multithread the MD5/IQM model CPU code using OpenMP

cmake/DaemonFlags.cmake

@@ -259,6 +259,10 @@ if (USE_FLOAT_EXCEPTIONS)
     add_definitions(-DDAEMON_USE_FLOAT_EXCEPTIONS)
 endif()
 
+if (NOT NACL AND BUILD_CLIENT)
+	option(USE_OPENMP "Use OpenMP to parallelize some tasks" OFF)
+endif()
+
 if (MSVC)
     set_c_cxx_flag("/MP")
 
@@ -267,6 +271,14 @@ if (MSVC)
         set_cxx_flag("/std:c++23preview")
     endif()
 
+	if (NOT NACL AND BUILD_CLIENT AND USE_OPENMP)
+		try_cxx_flag(OPENMP "/openmp")
+
+		if (NOT FLAG_OPENMP)
+			message(WARNING "Missing OpenMP")
+		endif()
+	endif()
+
     if (USE_FAST_MATH)
         set_c_cxx_flag("/fp:fast")
     else()
@@ -362,6 +374,14 @@ else()
 		endif()
 	endif()
 
+	if (NOT NACL AND BUILD_CLIENT AND USE_OPENMP)
+		try_cxx_flag(FOPENMP "-fopenmp")
+
+		if (NOT FLAG_FOPENMP)
+			message(WARNING "Missing OpenMP")
+		endif()
+	endif()
+
 	if (NACL AND USE_NACL_SAIGO AND SAIGO_ARCH STREQUAL "arm")
 		# This should be set for every build type because build type flags
 		# are set after the other custom flags and then have the last word.

src.cmake

@@ -188,6 +188,8 @@ set(ENGINELIST
     ${ENGINE_DIR}/framework/CvarSystem.h
     ${ENGINE_DIR}/framework/LogSystem.cpp
     ${ENGINE_DIR}/framework/LogSystem.h
+    ${ENGINE_DIR}/framework/Omp.cpp
+    ${ENGINE_DIR}/framework/Omp.h
     ${ENGINE_DIR}/framework/Resource.cpp
     ${ENGINE_DIR}/framework/Resource.h
     ${ENGINE_DIR}/framework/System.cpp

src/engine/framework/Omp.cpp

@@ -0,0 +1,104 @@
+/*
+===========================================================================
+Daemon BSD Source Code
+Copyright (c) 2025, Daemon Developers
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above copyright
+      notice, this list of conditions and the following disclaimer in the
+      documentation and/or other materials provided with the distribution.
+    * Neither the name of the Daemon developers nor the
+      names of its contributors may be used to endorse or promote products
+      derived from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL DAEMON DEVELOPERS BE LIABLE FOR ANY
+DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+===========================================================================
+*/
+
+#include <algorithm>
+
+#include "CvarSystem.h"
+#include "Omp.h"
+
+#if defined(_OPENMP)
+#include "omp.h"
+#endif
+
+#if defined(_OPENMP)
+static Cvar::Range<Cvar::Cvar<int>> common_ompThreads(
+	"common.ompThreads", "OpenMP threads", Cvar::NONE, 0, 0, 32 );
+#endif
+
+namespace Omp {
+#if defined(_OPENMP)
+static int ompMaxThreads = 1;
+#endif
+
+static int ompThreads = 1;
+
+static void ReadMaxThreads()
+{
+#if defined(_OPENMP)
+	ompMaxThreads = omp_get_max_threads();
+#endif
+}
+
+void EnlistThreads()
+{
+#if defined(_OPENMP)
+	omp_set_num_threads( ompThreads );
+#endif
+}
+
+void SetupThreads()
+{
+#if defined(_OPENMP)
+	if ( common_ompThreads.Get() )
+	{
+		ompThreads = common_ompThreads.Get();
+		return;
+	}
+
+	if ( ompMaxThreads <= 4 )
+	{
+		ompThreads = ompMaxThreads;
+		return;
+	}
+
+	if ( ompMaxThreads <= 16 )
+	{
+		ompThreads = ompMaxThreads - ( ompMaxThreads / 4 );
+		return;
+	}
+
+	ompThreads = 16;
+#endif
+
+	EnlistThreads();
+}
+
+void Init()
+{
+	ReadMaxThreads();
+	SetupThreads();
+	EnlistThreads();
+}
+
+int GetThreads()
+{
+	return ompThreads;
+}
+}

src/engine/framework/Omp.h

@@ -0,0 +1,41 @@
+/*
+===========================================================================
+Daemon BSD Source Code
+Copyright (c) 2025, Daemon Developers
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above copyright
+      notice, this list of conditions and the following disclaimer in the
+      documentation and/or other materials provided with the distribution.
+    * Neither the name of the Daemon developers nor the
+      names of its contributors may be used to endorse or promote products
+      derived from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL DAEMON DEVELOPERS BE LIABLE FOR ANY
+DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+===========================================================================
+*/
+
+#ifndef COMMON_OMP_H_
+#define COMMON_OMP_H_
+
+namespace Omp {
+void EnlistThreads();
+void SetupThreads();
+void Init();
+int GetThreads();
+};
+
+#endif // COMMON_OMP_H_

src/engine/framework/System.cpp

@@ -34,6 +34,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include "ConsoleHistory.h"
 #include "CommandSystem.h"
 #include "LogSystem.h"
+#include "Omp.h"
 #include "System.h"
 #include "CrashDump.h"
 #include "CvarSystem.h"
@@ -829,6 +830,8 @@ static void SetCvarsWithInitFlag(cmdlineArgs_t& cmdlineArgs)
 // Initialize the engine
 static void Init(int argc, char** argv)
 {
+	Omp::Init();
+
 	cmdlineArgs_t cmdlineArgs;
 
 #ifdef _WIN32

src/engine/qcommon/common.cpp

@@ -47,6 +47,7 @@ Maryland 20850 USA.
 #include "framework/CommandSystem.h"
 #include "framework/CvarSystem.h"
 #include "framework/LogSystem.h"
+#include "framework/Omp.h"
 #include "framework/System.h"
 #include "sys/sys_events.h"
 #include <common/FileSystem.h>
@@ -783,6 +784,8 @@ static Cvar::Cvar<bool> showTraceStats("common.showTraceStats", "are physics tra
 
 void Com_Frame()
 {
+	Omp::SetupThreads();
+
 	int             msec, minMsec;
 	static int      lastTime = 0;
 	//int             key;

src/engine/renderer/tr_backend.cpp

@@ -22,6 +22,7 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
 // tr_backend.c
 
+#include "framework/Omp.h"
 #include "tr_local.h"
 #include "gl_shader.h"
 #include "Material.h"
@@ -3829,6 +3830,8 @@ RB_RenderThread
 */
 void RB_RenderThread()
 {
+	Omp::EnlistThreads();
+
 	const void *data;
 
 	// wait for either a rendering command or a quit command

src/engine/renderer/tr_init.cpp

@@ -23,6 +23,7 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 // tr_init.c -- functions that are not called every frame
 #include "tr_local.h"
 #include "framework/CvarSystem.h"
+#include "framework/Omp.h"
 #include "DetectGLVendors.h"
 #include "Material.h"
 #include "GeometryCache.h"
@@ -1055,6 +1056,21 @@ ScreenshotCmd screenshotPNGRegistration("screenshotPNG", ssFormat_t::SSF_PNG, "p
 			Log::Notice("Using dual processor acceleration." );
 		}
 
+#if defined(_OPENMP)
+		int ompThreads = Omp::GetThreads();
+
+		if ( ompThreads == 1 )
+		{
+			Log::Notice("%sNot using OpenMP parallelism: only one thread.", Color::ToString( Color::Red ) );
+		}
+		else
+		{
+			Log::Notice("%sUsing OpenMP parallelism with %d threads.", Color::ToString( Color::Green ), ompThreads );
+		}
+#else
+		Log::Notice("%sNot using OpenMP parallelism: unavailable.", Color::ToString( Color::Red ) );
+#endif
+
 		if ( r_finish->integer )
 		{
 			Log::Notice("Forcing glFinish." );