Improved checks for timestamp GPU counter support on older devices.

Check that appropriate GPU counter set is supported on
the device before creating GPU counter sample buffer.
Don't attempt to timestamp using GPU counters unless
a GPU sample counter buffer has been created.

Docs/Whats_New.md

@@ -19,6 +19,7 @@ MoltenVK 1.1.6
 Released TBD
 
 - Support maximum point primitive size of 511.
+- Improved checks for timestamp GPU counter support on older devices.
 - Update to latest SPIRV-Cross version:
 	- Add support for `OpSpecConstantOp` ops `OpQuantizeToF16` and `OpSRem`.
 

MoltenVK/MoltenVK/Commands/MVKCommandBuffer.mm

@@ -768,8 +768,8 @@ void MVKCommandEncoder::markTimestamp(MVKTimestampQueryPool* pQueryPool, uint32_
     }
 	addActivatedQueries(pQueryPool, query, queryCount);
 
-	MVKCounterSamplingFlags sampPts = _device->_pMetalFeatures->counterSamplingPoints;
-	if (sampPts) {
+	if (pQueryPool->hasMTLCounterBuffer()) {
+		MVKCounterSamplingFlags sampPts = _device->_pMetalFeatures->counterSamplingPoints;
 		for (uint32_t qOfst = 0; qOfst < queryCount; qOfst++) {
 			if (mvkIsAnyFlagEnabled(sampPts, MVK_COUNTER_SAMPLING_AT_PIPELINE_STAGE)) {
 				_timestampStageCounterQueries.push_back({ pQueryPool, query + qOfst });

MoltenVK/MoltenVK/GPUObjects/MVKQueryPool.h

@@ -182,6 +182,9 @@ class MVKGPUCounterQueryPool : public MVKQueryPool {
 
 public:
 
+	/** Returns whether a MTLCounterBuffer is being used by this query pool. */
+	bool hasMTLCounterBuffer() { return _mtlCounterBuffer != nil; }
+
 	/**
 	 * Returns the MTLCounterBuffer being used by this query pool,
 	 * or returns nil if GPU counters are not supported.

MoltenVK/MoltenVK/GPUObjects/MVKQueryPool.mm

@@ -335,7 +335,7 @@ MVKGPUCounterQueryPool::MVKGPUCounterQueryPool(MVKDevice* device, const VkQueryP
 void MVKGPUCounterQueryPool::initMTLCounterSampleBuffer(const VkQueryPoolCreateInfo* pCreateInfo,
 														id<MTLCounterSet> mtlCounterSet,
 														const char* queryTypeName) {
-	if ( !_device->_pMetalFeatures->counterSamplingPoints ) { return; }
+	if ( !mtlCounterSet ) { return; }
 
 	@autoreleasepool {
 		MTLCounterSampleBufferDescriptor* tsDesc = [[[MTLCounterSampleBufferDescriptor alloc] init] autorelease];