SPIRV-Cross/spirv_msl.hpp

/*
 * Copyright 2016-2019 The Brenwill Workshop Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef SPIRV_CROSS_MSL_HPP
#define SPIRV_CROSS_MSL_HPP

#include "spirv_glsl.hpp"
#include <map>
#include <set>
#include <unordered_map>
#include <unordered_set>
#include <vector>

namespace spirv_cross
{

// Indicates the format of the vertex attribute. Currently limited to specifying
// if the attribute is an 8-bit unsigned integer, 16-bit unsigned integer, or
// some other format.
enum MSLVertexFormat
{
	MSL_VERTEX_FORMAT_OTHER,
	MSL_VERTEX_FORMAT_UINT8,
	MSL_VERTEX_FORMAT_UINT16
};

// Defines MSL characteristics of a vertex attribute at a particular location.
// The used_by_shader flag is set to true during compilation of SPIR-V to MSL
// if the shader makes use of this vertex attribute.
struct MSLVertexAttr
{
	uint32_t location = 0;
	uint32_t msl_buffer = 0;
	uint32_t msl_offset = 0;
	uint32_t msl_stride = 0;
	bool per_instance = false;
	MSLVertexFormat format = MSL_VERTEX_FORMAT_OTHER;
	bool used_by_shader = false;
};

// 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. Generally, only one of the buffer, texture,
// or sampler elements will be populated. The used_by_shader flag is set to true during
// compilation of SPIR-V to MSL if the shader makes use of this vertex attribute.
struct MSLResourceBinding
{
	spv::ExecutionModel stage;
	uint32_t desc_set = 0;
	uint32_t binding = 0;

	uint32_t msl_buffer = 0;
	uint32_t msl_texture = 0;
	uint32_t msl_sampler = 0;

	bool used_by_shader = false;
};

enum MSLSamplerCoord
{
	MSL_SAMPLER_COORD_NORMALIZED,
	MSL_SAMPLER_COORD_PIXEL
};

enum MSLSamplerFilter
{
	MSL_SAMPLER_FILTER_NEAREST,
	MSL_SAMPLER_FILTER_LINEAR
};

enum MSLSamplerMipFilter
{
	MSL_SAMPLER_MIP_FILTER_NONE,
	MSL_SAMPLER_MIP_FILTER_NEAREST,
	MSL_SAMPLER_MIP_FILTER_LINEAR,
};

enum MSLSamplerAddress
{
	MSL_SAMPLER_ADDRESS_CLAMP_TO_ZERO,
	MSL_SAMPLER_ADDRESS_CLAMP_TO_EDGE,
	MSL_SAMPLER_ADDRESS_CLAMP_TO_BORDER,
	MSL_SAMPLER_ADDRESS_REPEAT,
	MSL_SAMPLER_ADDRESS_MIRRORED_REPEAT
};

enum MSLSamplerCompareFunc
{
	MSL_SAMPLER_COMPARE_FUNC_NEVER,
	MSL_SAMPLER_COMPARE_FUNC_LESS,
	MSL_SAMPLER_COMPARE_FUNC_LESS_EQUAL,
	MSL_SAMPLER_COMPARE_FUNC_GREATER,
	MSL_SAMPLER_COMPARE_FUNC_GREATER_EQUAL,
	MSL_SAMPLER_COMPARE_FUNC_EQUAL,
	MSL_SAMPLER_COMPARE_FUNC_NOT_EQUAL,
	MSL_SAMPLER_COMPARE_FUNC_ALWAYS
};

enum MSLSamplerBorderColor
{
	MSL_SAMPLER_BORDER_COLOR_TRANSPARENT_BLACK,
	MSL_SAMPLER_BORDER_COLOR_OPAQUE_BLACK,
	MSL_SAMPLER_BORDER_COLOR_OPAQUE_WHITE
};

struct MSLConstexprSampler
{
	MSLSamplerCoord coord = MSL_SAMPLER_COORD_NORMALIZED;
	MSLSamplerFilter min_filter = MSL_SAMPLER_FILTER_NEAREST;
	MSLSamplerFilter mag_filter = MSL_SAMPLER_FILTER_NEAREST;
	MSLSamplerMipFilter mip_filter = MSL_SAMPLER_MIP_FILTER_NONE;
	MSLSamplerAddress s_address = MSL_SAMPLER_ADDRESS_CLAMP_TO_EDGE;
	MSLSamplerAddress t_address = MSL_SAMPLER_ADDRESS_CLAMP_TO_EDGE;
	MSLSamplerAddress r_address = MSL_SAMPLER_ADDRESS_CLAMP_TO_EDGE;
	MSLSamplerCompareFunc compare_func = MSL_SAMPLER_COMPARE_FUNC_NEVER;
	MSLSamplerBorderColor border_color = MSL_SAMPLER_BORDER_COLOR_TRANSPARENT_BLACK;
	float lod_clamp_min = 0.0f;
	float lod_clamp_max = 1000.0f;
	int max_anisotropy = 1;

	bool compare_enable = false;
	bool lod_clamp_enable = false;
	bool anisotropy_enable = false;
};

// Tracks the type ID and member index of a struct member
using MSLStructMemberKey = uint64_t;

// Special constant used in a MSLResourceBinding desc_set
// element to indicate the bindings for the push constants.
static const uint32_t kPushConstDescSet = ~(0u);

// Special constant used in a MSLResourceBinding binding
// element to indicate the bindings for the push constants.
static const uint32_t kPushConstBinding = 0;

// Decompiles SPIR-V to Metal Shading Language
class CompilerMSL : public CompilerGLSL
{
public:
	// Options for compiling to Metal Shading Language
	struct Options
	{
		typedef enum
		{
			iOS,
			macOS,
		} Platform;

		Platform platform = macOS;
		uint32_t msl_version = make_msl_version(1, 2);
		uint32_t texel_buffer_texture_width = 4096; // Width of 2D Metal textures used as 1D texel buffers
		uint32_t aux_buffer_index = 0;
		bool enable_point_size_builtin = true;
		bool disable_rasterization = false;
		bool swizzle_texture_samples = false;

		// Fragment output in MSL must have at least as many components as the render pass.
		// Add support to explicit pad out components.
		bool pad_fragment_output_components = false;

		bool is_ios()
		{
			return platform == iOS;
		}

		bool is_macos()
		{
			return platform == macOS;
		}

		void set_msl_version(uint32_t major, uint32_t minor = 0, uint32_t patch = 0)
		{
			msl_version = make_msl_version(major, minor, patch);
		}

		bool supports_msl_version(uint32_t major, uint32_t minor = 0, uint32_t patch = 0)
		{
			return msl_version >= make_msl_version(major, minor, patch);
		}

		static uint32_t make_msl_version(uint32_t major, uint32_t minor = 0, uint32_t patch = 0)
		{
			return (major * 10000) + (minor * 100) + patch;
		}
	};

	SPIRV_CROSS_DEPRECATED("CompilerMSL::get_options() is obsolete, use get_msl_options() instead.")
	const Options &get_options() const
	{
		return msl_options;
	}

	const Options &get_msl_options() const
	{
		return msl_options;
	}

	SPIRV_CROSS_DEPRECATED("CompilerMSL::set_options() is obsolete, use set_msl_options() instead.")
	void set_options(Options &opts)
	{
		msl_options = opts;
	}

	void set_msl_options(const Options &opts)
	{
		msl_options = opts;
	}

	// Provide feedback to calling API to allow runtime to disable pipeline
	// rasterization if vertex shader requires rasterization to be disabled.
	bool get_is_rasterization_disabled() const
	{
		return is_rasterization_disabled && (get_entry_point().model == spv::ExecutionModelVertex);
	}

	// Provide feedback to calling API to allow it to pass an auxiliary
	// buffer if the shader needs it.
	bool needs_aux_buffer() const
	{
		return used_aux_buffer;
	}

	// An enum of SPIR-V functions that are implemented in additional
	// source code that is added to the shader if necessary.
	enum SPVFuncImpl
	{
		SPVFuncImplNone,
		SPVFuncImplMod,
		SPVFuncImplRadians,
		SPVFuncImplDegrees,
		SPVFuncImplFindILsb,
		SPVFuncImplFindSMsb,
		SPVFuncImplFindUMsb,
		SPVFuncImplSSign,
		SPVFuncImplArrayCopyMultidimBase,
		// Unfortunately, we cannot use recursive templates in the MSL compiler properly,
		// so stamp out variants up to some arbitrary maximum.
		SPVFuncImplArrayCopy = SPVFuncImplArrayCopyMultidimBase + 1,
		SPVFuncImplArrayOfArrayCopy2Dim = SPVFuncImplArrayCopyMultidimBase + 2,
		SPVFuncImplArrayOfArrayCopy3Dim = SPVFuncImplArrayCopyMultidimBase + 3,
		SPVFuncImplArrayOfArrayCopy4Dim = SPVFuncImplArrayCopyMultidimBase + 4,
		SPVFuncImplArrayOfArrayCopy5Dim = SPVFuncImplArrayCopyMultidimBase + 5,
		SPVFuncImplArrayOfArrayCopy6Dim = SPVFuncImplArrayCopyMultidimBase + 6,
		SPVFuncImplTexelBufferCoords,
		SPVFuncImplInverse4x4,
		SPVFuncImplInverse3x3,
		SPVFuncImplInverse2x2,
		SPVFuncImplRowMajor2x3,
		SPVFuncImplRowMajor2x4,
		SPVFuncImplRowMajor3x2,
		SPVFuncImplRowMajor3x4,
		SPVFuncImplRowMajor4x2,
		SPVFuncImplRowMajor4x3,
		SPVFuncImplTextureSwizzle,
		SPVFuncImplArrayCopyMultidimMax = 6
	};

	// Constructs an instance to compile the SPIR-V code into Metal Shading Language,
	// using the configuration parameters, if provided:
	//  - p_vtx_attrs is an optional list of vertex attribute bindings used to match
	//    vertex content locations to MSL attributes. If vertex attributes are provided,
	//    the compiler will set the used_by_shader flag to true in any vertex attribute
	//    actually used by the MSL code.
	//  - p_res_bindings is a list of resource bindings to indicate the MSL buffer,
	//    texture or sampler index to use for a particular SPIR-V description set
	//    and binding. If resource bindings are provided, the compiler will set the
	//    used_by_shader flag to true in any resource binding actually used by the MSL code.
	CompilerMSL(std::vector<uint32_t> spirv, std::vector<MSLVertexAttr> *p_vtx_attrs = nullptr,
	            std::vector<MSLResourceBinding> *p_res_bindings = nullptr);

	// Alternate constructor avoiding use of std::vectors.
	CompilerMSL(const uint32_t *ir, size_t word_count, MSLVertexAttr *p_vtx_attrs = nullptr, size_t vtx_attrs_count = 0,
	            MSLResourceBinding *p_res_bindings = nullptr, size_t res_bindings_count = 0);

	// Alternate constructors taking pre-parsed IR directly.
	CompilerMSL(const ParsedIR &ir, MSLVertexAttr *p_vtx_attrs = nullptr, size_t vtx_attrs_count = 0,
	            MSLResourceBinding *p_res_bindings = nullptr, size_t res_bindings_count = 0);

	CompilerMSL(ParsedIR &&ir, MSLVertexAttr *p_vtx_attrs = nullptr, size_t vtx_attrs_count = 0,
	            MSLResourceBinding *p_res_bindings = nullptr, size_t res_bindings_count = 0);

	// Compiles the SPIR-V code into Metal Shading Language.
	std::string compile() override;

	// Compiles the SPIR-V code into Metal Shading Language, overriding configuration parameters.
	// Any of the parameters here may be null to indicate that the configuration provided in the
	// constructor should be used. They are not declared as optional to avoid a conflict with the
	// inherited and overridden zero-parameter compile() function.
	std::string compile(std::vector<MSLVertexAttr> *p_vtx_attrs, std::vector<MSLResourceBinding> *p_res_bindings);

	// This legacy method is deprecated.
	typedef Options MSLConfiguration;
	SPIRV_CROSS_DEPRECATED("Please use get_msl_options() and set_msl_options() instead.")
	std::string compile(MSLConfiguration &msl_cfg, std::vector<MSLVertexAttr> *p_vtx_attrs = nullptr,
	                    std::vector<MSLResourceBinding> *p_res_bindings = nullptr);

	// Remap a sampler with ID to a constexpr sampler.
	// Older iOS targets must use constexpr samplers in certain cases (PCF),
	// so a static sampler must be used.
	// The sampler will not consume a binding, but be declared in the entry point as a constexpr sampler.
	// This can be used on both combined image/samplers (sampler2D) or standalone samplers.
	// The remapped sampler must not be an array of samplers.
	void remap_constexpr_sampler(uint32_t id, const MSLConstexprSampler &sampler);

	// If using CompilerMSL::Options::pad_fragment_output_components, override the number of components we expect
	// to use for a particular location. The default is 4 if number of components is not overridden.
	void set_fragment_output_components(uint32_t location, uint32_t components);

protected:
	void emit_binary_unord_op(uint32_t result_type, uint32_t result_id, uint32_t op0, uint32_t op1, const char *op);
	void emit_instruction(const Instruction &instr) override;
	void emit_glsl_op(uint32_t result_type, uint32_t result_id, uint32_t op, const uint32_t *args,
	                  uint32_t count) override;
	void emit_header() override;
	void emit_function_prototype(SPIRFunction &func, const Bitset &return_flags) override;
	void emit_sampled_image_op(uint32_t result_type, uint32_t result_id, uint32_t image_id, uint32_t samp_id) override;
	void emit_fixup() override;
	void emit_struct_member(const SPIRType &type, uint32_t member_type_id, uint32_t index,
	                        const std::string &qualifier = "", uint32_t base_offset = 0) override;
	std::string type_to_glsl(const SPIRType &type, 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 builtin_to_glsl(spv::BuiltIn builtin, spv::StorageClass storage) override;
	size_t get_declared_struct_member_size(const SPIRType &struct_type, uint32_t index) const override;
	std::string to_func_call_arg(uint32_t id) override;
	std::string to_name(uint32_t id, bool allow_alias = true) const override;
	std::string to_function_name(uint32_t img, const SPIRType &imgtype, bool is_fetch, bool is_gather, bool is_proj,
	                             bool has_array_offsets, bool has_offset, bool has_grad, bool has_dref,
	                             uint32_t lod) override;
	std::string to_function_args(uint32_t img, const SPIRType &imgtype, bool is_fetch, bool is_gather, bool is_proj,
	                             uint32_t coord, uint32_t coord_components, uint32_t dref, uint32_t grad_x,
	                             uint32_t grad_y, uint32_t lod, uint32_t coffset, uint32_t offset, uint32_t bias,
	                             uint32_t comp, uint32_t sample, bool *p_forward) override;
	std::string to_initializer_expression(const SPIRVariable &var) override;
	std::string unpack_expression_type(std::string expr_str, const SPIRType &type, uint32_t packed_type_id) override;
	std::string bitcast_glsl_op(const SPIRType &result_type, const SPIRType &argument_type) override;
	bool skip_argument(uint32_t id) const override;
	std::string to_member_reference(uint32_t base, const SPIRType &type, uint32_t index, bool ptr_chain) override;
	std::string to_qualifiers_glsl(uint32_t id) override;
	void replace_illegal_names() override;
	void declare_undefined_values() override;
	void declare_constant_arrays();
	bool is_non_native_row_major_matrix(uint32_t id) override;
	bool member_is_non_native_row_major_matrix(const SPIRType &type, uint32_t index) override;
	std::string convert_row_major_matrix(std::string exp_str, const SPIRType &exp_type, bool is_packed) override;

	void preprocess_op_codes();
	void localize_global_variables();
	void extract_global_variables_from_functions();
	void mark_packable_structs();
	void mark_as_packable(SPIRType &type);

	std::unordered_map<uint32_t, std::set<uint32_t>> function_global_vars;
	void extract_global_variables_from_function(uint32_t func_id, std::set<uint32_t> &added_arg_ids,
	                                            std::unordered_set<uint32_t> &global_var_ids,
	                                            std::unordered_set<uint32_t> &processed_func_ids);
	uint32_t add_interface_block(spv::StorageClass storage);

	void add_variable_to_interface_block(spv::StorageClass storage, const std::string &ib_var_ref, SPIRType &ib_type,
	                                     SPIRVariable &var);
	void add_composite_variable_to_interface_block(spv::StorageClass storage, const std::string &ib_var_ref,
	                                               SPIRType &ib_type, SPIRVariable &var);
	void add_plain_variable_to_interface_block(spv::StorageClass storage, const std::string &ib_var_ref,
	                                           SPIRType &ib_type, SPIRVariable &var);
	void add_plain_member_variable_to_interface_block(spv::StorageClass storage, const std::string &ib_var_ref,
	                                                  SPIRType &ib_type, SPIRVariable &var, uint32_t index);
	void add_composite_member_variable_to_interface_block(spv::StorageClass storage, const std::string &ib_var_ref,
	                                                      SPIRType &ib_type, SPIRVariable &var, uint32_t index);
	uint32_t get_accumulated_member_location(const SPIRVariable &var, uint32_t mbr_idx);

	void mark_location_as_used_by_shader(uint32_t location, spv::StorageClass storage);
	uint32_t ensure_correct_builtin_type(uint32_t type_id, spv::BuiltIn builtin);
	uint32_t ensure_correct_attribute_type(uint32_t type_id, uint32_t location);

	void emit_custom_functions();
	void emit_resources();
	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);
	void add_convert_row_major_matrix_function(uint32_t cols, uint32_t rows);
	void fix_up_shader_inputs_outputs();

	std::string func_type_decl(SPIRType &type);
	std::string entry_point_args(bool append_comma);
	std::string to_qualified_member_name(const SPIRType &type, uint32_t index);
	std::string ensure_valid_name(std::string name, std::string pfx);
	std::string to_sampler_expression(uint32_t id);
	std::string to_swizzle_expression(uint32_t id);
	std::string builtin_qualifier(spv::BuiltIn builtin);
	std::string builtin_type_decl(spv::BuiltIn builtin);
	std::string built_in_func_arg(spv::BuiltIn builtin, bool prefix_comma);
	std::string member_attribute_qualifier(const SPIRType &type, uint32_t index);
	std::string argument_decl(const SPIRFunction::Parameter &arg);
	std::string round_fp_tex_coords(std::string tex_coords, bool coord_is_fp);
	uint32_t get_metal_resource_index(SPIRVariable &var, SPIRType::BaseType basetype);
	uint32_t get_ordered_member_location(uint32_t type_id, uint32_t index, uint32_t *comp = nullptr);
	size_t get_declared_struct_member_alignment(const SPIRType &struct_type, uint32_t index) const;
	std::string to_component_argument(uint32_t id);
	void align_struct(SPIRType &ib_type);
	bool is_member_packable(SPIRType &ib_type, uint32_t index);
	MSLStructMemberKey get_struct_member_key(uint32_t type_id, uint32_t index);
	std::string get_argument_address_space(const SPIRVariable &argument);
	std::string get_type_address_space(const SPIRType &type);
	void emit_atomic_func_op(uint32_t result_type, uint32_t result_id, const char *op, uint32_t mem_order_1,
	                         uint32_t mem_order_2, bool has_mem_order_2, uint32_t op0, uint32_t op1 = 0,
	                         bool op1_is_pointer = false, bool op1_is_literal = false, uint32_t op2 = 0);
	const char *get_memory_order(uint32_t spv_mem_sem);
	void add_pragma_line(const std::string &line);
	void add_typedef_line(const std::string &line);
	void emit_barrier(uint32_t id_exe_scope, uint32_t id_mem_scope, uint32_t id_mem_sem);
	void emit_array_copy(const std::string &lhs, uint32_t rhs_id) override;
	void build_implicit_builtins();
	void emit_entry_point_declarations() override;
	uint32_t builtin_frag_coord_id = 0;
	uint32_t builtin_sample_id_id = 0;
	uint32_t aux_buffer_id = 0;

	void bitcast_to_builtin_store(uint32_t target_id, std::string &expr, const SPIRType &expr_type) override;
	void bitcast_from_builtin_load(uint32_t source_id, std::string &expr, const SPIRType &expr_type) override;
	void emit_store_statement(uint32_t lhs_expression, uint32_t rhs_expression) override;

	void analyze_sampled_image_usage();

	Options msl_options;
	std::set<SPVFuncImpl> spv_function_implementations;
	std::unordered_map<uint32_t, MSLVertexAttr *> vtx_attrs_by_location;
	std::unordered_map<uint32_t, uint32_t> fragment_output_components;
	std::unordered_map<MSLStructMemberKey, uint32_t> struct_member_padding;
	std::set<std::string> pragma_lines;
	std::set<std::string> typedef_lines;
	std::vector<uint32_t> vars_needing_early_declaration;
	std::vector<MSLResourceBinding *> resource_bindings;
	MSLResourceBinding next_metal_resource_index;
	uint32_t stage_in_var_id = 0;
	uint32_t stage_out_var_id = 0;
	bool has_sampled_images = false;
	bool needs_vertex_idx_arg = false;
	bool needs_instance_idx_arg = false;
	bool is_rasterization_disabled = false;
	bool used_aux_buffer = false;
	std::string qual_pos_var_name;
	std::string stage_in_var_name = "in";
	std::string stage_out_var_name = "out";
	std::string sampler_name_suffix = "Smplr";
	std::string swizzle_name_suffix = "Swzl";
	spv::Op previous_instruction_opcode = spv::OpNop;

	std::unordered_map<uint32_t, MSLConstexprSampler> constexpr_samplers;
	std::vector<uint32_t> buffer_arrays;

	uint32_t get_target_components_for_fragment_location(uint32_t location) const;
	uint32_t build_extended_vector_type(uint32_t type_id, uint32_t components);

	// OpcodeHandler that handles several MSL preprocessing operations.
	struct OpCodePreprocessor : OpcodeHandler
	{
		OpCodePreprocessor(CompilerMSL &compiler_)
		    : compiler(compiler_)
		{
		}

		bool handle(spv::Op opcode, const uint32_t *args, uint32_t length) override;
		CompilerMSL::SPVFuncImpl get_spv_func_impl(spv::Op opcode, const uint32_t *args);
		void check_resource_write(uint32_t var_id);

		CompilerMSL &compiler;
		std::unordered_map<uint32_t, uint32_t> result_types;
		bool suppress_missing_prototypes = false;
		bool uses_atomics = false;
		bool uses_resource_write = false;
	};

	// OpcodeHandler that scans for uses of sampled images
	struct SampledImageScanner : OpcodeHandler
	{
		SampledImageScanner(CompilerMSL &compiler_)
		    : compiler(compiler_)
		{
		}

		bool handle(spv::Op opcode, const uint32_t *args, uint32_t) override;

		CompilerMSL &compiler;
	};

	// Sorts the members of a SPIRType and associated Meta info based on a settable sorting
	// aspect, which defines which aspect of the struct members will be used to sort them.
	// Regardless of the sorting aspect, built-in members always appear at the end of the struct.
	struct MemberSorter
	{
		enum SortAspect
		{
			Location,
			LocationReverse,
			Offset,
			OffsetThenLocationReverse,
			Alphabetical
		};

		void sort();
		bool operator()(uint32_t mbr_idx1, uint32_t mbr_idx2);
		MemberSorter(SPIRType &t, Meta &m, SortAspect sa);

		SPIRType &type;
		Meta &meta;
		SortAspect sort_aspect;
	};
};
} // namespace spirv_cross

#endif