Clean up render-test handling of input (#1766)

The original goal of this change was to streamline the `TEST_INPUT` system by eliminating options that are no longer relevant once we have eliminated the non-shader-object execution paths. The result is more or less a re-implementation/refactor of the logic around how input is parsed and represented, that tries to set things up for a more general sytem going forward.

The main changes isthat the `ShaderInputLayout` no longer tracks a simple flat list of `ShaderInputLayoutEntry` (that is a kind of pseudo-union of the various buffer/texture/value cases), and it instead uses a hierarchical representation composed of `RefObject`-derived classes to represent "values."

There are several "simple" cases of values

* Textures

* Samplers

* Uniform/ordinary data (`uniform`)

* Buffers composed of uniform/ordinary data (`ubuffer`)

Then there are composed/aggregate values that nest other values:

* An *aggregate* value is a set of *fields* which are name/value pairs. It can be used to fill in a structure, for example.

* An *array* value is a list of values for the elements of an array. It can be used to fill out an array-of-textures parameter, for example.

* A combined texture/sampler value is a pair of a texture value and a sampler value (easy enough)

* An *object* holds an optional type name for a shader object to allocate (it defaults to the type that is "under" the current shader cursor when binding), and a nested value that describes how to fill in the contents of that object

Finally there are cases of values that are just syntactic sugar:

* A `cbuffer` is just shorthand for creating an object value with a nested uniform/ordinary data value

The big idea with this recursive structure is that it gives us a way to handle more arbitrary data types with name-based binding. Supporting this new capability requires changes to both how input layouts get parsed, and also how they get bound into shader objects.

On the parsing side, things have been refactored a bit so that parsing isn't a single monolithic routine. The refactor also tries to make it so that the various options on an input item (e.g., the `size=...` option for textures) are only supported on the relevant type of entry (so you can't specify as many useless options that will be ignored).

The bigger change to parsing is that it now supports a hierarchical structure, where certain input elements like `begin_array` can push a new "parent" value onto a stack, and subsequent `TEST_INPUT` lines will be parsed as children of that item until a matching `end` item. This approach means that we can now in principle describe arbitrary hierarchical structures as part of test input without endlessly increasing the complexity of invididual `TEST_INPUT` lines.

On the binding side, we now have a central recursive operation called `assign(ShaderCursor, ShaderInputLayout::ValPtr)` that assigns from a parsed `ShaderInputLayout` value to a particular cursor. That operation can then recurse on the fields/elements/contents of whatever the cursor points to.

Major open directions:

* With this change it is still necessary to use `uniform` entries to set things like individual integers or `float`s and that is a little silly. It would be good to have some streamlines cases for setting individual scalar values.

* Further, once we have a hierarchical representation of the values for `TEST_INPUT` lines, it becomes clear that we really ought to move to a format more like `TEST_INPUT: dstLocation = srcValue;` where `srcValue` is some kind of hierarchial expression grammar. Refactoring things in this way should make the binding logic even more clear and easy to understand. The refactored parser should make parsing hierarchical expressions easier to do in the future (even if it uses the push/pop model for now)

* One detailed note is that the representation of buffers in this change is kind of a compromise. Just as an "object" value is a thin wrapper around a recursively-contained value for its "content" it seems clear that a buffer could be represented as a wrapper around a content value that could include hierarchical aggregates/objects instead of just flat binary data (this would be important for things like a buffer over a structure type that lays out different on different targets). The main problem right now with changing the representation is actually needing to compute the size of a buffer based on its content, so that can/should be addressed in a subsequent change.

Details:

* The base `RenderTestApp` class and the `ShaderObjectRenderTestApp` classes have been merged, since the hierarchy no longer serves any purpose.

* Disabled the tess that rely on `StructuredBuffer<IWhatever>` because they aren't really supported by our current shader object implementation

* Replaced used of `Uniform` and `root_constants` in `TEST_INPUT` lines with just `uniform`

* Removed a bunch of uses of `stride` from `cbuffer` inputs, where it wasn't really correct/meaningful

* Added the `copyBuffer()` operation to VK/D3D renderers, along with some missing `Usage` cases to support it.

* Made `ShaderCursor` handle the logic to look up a name in the entry points of a root shader object, rather than just having that logic in `render-test`. (We probably need to make a clear design choice on this issue)

1 files changed, 249 insertions, 239 deletions

diff --git a/tools/render-test/render-test-main.cpp b/tools/render-test/render-test-main.cpp
index 02f20dd40..325f12e49 100644
--- a/tools/render-test/render-test-main.cpp
+++ b/tools/render-test/render-test-main.cpp
@@ -74,7 +74,6 @@ struct ShaderOutputPlan
 {
     struct Item
     {
-        Index                           inputLayoutEntryIndex;
         ComPtr<IResource>               resource;
         slang::TypeLayoutReflection*    typeLayout = nullptr;
     };
@@ -82,25 +81,25 @@ struct ShaderOutputPlan
     List<Item> items;
 };
 
-class RenderTestApp : public RefObject
+class RenderTestApp
 {
 public:
     Result update();
 
     // At initialization time, we are going to load and compile our Slang shader
     // code, and then create the API objects we need for rendering.
-    virtual Result initialize(
+    Result initialize(
         SlangSession* session,
         IDevice* device,
         const Options& options,
-        const ShaderCompilerUtil::Input& input) = 0;
+        const ShaderCompilerUtil::Input& input);
     void runCompute(IComputeCommandEncoder* encoder);
     void renderFrame(IRenderCommandEncoder* encoder);
     void finalize();
 
-    virtual void applyBinding(PipelineType pipelineType, ICommandEncoder* encoder) = 0;
-    virtual void setProjectionMatrix(IResourceCommandEncoder* encoder) = 0;
-    virtual Result writeBindingOutput(const char* fileName) = 0;
+    void applyBinding(PipelineType pipelineType, ICommandEncoder* encoder);
+    void setProjectionMatrix(IResourceCommandEncoder* encoder);
+    Result writeBindingOutput(const char* fileName);
 
     Result writeScreen(const char* filename);
 
@@ -112,7 +111,6 @@ protected:
         Options::ShaderProgramType shaderType,
         const ShaderCompilerUtil::Input& input);
     void _initializeRenderPass();
-    virtual void finalizeImpl();
 
     uint64_t m_startTicks;
 
@@ -135,256 +133,253 @@ protected:
     ShaderInputLayout m_shaderInputLayout; ///< The binding layout
 
     Options m_options;
-};
-
-class ShaderObjectRenderTestApp : public RenderTestApp
-{
-public:
-    virtual void applyBinding(PipelineType pipelineType, ICommandEncoder* encoder) SLANG_OVERRIDE;
-    virtual void setProjectionMatrix(IResourceCommandEncoder* encoder) SLANG_OVERRIDE;
-    virtual Result initialize(
-        SlangSession* session,
-        IDevice* device,
-        const Options& options,
-        const ShaderCompilerUtil::Input& input) SLANG_OVERRIDE;
-    virtual Result writeBindingOutput(const char* fileName) override;
-
-protected:
-    virtual void finalizeImpl() SLANG_OVERRIDE;
 
     ComPtr<IShaderObject> m_programVars;
     ShaderOutputPlan m_outputPlan;
 };
 
-SlangResult _assignVarsFromLayout(
-    IDevice*                   device,
-    IShaderObject*               shaderObject,
-    ShaderInputLayout const&    layout,
-    ShaderOutputPlan&           ioOutputPlan,
-    slang::ProgramLayout*       slangReflection)
+struct AssignValsFromLayoutContext
 {
-    ShaderCursor rootCursor = ShaderCursor(shaderObject);
-
-    const int textureBindFlags = IResource::BindFlag::NonPixelShaderResource | IResource::BindFlag::PixelShaderResource;
-
-    Index entryCount = layout.entries.getCount();
-    for(Index entryIndex = 0; entryIndex < entryCount; ++entryIndex)
+    IDevice*                device;
+    ShaderOutputPlan&       outputPlan;
+    slang::ProgramLayout*   slangReflection;
+
+    AssignValsFromLayoutContext(
+        IDevice*                    device,
+        ShaderOutputPlan&           outputPlan,
+        slang::ProgramLayout*       slangReflection)
+        : device(device)
+        , outputPlan(outputPlan)
+        , slangReflection(slangReflection)
+    {}
+
+    void maybeAddOutput(ShaderCursor const& dstCursor, ShaderInputLayout::Val* srcVal, IResource* resource)
     {
-        auto& entry = layout.entries[entryIndex];
-        if(entry.name.getLength() == 0)
+        if(srcVal->isOutput)
         {
-            StdWriters::getError().print("error: entries in `ShaderInputLayout` must include a name\n");
-            return SLANG_E_INVALID_ARG;
+            ShaderOutputPlan::Item item;
+            item.resource = resource;
+            item.typeLayout = dstCursor.getTypeLayout();
+            outputPlan.items.add(item);
         }
+    }
 
-        auto entryCursor = rootCursor.getPath(entry.name.getBuffer());
+    SlangResult assignData(ShaderCursor const& dstCursor, ShaderInputLayout::DataVal* srcVal)
+    {
+        const size_t bufferSize = srcVal->bufferData.getCount() * sizeof(uint32_t);
 
-        if(!entryCursor.isValid())
+        ShaderCursor dataCursor = dstCursor;
+        switch(dataCursor.getTypeLayout()->getKind())
         {
-            for(gfx::UInt i = 0; i < shaderObject->getEntryPointCount(); i++)
-            {
-                entryCursor = ShaderCursor(shaderObject->getEntryPoint(i)).getPath(entry.name.getBuffer());
-                if(entryCursor.isValid())
-                    break;
-            }
+        case slang::TypeReflection::Kind::ConstantBuffer:
+        case slang::TypeReflection::Kind::ParameterBlock:
+            dataCursor = dataCursor.getDereferenced();
+            break;
+
+        default:
+            break;
+
         }
 
+        SLANG_RETURN_ON_FAIL(dataCursor.setData(srcVal->bufferData.getBuffer(), bufferSize));
+        return SLANG_OK;
+    }
+
+    SlangResult assignBuffer(ShaderCursor const& dstCursor, ShaderInputLayout::BufferVal* srcVal)
+    {
+        const InputBufferDesc& srcBuffer = srcVal->bufferDesc;
+        auto& bufferData = srcVal->bufferData;
+        const size_t bufferSize = bufferData.getCount() * sizeof(uint32_t);
+
+        ComPtr<IBufferResource> bufferResource;
+        SLANG_RETURN_ON_FAIL(ShaderRendererUtil::createBufferResource(srcBuffer, /*entry.isOutput,*/ bufferSize, bufferData.getBuffer(), device, bufferResource));
+
+        IResourceView::Desc viewDesc;
+        viewDesc.type = IResourceView::Type::UnorderedAccess;
+        viewDesc.format = srcBuffer.format;
+        auto bufferView = device->createBufferView(
+            bufferResource,
+            viewDesc);
+        dstCursor.setResource(bufferView);
+        maybeAddOutput(dstCursor, srcVal, bufferResource);
+
+        return SLANG_OK;
+    }
+
+    SlangResult assignCombinedTextureSampler(ShaderCursor const& dstCursor, ShaderInputLayout::CombinedTextureSamplerVal* srcVal)
+    {
+        auto& textureEntry = srcVal->textureVal;
+        auto& samplerEntry = srcVal->samplerVal;
+
+        ComPtr<ITextureResource> texture;
+        SLANG_RETURN_ON_FAIL(ShaderRendererUtil::generateTextureResource(
+            textureEntry->textureDesc, textureBindFlags, device, texture));
 
-        if(!entryCursor.isValid())
+        auto sampler = _createSamplerState(device, samplerEntry->samplerDesc);
+
+        IResourceView::Desc viewDesc;
+        viewDesc.type = IResourceView::Type::ShaderResource;
+        auto textureView = device->createTextureView(
+            texture,
+            viewDesc);
+
+        dstCursor.setCombinedTextureSampler(textureView, sampler);
+        maybeAddOutput(dstCursor, srcVal, texture);
+
+        return SLANG_OK;
+    }
+
+    static const int textureBindFlags = IResource::BindFlag::NonPixelShaderResource | IResource::BindFlag::PixelShaderResource;
+
+    SlangResult assignTexture(ShaderCursor const& dstCursor, ShaderInputLayout::TextureVal* srcVal)
+    {
+        ComPtr<ITextureResource> texture;
+        SLANG_RETURN_ON_FAIL(ShaderRendererUtil::generateTextureResource(
+            srcVal->textureDesc, textureBindFlags, device, texture));
+
+        // TODO: support UAV textures...
+
+        IResourceView::Desc viewDesc;
+        viewDesc.type = IResourceView::Type::ShaderResource;
+        viewDesc.format = texture->getDesc()->format;
+        auto textureView = device->createTextureView(
+            texture,
+            viewDesc);
+
+        if (!textureView)
         {
-            StdWriters::getError().print("error: could not find shader parameter matching '%s'\n", entry.name.begin());
-            return SLANG_E_INVALID_ARG;
+            return SLANG_FAIL;
         }
-        slang::TypeLayoutReflection* typeLayout = entryCursor.getTypeLayout();
 
-        ComPtr<IResource> resource;
-        switch(entry.type)
-        {
-        case ShaderInputType::Uniform:
-            {
-                const size_t bufferSize = entry.bufferData.getCount() * sizeof(uint32_t);
+        dstCursor.setResource(textureView);
+        maybeAddOutput(dstCursor, srcVal, texture);
+        return SLANG_OK;
+    }
 
-                ShaderCursor dataCursor = entryCursor;
-                switch(dataCursor.getTypeLayout()->getKind())
-                {
-                case slang::TypeReflection::Kind::ConstantBuffer:
-                case slang::TypeReflection::Kind::ParameterBlock:
-                    dataCursor = dataCursor.getDereferenced();
-                    break;
+    SlangResult assignSampler(ShaderCursor const& dstCursor, ShaderInputLayout::SamplerVal* srcVal)
+    {
+        auto sampler = _createSamplerState(device, srcVal->samplerDesc);
 
-                default:
-                    break;
+        dstCursor.setSampler(sampler);
+        return SLANG_OK;
+    }
 
-                }
+    SlangResult assignAggregate(ShaderCursor const& dstCursor, ShaderInputLayout::AggVal* srcVal)
+    {
+        Index fieldCount = srcVal->fields.getCount();
+        for(Index fieldIndex = 0; fieldIndex < fieldCount; ++fieldIndex)
+        {
+            auto& field = srcVal->fields[fieldIndex];
 
-                dataCursor.setData(entry.bufferData.getBuffer(), bufferSize);
+            if(field.name.getLength() == 0)
+            {
+                StdWriters::getError().print("error: entries in `ShaderInputLayout` must include a name\n");
+                return SLANG_E_INVALID_ARG;
             }
-            break;
 
-        case ShaderInputType::Buffer:
-            {
-                const InputBufferDesc& srcBuffer = entry.bufferDesc;
-                const size_t bufferSize = entry.bufferData.getCount() * sizeof(uint32_t);
+            auto fieldCursor = dstCursor.getPath(field.name.getBuffer());
 
-                switch(srcBuffer.type)
-                {
-                case InputBufferType::ConstantBuffer:
-                    {
-                        // A `cbuffer` input line actually represents the data we
-                        // want to write *into* the buffer, and shouldn't
-                        // allocate a buffer itself.
-                        //
-                        entryCursor.getDereferenced().setData(entry.bufferData.getBuffer(), bufferSize);
-                    }
-                    break;
-
-                case InputBufferType::RootConstantBuffer:
-                    {
-                        // A `root_constants` input line actually represents the data we
-                        // want to write *into* the buffer, and shouldn't
-                        // allocate a buffer itself.
-                        //
-                        // Note: we are not doing `.getDereferenced()` here because the
-                        // `root_constant` line should be referring to a parameter value
-                        // inside the root-constant range, and not the range/buffer itself.
-                        //
-                        entryCursor.setData(entry.bufferData.getBuffer(), bufferSize);
-                    }
-                    break;
-
-                default:
-                    {
-
-                        ComPtr<IBufferResource> bufferResource;
-                        SLANG_RETURN_ON_FAIL(ShaderRendererUtil::createBufferResource(entry.bufferDesc, entry.isOutput, bufferSize, entry.bufferData.getBuffer(), device, bufferResource));
-                        resource = bufferResource;
-
-                        IResourceView::Desc viewDesc;
-                        viewDesc.type = IResourceView::Type::UnorderedAccess;
-                        viewDesc.format = srcBuffer.format;
-                        auto bufferView = device->createBufferView(
-                            bufferResource,
-                            viewDesc);
-                        entryCursor.setResource(bufferView);
-                    }
-                    break;
-                }
+            if(!fieldCursor.isValid())
+            {
+                StdWriters::getError().print("error: could not find shader parameter matching '%s'\n", field.name.begin());
+                return SLANG_E_INVALID_ARG;
             }
-            break;
 
-        case ShaderInputType::CombinedTextureSampler:
-            {
-                ComPtr<ITextureResource> texture;
-                SLANG_RETURN_ON_FAIL(ShaderRendererUtil::generateTextureResource(
-                    entry.textureDesc, textureBindFlags, device, texture));
-                resource = texture;
+            assign(fieldCursor, field.val);
+        }
+        return SLANG_OK;
+    }
 
-                auto sampler = _createSamplerState(device, entry.samplerDesc);
+    SlangResult assignObject(ShaderCursor const& dstCursor, ShaderInputLayout::ObjectVal* srcVal)
+    {
+        auto typeName = srcVal->typeName;
+        slang::TypeReflection* slangType = nullptr;
+        if(typeName.getLength() != 0)
+        {
+            // If the input line specified the name of the type
+            // to allocate, then we use it directly.
+            //
+            slangType = slangReflection->findTypeByName(typeName.getBuffer());
+        }
+        else
+        {
+            // if the user did not specify what type to allocate,
+            // then we will infer the type from the type of the
+            // value pointed to by `entryCursor`.
+            //
+            auto slangTypeLayout = dstCursor.getTypeLayout();
+            switch(slangTypeLayout->getKind())
+            {
+            default:
+                break;
+
+            case slang::TypeReflection::Kind::ConstantBuffer:
+            case slang::TypeReflection::Kind::ParameterBlock:
+                // If the cursor is pointing at a constant buffer
+                // or parameter block, then we assume the user
+                // actually means to allocate an object based on
+                // the element type of the block.
+                //
+                slangTypeLayout = slangTypeLayout->getElementTypeLayout();
+                break;
+            }
+            slangType = slangTypeLayout->getType();
+        }
 
-                IResourceView::Desc viewDesc;
-                viewDesc.type = IResourceView::Type::ShaderResource;
-                auto textureView = device->createTextureView(
-                    texture,
-                    viewDesc);
+        ComPtr<IShaderObject> shaderObject = device->createShaderObject(slangType);
 
-                entryCursor.setCombinedTextureSampler(textureView, sampler);
-            }
-            break;
+        assign(ShaderCursor(shaderObject), srcVal->contentVal);
 
-        case ShaderInputType::Texture:
-            {
-                ComPtr<ITextureResource> texture;
-                SLANG_RETURN_ON_FAIL(ShaderRendererUtil::generateTextureResource(
-                    entry.textureDesc, textureBindFlags, device, texture));
-                resource = texture;
+        dstCursor.setObject(shaderObject);
+        return SLANG_OK;
+    }
 
-                // TODO: support UAV textures...
+    SlangResult assign(ShaderCursor const& dstCursor, ShaderInputLayout::ValPtr const& srcVal)
+    {
+        auto& entryCursor = dstCursor;
+        switch(srcVal->kind)
+        {
+        case ShaderInputType::UniformData:
+            return assignData(dstCursor, (ShaderInputLayout::DataVal*) srcVal.Ptr());
 
-                IResourceView::Desc viewDesc;
-                viewDesc.type = IResourceView::Type::ShaderResource;
-                viewDesc.format = texture->getDesc()->format;
-                auto textureView = device->createTextureView(
-                    texture,
-                    viewDesc);
+        case ShaderInputType::Buffer:
+            return assignBuffer(dstCursor, (ShaderInputLayout::BufferVal*) srcVal.Ptr());
 
-                if (!textureView)
-                {
-                    return SLANG_FAIL;
-                }
+        case ShaderInputType::CombinedTextureSampler:
+            return assignCombinedTextureSampler(dstCursor, (ShaderInputLayout::CombinedTextureSamplerVal*) srcVal.Ptr());
 
-                entryCursor.setResource(textureView);
-            }
-            break;
+        case ShaderInputType::Texture:
+            return assignTexture(dstCursor, (ShaderInputLayout::TextureVal*) srcVal.Ptr());
 
         case ShaderInputType::Sampler:
-            {
-                auto sampler = _createSamplerState(device, entry.samplerDesc);
-
-                entryCursor.setSampler(sampler);
-            }
-            break;
+            return assignSampler(dstCursor, (ShaderInputLayout::SamplerVal*) srcVal.Ptr());
 
         case ShaderInputType::Object:
-            {
-                auto typeName = entry.objectDesc.typeName;
-                slang::TypeReflection* slangType = nullptr;
-                if(typeName.getLength() != 0)
-                {
-                    // If the input line specified the name of the type
-                    // to allocate, then we use it directly.
-                    //
-                    slangType = slangReflection->findTypeByName(typeName.getBuffer());
-                }
-                else
-                {
-                    // if the user did not specify what type to allocate,
-                    // then we will infer the type from the type of the
-                    // value pointed to by `entryCursor`.
-                    //
-                    auto slangTypeLayout = entryCursor.getTypeLayout();
-                    switch(slangTypeLayout->getKind())
-                    {
-                    default:
-                        break;
-
-                    case slang::TypeReflection::Kind::ConstantBuffer:
-                    case slang::TypeReflection::Kind::ParameterBlock:
-                        // If the cursor is pointing at a constant buffer
-                        // or parameter block, then we assume the user
-                        // actually means to allocate an object based on
-                        // the element type of the block.
-                        //
-                        slangTypeLayout = slangTypeLayout->getElementTypeLayout();
-                        break;
-                    }
-                    slangType = slangTypeLayout->getType();
-                }
+            return assignObject(dstCursor, (ShaderInputLayout::ObjectVal*) srcVal.Ptr());
 
-                ComPtr<IShaderObject> shaderObject = device->createShaderObject(slangType);
-
-                entryCursor.setObject(shaderObject);
-            }
-            break;
+        case ShaderInputType::Aggregate:
+            return assignAggregate(dstCursor, (ShaderInputLayout::AggVal*) srcVal.Ptr());
 
         default:
             assert(!"Unhandled type");
             return SLANG_FAIL;
         }
-
-        if(entry.isOutput)
-        {
-            ShaderOutputPlan::Item item;
-            item.inputLayoutEntryIndex = entryIndex;
-            item.resource = resource;
-            item.typeLayout = typeLayout;
-            ioOutputPlan.items.add(item);
-        }
-
     }
-    return SLANG_OK;
+};
+
+SlangResult _assignVarsFromLayout(
+    IDevice*                   device,
+    IShaderObject*               shaderObject,
+    ShaderInputLayout const&    layout,
+    ShaderOutputPlan&           ioOutputPlan,
+    slang::ProgramLayout*       slangReflection)
+{
+    AssignValsFromLayoutContext context(device, ioOutputPlan, slangReflection);
+    ShaderCursor rootCursor = ShaderCursor(shaderObject);
+    return context.assign(rootCursor, layout.rootVal);
 }
 
-void ShaderObjectRenderTestApp::applyBinding(PipelineType pipelineType, ICommandEncoder* encoder)
+void RenderTestApp::applyBinding(PipelineType pipelineType, ICommandEncoder* encoder)
 {
     switch (pipelineType)
     {
@@ -409,7 +404,7 @@ void ShaderObjectRenderTestApp::applyBinding(PipelineType pipelineType, ICommand
     }
 }
 
-SlangResult ShaderObjectRenderTestApp::initialize(
+SlangResult RenderTestApp::initialize(
     SlangSession* session,
     IDevice* device,
     const Options& options,
@@ -507,12 +502,6 @@ SlangResult ShaderObjectRenderTestApp::initialize(
     return m_pipelineState ? SLANG_OK : SLANG_FAIL;
 }
 
-void ShaderObjectRenderTestApp::finalizeImpl()
-{
-    m_programVars = nullptr;
-    RenderTestApp::finalizeImpl();
-}
-
 Result RenderTestApp::_initializeShaders(
     SlangSession* session,
     IDevice* device,
@@ -602,7 +591,7 @@ void RenderTestApp::_initializeRenderPass()
     m_device->createRenderPassLayout(renderPassDesc, m_renderPass.writeRef());
 }
 
-void ShaderObjectRenderTestApp::setProjectionMatrix(IResourceCommandEncoder* encoder)
+void RenderTestApp::setProjectionMatrix(IResourceCommandEncoder* encoder)
 {
     SLANG_UNUSED(encoder);
     auto info = m_device->getDeviceInfo();
@@ -639,8 +628,7 @@ void RenderTestApp::runCompute(IComputeCommandEncoder* encoder)
 
 void RenderTestApp::finalize()
 {
-    finalizeImpl();
-
+    m_programVars = nullptr;
     m_inputLayout = nullptr;
     m_vertexBuffer = nullptr;
     m_shaderProgram = nullptr;
@@ -653,11 +641,7 @@ void RenderTestApp::finalize()
     m_device = nullptr;
 }
 
-void RenderTestApp::finalizeImpl()
-{
-}
-
-Result ShaderObjectRenderTestApp::writeBindingOutput(const char* fileName)
+Result RenderTestApp::writeBindingOutput(const char* fileName)
 {
     // Wait until everything is complete
     m_queue->wait();
@@ -671,23 +655,51 @@ Result ShaderObjectRenderTestApp::writeBindingOutput(const char* fileName)
 
     for(auto outputItem : m_outputPlan.items)
     {
-        auto& inputEntry = m_shaderInputLayout.entries[outputItem.inputLayoutEntryIndex];
-        assert(inputEntry.isOutput);
-
         auto resource = outputItem.resource;
         if (resource && resource->getType() == IResource::Type::Buffer)
         {
             IBufferResource* bufferResource = static_cast<IBufferResource*>(resource.get());
-            const size_t bufferSize = bufferResource->getDesc()->sizeInBytes;
+            auto bufferDesc = *bufferResource->getDesc();
+            const size_t bufferSize = bufferDesc.sizeInBytes;
 
             ComPtr<ISlangBlob> blob;
-            m_device->readBufferResource(bufferResource, 0, bufferSize, blob.writeRef());
+            if(bufferDesc.cpuAccessFlags & IResource::AccessFlag::Read)
+            {
+                // The buffer is already allocated for CPU access, so we can read it back directly.
+                //
+                m_device->readBufferResource(bufferResource, 0, bufferSize, blob.writeRef());
+            }
+            else
+            {
+                // The buffer is not CPU-readable, so we will copy it using a staging buffer.
+
+                auto stagingBufferDesc = bufferDesc;
+                stagingBufferDesc.cpuAccessFlags = IResource::AccessFlag::Read;
+                stagingBufferDesc.bindFlags = 0;
+
+                ComPtr<IBufferResource> stagingBuffer;
+                SLANG_RETURN_ON_FAIL(m_device->createBufferResource(IResource::Usage::CopyDest, stagingBufferDesc, nullptr, stagingBuffer.writeRef()));
+
+                ComPtr<ICommandBuffer> commandBuffer;
+                SLANG_RETURN_ON_FAIL(m_queue->createCommandBuffer(commandBuffer.writeRef()));
+
+                ComPtr<IResourceCommandEncoder> encoder;
+                commandBuffer->encodeResourceCommands(encoder.writeRef());
+                encoder->copyBuffer(stagingBuffer, 0, bufferResource, 0, bufferSize);
+                encoder->endEncoding();
+
+                commandBuffer->close();
+                m_queue->executeCommandBuffer(commandBuffer);
+                m_queue->wait();
+
+                m_device->readBufferResource(stagingBuffer, 0, bufferSize, blob.writeRef());
+            }
+
             if (!blob)
             {
                 return SLANG_FAIL;
             }
             const SlangResult res = ShaderInputLayout::writeBinding(
-                inputEntry,
                 m_options.outputUsingType ? outputItem.typeLayout : nullptr, // TODO: always output using type
                 blob->getBufferPointer(),
                 bufferSize,
@@ -696,7 +708,8 @@ Result ShaderObjectRenderTestApp::writeBindingOutput(const char* fileName)
         }
         else
         {
-            printf("invalid output type at %d.\n", int(outputItem.inputLayoutEntryIndex));
+            auto typeName = outputItem.typeLayout->getName();
+            printf("invalid output type '%s'.\n", typeName ? typeName : "UNKNOWN");
         }
     }
     return SLANG_OK;
@@ -1101,15 +1114,12 @@ static SlangResult _innerMain(Slang::StdWriters* stdWriters, SlangSession* sessi
     }
 
 	{
-        // TODO: We shouldn't need to heap-allocate the `ShaderObjectRenderTestApp`
-        // since there is no longer any meaningful inheritance going on.
-        //
-        RefPtr<RenderTestApp> app = new ShaderObjectRenderTestApp();
+        RenderTestApp app;
         renderDocBeginFrame();
-        SLANG_RETURN_ON_FAIL(app->initialize(session, device, options, input));
-        app->update();
+        SLANG_RETURN_ON_FAIL(app.initialize(session, device, options, input));
+        app.update();
         renderDocEndFrame();
-        app->finalize();
+        app.finalize();
         return SLANG_OK;
 	}
 }