Enable PrimitiveCulling capability if enabled.

For DXR 1.1, this capability must be enabled in case the shader uses ray
flags 0x100 or 0x200.

dxil_converter.cpp

@@ -4286,6 +4286,8 @@ bool Converter::Impl::emit_execution_modes_ray_tracing(spv::ExecutionModel model
 {
 	auto &builder = spirv_module.get_builder();
 	builder.addCapability(spv::CapabilityRayTracingKHR);
+	if (options.ray_tracing_primitive_culling_enabled && shader_analysis.can_require_primitive_culling)
+		builder.addCapability(spv::CapabilityRayTraversalPrimitiveCullingKHR);
 	builder.addExtension("SPV_KHR_ray_tracing");
 	builder.addExtension("SPV_EXT_descriptor_indexing");
 
@@ -4982,6 +4984,11 @@ void Converter::Impl::set_option(const OptionBase &cap)
 		options.shader_i8_dot_enabled = static_cast<const OptionShaderI8Dot &>(cap).supported;
 		break;
 
+	case Option::ShaderRayTracingPrimitiveCulling:
+		options.ray_tracing_primitive_culling_enabled =
+		    static_cast<const OptionShaderRayTracingPrimitiveCulling &>(cap).supported;
+		break;
+
 	default:
 		break;
 	}
@@ -5029,6 +5036,7 @@ bool Converter::recognizes_option(Option cap)
 	case Option::DescriptorQA:
 	case Option::MinPrecisionNative16Bit:
 	case Option::ShaderI8Dot:
+	case Option::ShaderRayTracingPrimitiveCulling:
 		return true;
 
 	default:

dxil_converter.hpp

@@ -207,7 +207,8 @@ enum class Option : uint32_t
 	StorageInputOutput16 = 14,
 	DescriptorQA = 15,
 	MinPrecisionNative16Bit = 16,
-	ShaderI8Dot = 17
+	ShaderI8Dot = 17,
+	ShaderRayTracingPrimitiveCulling = 18
 };
 
 enum class ResourceClass : uint32_t
@@ -402,6 +403,16 @@ struct OptionShaderI8Dot : OptionBase
 	bool supported = false;
 };
 
+struct OptionShaderRayTracingPrimitiveCulling : OptionBase
+{
+	OptionShaderRayTracingPrimitiveCulling()
+		: OptionBase(Option::ShaderRayTracingPrimitiveCulling)
+	{
+	}
+
+	bool supported = false;
+};
+
 struct DescriptorTableEntry
 {
 	ResourceClass type;

dxil_spirv.cpp

@@ -744,6 +744,13 @@ int main(int argc, char **argv)
 		dxil_spv_converter_add_option(converter, &helper.base);
 	}
 
+	{
+		const dxil_spv_option_shader_ray_tracing_primitive_culling helper =
+			{ { DXIL_SPV_OPTION_SHADER_RAY_TRACING_PRIMITIVE_CULLING },
+			  DXIL_SPV_TRUE };
+		dxil_spv_converter_add_option(converter, &helper.base);
+	}
+
 	if (args.dual_source_blending)
 	{
 		const dxil_spv_option_dual_source_blending helper = { { DXIL_SPV_OPTION_DUAL_SOURCE_BLENDING }, DXIL_SPV_TRUE };

dxil_spirv_c.cpp

@@ -803,6 +803,15 @@ dxil_spv_result dxil_spv_converter_add_option(dxil_spv_converter converter, cons
 		break;
 	}
 
+	case DXIL_SPV_OPTION_SHADER_RAY_TRACING_PRIMITIVE_CULLING:
+	{
+		OptionShaderRayTracingPrimitiveCulling helper;
+		helper.supported = bool(reinterpret_cast<const dxil_spv_option_shader_ray_tracing_primitive_culling *>(option)->supported);
+
+		converter->options.emplace_back(duplicate(helper));
+		break;
+	}
+
 	default:
 		return DXIL_SPV_ERROR_UNSUPPORTED_FEATURE;
 	}

dxil_spirv_c.h

@@ -28,7 +28,7 @@ extern "C" {
 #endif
 
 #define DXIL_SPV_API_VERSION_MAJOR 2
-#define DXIL_SPV_API_VERSION_MINOR 11
+#define DXIL_SPV_API_VERSION_MINOR 12
 #define DXIL_SPV_API_VERSION_PATCH 0
 
 #define DXIL_SPV_DESCRIPTOR_QA_INTERFACE_VERSION 1
@@ -278,6 +278,7 @@ typedef enum dxil_spv_option
 	DXIL_SPV_OPTION_DESCRIPTOR_QA = 15,
 	DXIL_SPV_OPTION_MIN_PRECISION_NATIVE_16BIT = 16,
 	DXIL_SPV_OPTION_SHADER_I8_DOT = 17,
+	DXIL_SPV_OPTION_SHADER_RAY_TRACING_PRIMITIVE_CULLING = 18,
 	DXIL_SPV_OPTION_INT_MAX = 0x7fffffff
 } dxil_spv_option;
 
@@ -415,6 +416,12 @@ typedef struct dxil_spv_option_shader_i8_dot
 	dxil_spv_bool supported;
 } dxil_spv_option_shader_i8_dot;
 
+typedef struct dxil_spv_option_shader_ray_tracing_primitive_culling
+{
+	dxil_spv_option_base base;
+	dxil_spv_bool supported;
+} dxil_spv_option_shader_ray_tracing_primitive_culling;
+
 /* Gets the ABI version used to build this library. Used to detect API/ABI mismatches. */
 DXIL_SPV_PUBLIC_API void dxil_spv_get_version(unsigned *major, unsigned *minor, unsigned *patch);
 

opcodes/converter_impl.hpp

@@ -406,6 +406,7 @@ struct Converter::Impl
 		bool descriptor_qa_sink_handles = true;
 		bool min_precision_prefer_native_16bit = false;
 		bool shader_i8_dot_enabled = false;
+		bool ray_tracing_primitive_culling_enabled = false;
 	} options;
 
 	struct BindlessInfo
@@ -462,6 +463,7 @@ struct Converter::Impl
 		// Only relevant for fragment shaders.
 		bool has_side_effects = false;
 		bool discards = false;
+		bool can_require_primitive_culling = false;
 	} shader_analysis;
 
 	// For descriptor QA, we need to rewrite how resource handles are emitted.

opcodes/opcodes_dxil_builtins.cpp

@@ -526,6 +526,21 @@ bool analyze_dxil_instruction(Converter::Impl &impl, const llvm::CallInst *instr
 				impl.handle_to_storage_class[alloca_inst] = spv::StorageClassRayPayloadKHR;
 			}
 		}
+
+		if (const auto *flags_inst = llvm::dyn_cast<llvm::ConstantInt>(instruction->getOperand(2)))
+		{
+			if ((flags_inst->getUniqueInteger().getZExtValue() & (spv::RayFlagsSkipTrianglesKHRMask |
+			                                                      spv::RayFlagsSkipAABBsKHRMask)) != 0)
+			{
+				impl.shader_analysis.can_require_primitive_culling = true;
+			}
+		}
+		else
+		{
+			// Non constant flags, so we must be conservative.
+			impl.shader_analysis.can_require_primitive_culling = true;
+		}
+
 		break;
 	}