Fix correct bindings for bindless resource model [SPIRV and GLSL] (#7131)

Fix correct bindings for bindless resource model [spirv and glsl]

fixes: #6952

Problem:
* Currently all bindless objects are placed in the same set (fine) and same binding (incorrect behavior for vulkan). This is incorrect since as per [spec](https://registry.khronos.org/vulkan/specs/latest/man/html/VkDescriptorType.html), only 1 resource type may be written to each index inside a set (these rules are loosened with VK_EXT_mutable_descriptor_type)
* This means currently generated bindings do not work in practice if we (for example) use `Sampler2D.Handle` and `Texture1D.Handle` in a shader since we would place 2 incompatible objects in the same binding-index and set.

Solution:
* `__getDynamicResourceHeap` was modified to allow bindings to chosen dynamically for a descriptor
* use `IOpaqueDescriptor` to check compile-time information of resource types so that we can identify different resources
* Using this information of `IOpaqueDescriptor`, we modify `defaultGetDescriptorFromHandle` to provide a binding model (1 resource per binding-index) which produces legal spirv/glsl.
* To support `VK_EXT_mutable_descriptor_type` the function `defaultGetDescriptorFromHandle` has a set of options (`BindlessDescriptorOptions`) for a user to pick-from to support their binding model. Capabilities are not used here for flexibility purposes (specifically old shaders mixed with modern vulkan extensions).

Other changes:
* Added `TexelBuffer` DescriptorKind to aid in generating correct bindings

* format code

* Add to docs bindless changes, make AccelerationStructure use its handle directly, adjust tests accordingly

---------

Co-authored-by: slangbot <186143334+slangbot@users.noreply.github.com>

1 files changed, 12 insertions, 4 deletions

diff --git a/source/slang/slang-ir-lower-dynamic-resource-heap.cpp b/source/slang/slang-ir-lower-dynamic-resource-heap.cpp
index 60ec688a0..b2199a174 100644
--- a/source/slang/slang-ir-lower-dynamic-resource-heap.cpp
+++ b/source/slang/slang-ir-lower-dynamic-resource-heap.cpp
@@ -58,10 +58,11 @@ UInt findUnusedSpaceIndex(TargetProgram* targetProgram, IRModule* module)
     return index;
 }
 
-IRVarLayout* createResourceHeapVarLayoutWithSpace(
+IRVarLayout* createResourceHeapVarLayoutWithSpaceAndBinding(
     IRBuilder& builder,
     IRInst* param,
-    UInt spaceIndex)
+    UInt spaceIndex,
+    UInt bindingIndex)
 {
     SLANG_UNUSED(param);
     IRTypeLayout::Builder typeLayoutBuilder(&builder);
@@ -71,7 +72,8 @@ IRVarLayout* createResourceHeapVarLayoutWithSpace(
     auto typeLayout = typeLayoutBuilder.build();
     IRVarLayout::Builder varLayoutBuilder(&builder, typeLayout);
     varLayoutBuilder.findOrAddResourceInfo(LayoutResourceKind::RegisterSpace)->offset = spaceIndex;
-    varLayoutBuilder.findOrAddResourceInfo(LayoutResourceKind::DescriptorTableSlot)->offset = 0;
+    varLayoutBuilder.findOrAddResourceInfo(LayoutResourceKind::DescriptorTableSlot)->offset =
+        bindingIndex;
     return varLayoutBuilder.build();
 }
 
@@ -93,8 +95,14 @@ void lowerDynamicResourceHeap(TargetProgram* targetProgram, IRModule* module, Di
         IRBuilder builder(inst);
         builder.setInsertBefore(inst);
 
+        auto bindingIndex = (UInt)as<IRIntLit>(inst->getOperand(0))->getValue();
+
         auto param = builder.createGlobalParam(arrayType);
-        auto varLayout = createResourceHeapVarLayoutWithSpace(builder, param, unusedSpaceIndex);
+        auto varLayout = createResourceHeapVarLayoutWithSpaceAndBinding(
+            builder,
+            param,
+            unusedSpaceIndex,
+            bindingIndex);
         builder.addLayoutDecoration(param, varLayout);
         builder.addNameHintDecoration(param, toSlice("__slang_resource_heap"));
         inst->replaceUsesWith(param);