Reimplement Vulkan shader objects. (#1764)

* Reimplement Vulkan shader objects.

This change reimplements Vulkan shader objects in the `gfx` layer so that it is no longer layered on top of the `DescriptorSet` abstraction. Since this is the last implementation that uses `DescriptorSet`, the change also removes all `DescriptorSet` related API from public `gfx` interface.

The Vulkan implementation now passes all test cases, but it still have two issues:
1. The PushConstant setting is not correct, this is because we don't seem to be able to get correct reflection data about the size of push constants for an entry-point.
2. The `shader-toy` example can't run on Vulkan, because it currently sets nullptr to `Texture` bindings, and this change doesn't properly handle setting resource to null in `ShaderObject`s yet. If we can use the `nullDescriptor` feature on vulkan, this implementation will be simple. However we still want to decide whether we want to use a Vulkan 1.2 feature for this.

* Fix up

4 files changed, 6 insertions, 53 deletions

diff --git a/examples/gpu-printing/main.cpp b/examples/gpu-printing/main.cpp
index 3fd1e460a..0315d4827 100644
--- a/examples/gpu-printing/main.cpp
+++ b/examples/gpu-printing/main.cpp
@@ -56,9 +56,7 @@ ComPtr<slang::ISession> gSlangSession;
 ComPtr<slang::IModule>   gSlangModule;
 ComPtr<gfx::IShaderProgram> gProgram;
 
-ComPtr<gfx::IPipelineLayout> gPipelineLayout;
 ComPtr<gfx::IPipelineState> gPipelineState;
-ComPtr<gfx::IDescriptorSet> gDescriptorSet;
 
 Slang::Dictionary<int, std::string> gHashedStrings;
 
@@ -74,21 +72,9 @@ ComPtr<gfx::IShaderProgram> loadComputeProgram(slang::IModule* slangModule, char
 
     gGPUPrinting.loadStrings(linkedProgram->getLayout());
 
-    ComPtr<ISlangBlob> codeBlob;
-    linkedProgram->getEntryPointCode(0, 0, codeBlob.writeRef());
-
-    char const* code = (char const*) codeBlob->getBufferPointer();
-    char const* codeEnd = code + codeBlob->getBufferSize();
-
-    gfx::IShaderProgram::KernelDesc kernelDescs[] =
-    {
-        { gfx::StageType::Compute,    code,     codeEnd },
-    };
-
     gfx::IShaderProgram::Desc programDesc = {};
     programDesc.pipelineType = gfx::PipelineType::Compute;
-    programDesc.kernels = &kernelDescs[0];
-    programDesc.kernelCount = 2;
+    programDesc.slangProgram = linkedProgram;
 
     auto shaderProgram = gDevice->createProgram(programDesc);
 
@@ -107,40 +93,7 @@ Result execute()
     gProgram = loadComputeProgram(gSlangModule, "computeMain");
     if(!gProgram) return SLANG_FAIL;
 
-    IDescriptorSetLayout::SlotRangeDesc slotRanges[] =
-    {
-        IDescriptorSetLayout::SlotRangeDesc(DescriptorSlotType::StorageBuffer),
-    };
-    IDescriptorSetLayout::Desc descriptorSetLayoutDesc;
-    descriptorSetLayoutDesc.slotRangeCount = 1;
-    descriptorSetLayoutDesc.slotRanges = &slotRanges[0];
-    auto descriptorSetLayout = gDevice->createDescriptorSetLayout(descriptorSetLayoutDesc);
-    if(!descriptorSetLayout) return SLANG_FAIL;
-
-    IPipelineLayout::DescriptorSetDesc descriptorSets[] =
-    {
-        IPipelineLayout::DescriptorSetDesc( descriptorSetLayout ),
-    };
-    IPipelineLayout::Desc pipelineLayoutDesc;
-    pipelineLayoutDesc.renderTargetCount = 1;
-    pipelineLayoutDesc.descriptorSetCount = 1;
-    pipelineLayoutDesc.descriptorSets = &descriptorSets[0];
-    auto pipelineLayout = gDevice->createPipelineLayout(pipelineLayoutDesc);
-    if(!pipelineLayout) return SLANG_FAIL;
-
-    gPipelineLayout = pipelineLayout;
-
-    // Once we have the descriptor set layout, we can allocate
-    // and fill in a descriptor set to hold our parameters.
-    //
-    auto descriptorSet =
-        gDevice->createDescriptorSet(descriptorSetLayout, IDescriptorSet::Flag::Transient);
-    if(!descriptorSet) return SLANG_FAIL;
-
-    gDescriptorSet = descriptorSet;
-
     ComputePipelineStateDesc desc;
-    desc.pipelineLayout = gPipelineLayout;
     desc.program = gProgram;
     auto pipelineState = gDevice->createComputePipelineState(desc);
     if(!pipelineState) return SLANG_FAIL;
@@ -164,12 +117,9 @@ Result execute()
     auto queue = gDevice->createCommandQueue(queueDesc);
     auto commandBuffer = queue->createCommandBuffer();
     auto encoder = commandBuffer->encodeComputeCommands();
-    // TODO: need to copy a zero into the start of the print buffer!
-
-    gDescriptorSet->setResource(0, 0, printBufferView);
-    encoder->setDescriptorSet(gPipelineLayout, 0, gDescriptorSet);
-
+    auto rootShaderObject = gDevice->createRootShaderObject(gProgram);
     encoder->setPipelineState(gPipelineState);
+    encoder->bindRootShaderObject(rootShaderObject);
     encoder->dispatchCompute(1, 1, 1);
     encoder->endEncoding();
     commandBuffer->close();
diff --git a/examples/hello-world/main.cpp b/examples/hello-world/main.cpp
index b3bee9c07..023c16304 100644
--- a/examples/hello-world/main.cpp
+++ b/examples/hello-world/main.cpp
@@ -244,6 +244,7 @@ Slang::Result initialize()
     // platforms/APIs.
     //
     IDevice::Desc deviceDesc = {};
+    deviceDesc.deviceType = DeviceType::Vulkan;
     gfx::Result res = gfxCreateDevice(&deviceDesc, gDevice.writeRef());
     if(SLANG_FAILED(res)) return res;
 
diff --git a/examples/shader-object/main.cpp b/examples/shader-object/main.cpp
index aaafc010a..4945de27b 100644
--- a/examples/shader-object/main.cpp
+++ b/examples/shader-object/main.cpp
@@ -136,6 +136,7 @@ int main()
     // interacting with the graphics API.
     Slang::ComPtr<gfx::IDevice> device;
     IDevice::Desc deviceDesc = {};
+    deviceDesc.deviceType = DeviceType::Vulkan;
     SLANG_RETURN_ON_FAIL(gfxCreateDevice(&deviceDesc, device.writeRef()));
 
     // Now we can load the shader code.
diff --git a/examples/shader-toy/main.cpp b/examples/shader-toy/main.cpp
index c4424b294..8e377b42f 100644
--- a/examples/shader-toy/main.cpp
+++ b/examples/shader-toy/main.cpp
@@ -315,6 +315,7 @@ Result initialize()
     gWindow->events.sizeChanged = Slang::Action<>(this, &ShaderToyApp::windowSizeChanged);
 
     IDevice::Desc deviceDesc;
+    deviceDesc.deviceType = DeviceType::Vulkan;
     Result res = gfxCreateDevice(&deviceDesc, gDevice.writeRef());
     if(SLANG_FAILED(res)) return res;