Add a CPU renderer implementation (#1750)

* Add a CPU renderer implementation

This change adds a CPU back-end to `gfx` and ensures that most of our existing CPU tests pass when using it.

Detailed notes:

* Most of the CPU renderer implementation is copy-pasted from the CUDA case, so they share a lot of similar logic

* The main addition to the CPU renderer is a semi-complete implementation of host-memory textures. The logic here handles all the main shapes (Buffer, 1D, 2D, 3D, Cube) and all the currently-supported `Format`s that are sample-able as-is (no D24S8). The implementation is not intended to be fast, and it currently only does nearest-neighbor sampling, but otherwise it tries to avoid cutting too many corners and should be ar reasonable starting point for a more complete (but not performance-oriented) implementation.

* Refactored the CPU prelude `IRWTexture` interface to inherit from `ITexture`, since in most cases a single type will end up implementing both. It might be worth it to collapse it all down to a single interface later.

* Changed the CPU prelude `ITexture`/`IRWTexture` interface so that it takes both a pointer *and* a size for output arguments. This change seems necessary to allow a shader variable declared as a `Texture2D<float>` to fetch a single `float` when the underlying texture might be using RGBA32F.

* Added to the `IComponentType` public API so that we can query a "host callable" for an entry point and not just a binary.

* Turned off the `-shaderobj` flag on two tests that weren't yet compatible with shader objects but still had the flag left in on the path (since previously the CPU path always used the non-`gfx` non-shader-object logic anyway)

* Disabled one test (`dynamic-dispatch-11`) that relied on the `ConstantBuffer<IInterface>` idiom that we know we are planning to chagne soon anyway.

* Made a few changes to the CUDA path to bring it into line with what I added for the CPU path. These were mostly bug fixes around indexing logic for sub-objects and resources.

* fixup

1 files changed, 4 insertions, 27 deletions

diff --git a/tools/gfx/render-graphics-common.cpp b/tools/gfx/render-graphics-common.cpp
index 10713e92b..5ae148ea0 100644
--- a/tools/gfx/render-graphics-common.cpp
+++ b/tools/gfx/render-graphics-common.cpp
@@ -109,29 +109,6 @@ public:
             }
         }
 
-        slang::TypeLayoutReflection* unwrapParameterGroups(slang::TypeLayoutReflection* typeLayout)
-        {
-            for (;;)
-            {
-                if (!typeLayout->getType())
-                {
-                    if (auto elementTypeLayout = typeLayout->getElementTypeLayout())
-                        typeLayout = elementTypeLayout;
-                }
-
-                switch (typeLayout->getKind())
-                {
-                default:
-                    return typeLayout;
-
-                case slang::TypeReflection::Kind::ConstantBuffer:
-                case slang::TypeReflection::Kind::ParameterBlock:
-                    typeLayout = typeLayout->getElementTypeLayout();
-                    continue;
-                }
-            }
-        }
-
         void _addDescriptorSets(
             slang::TypeLayoutReflection* typeLayout,
             slang::VariableLayoutReflection* varLayout = nullptr)
@@ -178,7 +155,7 @@ public:
 
         Result setElementTypeLayout(slang::TypeLayoutReflection* typeLayout)
         {
-            typeLayout = unwrapParameterGroups(typeLayout);
+            typeLayout = _unwrapParameterGroups(typeLayout);
 
             m_elementTypeLayout = typeLayout;
 
@@ -414,8 +391,8 @@ public:
 
     struct Builder : Super::Builder
     {
-        Builder(IDevice* renderer)
-            : Super::Builder(static_cast<RendererBase*>(renderer))
+        Builder(IDevice* device)
+            : Super::Builder(static_cast<RendererBase*>(device))
         {}
 
         Result build(EntryPointLayout** outLayout)
@@ -1249,7 +1226,7 @@ protected:
             return SLANG_OK;
 
         // Once we have computed how large the buffer should be, we can allocate
-        // it using the existing public `IRenderer` API.
+        // it using the existing public `IDevice` API.
         //
         IDevice* device = getRenderer();
         IBufferResource::Desc bufferDesc;