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, 5 insertions, 4 deletions

diff --git a/gdb/exceptions.c b/gdb/exceptions.c
index 078f3c3..ebdc71d 100644
--- a/gdb/exceptions.c
+++ b/gdb/exceptions.c
@@ -74,7 +74,7 @@ print_flush (void)
 }
 
 static void
-print_exception (struct ui_file *file, struct gdb_exception e)
+print_exception (struct ui_file *file, const struct gdb_exception &e)
 {
   /* KLUGE: cagney/2005-01-13: Write the string out one line at a time
      as that way the MI's behavior is preserved.  */
@@ -110,7 +110,7 @@ print_exception (struct ui_file *file, struct gdb_exception e)
 }
 
 void
-exception_print (struct ui_file *file, struct gdb_exception e)
+exception_print (struct ui_file *file, const struct gdb_exception &e)
 {
   if (e.reason < 0 && e.message != NULL)
     {
@@ -120,7 +120,7 @@ exception_print (struct ui_file *file, struct gdb_exception e)
 }
 
 void
-exception_fprintf (struct ui_file *file, struct gdb_exception e,
+exception_fprintf (struct ui_file *file, const struct gdb_exception &e,
 		   const char *prefix, ...)
 {
   if (e.reason < 0 && e.message != NULL)
@@ -141,7 +141,8 @@ exception_fprintf (struct ui_file *file, struct gdb_exception e,
 /* See exceptions.h.  */
 
 int
-exception_print_same (struct gdb_exception e1, struct gdb_exception e2)
+exception_print_same (const struct gdb_exception &e1,
+		      const struct gdb_exception &e2)
 {
   const char *msg1 = e1.message == nullptr ? "" : e1.what ();
   const char *msg2 = e2.message == nullptr ? "" : e2.what ();