Merge pull request #1516 from billhollings/VK_EXT_descriptor_indexing

MSL: Support run-time sized image and sampler arrays

spirv_glsl.cpp

@@ -10024,12 +10024,22 @@ void CompilerGLSL::emit_instruction(const Instruction &instruction)
 		bool pointer = get<SPIRType>(result_type).pointer;
 
 		auto *chain = maybe_get<SPIRAccessChain>(rhs);
+		auto *imgsamp = maybe_get<SPIRCombinedImageSampler>(rhs);
 		if (chain)
 		{
 			// Cannot lower to a SPIRExpression, just copy the object.
 			auto &e = set<SPIRAccessChain>(id, *chain);
 			e.self = id;
 		}
+		else if (imgsamp)
+		{
+			// Cannot lower to a SPIRExpression, just copy the object.
+			// GLSL does not currently use this type and will never get here, but MSL does.
+			// Handled here instead of CompilerMSL for better integration and general handling,
+			// and in case GLSL or other subclasses require it in the future.
+			auto &e = set<SPIRCombinedImageSampler>(id, *imgsamp);
+			e.self = id;
+		}
 		else if (expression_is_lvalue(rhs) && !pointer)
 		{
 			// Need a copy.

spirv_msl.cpp

@@ -103,6 +103,16 @@ bool CompilerMSL::is_msl_resource_binding_used(ExecutionModel model, uint32_t de
 	return itr != end(resource_bindings) && itr->second.second;
 }
 
+// Returns the size of the array of resources used by the variable with the specified id.
+// The returned value is retrieved from the resource binding added using add_msl_resource_binding().
+uint32_t CompilerMSL::get_resource_array_size(uint32_t id) const
+{
+	StageSetBinding tuple = { get_entry_point().model, get_decoration(id, DecorationDescriptorSet),
+		                      get_decoration(id, DecorationBinding) };
+	auto itr = resource_bindings.find(tuple);
+	return itr != end(resource_bindings) ? itr->second.first.count : 0;
+}
+
 uint32_t CompilerMSL::get_automatic_msl_resource_binding(uint32_t id) const
 {
 	return get_extended_decoration(id, SPIRVCrossDecorationResourceIndexPrimary);
@@ -8136,7 +8146,7 @@ void CompilerMSL::emit_function_prototype(SPIRFunction &func, const Bitset &)
 
 			// Manufacture automatic sampler arg for SampledImage texture
 			if (arg_type.image.dim != DimBuffer)
-				decl += join(", thread const ", sampler_type(arg_type), " ", to_sampler_expression(arg.id));
+				decl += join(", thread const ", sampler_type(arg_type, arg.id), " ", to_sampler_expression(arg.id));
 		}
 
 		// Manufacture automatic swizzle arg.
@@ -10449,7 +10459,7 @@ void CompilerMSL::entry_point_args_discrete_descriptors(string &ep_args)
 		case SPIRType::Sampler:
 			if (!ep_args.empty())
 				ep_args += ", ";
-			ep_args += sampler_type(type) + " " + r.name;
+			ep_args += sampler_type(type, var_id) + " " + r.name;
 			ep_args += " [[sampler(" + convert_to_string(r.index) + ")]]";
 			break;
 		case SPIRType::Image:
@@ -11709,7 +11719,7 @@ string CompilerMSL::type_to_glsl(const SPIRType &type, uint32_t id)
 		return image_type_glsl(type, id);
 
 	case SPIRType::Sampler:
-		return sampler_type(type);
+		return sampler_type(type, id);
 
 	case SPIRType::Void:
 		return "void";
@@ -11840,8 +11850,15 @@ std::string CompilerMSL::variable_decl(const SPIRType &type, const std::string &
 	return CompilerGLSL::variable_decl(type, name, id);
 }
 
-std::string CompilerMSL::sampler_type(const SPIRType &type)
+std::string CompilerMSL::sampler_type(const SPIRType &type, uint32_t id)
 {
+	auto *var = maybe_get<SPIRVariable>(id);
+	if (var && var->basevariable)
+	{
+		// Check against the base variable, and not a fake ID which might have been generated for this variable.
+		id = var->basevariable;
+	}
+
 	if (!type.array.empty())
 	{
 		if (!msl_options.supports_msl_version(2))
@@ -11851,12 +11868,16 @@ std::string CompilerMSL::sampler_type(const SPIRType &type)
 			SPIRV_CROSS_THROW("Arrays of arrays of samplers are not supported in MSL.");
 
 		// Arrays of samplers in MSL must be declared with a special array<T, N> syntax ala C++11 std::array.
+		// If we have a runtime array, it could be a variable-count descriptor set binding.
 		uint32_t array_size = to_array_size_literal(type);
+		if (array_size == 0)
+			array_size = get_resource_array_size(id);
+
 		if (array_size == 0)
 			SPIRV_CROSS_THROW("Unsized array of samplers is not supported in MSL.");
 
 		auto &parent = get<SPIRType>(get_pointee_type(type).parent_type);
-		return join("array<", sampler_type(parent), ", ", array_size, ">");
+		return join("array<", sampler_type(parent, id), ", ", array_size, ">");
 	}
 	else
 		return "sampler";
@@ -11893,7 +11914,11 @@ string CompilerMSL::image_type_glsl(const SPIRType &type, uint32_t id)
 			SPIRV_CROSS_THROW("Arrays of arrays of textures are not supported in MSL.");
 
 		// Arrays of images in MSL must be declared with a special array<T, N> syntax ala C++11 std::array.
+		// If we have a runtime array, it could be a variable-count descriptor set binding.
 		uint32_t array_size = to_array_size_literal(type);
+		if (array_size == 0)
+			array_size = get_resource_array_size(id);
+
 		if (array_size == 0)
 			SPIRV_CROSS_THROW("Unsized array of images is not supported in MSL.");
 

spirv_msl.hpp

@@ -60,7 +60,11 @@ struct MSLShaderInput
 
 // Matches the binding index of a MSL resource for a binding within a descriptor set.
 // Taken together, the stage, desc_set and binding combine to form a reference to a resource
-// descriptor used in a particular shading stage.
+// descriptor used in a particular shading stage. The count field indicates the number of
+// resources consumed by this binding, if the binding represents an array of resources.
+// If the resource array is a run-time-sized array, which are legal in GLSL or SPIR-V, this value
+// will be used to declare the array size in MSL, which does not support run-time-sized arrays.
+// For resources that are not held in a run-time-sized array, the count field does not need to be populated.
 // If using MSL 2.0 argument buffers, the descriptor set is not marked as a discrete descriptor set,
 // and (for iOS only) the resource is not a storage image (sampled != 2), the binding reference we
 // remap to will become an [[id(N)]] attribute within the "descriptor set" argument buffer structure.
@@ -71,6 +75,7 @@ struct MSLResourceBinding
 	spv::ExecutionModel stage = spv::ExecutionModelMax;
 	uint32_t desc_set = 0;
 	uint32_t binding = 0;
+	uint32_t count = 0;
 	uint32_t msl_buffer = 0;
 	uint32_t msl_texture = 0;
 	uint32_t msl_sampler = 0;
@@ -672,7 +677,7 @@ protected:
 	std::string variable_decl(const SPIRType &type, const std::string &name, uint32_t id = 0) override;
 
 	std::string image_type_glsl(const SPIRType &type, uint32_t id = 0) override;
-	std::string sampler_type(const SPIRType &type);
+	std::string sampler_type(const SPIRType &type, uint32_t id);
 	std::string builtin_to_glsl(spv::BuiltIn builtin, spv::StorageClass storage) override;
 	std::string to_func_call_arg(const SPIRFunction::Parameter &arg, uint32_t id) override;
 	std::string to_name(uint32_t id, bool allow_alias = true) const override;
@@ -756,6 +761,7 @@ protected:
 	void emit_specialization_constants_and_structs();
 	void emit_interface_block(uint32_t ib_var_id);
 	bool maybe_emit_array_assignment(uint32_t id_lhs, uint32_t id_rhs);
+	uint32_t get_resource_array_size(uint32_t id) const;
 
 	void fix_up_shader_inputs_outputs();