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, 23 insertions, 0 deletions

diff --git a/source/slang/slang-compiler.h b/source/slang/slang-compiler.h
index 0eb6f992d..01bdd8502 100755
--- a/source/slang/slang-compiler.h
+++ b/source/slang/slang-compiler.h
@@ -294,6 +294,11 @@ namespace Slang
         SLANG_NO_THROW SlangResult SLANG_MCALL link(
             slang::IComponentType**         outLinkedComponentType,
             ISlangBlob**                    outDiagnostics) SLANG_OVERRIDE;
+        SLANG_NO_THROW SlangResult SLANG_MCALL getEntryPointHostCallable(
+            int                     entryPointIndex,
+            int                     targetIndex,
+            ISlangSharedLibrary**   outSharedLibrary,
+            slang::IBlob**          outDiagnostics) SLANG_OVERRIDE;
 
             /// Get the linkage (aka "session" in the public API) for this component type.
         Linkage* getLinkage() { return m_linkage; }
@@ -705,6 +710,15 @@ namespace Slang
                 outDiagnostics);
         }
 
+        SLANG_NO_THROW SlangResult SLANG_MCALL getEntryPointHostCallable(
+            int                     entryPointIndex,
+            int                     targetIndex,
+            ISlangSharedLibrary**   outSharedLibrary,
+            slang::IBlob**          outDiagnostics) SLANG_OVERRIDE
+        {
+            return Super::getEntryPointHostCallable(entryPointIndex, targetIndex, outSharedLibrary, outDiagnostics);
+        }
+
             /// Create an entry point that refers to the given function.
         static RefPtr<EntryPoint> create(
             Linkage*            linkage,
@@ -912,6 +926,15 @@ namespace Slang
                 outDiagnostics);
         }
 
+        SLANG_NO_THROW SlangResult SLANG_MCALL getEntryPointHostCallable(
+            int                     entryPointIndex,
+            int                     targetIndex,
+            ISlangSharedLibrary**   outSharedLibrary,
+            slang::IBlob**          outDiagnostics) SLANG_OVERRIDE
+        {
+            return Super::getEntryPointHostCallable(entryPointIndex, targetIndex, outSharedLibrary, outDiagnostics);
+        }
+
         SLANG_NO_THROW SlangResult SLANG_MCALL findEntryPointByName(
             char const*             name,
             slang::IEntryPoint**     outEntryPoint) SLANG_OVERRIDE