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, 9 insertions, 9 deletions

diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index c74fc61..f6d2f36 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -2545,9 +2545,9 @@ insert_bp_location (struct bp_location *bl,
 	      if (val)
 		bp_excpt = gdb_exception {RETURN_ERROR, GENERIC_ERROR};
 	    }
-	  catch (const gdb_exception &e)
+	  catch (gdb_exception &e)
 	    {
-	      bp_excpt = e;
+	      bp_excpt = std::move (e);
 	    }
 	}
       else
@@ -2584,9 +2584,9 @@ insert_bp_location (struct bp_location *bl,
 			bp_excpt
 			  = gdb_exception {RETURN_ERROR, GENERIC_ERROR};
 		    }
-		  catch (const gdb_exception &e)
+		  catch (gdb_exception &e)
 		    {
-		      bp_excpt = e;
+		      bp_excpt = std::move (e);
 		    }
 
 		  if (bp_excpt.reason != 0)
@@ -2608,9 +2608,9 @@ insert_bp_location (struct bp_location *bl,
 		  if (val)
 		    bp_excpt = gdb_exception {RETURN_ERROR, GENERIC_ERROR};
 	        }
-	      catch (const gdb_exception &e)
+	      catch (gdb_exception &e)
 	        {
-		  bp_excpt = e;
+		  bp_excpt = std::move (e);
 	        }
 	    }
 	  else
@@ -13603,12 +13603,10 @@ location_to_sals (struct breakpoint *b, struct event_location *location,
     {
       sals = b->ops->decode_location (b, location, search_pspace);
     }
-  catch (const gdb_exception_error &e)
+  catch (gdb_exception_error &e)
     {
       int not_found_and_ok = 0;
 
-      exception = e;
-
       /* For pending breakpoints, it's expected that parsing will
 	 fail until the right shared library is loaded.  User has
 	 already told to create pending breakpoints and don't need
@@ -13637,6 +13635,8 @@ location_to_sals (struct breakpoint *b, struct event_location *location,
 	  b->enable_state = bp_disabled;
 	  throw;
 	}
+
+      exception = std::move (e);
     }
 
   if (exception.reason == 0 || exception.error != NOT_FOUND_ERROR)