Merge remote-tracking branch 'upstream/master' into forcefield

platforms/cuda/include/CudaPlatform.h

@@ -9,7 +9,7 @@
  * Biological Structures at Stanford, funded under the NIH Roadmap for        *
  * Medical Research, grant U54 GM072970. See https://simtk.org.               *
  *                                                                            *
- * Portions copyright (c) 2008-2012 Stanford University and the Authors.      *
+ * Portions copyright (c) 2008-2016 Stanford University and the Authors.      *
  * Authors: Peter Eastman                                                     *
  * Contributors:                                                              *
  *                                                                            *
@@ -109,19 +109,27 @@ public:
         static const std::string key = "CudaTempDirectory";
         return key;
     }
+    /**
+     * This is the name of the parameter for selecting whether to disable use of a separate stream for PME.
+     */
+    static const std::string& CudaDisablePmeStream() {
+        static const std::string key = "CudaDisablePmeStream";
+        return key;
+    }
 };
 
 class OPENMM_EXPORT_CUDA CudaPlatform::PlatformData {
 public:
     PlatformData(ContextImpl* context, const System& system, const std::string& deviceIndexProperty, const std::string& blockingProperty, const std::string& precisionProperty,
-            const std::string& cpuPmeProperty, const std::string& compilerProperty, const std::string& tempProperty, const std::string& hostCompilerProperty);
+            const std::string& cpuPmeProperty, const std::string& compilerProperty, const std::string& tempProperty, const std::string& hostCompilerProperty,
+            const std::string& pmeStreamProperty);
     ~PlatformData();
     void initializeContexts(const System& system);
     void syncContexts();
     ContextImpl* context;
     std::vector<CudaContext*> contexts;
     std::vector<double> contextEnergy;
-    bool hasInitializedContexts, removeCM, peerAccessSupported, useCpuPme;
+    bool hasInitializedContexts, removeCM, peerAccessSupported, useCpuPme, disablePmeStream;
     int cmMotionFrequency;
     int stepCount, computeForceCount;
     double time;

platforms/cuda/src/CudaKernels.cpp

@@ -6,7 +6,7 @@
  * Biological Structures at Stanford, funded under the NIH Roadmap for        *
  * Medical Research, grant U54 GM072970. See https://simtk.org.               *
  *                                                                            *
- * Portions copyright (c) 2008-2015 Stanford University and the Authors.      *
+ * Portions copyright (c) 2008-2016 Stanford University and the Authors.      *
  * Authors: Peter Eastman                                                     *
  * Contributors:                                                              *
  *                                                                            *
@@ -1645,7 +1645,7 @@ void CudaCalcNonbondedForceKernel::initialize(const System& system, const Nonbon
             ewaldSelfEnergy = -ONE_4PI_EPS0*alpha*sumSquaredCharges/sqrt(M_PI);
             char deviceName[100];
             cuDeviceGetName(deviceName, 100, cu.getDevice());
-            usePmeStream = (string(deviceName) != "GeForce GTX 980"); // Using a separate stream is slower on GTX 980
+            usePmeStream = (!cu.getPlatformData().disablePmeStream && string(deviceName) != "GeForce GTX 980"); // Using a separate stream is slower on GTX 980
             pmeDefines["PME_ORDER"] = cu.intToString(PmeOrder);
             pmeDefines["NUM_ATOMS"] = cu.intToString(numParticles);
             pmeDefines["PADDED_NUM_ATOMS"] = cu.intToString(cu.getPaddedNumAtoms());

platforms/cuda/src/CudaPlatform.cpp

@@ -6,7 +6,7 @@
  * Biological Structures at Stanford, funded under the NIH Roadmap for        *
  * Medical Research, grant U54 GM072970. See https://simtk.org.               *
  *                                                                            *
- * Portions copyright (c) 2008-2012 Stanford University and the Authors.      *
+ * Portions copyright (c) 2008-2016 Stanford University and the Authors.      *
  * Authors: Peter Eastman                                                     *
  * Contributors:                                                              *
  *                                                                            *
@@ -100,11 +100,13 @@ CudaPlatform::CudaPlatform() {
     platformProperties.push_back(CudaCompiler());
     platformProperties.push_back(CudaTempDirectory());
     platformProperties.push_back(CudaHostCompiler());
+    platformProperties.push_back(CudaDisablePmeStream());
     setPropertyDefaultValue(CudaDeviceIndex(), "");
     setPropertyDefaultValue(CudaDeviceName(), "");
     setPropertyDefaultValue(CudaUseBlockingSync(), "true");
     setPropertyDefaultValue(CudaPrecision(), "single");
     setPropertyDefaultValue(CudaUseCpuPme(), "false");
+    setPropertyDefaultValue(CudaDisablePmeStream(), "false");
 #ifdef _MSC_VER
     char* bindir = getenv("CUDA_BIN_PATH");
     string nvcc = (bindir == NULL ? "nvcc.exe" : string(bindir)+"\\nvcc.exe");
@@ -163,14 +165,17 @@ void CudaPlatform::contextCreated(ContextImpl& context, const map<string, string
             getPropertyDefaultValue(CudaTempDirectory()) : properties.find(CudaTempDirectory())->second);
     const string& hostCompilerPropValue = (properties.find(CudaHostCompiler()) == properties.end() ?
             getPropertyDefaultValue(CudaHostCompiler()) : properties.find(CudaHostCompiler())->second);
+    string pmeStreamPropValue = (properties.find(CudaDisablePmeStream()) == properties.end() ?
+            getPropertyDefaultValue(CudaDisablePmeStream()) : properties.find(CudaDisablePmeStream())->second);
     transform(blockingPropValue.begin(), blockingPropValue.end(), blockingPropValue.begin(), ::tolower);
     transform(precisionPropValue.begin(), precisionPropValue.end(), precisionPropValue.begin(), ::tolower);
     transform(cpuPmePropValue.begin(), cpuPmePropValue.end(), cpuPmePropValue.begin(), ::tolower);
+    transform(pmeStreamPropValue.begin(), pmeStreamPropValue.end(), pmeStreamPropValue.begin(), ::tolower);
     vector<string> pmeKernelName;
     pmeKernelName.push_back(CalcPmeReciprocalForceKernel::Name());
     if (!supportsKernels(pmeKernelName))
         cpuPmePropValue = "false";
-    context.setPlatformData(new PlatformData(&context, context.getSystem(), devicePropValue, blockingPropValue, precisionPropValue, cpuPmePropValue, compilerPropValue, tempPropValue, hostCompilerPropValue));
+    context.setPlatformData(new PlatformData(&context, context.getSystem(), devicePropValue, blockingPropValue, precisionPropValue, cpuPmePropValue, compilerPropValue, tempPropValue, hostCompilerPropValue, pmeStreamPropValue));
 }
 
 void CudaPlatform::contextDestroyed(ContextImpl& context) const {
@@ -179,7 +184,7 @@ void CudaPlatform::contextDestroyed(ContextImpl& context) const {
 }
 
 CudaPlatform::PlatformData::PlatformData(ContextImpl* context, const System& system, const string& deviceIndexProperty, const string& blockingProperty, const string& precisionProperty,
-            const string& cpuPmeProperty, const string& compilerProperty, const string& tempProperty, const string& hostCompilerProperty) : context(context), removeCM(false), stepCount(0), computeForceCount(0), time(0.0), hasInitializedContexts(false) {
+            const string& cpuPmeProperty, const string& compilerProperty, const string& tempProperty, const string& hostCompilerProperty, const string& pmeStreamProperty) : context(context), removeCM(false), stepCount(0), computeForceCount(0), time(0.0), hasInitializedContexts(false) {
     bool blocking = (blockingProperty == "true");
     vector<string> devices;
     size_t searchPos = 0, nextPos;
@@ -191,7 +196,7 @@ CudaPlatform::PlatformData::PlatformData(ContextImpl* context, const System& sys
     try {
         for (int i = 0; i < (int) devices.size(); i++) {
             if (devices[i].length() > 0) {
-                unsigned int deviceIndex;
+                int deviceIndex;
                 stringstream(devices[i]) >> deviceIndex;
                 contexts.push_back(new CudaContext(system, deviceIndex, blocking, precisionProperty, compilerProperty, tempProperty, hostCompilerProperty, *this));
             }
@@ -218,6 +223,7 @@ CudaPlatform::PlatformData::PlatformData(ContextImpl* context, const System& sys
         deviceName << name;
     }
     useCpuPme = (cpuPmeProperty == "true" && !contexts[0]->getUseDoublePrecision());
+    disablePmeStream = (pmeStreamProperty == "true");
     propertyValues[CudaPlatform::CudaDeviceIndex()] = deviceIndex.str();
     propertyValues[CudaPlatform::CudaDeviceName()] = deviceName.str();
     propertyValues[CudaPlatform::CudaUseBlockingSync()] = blocking ? "true" : "false";
@@ -226,6 +232,7 @@ CudaPlatform::PlatformData::PlatformData(ContextImpl* context, const System& sys
     propertyValues[CudaPlatform::CudaCompiler()] = compilerProperty;
     propertyValues[CudaPlatform::CudaTempDirectory()] = tempProperty;
     propertyValues[CudaPlatform::CudaHostCompiler()] = hostCompilerProperty;
+    propertyValues[CudaPlatform::CudaDisablePmeStream()] = disablePmeStream ? "true" : "false";
     contextEnergy.resize(contexts.size());
     
     // Determine whether peer-to-peer copying is supported, and enable it if so.

platforms/cuda/tests/TestCudaFFT3D.cpp

@@ -6,7 +6,7 @@
  * Biological Structures at Stanford, funded under the NIH Roadmap for        *
  * Medical Research, grant U54 GM072970. See https://simtk.org.               *
  *                                                                            *
- * Portions copyright (c) 2011-2015 Stanford University and the Authors.      *
+ * Portions copyright (c) 2011-2016 Stanford University and the Authors.      *
  * Authors: Peter Eastman                                                     *
  * Contributors:                                                              *
  *                                                                            *
@@ -56,7 +56,7 @@ void testTransform(bool realToComplex, int xsize, int ysize, int zsize) {
     system.addParticle(0.0);
     CudaPlatform::PlatformData platformData(NULL, system, "", "true", platform.getPropertyDefaultValue("CudaPrecision"), "false",
             platform.getPropertyDefaultValue(CudaPlatform::CudaCompiler()), platform.getPropertyDefaultValue(CudaPlatform::CudaTempDirectory()),
-            platform.getPropertyDefaultValue(CudaPlatform::CudaHostCompiler()));
+            platform.getPropertyDefaultValue(CudaPlatform::CudaHostCompiler()), platform.getPropertyDefaultValue(CudaPlatform::CudaDisablePmeStream()));
     CudaContext& context = *platformData.contexts[0];
     context.initialize();
     OpenMM_SFMT::SFMT sfmt;

platforms/cuda/tests/TestCudaRandom.cpp

@@ -6,7 +6,7 @@
  * Biological Structures at Stanford, funded under the NIH Roadmap for        *
  * Medical Research, grant U54 GM072970. See https://simtk.org.               *
  *                                                                            *
- * Portions copyright (c) 2008-2012 Stanford University and the Authors.      *
+ * Portions copyright (c) 2008-2016 Stanford University and the Authors.      *
  * Authors: Peter Eastman                                                     *
  * Contributors:                                                              *
  *                                                                            *
@@ -56,7 +56,7 @@ void testGaussian() {
         system.addParticle(1.0);
     CudaPlatform::PlatformData platformData(NULL, system, "", "true", platform.getPropertyDefaultValue("CudaPrecision"), "false",
             platform.getPropertyDefaultValue(CudaPlatform::CudaCompiler()), platform.getPropertyDefaultValue(CudaPlatform::CudaTempDirectory()),
-            platform.getPropertyDefaultValue(CudaPlatform::CudaHostCompiler()));
+            platform.getPropertyDefaultValue(CudaPlatform::CudaHostCompiler()), platform.getPropertyDefaultValue(CudaPlatform::CudaDisablePmeStream()));
     CudaContext& context = *platformData.contexts[0];
     context.initialize();
     context.getIntegrationUtilities().initRandomNumberGenerator(0);

platforms/cuda/tests/TestCudaSort.cpp

@@ -6,7 +6,7 @@
  * Biological Structures at Stanford, funded under the NIH Roadmap for        *
  * Medical Research, grant U54 GM072970. See https://simtk.org.               *
  *                                                                            *
- * Portions copyright (c) 2008-2012 Stanford University and the Authors.      *
+ * Portions copyright (c) 2008-2016 Stanford University and the Authors.      *
  * Authors: Peter Eastman                                                     *
  * Contributors:                                                              *
  *                                                                            *
@@ -66,7 +66,7 @@ void verifySorting(vector<float> array) {
     system.addParticle(0.0);
     CudaPlatform::PlatformData platformData(NULL, system, "", "true", platform.getPropertyDefaultValue("CudaPrecision"), "false",
             platform.getPropertyDefaultValue(CudaPlatform::CudaCompiler()), platform.getPropertyDefaultValue(CudaPlatform::CudaTempDirectory()),
-            platform.getPropertyDefaultValue(CudaPlatform::CudaHostCompiler()));
+            platform.getPropertyDefaultValue(CudaPlatform::CudaHostCompiler()), platform.getPropertyDefaultValue(CudaPlatform::CudaDisablePmeStream()));
     CudaContext& context = *platformData.contexts[0];
     context.initialize();
     CudaArray data(context, array.size(), 4, "sortData");

platforms/opencl/include/OpenCLPlatform.h

@@ -9,7 +9,7 @@
  * Biological Structures at Stanford, funded under the NIH Roadmap for        *
  * Medical Research, grant U54 GM072970. See https://simtk.org.               *
  *                                                                            *
- * Portions copyright (c) 2008 Stanford University and the Authors.           *
+ * Portions copyright (c) 2008-2016 Stanford University and the Authors.      *
  * Authors: Peter Eastman                                                     *
  * Contributors:                                                              *
  *                                                                            *
@@ -95,18 +95,26 @@ public:
         static const std::string key = "OpenCLUseCpuPme";
         return key;
     }
+    /**
+     * This is the name of the parameter for selecting whether to disable use of a separate stream for PME.
+     */
+    static const std::string& OpenCLDisablePmeStream() {
+        static const std::string key = "OpenCLDisablePmeStream";
+        return key;
+    }
 };
 
 class OPENMM_EXPORT_OPENCL OpenCLPlatform::PlatformData {
 public:
-    PlatformData(const System& system, const std::string& platformPropValue, const std::string& deviceIndexProperty, const std::string& precisionProperty, const std::string& cpuPmeProperty);
+    PlatformData(const System& system, const std::string& platformPropValue, const std::string& deviceIndexProperty, const std::string& precisionProperty,
+            const std::string& cpuPmeProperty, const std::string& pmeStreamProperty);
     ~PlatformData();
     void initializeContexts(const System& system);
     void syncContexts();
     ContextImpl* context;
     std::vector<OpenCLContext*> contexts;
     std::vector<double> contextEnergy;
-    bool hasInitializedContexts, removeCM, useCpuPme;
+    bool hasInitializedContexts, removeCM, useCpuPme, disablePmeStream;
     int cmMotionFrequency;
     int stepCount, computeForceCount;
     double time;

platforms/opencl/src/OpenCLKernels.cpp

@@ -6,7 +6,7 @@
  * Biological Structures at Stanford, funded under the NIH Roadmap for        *
  * Medical Research, grant U54 GM072970. See https://simtk.org.               *
  *                                                                            *
- * Portions copyright (c) 2008-2015 Stanford University and the Authors.      *
+ * Portions copyright (c) 2008-2016 Stanford University and the Authors.      *
  * Authors: Peter Eastman                                                     *
  * Contributors:                                                              *
  *                                                                            *
@@ -1685,7 +1685,7 @@ void OpenCLCalcNonbondedForceKernel::initialize(const System& system, const Nonb
                 bool isNvidia = (vendor.size() >= 6 && vendor.substr(0, 6) == "NVIDIA");
                 if (isNvidia)
                     pmeDefines["USE_ALTERNATE_MEMORY_ACCESS_PATTERN"] = "1";
-                usePmeQueue = isNvidia;
+                usePmeQueue = (!cl.getPlatformData().disablePmeStream && isNvidia);
                 if (usePmeQueue) {
                     pmeDefines["USE_PME_STREAM"] = "1";
                     pmeQueue = cl::CommandQueue(cl.getContext(), cl.getDevice());

platforms/opencl/src/OpenCLPlatform.cpp

@@ -6,7 +6,7 @@
  * Biological Structures at Stanford, funded under the NIH Roadmap for        *
  * Medical Research, grant U54 GM072970. See https://simtk.org.               *
  *                                                                            *
- * Portions copyright (c) 2008 Stanford University and the Authors.           *
+ * Portions copyright (c) 2008-2016 Stanford University and the Authors.      *
  * Authors: Peter Eastman                                                     *
  * Contributors:                                                              *
  *                                                                            *
@@ -92,12 +92,14 @@ OpenCLPlatform::OpenCLPlatform() {
     platformProperties.push_back(OpenCLPlatformName());
     platformProperties.push_back(OpenCLPrecision());
     platformProperties.push_back(OpenCLUseCpuPme());
+    platformProperties.push_back(OpenCLDisablePmeStream());
     setPropertyDefaultValue(OpenCLDeviceIndex(), "");
     setPropertyDefaultValue(OpenCLDeviceName(), "");
     setPropertyDefaultValue(OpenCLPlatformIndex(), "");
     setPropertyDefaultValue(OpenCLPlatformName(), "");
     setPropertyDefaultValue(OpenCLPrecision(), "single");
     setPropertyDefaultValue(OpenCLUseCpuPme(), "false");
+    setPropertyDefaultValue(OpenCLDisablePmeStream(), "false");
 }
 
 double OpenCLPlatform::getSpeed() const {
@@ -154,13 +156,16 @@ void OpenCLPlatform::contextCreated(ContextImpl& context, const map<string, stri
             getPropertyDefaultValue(OpenCLPrecision()) : properties.find(OpenCLPrecision())->second);
     string cpuPmePropValue = (properties.find(OpenCLUseCpuPme()) == properties.end() ?
             getPropertyDefaultValue(OpenCLUseCpuPme()) : properties.find(OpenCLUseCpuPme())->second);
+    string pmeStreamPropValue = (properties.find(OpenCLDisablePmeStream()) == properties.end() ?
+            getPropertyDefaultValue(OpenCLDisablePmeStream()) : properties.find(OpenCLDisablePmeStream())->second);
     transform(precisionPropValue.begin(), precisionPropValue.end(), precisionPropValue.begin(), ::tolower);
     transform(cpuPmePropValue.begin(), cpuPmePropValue.end(), cpuPmePropValue.begin(), ::tolower);
+    transform(pmeStreamPropValue.begin(), pmeStreamPropValue.end(), pmeStreamPropValue.begin(), ::tolower);
     vector<string> pmeKernelName;
     pmeKernelName.push_back(CalcPmeReciprocalForceKernel::Name());
     if (!supportsKernels(pmeKernelName))
         cpuPmePropValue = "false";
-    context.setPlatformData(new PlatformData(context.getSystem(), platformPropValue, devicePropValue, precisionPropValue, cpuPmePropValue));
+    context.setPlatformData(new PlatformData(context.getSystem(), platformPropValue, devicePropValue, precisionPropValue, cpuPmePropValue, pmeStreamPropValue));
 }
 
 void OpenCLPlatform::contextDestroyed(ContextImpl& context) const {
@@ -169,7 +174,7 @@ void OpenCLPlatform::contextDestroyed(ContextImpl& context) const {
 }
 
 OpenCLPlatform::PlatformData::PlatformData(const System& system, const string& platformPropValue, const string& deviceIndexProperty,
-        const string& precisionProperty, const string& cpuPmeProperty) : removeCM(false), stepCount(0), computeForceCount(0), time(0.0), hasInitializedContexts(false)  {
+        const string& precisionProperty, const string& cpuPmeProperty, const string& pmeStreamProperty) : removeCM(false), stepCount(0), computeForceCount(0), time(0.0), hasInitializedContexts(false)  {
     int platformIndex = -1;
     if (platformPropValue.length() > 0)
         stringstream(platformPropValue) >> platformIndex;
@@ -183,7 +188,7 @@ OpenCLPlatform::PlatformData::PlatformData(const System& system, const string& p
     try {
         for (int i = 0; i < (int) devices.size(); i++) {
             if (devices[i].length() > 0) {
-                unsigned int deviceIndex;
+                int deviceIndex;
                 stringstream(devices[i]) >> deviceIndex;
                 contexts.push_back(new OpenCLContext(system, platformIndex, deviceIndex, precisionProperty, *this));
             }
@@ -210,6 +215,7 @@ OpenCLPlatform::PlatformData::PlatformData(const System& system, const string& p
     platformIndex = contexts[0]->getPlatformIndex();
 
     useCpuPme = (cpuPmeProperty == "true" && !contexts[0]->getUseDoublePrecision());
+    disablePmeStream = (pmeStreamProperty == "true");
     propertyValues[OpenCLPlatform::OpenCLDeviceIndex()] = deviceIndex.str();
     propertyValues[OpenCLPlatform::OpenCLDeviceName()] = deviceName.str();
     propertyValues[OpenCLPlatform::OpenCLPlatformIndex()] = contexts[0]->intToString(platformIndex);
@@ -218,6 +224,7 @@ OpenCLPlatform::PlatformData::PlatformData(const System& system, const string& p
     propertyValues[OpenCLPlatform::OpenCLPlatformName()] = platforms[platformIndex].getInfo<CL_PLATFORM_NAME>();
     propertyValues[OpenCLPlatform::OpenCLPrecision()] = precisionProperty;
     propertyValues[OpenCLPlatform::OpenCLUseCpuPme()] = useCpuPme ? "true" : "false";
+    propertyValues[OpenCLPlatform::OpenCLDisablePmeStream()] = disablePmeStream ? "true" : "false";
     contextEnergy.resize(contexts.size());
 }
 

platforms/opencl/tests/TestOpenCLFFT.cpp

@@ -6,7 +6,7 @@
  * Biological Structures at Stanford, funded under the NIH Roadmap for        *
  * Medical Research, grant U54 GM072970. See https://simtk.org.               *
  *                                                                            *
- * Portions copyright (c) 2011-2015 Stanford University and the Authors.      *
+ * Portions copyright (c) 2011-2016 Stanford University and the Authors.      *
  * Authors: Peter Eastman                                                     *
  * Contributors:                                                              *
  *                                                                            *
@@ -54,7 +54,7 @@ template <class Real2>
 void testTransform(bool realToComplex, int xsize, int ysize, int zsize) {
     System system;
     system.addParticle(0.0);
-    OpenCLPlatform::PlatformData platformData(system, "", "", platform.getPropertyDefaultValue("OpenCLPrecision"), "false");
+    OpenCLPlatform::PlatformData platformData(system, "", "", platform.getPropertyDefaultValue("OpenCLPrecision"), "false", "false");
     OpenCLContext& context = *platformData.contexts[0];
     context.initialize();
     OpenMM_SFMT::SFMT sfmt;

platforms/opencl/tests/TestOpenCLRandom.cpp

@@ -6,7 +6,7 @@
  * Biological Structures at Stanford, funded under the NIH Roadmap for        *
  * Medical Research, grant U54 GM072970. See https://simtk.org.               *
  *                                                                            *
- * Portions copyright (c) 2008-2009 Stanford University and the Authors.      *
+ * Portions copyright (c) 2008-2016 Stanford University and the Authors.      *
  * Authors: Peter Eastman                                                     *
  * Contributors:                                                              *
  *                                                                            *
@@ -54,7 +54,7 @@ void testGaussian() {
     System system;
     for (int i = 0; i < numAtoms; i++)
         system.addParticle(1.0);
-    OpenCLPlatform::PlatformData platformData(system, "", "", platform.getPropertyDefaultValue("OpenCLPrecision"), "false");
+    OpenCLPlatform::PlatformData platformData(system, "", "", platform.getPropertyDefaultValue("OpenCLPrecision"), "false", "false");
     OpenCLContext& context = *platformData.contexts[0];
     context.initialize();
     context.getIntegrationUtilities().initRandomNumberGenerator(0);

platforms/opencl/tests/TestOpenCLSort.cpp

@@ -6,7 +6,7 @@
  * Biological Structures at Stanford, funded under the NIH Roadmap for        *
  * Medical Research, grant U54 GM072970. See https://simtk.org.               *
  *                                                                            *
- * Portions copyright (c) 2008-2009 Stanford University and the Authors.      *
+ * Portions copyright (c) 2008-2016 Stanford University and the Authors.      *
  * Authors: Peter Eastman                                                     *
  * Contributors:                                                              *
  *                                                                            *
@@ -64,7 +64,7 @@ void verifySorting(vector<float> array) {
 
     System system;
     system.addParticle(0.0);
-    OpenCLPlatform::PlatformData platformData(system, "", "", platform.getPropertyDefaultValue("OpenCLPrecision"), "false");
+    OpenCLPlatform::PlatformData platformData(system, "", "", platform.getPropertyDefaultValue("OpenCLPrecision"), "false", "false");
     OpenCLContext& context = *platformData.contexts[0];
     context.initialize();
     OpenCLArray data(context, array.size(), sizeof(float), "sortData");

wrappers/python/simtk/openmm/app/forcefield.py

@@ -320,11 +320,15 @@ class ForceField(object):
                     types.append(None) # Unknown atom class
                 else:
                     types.append(self._atomClasses[attrib[classAttrib]])
-            else:
-                if typeAttrib not in attrib or attrib[typeAttrib] not in self._atomTypes:
+            elif typeAttrib in attrib:
+                if attrib[typeAttrib] == '':
+                    types.append(self._atomClasses[''])
+                elif attrib[typeAttrib] not in self._atomTypes:
                     types.append(None) # Unknown atom type
                 else:
                     types.append([attrib[typeAttrib]])
+            else:
+                types.append(None) # Unknown atom type
         return types
 
     def _parseTorsion(self, attrib):

wrappers/python/tests/TestForceField.py

@@ -518,5 +518,44 @@ class AmoebaTestForceField(unittest.TestCase):
             diff = norm(f1-f2)
             self.assertTrue(diff < 0.1 or diff/norm(f1) < 1e-3)
 
+    def test_Wildcard(self):
+        """Test that PeriodicTorsionForces using wildcard ('') for atom types / classes in the ffxml are correctly registered"""
+
+        # Use wildcards in types
+        xml = """
+<ForceField>
+ <AtomTypes>
+  <Type name="C" class="C" element="C" mass="12.010000"/>
+  <Type name="O" class="O" element="O" mass="16.000000"/>
+ </AtomTypes>
+ <PeriodicTorsionForce>
+  <Proper type1="" type2="C" type3="C" type4="" periodicity1="2" phase1="3.141593" k1="15.167000"/>
+  <Improper type1="C" type2="" type3="" type4="O" periodicity1="2" phase1="3.141593" k1="43.932000"/>
+ </PeriodicTorsionForce>
+</ForceField>"""
+
+        ff = ForceField(StringIO(xml))
+
+        self.assertEqual(len(ff._forces[0].proper), 1)
+        self.assertEqual(len(ff._forces[0].improper), 1)
+
+       # Use wildcards in classes
+        xml = """
+<ForceField>
+ <AtomTypes>
+  <Type name="C" class="C" element="C" mass="12.010000"/>
+  <Type name="O" class="O" element="O" mass="16.000000"/>
+ </AtomTypes>
+ <PeriodicTorsionForce>
+  <Proper class1="" class2="C" class3="C" class4="" periodicity1="2" phase1="3.141593" k1="15.167000"/>
+  <Improper class1="C" class2="" class3="" class4="O" periodicity1="2" phase1="3.141593" k1="43.932000"/>
+ </PeriodicTorsionForce>
+</ForceField>"""
+
+        ff = ForceField(StringIO(xml))
+
+        self.assertEqual(len(ff._forces[0].proper), 1)
+        self.assertEqual(len(ff._forces[0].improper), 1)
+
 if __name__ == '__main__':
     unittest.main()