pspace);
 	}
-      catch (const gdb_exception_error &ex)
+      catch (gdb_exception_error &ex)
 	{
-	  file_exception = ex;
+	  file_exception = std::move (ex);
 	}
 
       if (file_exception.reason >= 0)
@@ -2663,7 +2663,7 @@ parse_linespec (linespec_parser *parser, const char *arg,
       /* The linespec didn't parse.  Re-throw the file exception if
 	 there was one.  */
       if (file_exception.reason < 0)
-	throw_exception (file_exception);
+	throw_exception (std::move (file_exception));
 
       /* Otherwise, the symbol is not found.  */
       symbol_not_found_error (PARSER_EXPLICIT (parser)->function_name,