gdb: add SYMBOL_LOOKUP_SCOPED_DEBUG_ENTER_EXIT

After the previous commit converted symbol-lookup debug to use the new
debug scheme, this commit adds SYMBOL_LOOKUP_SCOPED_DEBUG_ENTER_EXIT.

The previous commit didn't add SYMBOL_LOOKUP_SCOPED_DEBUG_ENTER_EXIT
because symbol-lookup debug is controlled by an 'unsigned int' rather
than a 'bool' control variable, we use the numeric value to offer
different levels of verbosity for symbol-lookup debug.

The *_SCOPED_DEBUG_ENTER_EXIT mechanism currently relies on capturing
a reference to the bool control variable, and evaluating the variable
both on entry, and at exit, this is done in the scoped_debug_start_end
class (see gdbsupport/common-debug.h).

This commit templates scoped_debug_start_end so that the class can
accept either a 'bool &' or an invokable object, e.g. a lambda
function, or a function pointer.

The existing scoped_debug_start_end and scoped_debug_enter_exit macros
in common-debug.h are updated to support scoped_debug_enter_exit being
templated, however, nothing outside of common-debug.h needs to change.

I've then added SYMBOL_LOOKUP_SCOPED_DEBUG_ENTER_EXIT in symtab.h, and
added a couple of token uses in symtab.c.  I didn't want to add too
much in this first commit, this is really about updating
common-debug.h to support this new functionality.

Within symtab.h I created a couple of global functions that can be
used to query the status of the symbol_lookup_debug control variable,
these functions are then used within the two existing macros:

  symbol_lookup_debug_printf
  symbol_lookup_debug_printf_v

and also in the new SYMBOL_LOOKUP_SCOPED_DEBUG_ENTER_EXIT macro.

2 files changed, 29 insertions, 4 deletions

diff --git a/gdb/symtab.c b/gdb/symtab.c
index 14d81f5..a7a5415 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -1950,6 +1950,8 @@ lookup_symbol_in_language (const char *name, const struct block *block,
 			   const domain_enum domain, enum language lang,
 			   struct field_of_this_result *is_a_field_of_this)
 {
+  SYMBOL_LOOKUP_SCOPED_DEBUG_ENTER_EXIT;
+
   demangle_result_storage storage;
   const char *modified_name = demangle_for_lookup (name, lang, storage);
 
@@ -2072,6 +2074,8 @@ lookup_symbol_aux (const char *name, symbol_name_match_type match_type,
 		   const domain_enum domain, enum language language,
 		   struct field_of_this_result *is_a_field_of_this)
 {
+  SYMBOL_LOOKUP_SCOPED_DEBUG_ENTER_EXIT;
+
   struct block_symbol result;
   const struct language_defn *langdef;
 
diff --git a/gdb/symtab.h b/gdb/symtab.h
index 6eca61a..d0fa3b1 100644
--- a/gdb/symtab.h
+++ b/gdb/symtab.h
@@ -2625,17 +2625,38 @@ extern unsigned int symtab_create_debug;
 
 extern unsigned int symbol_lookup_debug;
 
+/* Return true if symbol-lookup debug is turned on at all.  */
+
+static inline bool
+symbol_lookup_debug_enabled ()
+{
+  return symbol_lookup_debug > 0;
+}
+
+/* Return true if symbol-lookup debug is turned to verbose mode.  */
+
+static inline bool
+symbol_lookup_debug_enabled_v ()
+{
+  return symbol_lookup_debug > 1;
+}
+
 /* Print a "symbol-lookup" debug statement if symbol_lookup_debug is >= 1.  */
 
 #define symbol_lookup_debug_printf(fmt, ...) \
-  debug_prefixed_printf_cond (symbol_lookup_debug >= 1, "symbol-lookup", fmt, \
-			      ##__VA_ARGS__)
+  debug_prefixed_printf_cond (symbol_lookup_debug_enabled (),	\
+			      "symbol-lookup", fmt, ##__VA_ARGS__)
 
 /* Print a "symbol-lookup" debug statement if symbol_lookup_debug is >= 2.  */
 
 #define symbol_lookup_debug_printf_v(fmt, ...) \
-  debug_prefixed_printf_cond (symbol_lookup_debug >= 2, "symbol-lookup", fmt, \
-			      ##__VA_ARGS__)
+  debug_prefixed_printf_cond (symbol_lookup_debug_enabled_v (), \
+			      "symbol-lookup", fmt, ##__VA_ARGS__)
+
+/* Print "symbol-lookup" enter/exit debug statements.  */
+
+#define SYMBOL_LOOKUP_SCOPED_DEBUG_ENTER_EXIT \
+  scoped_debug_enter_exit (symbol_lookup_debug_enabled, "symbol-lookup")
 
 extern bool basenames_may_differ;