From d19f920b07c0b39306a0cc6655461009cd30f87d Mon Sep 17 00:00:00 2001 From: Lancelot SIX Date: Tue, 27 Jul 2021 21:50:54 +0100 Subject: gdb: Setting setter return a bool to tell if the value changed GDB can notify observers when a parameter is changed. To do that, do_set_command (in gdb/cli/cli-setshow.c) compares the new value against the old one before updating it, and based on that notifies observers. This looks like something like: int valuechanged = 0; switch (cmd->var.type ()) { case var_integer: { LONGEST new_val = parse_and_eval_long (arg) if (new_val != cmd->var.get ()) { cmd->var.get (new_val); value_changes = 1; } } break; case var_string: { std::string val = std::string (arg); if (new_val != cmd->var.get ()) { cmd->var.get (new_val); value_changes = 1; } } break; case... /* And so on for all possible var_types. */ } This comparison is done for each possible var_type, which leads to unnecessary code duplication. In this patch I propose to move all those checks in one place within the setting setter method. This limits the code duplication and simplifies the do_set_command implementation. This patch also changes slightly the way a value change is detected. Instead of comparing the user provided value against the current value of the setting, we compare the value of the setting before and after the set operation. This is meant to handle edge cases where trying to set an unrecognized value would be equivalent to a noop (the actual value remains unchanged). There should be no user visible change introduced by this commit. Tested on x86_64 GNU/Linux. [1] https://review.lttng.org/c/binutils-gdb/+/5831/41 --- gdb/cli/cli-setshow.c | 96 +++++++++++---------------------------------------- gdb/command.h | 6 +++- 2 files changed, 25 insertions(+), 77 deletions(-) diff --git a/gdb/cli/cli-setshow.c b/gdb/cli/cli-setshow.c index 3af99a5e917..591db466784 100644 --- a/gdb/cli/cli-setshow.c +++ b/gdb/cli/cli-setshow.c @@ -31,17 +31,17 @@ /* Return true if the change of command parameter should be notified. */ -static int -notify_command_param_changed_p (int param_changed, struct cmd_list_element *c) +static bool +notify_command_param_changed_p (bool param_changed, struct cmd_list_element *c) { - if (param_changed == 0) - return 0; + if (!param_changed) + return false; if (c->theclass == class_maintenance || c->theclass == class_deprecated || c->theclass == class_obscure) - return 0; + return false; - return 1; + return true; } @@ -305,7 +305,7 @@ void do_set_command (const char *arg, int from_tty, struct cmd_list_element *c) { /* A flag to indicate the option is changed or not. */ - int option_changed = 0; + bool option_changed = false; gdb_assert (c->type == set_cmd); @@ -353,26 +353,12 @@ do_set_command (const char *arg, int from_tty, struct cmd_list_element *c) *q++ = '\0'; newobj = (char *) xrealloc (newobj, q - newobj); - const std::string var = c->var.get (); - if (var != std::string (newobj)) - { - c->var.set (std::string (newobj)); - - option_changed = 1; - } + option_changed = c->var.set (std::string (newobj)); xfree (newobj); } break; case var_string_noescape: - { - const std::string var = c->var.get (); - if (var != arg) - { - c->var.set (std::string (arg)); - - option_changed = 1; - } - } + option_changed = c->var.set (std::string (arg)); break; case var_filename: if (*arg == '\0') @@ -398,13 +384,8 @@ do_set_command (const char *arg, int from_tty, struct cmd_list_element *c) else val = xstrdup (""); - const std::string var = c->var.get (); - if (var != std::string (val)) - { - c->var.set (std::string (val)); - - option_changed = 1; - } + option_changed + = c->var.set (std::string (val)); xfree (val); } break; @@ -414,38 +395,18 @@ do_set_command (const char *arg, int from_tty, struct cmd_list_element *c) if (val < 0) error (_("\"on\" or \"off\" expected.")); - if (val != c->var.get ()) - { - c->var.set (val); - option_changed = 1; - } + option_changed = c->var.set (val); } break; case var_auto_boolean: - { - enum auto_boolean val = parse_auto_binary_operation (arg); - - if (c->var.get () != val) - { - c->var.set (val); - - option_changed = 1; - } - } + option_changed = c->var.set (parse_auto_binary_operation (arg)); break; case var_uinteger: case var_zuinteger: - { - unsigned int val = parse_cli_var_uinteger (c->var.type (), &arg, true); - - if (c->var.get () != val) - { - c->var.set (val); - - option_changed = 1; - } - } + option_changed + = c->var.set (parse_cli_var_uinteger (c->var.type (), + &arg, true)); break; case var_integer: case var_zinteger: @@ -475,12 +436,7 @@ do_set_command (const char *arg, int from_tty, struct cmd_list_element *c) || (c->var.type () == var_zinteger && val > INT_MAX)) error (_("integer %s out of range"), plongest (val)); - if (c->var.get () != val) - { - c->var.set (val); - - option_changed = 1; - } + option_changed = c->var.set (val); } break; case var_enum: @@ -493,24 +449,12 @@ do_set_command (const char *arg, int from_tty, struct cmd_list_element *c) if (*after != '\0') error (_("Junk after item \"%.*s\": %s"), len, arg, after); - if (c->var.get () != match) - { - c->var.set (match); - - option_changed = 1; - } + option_changed = c->var.set (match); } break; case var_zuinteger_unlimited: - { - int val = parse_cli_var_zuinteger_unlimited (&arg, true); - - if (c->var.get () != val) - { - c->var.set (val); - option_changed = 1; - } - } + option_changed = c->var.set + (parse_cli_var_zuinteger_unlimited (&arg, true)); break; default: error (_("gdb internal error: bad var_type in do_setshow_command")); diff --git a/gdb/command.h b/gdb/command.h index f7a193334f6..dc662c87e54 100644 --- a/gdb/command.h +++ b/gdb/command.h @@ -420,12 +420,14 @@ struct base_setting The var_type of the setting must match T. */ template - void set (T v) + bool set (T v) { /* Check that the current instance is of one of the supported types for this instantiation. */ gdb_assert (var_type_uses (this->m_var_type)); + const T old_value = this->get (); + auto setter = get_setting_setter (this->m_setter); if (setter != nullptr) @@ -435,6 +437,8 @@ struct base_setting gdb_assert (this->m_var != nullptr); *static_cast (this->m_var) = v; } + + return old_value != this->get (); } /* Set the user provided setter and getter functions. */ -- cgit v1.2.1