Disable OpenCL platform on known-buggy macs

platforms/opencl/include/OpenCLPlatform.h

@@ -48,6 +48,7 @@ public:
     }
     double getSpeed() const;
     bool supportsDoublePrecision() const;
+    static bool isPlatformSupported();
     const std::string& getPropertyValue(const Context& context, const std::string& property) const;
     void setPropertyValue(Context& context, const std::string& property, const std::string& value) const;
     void contextCreated(ContextImpl& context, const std::map<std::string, std::string>& properties) const;

platforms/opencl/src/OpenCLPlatform.cpp

@@ -33,6 +33,10 @@
 #include "openmm/System.h"
 #include <algorithm>
 #include <sstream>
+#ifdef __APPLE__
+#include "sys/sysctl.h"
+#endif
+
 
 using namespace OpenMM;
 using std::map;
@@ -42,10 +46,12 @@ using std::vector;
 
 #ifdef OPENMM_OPENCL_BUILDING_STATIC_LIBRARY
 extern "C" void registerOpenCLPlatform() {
+    if (OpenCLPlatform::isPlatformSupported())
         Platform::registerPlatform(new OpenCLPlatform());
 }
 #else
 extern "C" OPENMM_EXPORT_OPENCL void registerPlatforms() {
+    if (OpenCLPlatform::isPlatformSupported())
         Platform::registerPlatform(new OpenCLPlatform());
 }
 #endif
@@ -102,6 +108,33 @@ bool OpenCLPlatform::supportsDoublePrecision() const {
     return true;
 }
 
+bool OpenCLPlatform::isPlatformSupported() {
+    // Return false for OpenCL implementations that are known
+    // to be buggy (Apple OSX since 10.7.5)
+
+#ifdef __APPLE__
+    char str[256];
+    size_t size = sizeof(str);
+    int ret = sysctlbyname("kern.osrelease", str, &size, NULL, 0);
+    if (ret != 0)
+        return false;
+
+    int major, minor, micro;
+    if (sscanf(str, "%d.%d.%d", &major, &minor, &micro) != 3)
+        return false;
+
+    if ((major > 11) || (major == 11 && minor > 4) || (major == 11 && minor == 4 && micro >= 2))
+        // 11.4.2 is the darwin release corresponding to OSX 10.7.5, which is the
+        // point at which a number of serious bugs were introduced into the
+        // Apple OpenCL libraries, resulting in catistrophically incorrect MD simulations
+        // (see https://github.com/SimTk/openmm/issues/395 for example). Once a fix is released,
+        // this version check should be updated.
+        return false;
+#endif
+
+    return true;
+}
+
 const string& OpenCLPlatform::getPropertyValue(const Context& context, const string& property) const {
     const ContextImpl& impl = getContextImpl(context);
     const PlatformData* data = reinterpret_cast<const PlatformData*>(impl.getPlatformData());