Fix some robustness issues in the examples (#5984)

* examples: Make hello-world example exit gracefully if VK cannot be initialized

- Check if VK API function pointers are valid before using them
- Return 0 and exit if VK initialization fails
- Enable hello-world example

* examples: Fixes for ray-tracing examples

- Assert that accelleration structure buffer is not nullptr
- Check if buffer creation succeeded before proceeding
 - This makes initialization not hang, but it still fails.
   Therefore, the test expectations are just updated to point to another issue.
- Enable ray-tracing tests on Windows

examples/hello-world/main.cpp

@@ -80,7 +80,11 @@ int main(int argc, char* argv[])
 
 int HelloWorldExample::run()
 {
-    RETURN_ON_FAIL(initVulkanInstanceAndDevice());
+    // If VK failed to initialize, skip running but return success anyway.
+    // This allows our automated testing to distinguish between essential failures and the
+    // case where the application is just not supported.
+    if (int result = initVulkanInstanceAndDevice())
+        return (vkAPI.device == VK_NULL_HANDLE) ? 0 : result;
     RETURN_ON_FAIL(createComputePipelineFromShader());
     RETURN_ON_FAIL(createInOutBuffers());
     RETURN_ON_FAIL(dispatchCompute());
@@ -511,6 +515,9 @@ int HelloWorldExample::printComputeResults()
 
 HelloWorldExample::~HelloWorldExample()
 {
+    if (vkAPI.device == VK_NULL_HANDLE)
+        return;
+
     vkAPI.vkDestroyPipeline(vkAPI.device, pipeline, nullptr);
     for (int i = 0; i < 3; i++)
     {

examples/ray-tracing-pipeline/main.cpp

@@ -382,13 +382,17 @@ struct RayTracing : public WindowedAppBase
             asDraftBufferDesc.sizeInBytes =
                 (size_t)accelerationStructurePrebuildInfo.resultDataMaxSize;
             ComPtr<IBufferResource> draftBuffer = gDevice->createBufferResource(asDraftBufferDesc);
+            if (!draftBuffer)
+                return SLANG_FAIL;
             IBufferResource::Desc scratchBufferDesc;
             scratchBufferDesc.type = IResource::Type::Buffer;
             scratchBufferDesc.defaultState = ResourceState::UnorderedAccess;
             scratchBufferDesc.sizeInBytes =
                 (size_t)accelerationStructurePrebuildInfo.scratchDataSize;
             ComPtr<IBufferResource> scratchBuffer =
                 gDevice->createBufferResource(scratchBufferDesc);
+            if (!scratchBuffer)
+                return SLANG_FAIL;
 
             // Build acceleration structure.
             ComPtr<IQueryPool> compactedSizeQuery;

examples/ray-tracing/main.cpp

@@ -373,12 +373,16 @@ struct RayTracing : public WindowedAppBase
             asDraftBufferDesc.defaultState = ResourceState::AccelerationStructure;
             asDraftBufferDesc.sizeInBytes = accelerationStructurePrebuildInfo.resultDataMaxSize;
             ComPtr<IBufferResource> draftBuffer = gDevice->createBufferResource(asDraftBufferDesc);
+            if (!draftBuffer)
+                return SLANG_FAIL;
             IBufferResource::Desc scratchBufferDesc;
             scratchBufferDesc.type = IResource::Type::Buffer;
             scratchBufferDesc.defaultState = ResourceState::UnorderedAccess;
             scratchBufferDesc.sizeInBytes = accelerationStructurePrebuildInfo.scratchDataSize;
             ComPtr<IBufferResource> scratchBuffer =
                 gDevice->createBufferResource(scratchBufferDesc);
+            if (!scratchBuffer)
+                return SLANG_FAIL;
 
             // Build acceleration structure.
             ComPtr<IQueryPool> compactedSizeQuery;

tests/expected-example-failure-github.txt

@@ -11,6 +11,5 @@ macos:aarch64:(debug|release):hello-world           # See issue 5520
 macos:aarch64:(debug|release):model-viewer          # See issue 5520
 macos:aarch64:(debug|release):ray-tracing           # See issue 5520
 macos:aarch64:(debug|release):ray-tracing-pipeline  # See issue 5520
-windows:x86_64:debug:hello-world                    # See issue 5520
-windows:x86_64:debug:ray-tracing                    # See issue 5520
-windows:x86_64:debug:ray-tracing-pipeline           # See issue 5520
+windows:x86_64:debug:ray-tracing                    # See issue 5988
+windows:x86_64:debug:ray-tracing-pipeline           # See issue 5988

tools/gfx/d3d12/d3d12-device.cpp

@@ -2231,6 +2231,7 @@ Result DeviceImpl::createAccelerationStructure(
     IAccelerationStructure** outAS)
 {
 #if SLANG_GFX_HAS_DXR_SUPPORT
+    assert(desc.buffer != nullptr);
     RefPtr<AccelerationStructureImpl> result = new AccelerationStructureImpl();
     result->m_device5 = m_device5;
     result->m_buffer = static_cast<BufferResourceImpl*>(desc.buffer);