Use uint64 AS descriptor heap stride

docs/command-line-slangc-reference.md

@@ -608,7 +608,7 @@ Specify the space index for the system defined global bindless resource array.
 
 **-spirv-resource-heap-stride <stride>**
 
-Specify the byte stride for the resource descriptor heap when generating SPIRV with spvDescriptorHeapEXT. Defaults to 0, which will use OpConstantSizeOfEXT(ResourceType). 
+Specify the byte stride for the resource descriptor heap when generating SPIRV with spvDescriptorHeapEXT. Defaults to 0, which will use OpConstantSizeOfEXT(ResourceType), except RaytracingAccelerationStructure entries emit a literal 8-byte ArrayStride for the uint64 device address elements. 
 
 
 <a id="spirv-sampler-heap-stride"></a>

docs/user-guide/03-convenience-features.md

@@ -702,9 +702,10 @@ stride with the `-spirv-resource-heap-stride` or `-spirv-sampler-heap-stride` co
 > **Note on `RaytracingAccelerationStructure`:** When the `spvDescriptorHeapEXT` capability is active and
 > a `DescriptorHandle<RaytracingAccelerationStructure>` is dereferenced, Slang loads a 64-bit device address
 > from the descriptor heap and converts it to an acceleration structure handle via
-> `OpConvertUToAccelerationStructureKHR`. This matches how GPU drivers expose acceleration structure
-> descriptors in the heap (as device addresses), and requires either the `SPV_KHR_ray_tracing` or
-> `SPV_KHR_ray_query` extension.
+> `OpConvertUToAccelerationStructureKHR`. The heap entry type is `uint64_t`, so the default heap stride is
+> based on the address width rather than the opaque acceleration structure type. This matches how GPU
+> drivers expose acceleration structure descriptors in the heap (as device addresses), and requires either
+> the `SPV_KHR_ray_tracing` or `SPV_KHR_ray_query` extension.
 
 ### Custom Descriptor Fetch
 

docs/user-guide/08-compiling.md

@@ -1089,7 +1089,7 @@ meanings of their `CompilerOptionValue` encodings.
 | GenerateWholeProgram | When set will emit target code for the entire program instead of for a specific entry point. `intValue0` specifies a bool value for the setting. |
 | UseUpToDateBinaryModule | When set will only load precompiled modules if it is up-to-date with its source. `intValue0` specifies a bool value for the setting. |
 | ValidateUniformity | When set will perform [uniformity analysis](a1-05-uniformity.md).|
-| SPIRVResourceHeapStride | Specifies the byte stride for the resource descriptor heap when generating SPIR-V with `spvDescriptorHeapEXT`. `intValue0` encodes the stride in bytes; use 0 to let the driver compute the stride via `OpConstantSizeOfEXT`. |
+| SPIRVResourceHeapStride | Specifies the byte stride for the resource descriptor heap when generating SPIR-V with `spvDescriptorHeapEXT`. `intValue0` encodes the stride in bytes; use 0 to emit `OpConstantSizeOfEXT(ResourceType)` as the default stride, except `RaytracingAccelerationStructure` entries emit a literal 8-byte `ArrayStride` for the `uint64` device address elements. |
 | SPIRVSamplerHeapStride | Specifies the byte stride for the sampler descriptor heap when generating SPIR-V with `spvDescriptorHeapEXT`. `intValue0` encodes the stride in bytes; use 0 to let the driver compute the stride via `OpConstantSizeOfEXT`. |
 | ForceDXLayout | When set forces the compiler to use DirectX-compatible (HLSL register packing) rules when laying out buffer struct fields during code generation. `intValue0` specifies a bool value for the setting. |
 | ForceCLayout | When set forces the compiler to use C struct layout rules (natural alignment, no HLSL/GLSL padding) when laying out buffer struct fields during code generation. `intValue0` specifies a bool value for the setting. |

source/slang/slang-emit-spirv.cpp

@@ -7052,8 +7052,14 @@ struct SPIRVEmitContext : public SourceEmitterBase, public SPIRVEmitSharedContex
         return type;
     }
 
-    SpvInst* getDescriptorRuntimeArrayType(SpvInst* descriptorElementType)
+    SpvInst* getDescriptorRuntimeArrayType(
+        SpvInst* descriptorElementType,
+        int defaultArrayStride = 0)
     {
+        SLANG_ASSERT(
+            descriptorElementType->opcode != SpvOpTypeAccelerationStructureKHR &&
+            "acceleration structure descriptor heaps must use uint64 elements");
+
         if (auto found = m_descriptorHeapRuntimeArrayTypes.tryGetValue(descriptorElementType))
             return *found;
 
@@ -7071,10 +7077,18 @@ struct SPIRVEmitContext : public SourceEmitterBase, public SPIRVEmitSharedContex
         }
         if (userDefinedStride == 0)
         {
-            IRBuilder builder(m_irModule);
-            builder.setInsertInto(m_irModule->getModuleInst());
+            if (defaultArrayStride != 0)
+            {
+                userDefinedStride = defaultArrayStride;
+            }
+            else
+            {
+                IRBuilder builder(m_irModule);
+                builder.setInsertInto(m_irModule->getModuleInst());
 
-            stride = emitOpConstantSizeOfEXT(nullptr, builder.getUIntType(), descriptorElementType);
+                stride =
+                    emitOpConstantSizeOfEXT(nullptr, builder.getUIntType(), descriptorElementType);
+            }
         }
 
         auto runtimeArrayType = emitOpTypeRuntimeArray(nullptr, descriptorElementType);
@@ -7106,11 +7120,19 @@ struct SPIRVEmitContext : public SourceEmitterBase, public SPIRVEmitSharedContex
         switch (valueType->getOp())
         {
         case kIROp_TextureType:
-        case kIROp_RaytracingAccelerationStructureType:
         case kIROp_SamplerStateType:
         case kIROp_SamplerComparisonStateType:
             descriptorElementType = ensureInst(valueType);
             break;
+        case kIROp_RaytracingAccelerationStructureType:
+            {
+                // Acceleration structure heap entries are 64-bit device addresses that are
+                // converted to acceleration structure handles after loading.
+                IRBuilder builder(m_irModule);
+                builder.setInsertInto(m_irModule->getModuleInst());
+                descriptorElementType = ensureInst(builder.getUInt64Type());
+                break;
+            }
         default:
             isBufferResource = true;
             descriptorElementType = ensureDescriptorHeapBufferDescriptorType(
@@ -7121,7 +7143,12 @@ struct SPIRVEmitContext : public SourceEmitterBase, public SPIRVEmitSharedContex
         if (outIsBufferResource)
             *outIsBufferResource = isBufferResource;
 
-        return getDescriptorRuntimeArrayType(descriptorElementType);
+        const int defaultAccelerationStructureStride = 8;
+        return getDescriptorRuntimeArrayType(
+            descriptorElementType,
+            valueType->getOp() == kIROp_RaytracingAccelerationStructureType
+                ? defaultAccelerationStructureStride
+                : 0);
     }
 
     SpvInst* emitAccelerationStructureFromDescriptorHeap(

source/slang/slang-options.cpp

@@ -883,7 +883,9 @@ void initCommandOptions(CommandOptions& options)
          "-spirv-resource-heap-stride",
          "-spirv-resource-heap-stride <stride>",
          "Specify the byte stride for the resource descriptor heap when generating SPIRV with "
-         "spvDescriptorHeapEXT. Defaults to 0, which will use OpConstantSizeOfEXT(ResourceType)."},
+         "spvDescriptorHeapEXT. Defaults to 0, which will use OpConstantSizeOfEXT(ResourceType), "
+         "except RaytracingAccelerationStructure entries emit a literal 8-byte ArrayStride for "
+         "the uint64 device address elements."},
         {OptionKind::SPIRVSamplerHeapStride,
          "-spirv-sampler-heap-stride",
          "-spirv-sampler-heap-stride <stride>",

tests/spirv/descriptor-heap-acceleration-structure-raygen.slang

@@ -2,7 +2,7 @@
 // Exercises the RayTracingKHR branch of requireSPIRVAnyCapability when
 // loading a RaytracingAccelerationStructure from a descriptor heap in a
 // raygeneration shader (which already requires SpvCapabilityRayTracingKHR).
-//TEST:SIMPLE(filecheck=CHECK): -target spirv-asm -stage raygeneration -entry rayGenMain -profile sm_6_6 -capability spvDescriptorHeapEXT -spirv-resource-heap-stride 32
+//TEST:SIMPLE(filecheck=CHECK): -target spirv-asm -stage raygeneration -entry rayGenMain -profile sm_6_6 -capability spvDescriptorHeapEXT
 
 struct PushConstants
 {
@@ -20,8 +20,8 @@ void rayGenMain(uniform PushConstants pushConstants)
 {
     // CHECK-DAG: %[[U64:[A-Za-z0-9_]+]] = OpTypeInt 64 0
     // CHECK-DAG: %[[AS_TYPE:[A-Za-z0-9_]+]] = OpTypeAccelerationStructureKHR
-    // CHECK-DAG: %[[AS_HEAP_ARRAY:[A-Za-z0-9_]+]] = OpTypeRuntimeArray %[[AS_TYPE]]
-    // CHECK-DAG: OpDecorate %[[AS_HEAP_ARRAY]] ArrayStride 32
+    // CHECK-DAG: %[[AS_HEAP_ARRAY:[A-Za-z0-9_]+]] = OpTypeRuntimeArray %[[U64]]
+    // CHECK-DAG: OpDecorate %[[AS_HEAP_ARRAY]] ArrayStride 8
     // CHECK-DAG: OpCapability RayTracingKHR
     // CHECK: OpUntypedAccessChainKHR %_ptr_UniformConstant %[[AS_HEAP_ARRAY]] %slang_resourceHeap
     // CHECK-NEXT: %[[AS_ADDR:[A-Za-z0-9_]+]] = OpLoad %[[U64]]

tests/spirv/descriptor-heap-acceleration-structure.slang

@@ -1,5 +1,6 @@
-// Regression test for GitHub issue #10671.
-//TEST:SIMPLE(filecheck=CHECK): -target spirv-asm -stage compute -entry computeMain -profile sm_6_6 -capability spvDescriptorHeapEXT -capability spvRayQueryKHR -spirv-resource-heap-stride 32
+// Regression test for GitHub issues #10671 and #11231.
+//TEST:SIMPLE(filecheck=CHECK): -target spirv-asm -stage compute -entry computeMain -profile sm_6_6 -capability spvDescriptorHeapEXT -capability spvRayQueryKHR
+//TEST:SIMPLE(filecheck=OVERRIDE): -target spirv-asm -stage compute -entry computeMain -profile sm_6_6 -capability spvDescriptorHeapEXT -capability spvRayQueryKHR -spirv-resource-heap-stride 32
 
 struct PushConstants
 {
@@ -39,8 +40,11 @@ void computeMain(uint3 dispatchThreadID: SV_DispatchThreadID, uniform PushConsta
 {
     // CHECK-DAG: %[[U64:[A-Za-z0-9_]+]] = OpTypeInt 64 0
     // CHECK-DAG: %[[AS_TYPE:[A-Za-z0-9_]+]] = OpTypeAccelerationStructureKHR
-    // CHECK-DAG: %[[AS_HEAP_ARRAY:[A-Za-z0-9_]+]] = OpTypeRuntimeArray %[[AS_TYPE]]
-    // CHECK-DAG: OpDecorate %[[AS_HEAP_ARRAY]] ArrayStride 32
+    // CHECK-DAG: %[[AS_HEAP_ARRAY:[A-Za-z0-9_]+]] = OpTypeRuntimeArray %[[U64]]
+    // CHECK-DAG: OpDecorate %[[AS_HEAP_ARRAY]] ArrayStride 8
+    // OVERRIDE-DAG: %[[OVERRIDE_U64:[A-Za-z0-9_]+]] = OpTypeInt 64 0
+    // OVERRIDE-DAG: %[[OVERRIDE_AS_HEAP_ARRAY:[A-Za-z0-9_]+]] = OpTypeRuntimeArray %[[OVERRIDE_U64]]
+    // OVERRIDE-DAG: OpDecorate %[[OVERRIDE_AS_HEAP_ARRAY]] ArrayStride 32
     // CHECK-DAG: OpCapability RayQueryKHR
     // CHECK: OpUntypedAccessChainKHR %_ptr_UniformConstant %[[AS_HEAP_ARRAY]] %slang_resourceHeap
     // CHECK-NEXT: %[[AS_ADDR:[A-Za-z0-9_]+]] = OpLoad %[[U64]]