Finished changes to reduce memory use for large systems

platforms/opencl/src/OpenCLKernels.cpp

@@ -1691,6 +1691,8 @@ double OpenCLCalcGBSAOBCForceKernel::execute(ContextImpl& context, bool includeF
         defines["NUM_ATOMS"] = intToString(cl.getNumAtoms());
         defines["PADDED_NUM_ATOMS"] = intToString(cl.getPaddedNumAtoms());
         defines["NUM_BLOCKS"] = OpenCLExpressionUtilities::intToString(cl.getNumAtomBlocks());
+        if (nb.getUseCutoff())
+            defines["MAX_TILES"] = OpenCLExpressionUtilities::intToString(nb.getInteractingTiles().getSize());
         string file = (cl.getSIMDWidth() == 32 ? OpenCLKernelSources::gbsaObc_nvidia : OpenCLKernelSources::gbsaObc_default);
         cl::Program program = cl.createProgram(file, defines);
         int index = 0;
@@ -1702,8 +1704,9 @@ double OpenCLCalcGBSAOBCForceKernel::execute(ContextImpl& context, bool includeF
         computeBornSumKernel.setArg(index++, OpenCLContext::ThreadBlockSize*sizeof(cl_float), NULL);
         if (nb.getUseCutoff()) {
             computeBornSumKernel.setArg<cl::Buffer>(index++, nb.getInteractingTiles().getDeviceBuffer());
-            computeBornSumKernel.setArg<cl::Buffer>(index++, nb.getInteractionFlags().getDeviceBuffer());
             computeBornSumKernel.setArg<cl::Buffer>(index++, nb.getInteractionCount().getDeviceBuffer());
+            if (cl.getSIMDWidth() == 32)
+                computeBornSumKernel.setArg<cl::Buffer>(index+2, nb.getInteractionFlags().getDeviceBuffer());
         }
         else
             computeBornSumKernel.setArg<cl_uint>(index++, cl.getNumAtomBlocks()*(cl.getNumAtomBlocks()+1)/2);
@@ -1718,8 +1721,9 @@ double OpenCLCalcGBSAOBCForceKernel::execute(ContextImpl& context, bool includeF
         force1Kernel.setArg(index++, OpenCLContext::ThreadBlockSize*sizeof(mm_float4), NULL);
         if (nb.getUseCutoff()) {
             force1Kernel.setArg<cl::Buffer>(index++, nb.getInteractingTiles().getDeviceBuffer());
-            force1Kernel.setArg<cl::Buffer>(index++, nb.getInteractionFlags().getDeviceBuffer());
             force1Kernel.setArg<cl::Buffer>(index++, nb.getInteractionCount().getDeviceBuffer());
+            if (cl.getSIMDWidth() == 32)
+                force1Kernel.setArg<cl::Buffer>(index+2, nb.getInteractionFlags().getDeviceBuffer());
         }
         else
             force1Kernel.setArg<cl_uint>(index++, cl.getNumAtomBlocks()*(cl.getNumAtomBlocks()+1)/2);
@@ -1744,10 +1748,10 @@ double OpenCLCalcGBSAOBCForceKernel::execute(ContextImpl& context, bool includeF
         reduceBornForceKernel.setArg<cl::Buffer>(6, obcChain->getDeviceBuffer());
     }
     if (nb.getUseCutoff()) {
-        computeBornSumKernel.setArg<mm_float4>(8, cl.getPeriodicBoxSize());
-        computeBornSumKernel.setArg<mm_float4>(9, cl.getInvPeriodicBoxSize());
-        force1Kernel.setArg<mm_float4>(10, cl.getPeriodicBoxSize());
-        force1Kernel.setArg<mm_float4>(11, cl.getInvPeriodicBoxSize());
+        computeBornSumKernel.setArg<mm_float4>(7, cl.getPeriodicBoxSize());
+        computeBornSumKernel.setArg<mm_float4>(8, cl.getInvPeriodicBoxSize());
+        force1Kernel.setArg<mm_float4>(9, cl.getPeriodicBoxSize());
+        force1Kernel.setArg<mm_float4>(10, cl.getInvPeriodicBoxSize());
     }
     int numTiles = cl.getNumAtomBlocks()*(cl.getNumAtomBlocks()+1)/2;
     cl.executeKernel(computeBornSumKernel, numTiles*OpenCLContext::TileSize);
@@ -2399,9 +2403,11 @@ double OpenCLCalcCustomGBForceKernel::execute(ContextImpl& context, bool include
         pairValueKernel.setArg(index++, OpenCLContext::ThreadBlockSize*sizeof(cl_float), NULL);
         if (nb.getUseCutoff()) {
             pairValueKernel.setArg<cl::Buffer>(index++, nb.getInteractingTiles().getDeviceBuffer());
-            pairValueKernel.setArg<cl::Buffer>(index++, nb.getInteractionFlags().getDeviceBuffer());
             pairValueKernel.setArg<cl::Buffer>(index++, nb.getInteractionCount().getDeviceBuffer());
             index += 2; // Periodic box size arguments are set when the kernel is executed.
+            pairValueKernel.setArg<cl_uint>(index++, nb.getInteractingTiles().getSize());
+            if (cl.getSIMDWidth() == 32)
+                pairValueKernel.setArg<cl::Buffer>(index++, nb.getInteractionFlags().getDeviceBuffer());
         }
         else
             pairValueKernel.setArg<cl_uint>(index++, cl.getNumAtomBlocks()*(cl.getNumAtomBlocks()+1)/2);
@@ -2445,9 +2451,11 @@ double OpenCLCalcCustomGBForceKernel::execute(ContextImpl& context, bool include
         pairEnergyKernel.setArg(index++, OpenCLContext::ThreadBlockSize*sizeof(cl_float4), NULL);
         if (nb.getUseCutoff()) {
             pairEnergyKernel.setArg<cl::Buffer>(index++, nb.getInteractingTiles().getDeviceBuffer());
-            pairEnergyKernel.setArg<cl::Buffer>(index++, nb.getInteractionFlags().getDeviceBuffer());
             pairEnergyKernel.setArg<cl::Buffer>(index++, nb.getInteractionCount().getDeviceBuffer());
             index += 2; // Periodic box size arguments are set when the kernel is executed.
+            pairEnergyKernel.setArg<cl_uint>(index++, nb.getInteractingTiles().getSize());
+            if (cl.getSIMDWidth() == 32)
+                pairEnergyKernel.setArg<cl::Buffer>(index++, nb.getInteractionFlags().getDeviceBuffer());
         }
         else
             pairEnergyKernel.setArg<cl_uint>(index++, cl.getNumAtomBlocks()*(cl.getNumAtomBlocks()+1)/2);
@@ -2518,10 +2526,10 @@ double OpenCLCalcCustomGBForceKernel::execute(ContextImpl& context, bool include
             globals->upload(globalParamValues);
     }
     if (nb.getUseCutoff()) {
-        pairValueKernel.setArg<mm_float4>(11, cl.getPeriodicBoxSize());
-        pairValueKernel.setArg<mm_float4>(12, cl.getInvPeriodicBoxSize());
-        pairEnergyKernel.setArg<mm_float4>(12, cl.getPeriodicBoxSize());
-        pairEnergyKernel.setArg<mm_float4>(13, cl.getInvPeriodicBoxSize());
+        pairValueKernel.setArg<mm_float4>(10, cl.getPeriodicBoxSize());
+        pairValueKernel.setArg<mm_float4>(11, cl.getInvPeriodicBoxSize());
+        pairEnergyKernel.setArg<mm_float4>(11, cl.getPeriodicBoxSize());
+        pairEnergyKernel.setArg<mm_float4>(12, cl.getInvPeriodicBoxSize());
     }
     int numTiles = cl.getNumAtomBlocks()*(cl.getNumAtomBlocks()+1)/2;
     cl.executeKernel(pairValueKernel, numTiles*OpenCLContext::TileSize);

platforms/opencl/src/OpenCLNonbondedUtilities.cpp

@@ -200,8 +200,18 @@ void OpenCLNonbondedUtilities::initialize(const System& system) {
     // Create data structures for the neighbor list.
 
     if (useCutoff) {
-        interactingTiles = new OpenCLArray<mm_ushort2>(context, numTiles, "interactingTiles");
-        interactionFlags = new OpenCLArray<cl_uint>(context, numTiles, "interactionFlags");
+        // Select a size for the arrays that hold the neighbor list.  This estimate is intentionally very
+        // high, because if it ever is too small, we have to fall back to the N^2 algorithm.
+
+        mm_float4 boxSize = context.getPeriodicBoxSize();
+        int maxInteractingTiles = (int) (numTiles*(cutoff/boxSize.x+cutoff/boxSize.y+cutoff/boxSize.z));
+        if (maxInteractingTiles < 1)
+            maxInteractingTiles = 1;
+        if (maxInteractingTiles > numTiles)
+            maxInteractingTiles = numTiles;
+        interactingTiles = new OpenCLArray<mm_ushort2>(context, maxInteractingTiles, "interactingTiles");
+        if (context.getSIMDWidth() == 32)
+            interactionFlags = new OpenCLArray<cl_uint>(context, maxInteractingTiles, "interactionFlags");
         interactionCount = new OpenCLArray<cl_uint>(context, 1, "interactionCount");
         blockCenter = new OpenCLArray<mm_float4>(context, numAtomBlocks, "blockCenter");
         blockBoundingBox = new OpenCLArray<mm_float4>(context, numAtomBlocks, "blockBoundingBox");
@@ -213,6 +223,7 @@ void OpenCLNonbondedUtilities::initialize(const System& system) {
     if (useCutoff) {
         map<string, string> defines;
         defines["NUM_BLOCKS"] = OpenCLExpressionUtilities::intToString(context.getNumAtomBlocks());
+        defines["MAX_TILES"] = OpenCLExpressionUtilities::intToString(interactingTiles->getSize());
         if (forceBufferPerAtomBlock)
             defines["USE_OUTPUT_BUFFER_PER_BLOCK"] = "1";
         if (usePeriodic)
@@ -231,6 +242,7 @@ void OpenCLNonbondedUtilities::initialize(const System& system) {
         findInteractingBlocksKernel.setArg<cl::Buffer>(5, interactionCount->getDeviceBuffer());
         findInteractingBlocksKernel.setArg<cl::Buffer>(6, interactingTiles->getDeviceBuffer());
         findInteractingBlocksKernel.setArg<cl::Buffer>(7, context.getPosq().getDeviceBuffer());
+        if (context.getSIMDWidth() == 32) {
             findInteractionsWithinBlocksKernel = cl::Kernel(interactingBlocksProgram, "findInteractionsWithinBlocks");
             findInteractionsWithinBlocksKernel.setArg<cl_float>(0, (cl_float) (cutoff*cutoff));
             findInteractionsWithinBlocksKernel.setArg<cl::Buffer>(3, context.getPosq().getDeviceBuffer());
@@ -241,6 +253,7 @@ void OpenCLNonbondedUtilities::initialize(const System& system) {
             findInteractionsWithinBlocksKernel.setArg<cl::Buffer>(8, interactionCount->getDeviceBuffer());
             findInteractionsWithinBlocksKernel.setArg(9, OpenCLContext::ThreadBlockSize*sizeof(cl_uint), NULL);
         }
+    }
 }
 
 int OpenCLNonbondedUtilities::findExclusionIndex(int x, int y, const vector<cl_uint>& exclusionIndices, const vector<cl_uint>& exclusionRowIndices) {
@@ -264,6 +277,8 @@ void OpenCLNonbondedUtilities::prepareInteractions() {
     findInteractingBlocksKernel.setArg<mm_float4>(1, context.getPeriodicBoxSize());
     findInteractingBlocksKernel.setArg<mm_float4>(2, context.getInvPeriodicBoxSize());
     context.executeKernel(findInteractingBlocksKernel, context.getNumAtoms());
+    vector<cl_uint> count;
+    interactionCount->download(count);
     if (context.getSIMDWidth() == 32) {
         findInteractionsWithinBlocksKernel.setArg<mm_float4>(1, context.getPeriodicBoxSize());
         findInteractionsWithinBlocksKernel.setArg<mm_float4>(2, context.getInvPeriodicBoxSize());
@@ -274,8 +289,8 @@ void OpenCLNonbondedUtilities::prepareInteractions() {
 void OpenCLNonbondedUtilities::computeInteractions() {
     if (cutoff != -1.0) {
         if (useCutoff) {
-            forceKernel.setArg<mm_float4>(11, context.getPeriodicBoxSize());
-            forceKernel.setArg<mm_float4>(12, context.getInvPeriodicBoxSize());
+            forceKernel.setArg<mm_float4>(10, context.getPeriodicBoxSize());
+            forceKernel.setArg<mm_float4>(11, context.getInvPeriodicBoxSize());
         }
         context.executeKernel(forceKernel, (context.getNumAtomBlocks()*(context.getNumAtomBlocks()+1)/2)*OpenCLContext::TileSize);
     }
@@ -388,6 +403,8 @@ cl::Kernel OpenCLNonbondedUtilities::createInteractionKernel(const string& sourc
     defines["NUM_ATOMS"] = OpenCLExpressionUtilities::intToString(context.getNumAtoms());
     defines["PADDED_NUM_ATOMS"] = OpenCLExpressionUtilities::intToString(context.getPaddedNumAtoms());
     defines["NUM_BLOCKS"] = OpenCLExpressionUtilities::intToString(context.getNumAtomBlocks());
+    if (useCutoff)
+        defines["MAX_TILES"] = OpenCLExpressionUtilities::intToString(interactingTiles->getSize());
     string file = (context.getSIMDWidth() == 32 ? OpenCLKernelSources::nonbonded_nvidia : OpenCLKernelSources::nonbonded_default);
     cl::Program program = context.createProgram(context.replaceStrings(file, replacements), defines);
     cl::Kernel kernel(program, "computeNonbonded");
@@ -405,9 +422,10 @@ cl::Kernel OpenCLNonbondedUtilities::createInteractionKernel(const string& sourc
     kernel.setArg(index++, OpenCLContext::ThreadBlockSize*sizeof(cl_float4), NULL);
     if (useCutoff) {
         kernel.setArg<cl::Buffer>(index++, interactingTiles->getDeviceBuffer());
-        kernel.setArg<cl::Buffer>(index++, interactionFlags->getDeviceBuffer());
         kernel.setArg<cl::Buffer>(index++, interactionCount->getDeviceBuffer());
         index += 2; // The periodic box size arguments are set when the kernel is executed.
+        if (context.getSIMDWidth() == 32)
+            kernel.setArg<cl::Buffer>(index++, interactionFlags->getDeviceBuffer());
     }
     else {
         kernel.setArg<cl_uint>(index++, context.getNumAtomBlocks()*(context.getNumAtomBlocks()+1)/2);

platforms/opencl/src/kernels/customGBEnergyN2_default.cl

@@ -11,16 +11,19 @@ void computeN2Energy(__global float4* forceBuffers, __global float* energyBuffer
 	__global float4* posq, __local float4* local_posq, __global unsigned int* exclusions, __global unsigned int* exclusionIndices,
         __global unsigned int* exclusionRowIndices, __local float4* tempForceBuffer,
 #ifdef USE_CUTOFF
-        __global ushort2* tiles, __global unsigned int* interactionFlags, __global unsigned int* interactionCount, float4 periodicBoxSize, float4 invPeriodicBoxSize
+        __global ushort2* tiles, __global unsigned int* interactionCount, float4 periodicBoxSize, float4 invPeriodicBoxSize, unsigned int maxTiles
 #else
         unsigned int numTiles
 #endif
         PARAMETER_ARGUMENTS) {
 #ifdef USE_CUTOFF
     unsigned int numTiles = interactionCount[0];
-#endif
+    unsigned int pos = get_group_id(0)*(numTiles > maxTiles ? NUM_BLOCKS*(NUM_BLOCKS+1)/2 : numTiles)/get_num_groups(0);
+    unsigned int end = (get_group_id(0)+1)*(numTiles > maxTiles ? NUM_BLOCKS*(NUM_BLOCKS+1)/2 : numTiles)/get_num_groups(0);
+#else
     unsigned int pos = get_group_id(0)*numTiles/get_num_groups(0);
     unsigned int end = (get_group_id(0)+1)*numTiles/get_num_groups(0);
+#endif
     float energy = 0.0f;
     unsigned int lasty = 0xFFFFFFFF;
     __local unsigned int exclusionRange[2];
@@ -29,18 +32,23 @@ void computeN2Energy(__global float4* forceBuffers, __global float* energyBuffer
 
     while (pos < end) {
         // Extract the coordinates of this tile
+        unsigned int x, y;
 #ifdef USE_CUTOFF
+        if (numTiles <= maxTiles) {
             ushort2 tileIndices = tiles[pos];
-        unsigned int x = tileIndices.x;
-        unsigned int y = tileIndices.y;
-#else
-        unsigned int y = (unsigned int) floor(NUM_BLOCKS+0.5f-sqrt((NUM_BLOCKS+0.5f)*(NUM_BLOCKS+0.5f)-2*pos));
-        unsigned int x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
+            x = tileIndices.x;
+            y = tileIndices.y;
+        }
+        else
+#endif
+        {
+            y = (unsigned int) floor(NUM_BLOCKS+0.5f-sqrt((NUM_BLOCKS+0.5f)*(NUM_BLOCKS+0.5f)-2*pos));
+            x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
             if (x >= NUM_BLOCKS) { // Occasionally happens due to roundoff error.
                 y++;
                 x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
             }
-#endif
+        }
         unsigned int baseLocalAtom = (get_local_id(0) < TILE_SIZE ? 0 : TILE_SIZE/2);
         unsigned int tgx = get_local_id(0) & (TILE_SIZE-1);
         unsigned int forceBufferOffset = (tgx < TILE_SIZE/2 ? 0 : TILE_SIZE);

platforms/opencl/src/kernels/customGBEnergyN2_nvidia.cl

@@ -11,18 +11,21 @@ void computeN2Energy(__global float4* forceBuffers, __global float* energyBuffer
 	__global float4* posq, __local float4* local_posq, __global unsigned int* exclusions, __global unsigned int* exclusionIndices,
         __global unsigned int* exclusionRowIndices, __local float4* tempBuffer,
 #ifdef USE_CUTOFF
-        __global ushort2* tiles, __global unsigned int* interactionFlags, __global unsigned int* interactionCount, float4 periodicBoxSize, float4 invPeriodicBoxSize
+        __global ushort2* tiles, __global unsigned int* interactionCount, float4 periodicBoxSize, float4 invPeriodicBoxSize, unsigned int maxTiles, __global unsigned int* interactionFlags
 #else
         unsigned int numTiles
 #endif
         PARAMETER_ARGUMENTS) {
-#ifdef USE_CUTOFF
-    unsigned int numTiles = interactionCount[0];
-#endif
     unsigned int totalWarps = get_global_size(0)/TILE_SIZE;
     unsigned int warp = get_global_id(0)/TILE_SIZE;
+#ifdef USE_CUTOFF
+    unsigned int numTiles = interactionCount[0];
+    unsigned int pos = warp*(numTiles > maxTiles ? NUM_BLOCKS*(NUM_BLOCKS+1)/2 : numTiles)/totalWarps;
+    unsigned int end = (warp+1)*(numTiles > maxTiles ? NUM_BLOCKS*(NUM_BLOCKS+1)/2 : numTiles)/totalWarps;
+#else
     unsigned int pos = warp*numTiles/totalWarps;
     unsigned int end = (warp+1)*numTiles/totalWarps;
+#endif
     float energy = 0.0f;
     unsigned int lasty = 0xFFFFFFFF;
     __local unsigned int exclusionRange[4];
@@ -30,18 +33,23 @@ void computeN2Energy(__global float4* forceBuffers, __global float* energyBuffer
 
     while (pos < end) {
         // Extract the coordinates of this tile
+        unsigned int x, y;
 #ifdef USE_CUTOFF
+        if (numTiles <= maxTiles) {
             ushort2 tileIndices = tiles[pos];
-        unsigned int x = tileIndices.x;
-        unsigned int y = tileIndices.y;
-#else
-        unsigned int y = (unsigned int) floor(NUM_BLOCKS+0.5f-sqrt((NUM_BLOCKS+0.5f)*(NUM_BLOCKS+0.5f)-2*pos));
-        unsigned int x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
+            x = tileIndices.x;
+            y = tileIndices.y;
+        }
+        else
+#endif
+        {
+            y = (unsigned int) floor(NUM_BLOCKS+0.5f-sqrt((NUM_BLOCKS+0.5f)*(NUM_BLOCKS+0.5f)-2*pos));
+            x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
             if (x >= NUM_BLOCKS) { // Occasionally happens due to roundoff error.
                 y++;
                 x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
             }
-#endif
+        }
         unsigned int tgx = get_local_id(0) & (TILE_SIZE-1);
         unsigned int tbx = get_local_id(0) - tgx;
         unsigned int atom1 = x*TILE_SIZE + tgx;
@@ -128,7 +136,7 @@ void computeN2Energy(__global float4* forceBuffers, __global float* energyBuffer
             local_force[get_local_id(0)] = 0.0f;
             CLEAR_LOCAL_DERIVATIVES
 #ifdef USE_CUTOFF
-            unsigned int flags = interactionFlags[pos];
+            unsigned int flags = (numTiles <= maxTiles ? interactionFlags[pos] : 0xFFFFFFFF);
             if (!hasExclusions && flags == 0) {
                 // No interactions in this tile.
             }

platforms/opencl/src/kernels/customGBValueN2_default.cl

@@ -9,16 +9,19 @@ void computeN2Value(__global float4* posq, __local float4* local_posq, __global
         __global unsigned int* exclusionIndices, __global unsigned int* exclusionRowIndices, __global float* global_value, __local float* local_value,
         __local float* tempBuffer,
 #ifdef USE_CUTOFF
-        __global ushort2* tiles, __global unsigned int* interactionFlags, __global unsigned int* interactionCount, float4 periodicBoxSize, float4 invPeriodicBoxSize
+        __global ushort2* tiles, __global unsigned int* interactionCount, float4 periodicBoxSize, float4 invPeriodicBoxSize, unsigned int maxTiles
 #else
         unsigned int numTiles
 #endif
         PARAMETER_ARGUMENTS) {
 #ifdef USE_CUTOFF
     unsigned int numTiles = interactionCount[0];
-#endif
+    unsigned int pos = get_group_id(0)*(numTiles > maxTiles ? NUM_BLOCKS*(NUM_BLOCKS+1)/2 : numTiles)/get_num_groups(0);
+    unsigned int end = (get_group_id(0)+1)*(numTiles > maxTiles ? NUM_BLOCKS*(NUM_BLOCKS+1)/2 : numTiles)/get_num_groups(0);
+#else
     unsigned int pos = get_group_id(0)*numTiles/get_num_groups(0);
     unsigned int end = (get_group_id(0)+1)*numTiles/get_num_groups(0);
+#endif
     float energy = 0.0f;
     unsigned int lasty = 0xFFFFFFFF;
     __local unsigned int exclusionRange[2];
@@ -26,18 +29,23 @@ void computeN2Value(__global float4* posq, __local float4* local_posq, __global
 
     while (pos < end) {
         // Extract the coordinates of this tile
+        unsigned int x, y;
 #ifdef USE_CUTOFF
+        if (numTiles <= maxTiles) {
             ushort2 tileIndices = tiles[pos];
-        unsigned int x = tileIndices.x;
-        unsigned int y = tileIndices.y;
-#else
-        unsigned int y = (unsigned int) floor(NUM_BLOCKS+0.5f-sqrt((NUM_BLOCKS+0.5f)*(NUM_BLOCKS+0.5f)-2*pos));
-        unsigned int x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
+            x = tileIndices.x;
+            y = tileIndices.y;
+        }
+        else
+#endif
+        {
+            y = (unsigned int) floor(NUM_BLOCKS+0.5f-sqrt((NUM_BLOCKS+0.5f)*(NUM_BLOCKS+0.5f)-2*pos));
+            x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
             if (x >= NUM_BLOCKS) { // Occasionally happens due to roundoff error.
                 y++;
                 x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
             }
-#endif
+        }
         unsigned int baseLocalAtom = (get_local_id(0) < TILE_SIZE ? 0 : TILE_SIZE/2);
         unsigned int tgx = get_local_id(0) & (TILE_SIZE-1);
         unsigned int valueBufferOffset = (tgx < TILE_SIZE/2 ? 0 : TILE_SIZE);

platforms/opencl/src/kernels/customGBValueN2_nvidia.cl

@@ -9,18 +9,21 @@ void computeN2Value(__global float4* posq, __local float4* local_posq, __global
         __global unsigned int* exclusionIndices, __global unsigned int* exclusionRowIndices, __global float* global_value, __local float* local_value,
         __local float* tempBuffer,
 #ifdef USE_CUTOFF
-        __global ushort2* tiles, __global unsigned int* interactionFlags, __global unsigned int* interactionCount, float4 periodicBoxSize, float4 invPeriodicBoxSize
+        __global ushort2* tiles, __global unsigned int* interactionCount, float4 periodicBoxSize, float4 invPeriodicBoxSize, unsigned int maxTiles, __global unsigned int* interactionFlags
 #else
         unsigned int numTiles
 #endif
         PARAMETER_ARGUMENTS) {
-#ifdef USE_CUTOFF
-    unsigned int numTiles = interactionCount[0];
-#endif
     unsigned int totalWarps = get_global_size(0)/TILE_SIZE;
     unsigned int warp = get_global_id(0)/TILE_SIZE;
+#ifdef USE_CUTOFF
+    unsigned int numTiles = interactionCount[0];
+    unsigned int pos = warp*(numTiles > maxTiles ? NUM_BLOCKS*(NUM_BLOCKS+1)/2 : numTiles)/totalWarps;
+    unsigned int end = (warp+1)*(numTiles > maxTiles ? NUM_BLOCKS*(NUM_BLOCKS+1)/2 : numTiles)/totalWarps;
+#else
     unsigned int pos = warp*numTiles/totalWarps;
     unsigned int end = (warp+1)*numTiles/totalWarps;
+#endif
     float energy = 0.0f;
     unsigned int lasty = 0xFFFFFFFF;
     __local unsigned int exclusionRange[4];
@@ -28,18 +31,23 @@ void computeN2Value(__global float4* posq, __local float4* local_posq, __global
 
     while (pos < end) {
         // Extract the coordinates of this tile
+        unsigned int x, y;
 #ifdef USE_CUTOFF
+        if (numTiles <= maxTiles) {
             ushort2 tileIndices = tiles[pos];
-        unsigned int x = tileIndices.x;
-        unsigned int y = tileIndices.y;
-#else
-        unsigned int y = (unsigned int) floor(NUM_BLOCKS+0.5f-sqrt((NUM_BLOCKS+0.5f)*(NUM_BLOCKS+0.5f)-2*pos));
-        unsigned int x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
+            x = tileIndices.x;
+            y = tileIndices.y;
+        }
+        else
+#endif
+        {
+            y = (unsigned int) floor(NUM_BLOCKS+0.5f-sqrt((NUM_BLOCKS+0.5f)*(NUM_BLOCKS+0.5f)-2*pos));
+            x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
             if (x >= NUM_BLOCKS) { // Occasionally happens due to roundoff error.
                 y++;
                 x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
             }
-#endif
+        }
         unsigned int tgx = get_local_id(0) & (TILE_SIZE-1);
         unsigned int tbx = get_local_id(0) - tgx;
         unsigned int atom1 = x*TILE_SIZE + tgx;
@@ -125,7 +133,7 @@ void computeN2Value(__global float4* posq, __local float4* local_posq, __global
             }
             local_value[get_local_id(0)] = 0.0f;
 #ifdef USE_CUTOFF
-            unsigned int flags = interactionFlags[pos];
+            unsigned int flags = (numTiles <= maxTiles ? interactionFlags[pos] : 0xFFFFFFFF);
             if (!hasExclusions && flags != 0xFFFFFFFF) {
                 if (flags == 0) {
                     // No interactions in this tile.

platforms/opencl/src/kernels/findInteractingBlocks.cl

@@ -147,6 +147,7 @@ void storeInteractionData(__local ushort2* buffer, __local int* valid, __local s
     if (get_local_id(0) == 0)
         *baseIndex = atom_add(interactionCount, numValid);
     barrier(CLK_LOCAL_MEM_FENCE);
+    if (*baseIndex+numValid <= MAX_TILES)
         for (int i = get_local_id(0); i < numValid; i += GROUP_SIZE)
             interactingTiles[*baseIndex+i] = temp[i];
     barrier(CLK_LOCAL_MEM_FENCE);
@@ -232,6 +233,8 @@ __kernel void findInteractionsWithinBlocks(float cutoffSquared, float4 periodicB
     unsigned int end = (warp+1)*numTiles/totalWarps;
     unsigned int index = get_local_id(0) & (TILE_SIZE - 1);
 
+    if (numTiles > MAX_TILES)
+        return;
     unsigned int lasty = 0xFFFFFFFF;
     float4 apos;
     while (pos < end) {

platforms/opencl/src/kernels/gbsaObc_default.cl

@@ -17,32 +17,40 @@ typedef struct {
 __kernel __attribute__((reqd_work_group_size(WORK_GROUP_SIZE, 1, 1)))
 void computeBornSum(__global float* global_bornSum, __global float4* posq, __global float2* global_params, __local AtomData* localData, __local float* tempBuffer,
 #ifdef USE_CUTOFF
-        __global ushort2* tiles, __global unsigned int* interactionFlags, __global unsigned int* interactionCount, float4 periodicBoxSize, float4 invPeriodicBoxSize) {
+        __global ushort2* tiles, __global unsigned int* interactionCount, float4 periodicBoxSize, float4 invPeriodicBoxSize) {
 #else
         unsigned int numTiles) {
 #endif
 #ifdef USE_CUTOFF
     unsigned int numTiles = interactionCount[0];
-#endif
+    unsigned int pos = get_group_id(0)*(numTiles > MAX_TILES ? NUM_BLOCKS*(NUM_BLOCKS+1)/2 : numTiles)/get_num_groups(0);
+    unsigned int end = (get_group_id(0)+1)*(numTiles > MAX_TILES ? NUM_BLOCKS*(NUM_BLOCKS+1)/2 : numTiles)/get_num_groups(0);
+#else
     unsigned int pos = get_group_id(0)*numTiles/get_num_groups(0);
     unsigned int end = (get_group_id(0)+1)*numTiles/get_num_groups(0);
+#endif
     float energy = 0.0f;
     unsigned int lasty = 0xFFFFFFFF;
 
     while (pos < end) {
         // Extract the coordinates of this tile
+        unsigned int x, y;
 #ifdef USE_CUTOFF
+        if (numTiles <= MAX_TILES) {
             ushort2 tileIndices = tiles[pos];
-        unsigned int x = tileIndices.x;
-        unsigned int y = tileIndices.y;
-#else
-        unsigned int y = (unsigned int) floor(NUM_BLOCKS+0.5f-sqrt((NUM_BLOCKS+0.5f)*(NUM_BLOCKS+0.5f)-2*pos));
-        unsigned int x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
+            x = tileIndices.x;
+            y = tileIndices.y;
+        }
+        else
+#endif
+        {
+            y = (unsigned int) floor(NUM_BLOCKS+0.5f-sqrt((NUM_BLOCKS+0.5f)*(NUM_BLOCKS+0.5f)-2*pos));
+            x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
             if (x >= NUM_BLOCKS) { // Occasionally happens due to roundoff error.
                 y++;
                 x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
             }
-#endif
+        }
         unsigned int baseLocalAtom = (get_local_id(0) < TILE_SIZE ? 0 : TILE_SIZE/2);
         unsigned int tgx = get_local_id(0) & (TILE_SIZE-1);
         unsigned int forceBufferOffset = (tgx < TILE_SIZE/2 ? 0 : TILE_SIZE);
@@ -196,32 +204,40 @@ void computeGBSAForce1(__global float4* forceBuffers, __global float* energyBuff
         __global float4* posq, __global float* global_bornRadii,
         __global float* global_bornForce, __local AtomData* localData, __local float4* tempBuffer,
 #ifdef USE_CUTOFF
-        __global ushort2* tiles, __global unsigned int* interactionFlags, __global unsigned int* interactionCount, float4 periodicBoxSize, float4 invPeriodicBoxSize) {
+        __global ushort2* tiles, __global unsigned int* interactionCount, float4 periodicBoxSize, float4 invPeriodicBoxSize) {
 #else
         unsigned int numTiles) {
 #endif
 #ifdef USE_CUTOFF
     unsigned int numTiles = interactionCount[0];
-#endif
+    unsigned int pos = get_group_id(0)*(numTiles > MAX_TILES ? NUM_BLOCKS*(NUM_BLOCKS+1)/2 : numTiles)/get_num_groups(0);
+    unsigned int end = (get_group_id(0)+1)*(numTiles > MAX_TILES ? NUM_BLOCKS*(NUM_BLOCKS+1)/2 : numTiles)/get_num_groups(0);
+#else
     unsigned int pos = get_group_id(0)*numTiles/get_num_groups(0);
     unsigned int end = (get_group_id(0)+1)*numTiles/get_num_groups(0);
+#endif
     float energy = 0.0f;
     unsigned int lasty = 0xFFFFFFFF;
 
     while (pos < end) {
         // Extract the coordinates of this tile
+        unsigned int x, y;
 #ifdef USE_CUTOFF
+        if (numTiles <= MAX_TILES) {
             ushort2 tileIndices = tiles[pos];
-        unsigned int x = tileIndices.x;
-        unsigned int y = tileIndices.y;
-#else
-        unsigned int y = (unsigned int) floor(NUM_BLOCKS+0.5f-sqrt((NUM_BLOCKS+0.5f)*(NUM_BLOCKS+0.5f)-2*pos));
-        unsigned int x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
+            x = tileIndices.x;
+            y = tileIndices.y;
+        }
+        else
+#endif
+        {
+            y = (unsigned int) floor(NUM_BLOCKS+0.5f-sqrt((NUM_BLOCKS+0.5f)*(NUM_BLOCKS+0.5f)-2*pos));
+            x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
             if (x >= NUM_BLOCKS) { // Occasionally happens due to roundoff error.
                 y++;
                 x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
             }
-#endif
+        }
         unsigned int baseLocalAtom = (get_local_id(0) < TILE_SIZE ? 0 : TILE_SIZE/2);
         unsigned int tgx = get_local_id(0) & (TILE_SIZE-1);
         unsigned int forceBufferOffset = (tgx < TILE_SIZE/2 ? 0 : TILE_SIZE);

platforms/opencl/src/kernels/gbsaObc_nvidia.cl

@@ -17,34 +17,42 @@ typedef struct {
 __kernel __attribute__((reqd_work_group_size(WORK_GROUP_SIZE, 1, 1)))
 void computeBornSum(__global float* global_bornSum, __global float4* posq, __global float2* global_params, __local AtomData* localData, __local float* tempBuffer,
 #ifdef USE_CUTOFF
-        __global ushort2* tiles, __global unsigned int* interactionFlags, __global unsigned int* interactionCount, float4 periodicBoxSize, float4 invPeriodicBoxSize) {
+        __global ushort2* tiles, __global unsigned int* interactionCount, float4 periodicBoxSize, float4 invPeriodicBoxSize, __global unsigned int* interactionFlags) {
 #else
         unsigned int numTiles) {
-#endif
-#ifdef USE_CUTOFF
-    unsigned int numTiles = interactionCount[0];
 #endif
     unsigned int totalWarps = get_global_size(0)/TILE_SIZE;
     unsigned int warp = get_global_id(0)/TILE_SIZE;
+#ifdef USE_CUTOFF
+    unsigned int numTiles = interactionCount[0];
+    unsigned int pos = warp*(numTiles > MAX_TILES ? NUM_BLOCKS*(NUM_BLOCKS+1)/2 : numTiles)/totalWarps;
+    unsigned int end = (warp+1)*(numTiles > MAX_TILES ? NUM_BLOCKS*(NUM_BLOCKS+1)/2 : numTiles)/totalWarps;
+#else
     unsigned int pos = warp*numTiles/totalWarps;
     unsigned int end = (warp+1)*numTiles/totalWarps;
+#endif
     float energy = 0.0f;
     unsigned int lasty = 0xFFFFFFFF;
 
     while (pos < end) {
         // Extract the coordinates of this tile
+        unsigned int x, y;
 #ifdef USE_CUTOFF
+        if (numTiles <= MAX_TILES) {
             ushort2 tileIndices = tiles[pos];
-        unsigned int x = tileIndices.x;
-        unsigned int y = tileIndices.y;
-#else
-        unsigned int y = (unsigned int) floor(NUM_BLOCKS+0.5f-sqrt((NUM_BLOCKS+0.5f)*(NUM_BLOCKS+0.5f)-2*pos));
-        unsigned int x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
+            x = tileIndices.x;
+            y = tileIndices.y;
+        }
+        else
+#endif
+        {
+            y = (unsigned int) floor(NUM_BLOCKS+0.5f-sqrt((NUM_BLOCKS+0.5f)*(NUM_BLOCKS+0.5f)-2*pos));
+            x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
             if (x >= NUM_BLOCKS) { // Occasionally happens due to roundoff error.
                 y++;
                 x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
             }
-#endif
+        }
         unsigned int tgx = get_local_id(0) & (TILE_SIZE-1);
         unsigned int tbx = get_local_id(0) - tgx;
         unsigned int atom1 = x*TILE_SIZE + tgx;
@@ -115,7 +123,7 @@ void computeBornSum(__global float* global_bornSum, __global float4* posq, __glo
             }
             localData[get_local_id(0)].bornSum = 0.0f;
 #ifdef USE_CUTOFF
-            unsigned int flags = interactionFlags[pos];
+            unsigned int flags = (numTiles <= MAX_TILES ? interactionFlags[pos] : 0xFFFFFFFF);
             if (flags != 0xFFFFFFFF && false) { // TODO: Fix this: should be checking for exclusions
                 if (flags == 0) {
                     // No interactions in this tile.
@@ -262,34 +270,42 @@ void computeGBSAForce1(__global float4* forceBuffers, __global float* energyBuff
         __global float4* posq, __global float* global_bornRadii,
         __global float* global_bornForce, __local AtomData* localData, __local float4* tempBuffer,
 #ifdef USE_CUTOFF
-        __global ushort2* tiles, __global unsigned int* interactionFlags, __global unsigned int* interactionCount, float4 periodicBoxSize, float4 invPeriodicBoxSize) {
+        __global ushort2* tiles, __global unsigned int* interactionCount, float4 periodicBoxSize, float4 invPeriodicBoxSize, __global unsigned int* interactionFlags) {
 #else
         unsigned int numTiles) {
-#endif
-#ifdef USE_CUTOFF
-    unsigned int numTiles = interactionCount[0];
 #endif
     unsigned int totalWarps = get_global_size(0)/TILE_SIZE;
     unsigned int warp = get_global_id(0)/TILE_SIZE;
+#ifdef USE_CUTOFF
+    unsigned int numTiles = interactionCount[0];
+    unsigned int pos = warp*(numTiles > MAX_TILES ? NUM_BLOCKS*(NUM_BLOCKS+1)/2 : numTiles)/totalWarps;
+    unsigned int end = (warp+1)*(numTiles > MAX_TILES ? NUM_BLOCKS*(NUM_BLOCKS+1)/2 : numTiles)/totalWarps;
+#else
     unsigned int pos = warp*numTiles/totalWarps;
     unsigned int end = (warp+1)*numTiles/totalWarps;
+#endif
     float energy = 0.0f;
     unsigned int lasty = 0xFFFFFFFF;
 
     while (pos < end) {
         // Extract the coordinates of this tile
+        unsigned int x, y;
 #ifdef USE_CUTOFF
+        if (numTiles <= MAX_TILES) {
             ushort2 tileIndices = tiles[pos];
-        unsigned int x = tileIndices.x;
-        unsigned int y = tileIndices.y;
-#else
-        unsigned int y = (unsigned int) floor(NUM_BLOCKS+0.5f-sqrt((NUM_BLOCKS+0.5f)*(NUM_BLOCKS+0.5f)-2*pos));
-        unsigned int x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
+            x = tileIndices.x;
+            y = tileIndices.y;
+        }
+        else
+#endif
+        {
+            y = (unsigned int) floor(NUM_BLOCKS+0.5f-sqrt((NUM_BLOCKS+0.5f)*(NUM_BLOCKS+0.5f)-2*pos));
+            x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
             if (x >= NUM_BLOCKS) { // Occasionally happens due to roundoff error.
                 y++;
                 x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
             }
-#endif
+        }
         unsigned int tgx = get_local_id(0) & (TILE_SIZE-1);
         unsigned int tbx = get_local_id(0) - tgx;
         unsigned int atom1 = x*TILE_SIZE + tgx;
@@ -365,7 +381,7 @@ void computeGBSAForce1(__global float4* forceBuffers, __global float* energyBuff
             localData[get_local_id(0)].fz = 0.0f;
             localData[get_local_id(0)].fw = 0.0f;
 #ifdef USE_CUTOFF
-            unsigned int flags = interactionFlags[pos];
+            unsigned int flags = (numTiles <= MAX_TILES ? interactionFlags[pos] : 0xFFFFFFFF);
             if (flags != 0xFFFFFFFF && false) { // TODO: Fix this: should be checking for exclusions
                 if (flags == 0) {
                     // No interactions in this tile.

platforms/opencl/src/kernels/nonbonded_default.cl

@@ -15,16 +15,19 @@ __kernel __attribute__((reqd_work_group_size(WORK_GROUP_SIZE, 1, 1)))
 void computeNonbonded(__global float4* forceBuffers, __global float* energyBuffer, __global float4* posq, __global unsigned int* exclusions,
         __global unsigned int* exclusionIndices, __global unsigned int* exclusionRowIndices, __local AtomData* localData, __local float4* tempBuffer,
 #ifdef USE_CUTOFF
-        __global ushort2* tiles, __global unsigned int* interactionFlags, __global unsigned int* interactionCount, float4 periodicBoxSize, float4 invPeriodicBoxSize
+        __global ushort2* tiles, __global unsigned int* interactionCount, float4 periodicBoxSize, float4 invPeriodicBoxSize
 #else
         unsigned int numTiles
 #endif
         PARAMETER_ARGUMENTS) {
 #ifdef USE_CUTOFF
     unsigned int numTiles = interactionCount[0];
-#endif
+    unsigned int pos = get_group_id(0)*(numTiles > MAX_TILES ? NUM_BLOCKS*(NUM_BLOCKS+1)/2 : numTiles)/get_num_groups(0);
+    unsigned int end = (get_group_id(0)+1)*(numTiles > MAX_TILES ? NUM_BLOCKS*(NUM_BLOCKS+1)/2 : numTiles)/get_num_groups(0);
+#else
     unsigned int pos = get_group_id(0)*numTiles/get_num_groups(0);
     unsigned int end = (get_group_id(0)+1)*numTiles/get_num_groups(0);
+#endif
     float energy = 0.0f;
     unsigned int lasty = 0xFFFFFFFF;
     __local unsigned int exclusionRange[2];
@@ -32,18 +35,23 @@ void computeNonbonded(__global float4* forceBuffers, __global float* energyBuffe
 
     while (pos < end) {
         // Extract the coordinates of this tile
+        unsigned int x, y;
 #ifdef USE_CUTOFF
+        if (numTiles <= MAX_TILES) {
             ushort2 tileIndices = tiles[pos];
-        unsigned int x = tileIndices.x;
-        unsigned int y = tileIndices.y;
-#else
-        unsigned int y = (unsigned int) floor(NUM_BLOCKS+0.5f-sqrt((NUM_BLOCKS+0.5f)*(NUM_BLOCKS+0.5f)-2*pos));
-        unsigned int x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
+            x = tileIndices.x;
+            y = tileIndices.y;
+        }
+        else
+#endif
+        {
+            y = (unsigned int) floor(NUM_BLOCKS+0.5f-sqrt((NUM_BLOCKS+0.5f)*(NUM_BLOCKS+0.5f)-2*pos));
+            x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
             if (x >= NUM_BLOCKS) { // Occasionally happens due to roundoff error.
                 y++;
                 x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
             }
-#endif
+        }
         unsigned int baseLocalAtom = (get_local_id(0) < TILE_SIZE ? 0 : TILE_SIZE/2);
         unsigned int tgx = get_local_id(0) & (TILE_SIZE-1);
         unsigned int forceBufferOffset = (tgx < TILE_SIZE/2 ? 0 : TILE_SIZE);

platforms/opencl/src/kernels/nonbonded_nvidia.cl

@@ -15,18 +15,21 @@ __kernel __attribute__((reqd_work_group_size(WORK_GROUP_SIZE, 1, 1)))
 void computeNonbonded(__global float4* forceBuffers, __global float* energyBuffer, __global float4* posq, __global unsigned int* exclusions,
         __global unsigned int* exclusionIndices, __global unsigned int* exclusionRowIndices, __local AtomData* localData, __local float4* tempBuffer,
 #ifdef USE_CUTOFF
-        __global ushort2* tiles, __global unsigned int* interactionFlags, __global unsigned int* interactionCount, float4 periodicBoxSize, float4 invPeriodicBoxSize
+        __global ushort2* tiles, __global unsigned int* interactionCount, float4 periodicBoxSize, float4 invPeriodicBoxSize, __global unsigned int* interactionFlags
 #else
         unsigned int numTiles
 #endif
         PARAMETER_ARGUMENTS) {
-#ifdef USE_CUTOFF
-    unsigned int numTiles = interactionCount[0];
-#endif
     unsigned int totalWarps = get_global_size(0)/TILE_SIZE;
     unsigned int warp = get_global_id(0)/TILE_SIZE;
+#ifdef USE_CUTOFF
+    unsigned int numTiles = interactionCount[0];
+    unsigned int pos = warp*(numTiles > MAX_TILES ? NUM_BLOCKS*(NUM_BLOCKS+1)/2 : numTiles)/totalWarps;
+    unsigned int end = (warp+1)*(numTiles > MAX_TILES ? NUM_BLOCKS*(NUM_BLOCKS+1)/2 : numTiles)/totalWarps;
+#else
     unsigned int pos = warp*numTiles/totalWarps;
     unsigned int end = (warp+1)*numTiles/totalWarps;
+#endif
     float energy = 0.0f;
     unsigned int lasty = 0xFFFFFFFF;
     __local unsigned int exclusionRange[4];
@@ -34,18 +37,23 @@ void computeNonbonded(__global float4* forceBuffers, __global float* energyBuffe
 
     while (pos < end) {
         // Extract the coordinates of this tile
+        unsigned int x, y;
 #ifdef USE_CUTOFF
+        if (numTiles <= MAX_TILES) {
             ushort2 tileIndices = tiles[pos];
-        unsigned int x = tileIndices.x;
-        unsigned int y = tileIndices.y;
-#else
-        unsigned int y = (unsigned int) floor(NUM_BLOCKS+0.5f-sqrt((NUM_BLOCKS+0.5f)*(NUM_BLOCKS+0.5f)-2*pos));
-        unsigned int x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
+            x = tileIndices.x;
+            y = tileIndices.y;
+        }
+        else
+#endif
+        {
+            y = (unsigned int) floor(NUM_BLOCKS+0.5f-sqrt((NUM_BLOCKS+0.5f)*(NUM_BLOCKS+0.5f)-2*pos));
+            x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
             if (x >= NUM_BLOCKS) { // Occasionally happens due to roundoff error.
                 y++;
                 x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
             }
-#endif
+        }
         unsigned int tgx = get_local_id(0) & (TILE_SIZE-1);
         unsigned int tbx = get_local_id(0) - tgx;
         unsigned int atom1 = x*TILE_SIZE + tgx;
@@ -137,7 +145,7 @@ void computeNonbonded(__global float4* forceBuffers, __global float* energyBuffe
             localData[get_local_id(0)].fy = 0.0f;
             localData[get_local_id(0)].fz = 0.0f;
 #ifdef USE_CUTOFF
-            unsigned int flags = interactionFlags[pos];
+            unsigned int flags = (numTiles <= MAX_TILES ? interactionFlags[pos] : 0xFFFFFFFF);
             if (!hasExclusions && flags != 0xFFFFFFFF) {
                 if (flags == 0) {
                     // No interactions in this tile.

platforms/opencl/tests/TestOpenCLNonbondedForce.cpp

@@ -523,6 +523,7 @@ void testBlockInteractions(bool periodic) {
     int numWithInteractions = interactionCount[0];
     vector<bool> hasInteractions(numBlocks*(numBlocks+1)/2, false);
     nb.getInteractingTiles().download(interactingTiles);
+    if (clcontext.getSIMDWidth() == 32)
         nb.getInteractionFlags().download(interactionFlags);
     const unsigned int atoms = clcontext.getPaddedNumAtoms();
     const unsigned int grid = OpenCLContext::TileSize;