--enable-propagate-signal, --with...default, less locks, omit UNUSED

ChangeLog

@@ -1,5 +1,15 @@
 # ChangeLog for chessproblem
 
+*chessproblem-2.2
+	- Support --enable-propagate-signal: This is a different inter-thread
+	  communication strategy which needs more memory and might perhaps be
+	  faster, but can also be slower. It is a good strategy if there are
+	  many bad last moves to try before a "winning" one is found.
+	- ./configure --with-max-parallel-default=...
+	- ./configure ----with-min-half-move-depth-default=...
+	- Micro-optimization: avoid atomic locks where unneeded
+	- Cleanup code: Avoid compiler UNUSED magic/attributes
+
 *chessproblem-2.1
 	- Rework multithreading strategy:
 	- Use one Communication object common to all equally ranked threads:

config.h.in

@@ -9,9 +9,6 @@
 /* Define if [[fallthrough]] can be used */
 #undef HAVE_ATTRIBUTE_FALLTHROUGH
 
-/* [Define if [[maybe_unused]] can be used] */
-#undef HAVE_ATTRIBUTE_MAYBE_UNUSED
-
 /* [Define if [[nodiscard]] can be used] */
 #undef HAVE_ATTRIBUTE_NODISCARD
 
@@ -27,9 +24,6 @@
 /* Define if __attribute__ ((pure)) can be used */
 #undef HAVE_ATTRIBUTE_PURE
 
-/* Define if __attribute__ ((unused)) can be used */
-#undef HAVE_ATTRIBUTE_UNUSED
-
 /* Define if __attribute__ ((warn_unused_result)) can be used */
 #undef HAVE_ATTRIBUTE_WARN_UNUSED_RESULT
 
@@ -69,6 +63,12 @@
 /* Define if __builtin_expect can be used */
 #undef HAVE___BUILTIN_EXPECT
 
+/* default maximal parallel threads if defined */
+#undef MAX_PARALLEL_DEFAULT
+
+/* default minimal half move depth for a new thread if defined */
+#undef MIN_HALF_MOVE_DEPTH_DEFAULT
+
 /* Define if multithreading is not wanted/possible */
 #undef NO_CHESSPROBLEM_THREADS
 
@@ -93,6 +93,10 @@
 /* Define to the version of this package. */
 #undef PACKAGE_VERSION
 
+/* Define if memory intensive (faster?/slower?) thread policy should be used
+   */
+#undef PROPAGATE_SIGNAL
+
 /* Define to 1 if you have the ANSI C header files. */
 #undef STDC_HEADERS
 

configure.ac

@@ -5,7 +5,7 @@
 #  Martin V\"ath <martin@mvath.de>
 
 dnl keep version in same line as AC_INIT for possible usage in scripts
-AC_INIT([chessproblem], [2.1],
+AC_INIT([chessproblem], [2.2],
   [https://github.com/vaeth/chessproblem/issues/],
   [chessproblem],
   [https://github.com/vaeth/chessproblem/])
@@ -463,44 +463,6 @@ AS_IF([$attr_deprecated],
 		[1],
 		[[Define if __attribute__ ((deprecated("a"))) can be used]])])
 
-# Check if [[maybe_unused]] works
-AC_MSG_CHECKING([[whether [[maybe_unused]] can be used]])
-AC_LINK_IFELSE([AC_LANG_PROGRAM([[
-static int dummy(int i);
-static int
-dummy([[maybe_unused]] int i)
-{ return 0; }
-		]], [[
-return dummy(1);
-		]])],
-		[MV_MSG_RESULT([yes])
-		AS_VAR_SET([attr_maybe_unused], [:])],
-		[MV_MSG_RESULT([no])
-		AS_VAR_SET([attr_maybe_unused], [false])])
-AS_IF([$attr_maybe_unused],
-	[AC_DEFINE([HAVE_ATTRIBUTE_MAYBE_UNUSED],
-		[1],
-		[[Define if [[maybe_unused]] can be used]])])
-
-# Check if __attribute__ ((unused)) works
-AC_MSG_CHECKING([whether __attribute__ ((unused)) can be used])
-AC_LINK_IFELSE([AC_LANG_PROGRAM([[
-static int dummy(int i);
-static int
-dummy(__attribute__ ((unused)) int i)
-{ return 0; }
-		]], [[
-return dummy(1);
-		]])],
-		[MV_MSG_RESULT([yes])
-		AS_VAR_SET([attr_unused], [:])],
-		[MV_MSG_RESULT([no])
-		AS_VAR_SET([attr_unused], [false])])
-AS_IF([$attr_unused],
-	[AC_DEFINE([HAVE_ATTRIBUTE_UNUSED],
-		[1],
-		[Define if __attribute__ ((unused)) can be used])])
-
 # Check if [[noreturn]] works
 AC_MSG_CHECKING([[whether [[noreturn]] can be used]])
 AC_LINK_IFELSE([AC_LANG_PROGRAM([[
@@ -757,6 +719,42 @@ AS_IF([$support_multithreading],
 	AS_VAR_SET([MULTITHREAD_LIBS], [])])
 AC_SUBST([MULTITHREAD_LIBS])
 
+AC_MSG_CHECKING([maximal parallel threads default])
+AC_ARG_WITH([max-parallel-default],
+	[AS_HELP_STRING([--with-max-parallel-default=STR],
+		[default maximal parallel threads])],
+	[AS_VAR_COPY([MAX_PARALLEL_DEFAULT], [withval])],
+	[AS_VAR_SET([MAX_PARALLEL_DEFAULT], [])])
+MV_MSG_RESULT_VAR([MAX_PARALLEL_DEFAULT])
+MV_IF_NONEMPTY([$MAX_PARALLEL_DEFAULT],
+	[AC_DEFINE_UNQUOTED([MAX_PARALLEL_DEFAULT],
+		[$MAX_PARALLEL_DEFAULT],
+		[default maximal parallel threads if defined])])
+
+AC_MSG_CHECKING([minimal half move depth for a new thread])
+AC_ARG_WITH([min-half-move-depth-default],
+	[AS_HELP_STRING([--with-min-half-move-depth-default=STR],
+		[default minimal half move depth for a new thread])],
+	[AS_VAR_COPY([MIN_HALF_MOVE_DEPTH_DEFAULT], [withval])],
+	[AS_VAR_SET([MIN_HALF_MOVE_DEPTH_DEFAULT], [])])
+MV_MSG_RESULT_VAR([MIN_HALF_MOVE_DEPTH_DEFAULT])
+MV_IF_NONEMPTY([$MIN_HALF_MOVE_DEPTH_DEFAULT],
+	[AC_DEFINE_UNQUOTED([MIN_HALF_MOVE_DEPTH_DEFAULT],
+		[$MIN_HALF_MOVE_DEPTH_DEFAULT],
+		[default minimal half move depth for a new thread if defined])])
+
+AC_MSG_CHECKING([propagate-signal])
+AC_ARG_ENABLE([propagate-signal],
+	[AS_HELP_STRING([--enable-propagate-signal],
+		[use memory intensive (faster?/slower?) thread policy])],
+	[MV_ENABLE([propagate_signal])],
+	[AS_VAR_SET([propagate_signal], [false])])
+MV_MSG_RESULT_BIN([$propagate_signal])
+AS_IF([$propagate_signal],
+	[AC_DEFINE([PROPAGATE_SIGNAL],
+		[1],
+		[Define if memory intensive (faster?/slower?) thread policy should be used])])
+
 # Done!
 AC_OUTPUT()
 

contrib/make.sh

@@ -15,7 +15,8 @@ Available options are
   -n  Stop after ./configure, i.e. do not run make
   -e  Keep environment - do not modify LDFLAGS, CXXFLAGS, CFLAGS, CC
   -w  Enable warnings
-  -t  No multithreading
+  -t  With propagate-signal (for multithreading)
+  -T  No multithreading
   -o  Enable optimization
   -g  Use clang++, setting CXX, filtering some flags (default if available)
   -G  Use default CXX (mnemonic: GNU)
@@ -91,6 +92,7 @@ quiet=false
 dep_default=:
 earlystop=false
 keepenv=false
+propagate_signal=:
 multithreading=:
 warnings=false
 use_chown=false
@@ -105,15 +107,16 @@ debugging=false
 command -v clang++ >/dev/null 2>&1 && clang=: || clang=false
 dialect='enable'
 OPTIND=1
-while getopts 'qgGdnewtoCxXyYdc:j:rhH' opt
+while getopts 'qgGdnewtToCxXyYdc:j:rhH' opt
 do	case $opt in
 	q)	quiet=:;;
 	g)	clang=:;;
 	G)	clang=false;;
 	n)	earlystop=:;;
 	e)	keepenv=:;;
 	w)	warnings=:;;
-	t)	multithreading=false;;
+	t)	propagate_signal=:;;
+	T)	multithreading=false;;
 	o)	optimization=:;;
 	C)	use_ccache=false;;
 	x)	recache=:;;
@@ -142,6 +145,8 @@ SetCcache
 ! $warnings || configure_extra=$configure_extra' --enable-warnings'
 $multithreading && configure_extra=$configure_extra' --with-multithreading' \
 	|| configure_extra=$configure_extra' --without-multithreading'
+! $propagate_signal \
+	|| configure_extra=$configure_extra' --with-propagate-signal'
 $quiet && quietredirect='>/dev/null' || quietredirect=
 
 if $use_chown