From de7ccaf127d8bb847a0ad25f45e8d1902dc1b958 Mon Sep 17 00:00:00 2001
From: Yong He <yonghe@outlook.com>
Date: Wed, 6 Aug 2025 15:56:27 -0700
Subject: Fix unused space discovery for bindless heap. (#8075)

---
 .../compiler-core/slang-artifact-associated-impl.h |  1 +
 .../slang/slang-ir-lower-dynamic-resource-heap.cpp |  2 +-
 tests/spirv/descriptor-heap-space.slang            | 41 ++++++++++++++++++++++
 3 files changed, 43 insertions(+), 1 deletion(-)
 create mode 100644 tests/spirv/descriptor-heap-space.slang

diff --git a/source/compiler-core/slang-artifact-associated-impl.h b/source/compiler-core/slang-artifact-associated-impl.h
index 6ae01626a..9f60c51b6 100644
--- a/source/compiler-core/slang-artifact-associated-impl.h
+++ b/source/compiler-core/slang-artifact-associated-impl.h
@@ -166,6 +166,7 @@ struct ShaderBindingRange
         case slang::VaryingInput:
         case slang::VaryingOutput:
         case slang::SpecializationConstant:
+        case slang::SubElementRegisterSpace:
             return true;
         default:
             return false;
diff --git a/source/slang/slang-ir-lower-dynamic-resource-heap.cpp b/source/slang/slang-ir-lower-dynamic-resource-heap.cpp
index b2199a174..495795cca 100644
--- a/source/slang/slang-ir-lower-dynamic-resource-heap.cpp
+++ b/source/slang/slang-ir-lower-dynamic-resource-heap.cpp
@@ -11,7 +11,7 @@ UInt findUnusedSpaceIndex(TargetProgram* targetProgram, IRModule* module)
     auto processVarLayout = [&](IRVarLayout* varLayout)
     {
         UInt spaceOffset = 0;
-        if (auto spaceAttr = varLayout->findOffsetAttr(LayoutResourceKind::RegisterSpace))
+        if (auto spaceAttr = varLayout->findOffsetAttr(LayoutResourceKind::SubElementRegisterSpace))
         {
             spaceOffset = spaceAttr->getOffset();
         }
diff --git a/tests/spirv/descriptor-heap-space.slang b/tests/spirv/descriptor-heap-space.slang
new file mode 100644
index 000000000..8ab905b87
--- /dev/null
+++ b/tests/spirv/descriptor-heap-space.slang
@@ -0,0 +1,41 @@
+//TEST:SIMPLE(filecheck=CHECK): -target glsl -entry main
+
+// Test that we can find the correct unused descriptor set index when there is `ParameterBlock` in the shader.
+
+//CHECK: layout(binding = 2, set = 2)
+//CHECK-NEXT: uniform texture2D  _slang_resource_heap
+
+struct VSInput{
+    float3 position;
+}
+
+struct VSOutput{
+    float4 position : SV_Position;
+}
+
+struct CameraData{
+    float3 position;
+}
+
+ParameterBlock<CameraData> cameraData;
+
+
+struct Material{
+    DescriptorHandle<Texture2D> texture;
+    DescriptorHandle<SamplerState> samplerState;
+}
+
+StructuredBuffer<Material> materials;
+
+struct FSOutput{
+    float4 outColor : SV_Target0;
+}
+
+
+[shader("fragment")]
+FSOutput main(){
+    FSOutput output;
+    output.outColor = materials[0].texture.Sample(materials[0].samplerState, float2(0));
+    output.outColor.x *= cameraData.position.x;
+    return output;
+}
\ No newline at end of file
-- 
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