spirv_hlsl.cpp

/*
 * Copyright 2016-2017 Robert Konrad
 *
 * 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.
 */

#include "spirv_hlsl.hpp"
#include "GLSL.std.450.h"
#include <algorithm>
#include <assert.h>

using namespace spv;
using namespace spirv_cross;
using namespace std;

static unsigned image_format_to_components(ImageFormat fmt)
{
	switch (fmt)
	{
	case ImageFormatR8:
	case ImageFormatR16:
	case ImageFormatR8Snorm:
	case ImageFormatR16Snorm:
	case ImageFormatR16f:
	case ImageFormatR32f:
	case ImageFormatR8i:
	case ImageFormatR16i:
	case ImageFormatR32i:
	case ImageFormatR8ui:
	case ImageFormatR16ui:
	case ImageFormatR32ui:
		return 1;

	case ImageFormatRg8:
	case ImageFormatRg16:
	case ImageFormatRg8Snorm:
	case ImageFormatRg16Snorm:
	case ImageFormatRg16f:
	case ImageFormatRg32f:
	case ImageFormatRg8i:
	case ImageFormatRg16i:
	case ImageFormatRg32i:
	case ImageFormatRg8ui:
	case ImageFormatRg16ui:
	case ImageFormatRg32ui:
		return 2;

	case ImageFormatR11fG11fB10f:
		return 3;

	case ImageFormatRgba8:
	case ImageFormatRgba16:
	case ImageFormatRgb10A2:
	case ImageFormatRgba8Snorm:
	case ImageFormatRgba16Snorm:
	case ImageFormatRgba16f:
	case ImageFormatRgba32f:
	case ImageFormatRgba8i:
	case ImageFormatRgba16i:
	case ImageFormatRgba32i:
	case ImageFormatRgba8ui:
	case ImageFormatRgba16ui:
	case ImageFormatRgba32ui:
	case ImageFormatRgb10a2ui:
		return 4;

	default:
		SPIRV_CROSS_THROW("Unrecognized typed image format.");
	}
}

static string image_format_to_type(ImageFormat fmt)
{
	switch (fmt)
	{
	case ImageFormatR8:
	case ImageFormatR16:
		return "unorm float";
	case ImageFormatRg8:
	case ImageFormatRg16:
		return "unorm float2";
	case ImageFormatRgba8:
	case ImageFormatRgba16:
		return "unorm float4";
	case ImageFormatRgb10A2:
		return "unorm float4";

	case ImageFormatR8Snorm:
	case ImageFormatR16Snorm:
		return "snorm float";
	case ImageFormatRg8Snorm:
	case ImageFormatRg16Snorm:
		return "snorm float2";
	case ImageFormatRgba8Snorm:
	case ImageFormatRgba16Snorm:
		return "snorm float4";

	case ImageFormatR16f:
	case ImageFormatR32f:
		return "float";
	case ImageFormatRg16f:
	case ImageFormatRg32f:
		return "float2";
	case ImageFormatRgba16f:
	case ImageFormatRgba32f:
		return "float4";

	case ImageFormatR11fG11fB10f:
		return "float3";

	case ImageFormatR8i:
	case ImageFormatR16i:
	case ImageFormatR32i:
		return "int";
	case ImageFormatRg8i:
	case ImageFormatRg16i:
	case ImageFormatRg32i:
		return "int2";
	case ImageFormatRgba8i:
	case ImageFormatRgba16i:
	case ImageFormatRgba32i:
		return "int4";

	case ImageFormatR8ui:
	case ImageFormatR16ui:
	case ImageFormatR32ui:
		return "uint";
	case ImageFormatRg8ui:
	case ImageFormatRg16ui:
	case ImageFormatRg32ui:
		return "uint2";
	case ImageFormatRgba8ui:
	case ImageFormatRgba16ui:
	case ImageFormatRgba32ui:
		return "uint4";
	case ImageFormatRgb10a2ui:
		return "int4";

	default:
		SPIRV_CROSS_THROW("Unrecognized typed image format.");
	}
}

// Returns true if an arithmetic operation does not change behavior depending on signedness.
static bool opcode_is_sign_invariant(Op opcode)
{
	switch (opcode)
	{
	case OpIEqual:
	case OpINotEqual:
	case OpISub:
	case OpIAdd:
	case OpIMul:
	case OpShiftLeftLogical:
	case OpBitwiseOr:
	case OpBitwiseXor:
	case OpBitwiseAnd:
		return true;

	default:
		return false;
	}
}

string CompilerHLSL::image_type_hlsl_modern(const SPIRType &type)
{
	auto &imagetype = get<SPIRType>(type.image.type);
	const char *dim = nullptr;
	bool typed_load = false;
	uint32_t components = 4;

	switch (type.image.dim)
	{
	case Dim1D:
		typed_load = type.image.sampled == 2;
		dim = "1D";
		break;
	case Dim2D:
		typed_load = type.image.sampled == 2;
		dim = "2D";
		break;
	case Dim3D:
		typed_load = type.image.sampled == 2;
		dim = "3D";
		break;
	case DimCube:
		if (type.image.sampled == 2)
			SPIRV_CROSS_THROW("RWTextureCube does not exist in HLSL.");
		dim = "Cube";
		break;
	case DimRect:
		SPIRV_CROSS_THROW("Rectangle texture support is not yet implemented for HLSL."); // TODO
	case DimBuffer:
		if (type.image.sampled == 1)
			return join("Buffer<", type_to_glsl(imagetype), components, ">");
		else if (type.image.sampled == 2)
			return join("RWBuffer<", image_format_to_type(type.image.format), ">");
		else
			SPIRV_CROSS_THROW("Sampler buffers must be either sampled or unsampled. Cannot deduce in runtime.");
	case DimSubpassData:
		// This should be implemented same way as desktop GL. Fetch on a 2D texture based on int2(SV_Position).
		SPIRV_CROSS_THROW("Subpass data support is not yet implemented for HLSL"); // TODO
	default:
		SPIRV_CROSS_THROW("Invalid dimension.");
	}
	const char *arrayed = type.image.arrayed ? "Array" : "";
	const char *ms = type.image.ms ? "MS" : "";
	const char *rw = typed_load ? "RW" : "";
	return join(rw, "Texture", dim, ms, arrayed, "<",
	            typed_load ? image_format_to_type(type.image.format) : join(type_to_glsl(imagetype), components), ">");
}

string CompilerHLSL::image_type_hlsl_legacy(const SPIRType &type)
{
	auto &imagetype = get<SPIRType>(type.image.type);
	string res;

	switch (imagetype.basetype)
	{
	case SPIRType::Int:
		res = "i";
		break;
	case SPIRType::UInt:
		res = "u";
		break;
	default:
		break;
	}

	if (type.basetype == SPIRType::Image && type.image.dim == DimSubpassData)
		return res + "subpassInput" + (type.image.ms ? "MS" : "");

	// If we're emulating subpassInput with samplers, force sampler2D
	// so we don't have to specify format.
	if (type.basetype == SPIRType::Image && type.image.dim != DimSubpassData)
	{
		// Sampler buffers are always declared as samplerBuffer even though they might be separate images in the SPIR-V.
		if (type.image.dim == DimBuffer && type.image.sampled == 1)
			res += "sampler";
		else
			res += type.image.sampled == 2 ? "image" : "texture";
	}
	else
		res += "sampler";

	switch (type.image.dim)
	{
	case Dim1D:
		res += "1D";
		break;
	case Dim2D:
		res += "2D";
		break;
	case Dim3D:
		res += "3D";
		break;
	case DimCube:
		res += "CUBE";
		break;

	case DimBuffer:
		res += "Buffer";
		break;

	case DimSubpassData:
		res += "2D";
		break;
	default:
		SPIRV_CROSS_THROW("Only 1D, 2D, 3D, Buffer, InputTarget and Cube textures supported.");
	}

	if (type.image.ms)
		res += "MS";
	if (type.image.arrayed)
		res += "Array";
	if (type.image.depth)
		res += "Shadow";

	return res;
}

string CompilerHLSL::image_type_hlsl(const SPIRType &type)
{
	if (options.shader_model <= 30)
		return image_type_hlsl_legacy(type);
	else
		return image_type_hlsl_modern(type);
}

// The optional id parameter indicates the object whose type we are trying
// to find the description for. It is optional. Most type descriptions do not
// depend on a specific object's use of that type.
string CompilerHLSL::type_to_glsl(const SPIRType &type, uint32_t id)
{
	// Ignore the pointer type since GLSL doesn't have pointers.

	switch (type.basetype)
	{
	case SPIRType::Struct:
		// Need OpName lookup here to get a "sensible" name for a struct.
		if (backend.explicit_struct_type)
			return join("struct ", to_name(type.self));
		else
			return to_name(type.self);

	case SPIRType::Image:
	case SPIRType::SampledImage:
		return image_type_hlsl(type);

	case SPIRType::Sampler:
		return comparison_samplers.count(id) ? "SamplerComparisonState" : "SamplerState";

	case SPIRType::Void:
		return "void";

	default:
		break;
	}

	if (type.vecsize == 1 && type.columns == 1) // Scalar builtin
	{
		switch (type.basetype)
		{
		case SPIRType::Boolean:
			return "bool";
		case SPIRType::Int:
			return backend.basic_int_type;
		case SPIRType::UInt:
			return backend.basic_uint_type;
		case SPIRType::AtomicCounter:
			return "atomic_uint";
		case SPIRType::Float:
			return "float";
		case SPIRType::Double:
			return "double";
		case SPIRType::Int64:
			return "int64_t";
		case SPIRType::UInt64:
			return "uint64_t";
		default:
			return "???";
		}
	}
	else if (type.vecsize > 1 && type.columns == 1) // Vector builtin
	{
		switch (type.basetype)
		{
		case SPIRType::Boolean:
			return join("bool", type.vecsize);
		case SPIRType::Int:
			return join("int", type.vecsize);
		case SPIRType::UInt:
			return join("uint", type.vecsize);
		case SPIRType::Float:
			return join("float", type.vecsize);
		case SPIRType::Double:
			return join("double", type.vecsize);
		case SPIRType::Int64:
			return join("i64vec", type.vecsize);
		case SPIRType::UInt64:
			return join("u64vec", type.vecsize);
		default:
			return "???";
		}
	}
	else
	{
		switch (type.basetype)
		{
		case SPIRType::Boolean:
			return join("bool", type.columns, "x", type.vecsize);
		case SPIRType::Int:
			return join("int", type.columns, "x", type.vecsize);
		case SPIRType::UInt:
			return join("uint", type.columns, "x", type.vecsize);
		case SPIRType::Float:
			return join("float", type.columns, "x", type.vecsize);
		case SPIRType::Double:
			return join("double", type.columns, "x", type.vecsize);
		// Matrix types not supported for int64/uint64.
		default:
			return "???";
		}
	}
}

void CompilerHLSL::emit_header()
{
	for (auto &header : header_lines)
		statement(header);

	if (header_lines.size() > 0)
	{
		statement("");
	}
}

void CompilerHLSL::emit_interface_block_globally(const SPIRVariable &var)
{
	add_resource_name(var.self);

	// The global copies of I/O variables should not contain interpolation qualifiers.
	// These are emitted inside the interface structs.
	auto &flags = meta[var.self].decoration.decoration_flags;
	auto old_flags = flags;
	flags = 0;
	statement("static ", variable_decl(var), ";");
	flags = old_flags;
}

const char *CompilerHLSL::to_storage_qualifiers_glsl(const SPIRVariable &var)
{
	// Input and output variables are handled specially in HLSL backend.
	// The variables are declared as global, private variables, and do not need any qualifiers.
	if (var.storage == StorageClassUniformConstant || var.storage == StorageClassUniform ||
	    var.storage == StorageClassPushConstant)
	{
		return "uniform ";
	}

	return "";
}

void CompilerHLSL::emit_builtin_outputs_in_struct()
{
	bool legacy = options.shader_model <= 30;
	for (uint32_t i = 0; i < 64; i++)
	{
		if (!(active_output_builtins & (1ull << i)))
			continue;

		const char *type = nullptr;
		const char *semantic = nullptr;
		auto builtin = static_cast<BuiltIn>(i);
		switch (builtin)
		{
		case BuiltInPosition:
			type = "float4";
			semantic = legacy ? "POSITION" : "SV_Position";
			break;

		case BuiltInFragDepth:
			type = "float";
			semantic = legacy ? "DEPTH" : "SV_Depth";
			break;

		case BuiltInPointSize:
			// If point_size_compat is enabled, just ignore PointSize.
			// PointSize does not exist in HLSL, but some code bases might want to be able to use these shaders,
			// even if it means working around the missing feature.
			if (options.point_size_compat)
				break;
			else
				SPIRV_CROSS_THROW("Unsupported builtin in HLSL.");

		default:
			SPIRV_CROSS_THROW("Unsupported builtin in HLSL.");
			break;
		}

		if (type && semantic)
			statement(type, " ", builtin_to_glsl(builtin, StorageClassOutput), " : ", semantic, ";");
	}
}

void CompilerHLSL::emit_builtin_inputs_in_struct()
{
	bool legacy = options.shader_model <= 30;
	for (uint32_t i = 0; i < 64; i++)
	{
		if (!(active_input_builtins & (1ull << i)))
			continue;

		const char *type = nullptr;
		const char *semantic = nullptr;
		auto builtin = static_cast<BuiltIn>(i);
		switch (builtin)
		{
		case BuiltInFragCoord:
			type = "float4";
			semantic = legacy ? "VPOS" : "SV_Position";
			break;

		case BuiltInVertexIndex:
			if (legacy)
				SPIRV_CROSS_THROW("Vertex index not supported in SM 3.0 or lower.");
			type = "uint";
			semantic = "SV_VertexID";
			break;

		case BuiltInInstanceIndex:
			if (legacy)
				SPIRV_CROSS_THROW("Instance index not supported in SM 3.0 or lower.");
			type = "uint";
			semantic = "SV_InstanceID";
			break;

		case BuiltInSampleId:
			if (legacy)
				SPIRV_CROSS_THROW("Sample ID not supported in SM 3.0 or lower.");
			type = "uint";
			semantic = "SV_SampleIndex";
			break;

		case BuiltInGlobalInvocationId:
			type = "uint3";
			semantic = "SV_DispatchThreadID";
			break;

		case BuiltInLocalInvocationId:
			type = "uint3";
			semantic = "SV_GroupThreadID";
			break;

		case BuiltInLocalInvocationIndex:
			type = "uint";
			semantic = "SV_GroupIndex";
			break;

		case BuiltInWorkgroupId:
			type = "uint3";
			semantic = "SV_GroupID";
			break;

		default:
			SPIRV_CROSS_THROW("Unsupported builtin in HLSL.");
			break;
		}

		if (type && semantic)
			statement(type, " ", builtin_to_glsl(builtin, StorageClassInput), " : ", semantic, ";");
	}
}

uint32_t CompilerHLSL::type_to_consumed_locations(const SPIRType &type) const
{
	// TODO: Need to verify correctness.
	uint32_t elements = 0;

	if (type.basetype == SPIRType::Struct)
	{
		for (uint32_t i = 0; i < uint32_t(type.member_types.size()); i++)
			elements += type_to_consumed_locations(get<SPIRType>(type.member_types[i]));
	}
	else
	{
		uint32_t array_multiplier = 1;
		for (uint32_t i = 0; i < uint32_t(type.array.size()); i++)
		{
			if (type.array_size_literal[i])
				array_multiplier *= type.array[i];
			else
				array_multiplier *= get<SPIRConstant>(type.array[i]).scalar();
		}
		elements += array_multiplier * type.columns;
	}
	return elements;
}

string CompilerHLSL::to_interpolation_qualifiers(uint64_t flags)
{
	string res;
	//if (flags & (1ull << DecorationSmooth))
	//    res += "linear ";
	if (flags & (1ull << DecorationFlat))
		res += "nointerpolation ";
	if (flags & (1ull << DecorationNoPerspective))
		res += "noperspective ";
	if (flags & (1ull << DecorationCentroid))
		res += "centroid ";
	if (flags & (1ull << DecorationPatch))
		res += "patch "; // Seems to be different in actual HLSL.
	if (flags & (1ull << DecorationSample))
		res += "sample ";
	if (flags & (1ull << DecorationInvariant))
		res += "invariant "; // Not supported?

	return res;
}

std::string CompilerHLSL::to_semantic(uint32_t vertex_location)
{
	for (auto &attribute : remap_vertex_attributes)
		if (attribute.location == vertex_location)
			return attribute.semantic;

	return join("TEXCOORD", vertex_location);
}

void CompilerHLSL::emit_io_block(const SPIRVariable &var)
{
	auto &type = get<SPIRType>(var.basetype);
	add_resource_name(type.self);

	statement("struct ", to_name(type.self));
	begin_scope();
	type.member_name_cache.clear();

	uint32_t base_location = get_decoration(var.self, DecorationLocation);

	for (uint32_t i = 0; i < uint32_t(type.member_types.size()); i++)
	{
		string semantic;
		if (has_member_decoration(type.self, i, DecorationLocation))
		{
			uint32_t location = get_member_decoration(type.self, i, DecorationLocation);
			semantic = join(" : ", to_semantic(location));
		}
		else
		{
			// If the block itself has a location, but not its members, use the implicit location.
			// There could be a conflict if the block members partially specialize the locations.
			// It is unclear how SPIR-V deals with this. Assume this does not happen for now.
			uint32_t location = base_location + i;
			semantic = join(" : ", to_semantic(location));
		}

		add_member_name(type, i);

		auto &membertype = get<SPIRType>(type.member_types[i]);
		statement(to_interpolation_qualifiers(get_member_decoration_mask(type.self, i)),
		          variable_decl(membertype, to_member_name(type, i)), semantic, ";");
	}

	end_scope_decl();
	statement("");

	statement("static ", variable_decl(var), ";");
	statement("");
}

void CompilerHLSL::emit_interface_block_in_struct(const SPIRVariable &var, unordered_set<uint32_t> &active_locations)
{
	auto &execution = get_entry_point();
	auto &type = get<SPIRType>(var.basetype);

	string binding;
	bool use_location_number = true;
	bool legacy = options.shader_model <= 30;
	if (execution.model == ExecutionModelFragment && var.storage == StorageClassOutput)
	{
		binding = join(legacy ? "COLOR" : "SV_Target", get_decoration(var.self, DecorationLocation));
		use_location_number = false;
	}

	const auto get_vacant_location = [&]() -> uint32_t {
		for (uint32_t i = 0; i < 64; i++)
			if (!active_locations.count(i))
				return i;
		SPIRV_CROSS_THROW("All locations from 0 to 63 are exhausted.");
	};

	bool need_matrix_unroll = var.storage == StorageClassInput && execution.model == ExecutionModelVertex;

	auto &m = meta[var.self].decoration;
	auto name = to_name(var.self);
	if (use_location_number)
	{
		uint32_t location_number;

		// If an explicit location exists, use it with TEXCOORD[N] semantic.
		// Otherwise, pick a vacant location.
		if (m.decoration_flags & (1ull << DecorationLocation))
			location_number = m.location;
		else
			location_number = get_vacant_location();

		// Allow semantic remap if specified.
		auto semantic = to_semantic(location_number);

		if (need_matrix_unroll && type.columns > 1)
		{
			if (!type.array.empty())
				SPIRV_CROSS_THROW("Arrays of matrices used as input/output. This is not supported.");

			// Unroll matrices.
			for (uint32_t i = 0; i < type.columns; i++)
			{
				SPIRType newtype = type;
				newtype.columns = 1;
				statement(to_interpolation_qualifiers(get_decoration_mask(var.self)),
				          variable_decl(newtype, join(name, "_", i)), " : ", semantic, "_", i, ";");
				active_locations.insert(location_number++);
			}
		}
		else
		{
			statement(to_interpolation_qualifiers(get_decoration_mask(var.self)), variable_decl(type, name), " : ",
			          semantic, ";");

			// Structs and arrays should consume more locations.
			uint32_t consumed_locations = type_to_consumed_locations(type);
			for (uint32_t i = 0; i < consumed_locations; i++)
				active_locations.insert(location_number + i);
		}
	}
	else
		statement(variable_decl(type, name), " : ", binding, ";");
}

void CompilerHLSL::emit_builtin_variables()
{
	// Emit global variables for the interface variables which are statically used by the shader.
	for (uint32_t i = 0; i < 64; i++)
	{
		if (!((active_input_builtins | active_output_builtins) & (1ull << i)))
			continue;

		const char *type = nullptr;
		auto builtin = static_cast<BuiltIn>(i);

		switch (builtin)
		{
		case BuiltInFragCoord:
		case BuiltInPosition:
			type = "float4";
			break;

		case BuiltInFragDepth:
			type = "float";
			break;

		case BuiltInVertexIndex:
		case BuiltInInstanceIndex:
		case BuiltInSampleId:
			type = "int";
			break;

		case BuiltInPointSize:
			if (options.point_size_compat)
			{
				// Just emit the global variable, it will be ignored.
				type = "float";
				break;
			}
			else
				SPIRV_CROSS_THROW(join("Unsupported builtin in HLSL: ", unsigned(builtin)));

		case BuiltInGlobalInvocationId:
		case BuiltInLocalInvocationId:
		case BuiltInWorkgroupId:
			type = "uint3";
			break;

		case BuiltInLocalInvocationIndex:
			type = "uint";
			break;

		default:
			SPIRV_CROSS_THROW(join("Unsupported builtin in HLSL: ", unsigned(builtin)));
			break;
		}

		StorageClass storage = (active_input_builtins & (1ull << i)) != 0 ? StorageClassInput : StorageClassOutput;
		// FIXME: SampleMask can be both in and out with sample builtin,
		// need to distinguish that when we add support for that.

		if (type)
			statement("static ", type, " ", builtin_to_glsl(builtin, storage), ";");
	}
}

void CompilerHLSL::emit_specialization_constants()
{
	bool emitted = false;
	SpecializationConstant wg_x, wg_y, wg_z;
	uint32_t workgroup_size_id = get_work_group_size_specialization_constants(wg_x, wg_y, wg_z);

	for (auto &id : ids)
	{
		if (id.get_type() == TypeConstant)
		{
			auto &c = id.get<SPIRConstant>();
			if (!c.specialization)
				continue;
			if (c.self == workgroup_size_id)
				continue;

			auto &type = get<SPIRType>(c.constant_type);
			auto name = to_name(c.self);

			statement("static const ", variable_decl(type, name), " = ", constant_expression(c), ";");
			emitted = true;
		}
	}

	if (workgroup_size_id)
	{
		statement("static const uint3 gl_WorkGroupSize = ", constant_expression(get<SPIRConstant>(workgroup_size_id)),
		          ";");
		emitted = true;
	}

	if (emitted)
		statement("");
}

void CompilerHLSL::emit_resources()
{
	auto &execution = get_entry_point();

	emit_specialization_constants();

	// Output all basic struct types which are not Block or BufferBlock as these are declared inplace
	// when such variables are instantiated.
	for (auto &id : ids)
	{
		if (id.get_type() == TypeType)
		{
			auto &type = id.get<SPIRType>();
			if (type.basetype == SPIRType::Struct && type.array.empty() && !type.pointer &&
			    (meta[type.self].decoration.decoration_flags &
			     ((1ull << DecorationBlock) | (1ull << DecorationBufferBlock))) == 0)
			{
				emit_struct(type);
			}
		}
	}

	bool emitted = false;

	// Output UBOs and SSBOs
	for (auto &id : ids)
	{
		if (id.get_type() == TypeVariable)
		{
			auto &var = id.get<SPIRVariable>();
			auto &type = get<SPIRType>(var.basetype);

			bool is_block_storage = type.storage == StorageClassStorageBuffer || type.storage == StorageClassUniform;
			bool has_block_flags = (meta[type.self].decoration.decoration_flags &
			                        ((1ull << DecorationBlock) | (1ull << DecorationBufferBlock))) != 0;

			if (var.storage != StorageClassFunction && type.pointer && is_block_storage && !is_hidden_variable(var) &&
			    has_block_flags)
			{
				emit_buffer_block(var);
				emitted = true;
			}
		}
	}

	// Output push constant blocks
	for (auto &id : ids)
	{
		if (id.get_type() == TypeVariable)
		{
			auto &var = id.get<SPIRVariable>();
			auto &type = get<SPIRType>(var.basetype);
			if (var.storage != StorageClassFunction && type.pointer && type.storage == StorageClassPushConstant &&
			    !is_hidden_variable(var))
			{
				emit_push_constant_block(var);
				emitted = true;
			}
		}
	}

	if (execution.model == ExecutionModelVertex && options.shader_model <= 30)
	{
		statement("uniform float4 gl_HalfPixel;");
		emitted = true;
	}

	// Output Uniform Constants (values, samplers, images, etc).
	for (auto &id : ids)
	{
		if (id.get_type() == TypeVariable)
		{
			auto &var = id.get<SPIRVariable>();
			auto &type = get<SPIRType>(var.basetype);

			if (var.storage != StorageClassFunction && !is_builtin_variable(var) && !var.remapped_variable &&
			    type.pointer &&
			    (type.storage == StorageClassUniformConstant || type.storage == StorageClassAtomicCounter))
			{
				emit_uniform(var);
				emitted = true;
			}
		}
	}

	if (emitted)
		statement("");
	emitted = false;

	// Emit builtin input and output variables here.
	emit_builtin_variables();

	for (auto &id : ids)
	{
		if (id.get_type() == TypeVariable)
		{
			auto &var = id.get<SPIRVariable>();
			auto &type = get<SPIRType>(var.basetype);
			bool block = (meta[type.self].decoration.decoration_flags & (1ull << DecorationBlock)) != 0;

			// Do not emit I/O blocks here.
			// I/O blocks can be arrayed, so we must deal with them separately to support geometry shaders
			// and tessellation down the line.
			if (!block && var.storage != StorageClassFunction && !var.remapped_variable && type.pointer &&
			    (var.storage == StorageClassInput || var.storage == StorageClassOutput) && !is_builtin_variable(var) &&
			    interface_variable_exists_in_entry_point(var.self))
			{
				// Only emit non-builtins which are not blocks here. Builtin variables are handled separately.
				emit_interface_block_globally(var);
				emitted = true;
			}
		}
	}

	if (emitted)
		statement("");
	emitted = false;

	require_input = false;
	require_output = false;
	unordered_set<uint32_t> active_inputs;
	unordered_set<uint32_t> active_outputs;
	vector<SPIRVariable *> input_variables;
	vector<SPIRVariable *> output_variables;
	for (auto &id : ids)
	{
		if (id.get_type() == TypeVariable)
		{
			auto &var = id.get<SPIRVariable>();
			auto &type = get<SPIRType>(var.basetype);
			bool block = (meta[type.self].decoration.decoration_flags & (1ull << DecorationBlock)) != 0;

			if (var.storage != StorageClassInput && var.storage != StorageClassOutput)
				continue;

			// Do not emit I/O blocks here.
			// I/O blocks can be arrayed, so we must deal with them separately to support geometry shaders
			// and tessellation down the line.
			if (!block && !var.remapped_variable && type.pointer && !is_builtin_variable(var) &&
			    interface_variable_exists_in_entry_point(var.self))
			{
				if (var.storage == StorageClassInput)
					input_variables.push_back(&var);
				else
					output_variables.push_back(&var);
			}

			// Reserve input and output locations for block variables as necessary.
			if (block && !is_builtin_variable(var) && interface_variable_exists_in_entry_point(var.self))
			{
				auto &active = var.storage == StorageClassInput ? active_inputs : active_outputs;
				for (uint32_t i = 0; i < uint32_t(type.member_types.size()); i++)
				{
					if (has_member_decoration(type.self, i, DecorationLocation))
					{
						uint32_t location = get_member_decoration(type.self, i, DecorationLocation);
						active.insert(location);
					}
				}

				// Emit the block struct and a global variable here.
				emit_io_block(var);
			}
		}
	}

	const auto variable_compare = [&](const SPIRVariable *a, const SPIRVariable *b) -> bool {
		// Sort input and output variables based on, from more robust to less robust:
		// - Location
		// - Variable has a location
		// - Name comparison
		// - Variable has a name
		// - Fallback: ID
		bool has_location_a = has_decoration(a->self, DecorationLocation);
		bool has_location_b = has_decoration(b->self, DecorationLocation);

		if (has_location_a && has_location_b)
		{
			return get_decoration(a->self, DecorationLocation) < get_decoration(b->self, DecorationLocation);
		}
		else if (has_location_a && !has_location_b)
			return true;
		else if (!has_location_a && has_location_b)
			return false;

		const auto &name1 = to_name(a->self);
		const auto &name2 = to_name(b->self);

		if (name1.empty() && name2.empty())
			return a->self < b->self;
		else if (name1.empty())
			return true;
		else if (name2.empty())
			return false;

		return name1.compare(name2) < 0;
	};

	if (!input_variables.empty() || active_input_builtins)
	{
		require_input = true;
		statement("struct SPIRV_Cross_Input");

		begin_scope();
		sort(input_variables.begin(), input_variables.end(), variable_compare);
		for (auto var : input_variables)
			emit_interface_block_in_struct(*var, active_inputs);
		emit_builtin_inputs_in_struct();
		end_scope_decl();
		statement("");
	}

	if (!output_variables.empty() || active_output_builtins)
	{
		require_output = true;
		statement("struct SPIRV_Cross_Output");

		begin_scope();
		// FIXME: Use locations properly if they exist.
		sort(output_variables.begin(), output_variables.end(), variable_compare);
		for (auto var : output_variables)
			emit_interface_block_in_struct(*var, active_outputs);
		emit_builtin_outputs_in_struct();
		end_scope_decl();
		statement("");
	}

	// Global variables.
	for (auto global : global_variables)
	{
		auto &var = get<SPIRVariable>(global);
		if (var.storage != StorageClassOutput)
		{
			add_resource_name(var.self);

			const char *storage = nullptr;
			switch (var.storage)
			{
			case StorageClassWorkgroup:
				storage = "groupshared";
				break;

			default:
				storage = "static";
				break;
			}
			statement(storage, " ", variable_decl(var), ";");
			emitted = true;
		}
	}

	if (emitted)
		statement("");

	declare_undefined_values();

	if (requires_op_fmod)
	{
		static const char *types[] = {
			"float",
			"float2",
			"float3",
			"float4",
		};

		for (auto &type : types)
		{
			statement(type, " mod(", type, " x, ", type, " y)");
			begin_scope();
			statement("return x - y * floor(x / y);");
			end_scope();
			statement("");
		}
	}

	if (requires_textureProj)
	{
		if (options.shader_model >= 40)
		{
			statement("float SPIRV_Cross_projectTextureCoordinate(float2 coord)");
			begin_scope();
			statement("return coord.x / coord.y;");
			end_scope();
			statement("");

			statement("float2 SPIRV_Cross_projectTextureCoordinate(float3 coord)");
			begin_scope();
			statement("return float2(coord.x, coord.y) / coord.z;");
			end_scope();
			statement("");

			statement("float3 SPIRV_Cross_projectTextureCoordinate(float4 coord)");
			begin_scope();
			statement("return float3(coord.x, coord.y, coord.z) / coord.w;");
			end_scope();
			statement("");
		}
		else
		{
			statement("float4 SPIRV_Cross_projectTextureCoordinate(float2 coord)");
			begin_scope();
			statement("return float4(coord.x, 0.0, 0.0, coord.y);");
			end_scope();
			statement("");

			statement("float4 SPIRV_Cross_projectTextureCoordinate(float3 coord)");
			begin_scope();
			statement("return float4(coord.x, coord.y, 0.0, coord.z);");
			end_scope();
			statement("");

			statement("float4 SPIRV_Cross_projectTextureCoordinate(float4 coord)");
			begin_scope();
			statement("return coord;");
			end_scope();
			statement("");
		}
	}

	if (required_textureSizeVariants != 0)
	{
		static const char *types[QueryTypeCount] = { "float4", "int4", "uint4" };
		static const char *dims[QueryDimCount] = { "Texture1D",   "Texture1DArray",  "Texture2D",   "Texture2DArray",
			                                       "Texture3D",   "Buffer",          "TextureCube", "TextureCubeArray",
			                                       "Texture2DMS", "Texture2DMSArray" };

		static const bool has_lod[QueryDimCount] = { true, true, true, true, true, false, true, true, false, false };

		static const char *ret_types[QueryDimCount] = {
			"uint", "uint2", "uint2", "uint3", "uint3", "uint", "uint2", "uint3", "uint2", "uint3",
		};

		static const uint32_t return_arguments[QueryDimCount] = {
			1, 2, 2, 3, 3, 1, 2, 3, 2, 3,
		};

		for (uint32_t index = 0; index < QueryDimCount; index++)
		{
			for (uint32_t type_index = 0; type_index < QueryTypeCount; type_index++)
			{
				uint32_t bit = 16 * type_index + index;
				uint64_t mask = 1ull << bit;

				if ((required_textureSizeVariants & mask) == 0)
					continue;

				statement(ret_types[index], " SPIRV_Cross_textureSize(", dims[index], "<", types[type_index],
				          "> Tex, uint Level, out uint Param)");
				begin_scope();
				statement(ret_types[index], " ret;");
				switch (return_arguments[index])
				{
				case 1:
					if (has_lod[index])
						statement("Tex.GetDimensions(Level, ret.x, Param);");
					else
						statement("Tex.GetDimensions(ret.x);");
					break;
				case 2:
					if (has_lod[index])
						statement("Tex.GetDimensions(Level, ret.x, ret.y, Param);");
					else
						statement("Tex.GetDimensions(ret.x, ret.y, Param);");
					break;
				case 3:
					if (has_lod[index])
						statement("Tex.GetDimensions(Level, ret.x, ret.y, ret.z, Param);");
					else
						statement("Tex.GetDimensions(ret.x, ret.y, ret.z, Param);");
					break;
				}

				statement("return ret;");
				end_scope();
				statement("");
			}
		}
	}
}

string CompilerHLSL::layout_for_member(const SPIRType &type, uint32_t index)
{
	auto flags = combined_decoration_for_member(type, index);

	bool is_block = (meta[type.self].decoration.decoration_flags &
	                 ((1ull << DecorationBlock) | (1ull << DecorationBufferBlock))) != 0;

	if (!is_block)
		return "";

	// Flip the convention. HLSL is a bit odd in that the memory layout is column major ... but the language API is "row-major".
	// The way to deal with this is to multiply everything in inverse order, and reverse the memory layout.
	if (flags & (1ull << DecorationColMajor))
		return "row_major ";
	else if (flags & (1ull << DecorationRowMajor))
		return "column_major ";

	return "";
}

void CompilerHLSL::emit_struct_member(const SPIRType &type, uint32_t member_type_id, uint32_t index,
                                      const string &qualifier)
{
	auto &membertype = get<SPIRType>(member_type_id);

	uint64_t memberflags = 0;
	auto &memb = meta[type.self].members;
	if (index < memb.size())
		memberflags = memb[index].decoration_flags;

	string qualifiers;
	bool is_block = (meta[type.self].decoration.decoration_flags &
	                 ((1ull << DecorationBlock) | (1ull << DecorationBufferBlock))) != 0;
	if (is_block)
		qualifiers = to_interpolation_qualifiers(memberflags);

	string packing_offset;
	if (has_decoration(type.self, DecorationCPacked) && has_member_decoration(type.self, index, DecorationOffset))
	{
		uint32_t offset = memb[index].offset;
		if (offset & 3)
			SPIRV_CROSS_THROW("Cannot pack on tighter bounds than 4 bytes in HLSL.");

		static const char *packing_swizzle[] = { "", ".y", ".z", ".w" };
		packing_offset = join(" : packoffset(c", offset / 16, packing_swizzle[(offset & 15) >> 2], ")");
	}

	statement(layout_for_member(type, index), qualifiers, qualifier,
	          variable_decl(membertype, to_member_name(type, index)), packing_offset, ";");
}

void CompilerHLSL::emit_buffer_block(const SPIRVariable &var)
{
	auto &type = get<SPIRType>(var.basetype);

	bool is_uav = var.storage == StorageClassStorageBuffer || has_decoration(type.self, DecorationBufferBlock);

	if (is_uav)
	{
		uint64_t flags = get_buffer_block_flags(var);
		bool is_readonly = (flags & (1ull << DecorationNonWritable)) != 0;
		add_resource_name(var.self);
		statement(is_readonly ? "ByteAddressBuffer " : "RWByteAddressBuffer ", to_name(var.self),
		          type_to_array_glsl(type), to_resource_binding(var), ";");
	}
	else
	{
		if (type.array.empty())
		{
			if (buffer_is_packing_standard(type, BufferPackingHLSLCbufferPackOffset))
				set_decoration(type.self, DecorationCPacked);
			else
				SPIRV_CROSS_THROW("cbuffer cannot be expressed with either HLSL packing layout or packoffset.");

			// Flatten the top-level struct so we can use packoffset,
			// this restriction is similar to GLSL where layout(offset) is not possible on sub-structs.
			flattened_structs.insert(var.self);

			type.member_name_cache.clear();
			add_resource_name(var.self);
			statement("cbuffer ", to_name(var.self), to_resource_binding(var));
			begin_scope();

			uint32_t i = 0;
			for (auto &member : type.member_types)
			{
				add_member_name(type, i);
				auto backup_name = get_member_name(type.self, i);
				auto member_name = to_member_name(type, i);
				set_member_name(type.self, i, sanitize_underscores(join(to_name(type.self), "_", member_name)));
				emit_struct_member(type, member, i, "");
				set_member_name(type.self, i, backup_name);
				i++;
			}

			end_scope_decl();
		}
		else
		{
			if (options.shader_model < 51)
				SPIRV_CROSS_THROW(
				    "Need ConstantBuffer<T> to use arrays of UBOs, but this is only supported in SM 5.1.");

			// ConstantBuffer<T> does not support packoffset, so it is unuseable unless everything aligns as we expect.
			if (!buffer_is_packing_standard(type, BufferPackingHLSLCbuffer))
				SPIRV_CROSS_THROW("HLSL ConstantBuffer<T> cannot be expressed with normal HLSL packing rules.");

			add_resource_name(type.self);
			add_resource_name(var.self);

			emit_struct(get<SPIRType>(type.self));
			statement("ConstantBuffer<", to_name(type.self), "> ", to_name(var.self), type_to_array_glsl(type),
			          to_resource_binding(var), ";");
		}
	}
}

void CompilerHLSL::emit_push_constant_block(const SPIRVariable &var)
{
	emit_buffer_block(var);
}

string CompilerHLSL::to_sampler_expression(uint32_t id)
{
	return join("_", to_expression(id), "_sampler");
}

void CompilerHLSL::emit_sampled_image_op(uint32_t result_type, uint32_t result_id, uint32_t image_id, uint32_t samp_id)
{
	set<SPIRCombinedImageSampler>(result_id, result_type, image_id, samp_id);
}

string CompilerHLSL::to_func_call_arg(uint32_t id)
{
	string arg_str = CompilerGLSL::to_func_call_arg(id);

	if (options.shader_model <= 30)
		return arg_str;

	// Manufacture automatic sampler arg if the arg is a SampledImage texture and we're in modern HLSL.
	auto *var = maybe_get<SPIRVariable>(id);
	if (var)
	{
		auto &type = get<SPIRType>(var->basetype);

		// We don't have to consider combined image samplers here via OpSampledImage because
		// those variables cannot be passed as arguments to functions.
		// Only global SampledImage variables may be used as arguments.
		if (type.basetype == SPIRType::SampledImage && type.image.dim != DimBuffer)
			arg_str += ", " + to_sampler_expression(id);
	}

	return arg_str;
}

void CompilerHLSL::emit_function_prototype(SPIRFunction &func, uint64_t return_flags)
{
	auto &execution = get_entry_point();
	// Avoid shadow declarations.
	local_variable_names = resource_names;

	string decl;

	auto &type = get<SPIRType>(func.return_type);
	decl += flags_to_precision_qualifiers_glsl(type, return_flags);
	decl += type_to_glsl(type);
	decl += " ";

	if (func.self == entry_point)
	{
		if (execution.model == ExecutionModelVertex)
			decl += "vert_main";
		else if (execution.model == ExecutionModelFragment)
			decl += "frag_main";
		else if (execution.model == ExecutionModelGLCompute)
			decl += "comp_main";
		else
			SPIRV_CROSS_THROW("Unsupported execution model.");
		processing_entry_point = true;
	}
	else
		decl += to_name(func.self);

	decl += "(";
	for (auto &arg : func.arguments)
	{
		// Might change the variable name if it already exists in this function.
		// SPIRV OpName doesn't have any semantic effect, so it's valid for an implementation
		// to use same name for variables.
		// Since we want to make the GLSL debuggable and somewhat sane, use fallback names for variables which are duplicates.
		add_local_variable_name(arg.id);

		decl += argument_decl(arg);

		// Flatten a combined sampler to two separate arguments in modern HLSL.
		auto &arg_type = get<SPIRType>(arg.type);
		if (options.shader_model > 30 && arg_type.basetype == SPIRType::SampledImage && arg_type.image.dim != DimBuffer)
		{
			// Manufacture automatic sampler arg for SampledImage texture
			decl += ", ";
			decl +=
			    join(arg_type.image.depth ? "SamplerComparisonState " : "SamplerState ", to_sampler_expression(arg.id));
		}

		if (&arg != &func.arguments.back())
			decl += ", ";

		// Hold a pointer to the parameter so we can invalidate the readonly field if needed.
		auto *var = maybe_get<SPIRVariable>(arg.id);
		if (var)
			var->parameter = &arg;
	}

	decl += ")";
	statement(decl);
}

void CompilerHLSL::emit_hlsl_entry_point()
{
	vector<string> arguments;

	if (require_input)
		arguments.push_back("SPIRV_Cross_Input stage_input");

	// Add I/O blocks as separate arguments with appropriate storage qualifier.
	for (auto &id : ids)
	{
		if (id.get_type() == TypeVariable)
		{
			auto &var = id.get<SPIRVariable>();
			auto &type = get<SPIRType>(var.basetype);
			bool block = (meta[type.self].decoration.decoration_flags & (1ull << DecorationBlock)) != 0;

			if (var.storage != StorageClassInput && var.storage != StorageClassOutput)
				continue;

			if (block && !is_builtin_variable(var) && interface_variable_exists_in_entry_point(var.self))
			{
				if (var.storage == StorageClassInput)
				{
					arguments.push_back(join("in ", variable_decl(type, join("stage_input", to_name(var.self)))));
				}
				else if (var.storage == StorageClassOutput)
				{
					arguments.push_back(join("out ", variable_decl(type, join("stage_output", to_name(var.self)))));
				}
			}
		}
	}

	auto &execution = get_entry_point();

	switch (execution.model)
	{
	case ExecutionModelGLCompute:
	{
		SpecializationConstant wg_x, wg_y, wg_z;
		get_work_group_size_specialization_constants(wg_x, wg_y, wg_z);

		uint32_t x = execution.workgroup_size.x;
		uint32_t y = execution.workgroup_size.y;
		uint32_t z = execution.workgroup_size.z;

		if (wg_x.id)
			x = get<SPIRConstant>(wg_x.id).scalar();
		if (wg_y.id)
			y = get<SPIRConstant>(wg_y.id).scalar();
		if (wg_z.id)
			z = get<SPIRConstant>(wg_z.id).scalar();

		statement("[numthreads(", x, ", ", y, ", ", z, ")]");
		break;
	}
	case ExecutionModelFragment:
		if (execution.flags & (1ull << ExecutionModeEarlyFragmentTests))
			statement("[earlydepthstencil]");
		break;
	default:
		break;
	}

	statement(require_output ? "SPIRV_Cross_Output " : "void ", "main(", merge(arguments), ")");
	begin_scope();
	bool legacy = options.shader_model <= 30;

	// Copy builtins from entry point arguments to globals.
	for (uint32_t i = 0; i < 64; i++)
	{
		if (!(active_input_builtins & (1ull << i)))
			continue;

		auto builtin = builtin_to_glsl(static_cast<BuiltIn>(i), StorageClassInput);
		switch (static_cast<BuiltIn>(i))
		{
		case BuiltInFragCoord:
			// VPOS in D3D9 is sampled at integer locations, apply half-pixel offset to be consistent.
			// TODO: Do we need an option here? Any reason why a D3D9 shader would be used
			// on a D3D10+ system with a different rasterization config?
			if (legacy)
				statement(builtin, " = stage_input.", builtin, " + float4(0.5f, 0.5f, 0.0f, 0.0f);");
			else
				statement(builtin, " = stage_input.", builtin, ";");
			break;

		case BuiltInVertexIndex:
		case BuiltInInstanceIndex:
			// D3D semantics are uint, but shader wants int.
			statement(builtin, " = int(stage_input.", builtin, ");");
			break;

		default:
			statement(builtin, " = stage_input.", builtin, ";");
			break;
		}
	}

	// Copy from stage input struct to globals.
	for (auto &id : ids)
	{
		if (id.get_type() == TypeVariable)
		{
			auto &var = id.get<SPIRVariable>();
			auto &type = get<SPIRType>(var.basetype);
			bool block = (meta[type.self].decoration.decoration_flags & (1ull << DecorationBlock)) != 0;

			if (var.storage != StorageClassInput)
				continue;

			bool need_matrix_unroll = var.storage == StorageClassInput && execution.model == ExecutionModelVertex;

			if (!block && !var.remapped_variable && type.pointer && !is_builtin_variable(var) &&
			    interface_variable_exists_in_entry_point(var.self))
			{
				auto name = to_name(var.self);
				auto &mtype = get<SPIRType>(var.basetype);
				if (need_matrix_unroll && mtype.columns > 1)
				{
					// Unroll matrices.
					for (uint32_t col = 0; col < mtype.columns; col++)
						statement(name, "[", col, "] = stage_input.", name, "_", col, ";");
				}
				else
				{
					statement(name, " = stage_input.", name, ";");
				}
			}

			// I/O blocks don't use the common stage input/output struct, but separate outputs.
			if (block && !is_builtin_variable(var) && interface_variable_exists_in_entry_point(var.self))
			{
				auto name = to_name(var.self);
				statement(name, " = stage_input", name, ";");
			}
		}
	}

	// Run the shader.
	if (execution.model == ExecutionModelVertex)
		statement("vert_main();");
	else if (execution.model == ExecutionModelFragment)
		statement("frag_main();");
	else if (execution.model == ExecutionModelGLCompute)
		statement("comp_main();");
	else
		SPIRV_CROSS_THROW("Unsupported shader stage.");

	// Copy block outputs.
	for (auto &id : ids)
	{
		if (id.get_type() == TypeVariable)
		{
			auto &var = id.get<SPIRVariable>();
			auto &type = get<SPIRType>(var.basetype);
			bool block = (meta[type.self].decoration.decoration_flags & (1ull << DecorationBlock)) != 0;

			if (var.storage != StorageClassOutput)
				continue;

			// I/O blocks don't use the common stage input/output struct, but separate outputs.
			if (block && !is_builtin_variable(var) && interface_variable_exists_in_entry_point(var.self))
			{
				auto name = to_name(var.self);
				statement("stage_output", name, " = ", name, ";");
			}
		}
	}

	// Copy stage outputs.
	if (require_output)
	{
		statement("SPIRV_Cross_Output stage_output;");

		// Copy builtins from globals to return struct.
		for (uint32_t i = 0; i < 64; i++)
		{
			if (!(active_output_builtins & (1ull << i)))
				continue;

			// PointSize doesn't exist in HLSL.
			if (i == BuiltInPointSize)
				continue;

			auto builtin = builtin_to_glsl(static_cast<BuiltIn>(i), StorageClassOutput);
			statement("stage_output.", builtin, " = ", builtin, ";");
		}

		for (auto &id : ids)
		{
			if (id.get_type() == TypeVariable)
			{
				auto &var = id.get<SPIRVariable>();
				auto &type = get<SPIRType>(var.basetype);
				bool block = (meta[type.self].decoration.decoration_flags & (1ull << DecorationBlock)) != 0;

				if (var.storage != StorageClassOutput)
					continue;

				if (!block && var.storage != StorageClassFunction && !var.remapped_variable && type.pointer &&
				    !is_builtin_variable(var) && interface_variable_exists_in_entry_point(var.self))
				{
					auto name = to_name(var.self);
					statement("stage_output.", name, " = ", name, ";");
				}
			}
		}

		statement("return stage_output;");
	}

	end_scope();
}

void CompilerHLSL::emit_fixup()
{
	if (get_entry_point().model == ExecutionModelVertex)
	{
		// Do various mangling on the gl_Position.
		if (options.shader_model <= 30)
		{
			statement("gl_Position.x = gl_Position.x - gl_HalfPixel.x * "
			          "gl_Position.w;");
			statement("gl_Position.y = gl_Position.y + gl_HalfPixel.y * "
			          "gl_Position.w;");
		}

		if (CompilerGLSL::options.vertex.flip_vert_y)
			statement("gl_Position.y = -gl_Position.y;");
		if (CompilerGLSL::options.vertex.fixup_clipspace)
			statement("gl_Position.z = (gl_Position.z + gl_Position.w) * 0.5;");
	}
}

void CompilerHLSL::emit_texture_op(const Instruction &i)
{
	auto ops = stream(i);
	auto op = static_cast<Op>(i.op);
	uint32_t length = i.length;

	if (i.offset + length > spirv.size())
		SPIRV_CROSS_THROW("Compiler::parse() opcode out of range.");

	uint32_t result_type = ops[0];
	uint32_t id = ops[1];
	uint32_t img = ops[2];
	uint32_t coord = ops[3];
	uint32_t dref = 0;
	uint32_t comp = 0;
	bool gather = false;
	bool proj = false;
	const uint32_t *opt = nullptr;
	auto *combined_image = maybe_get<SPIRCombinedImageSampler>(img);
	auto img_expr = to_expression(combined_image ? combined_image->image : img);

	switch (op)
	{
	case OpImageSampleDrefImplicitLod:
	case OpImageSampleDrefExplicitLod:
		dref = ops[4];
		opt = &ops[5];
		length -= 5;
		break;

	case OpImageSampleProjDrefImplicitLod:
	case OpImageSampleProjDrefExplicitLod:
		dref = ops[4];
		proj = true;
		opt = &ops[5];
		length -= 5;
		break;

	case OpImageDrefGather:
		dref = ops[4];
		opt = &ops[5];
		gather = true;
		length -= 5;
		break;

	case OpImageGather:
		comp = ops[4];
		opt = &ops[5];
		gather = true;
		length -= 5;
		break;

	case OpImageSampleProjImplicitLod:
	case OpImageSampleProjExplicitLod:
		opt = &ops[4];
		length -= 4;
		proj = true;
		break;

	default:
		opt = &ops[4];
		length -= 4;
		break;
	}

	auto &imgtype = expression_type(img);
	uint32_t coord_components = 0;
	switch (imgtype.image.dim)
	{
	case spv::Dim1D:
		coord_components = 1;
		break;
	case spv::Dim2D:
		coord_components = 2;
		break;
	case spv::Dim3D:
		coord_components = 3;
		break;
	case spv::DimCube:
		coord_components = 3;
		break;
	case spv::DimBuffer:
		coord_components = 1;
		break;
	default:
		coord_components = 2;
		break;
	}

	if (proj)
		coord_components++;
	if (imgtype.image.arrayed)
		coord_components++;

	uint32_t bias = 0;
	uint32_t lod = 0;
	uint32_t grad_x = 0;
	uint32_t grad_y = 0;
	uint32_t coffset = 0;
	uint32_t offset = 0;
	uint32_t coffsets = 0;
	uint32_t sample = 0;
	uint32_t flags = 0;

	if (length)
	{
		flags = opt[0];
		opt++;
		length--;
	}

	auto test = [&](uint32_t &v, uint32_t flag) {
		if (length && (flags & flag))
		{
			v = *opt++;
			length--;
		}
	};

	test(bias, ImageOperandsBiasMask);
	test(lod, ImageOperandsLodMask);
	test(grad_x, ImageOperandsGradMask);
	test(grad_y, ImageOperandsGradMask);
	test(coffset, ImageOperandsConstOffsetMask);
	test(offset, ImageOperandsOffsetMask);
	test(coffsets, ImageOperandsConstOffsetsMask);
	test(sample, ImageOperandsSampleMask);

	string expr;
	string texop;

	if (op == OpImageFetch)
	{
		if (options.shader_model < 40)
		{
			SPIRV_CROSS_THROW("texelFetch is not supported in HLSL shader model 2/3.");
		}
		texop += img_expr;
		texop += ".Load";
	}
	else
	{
		auto &imgformat = get<SPIRType>(imgtype.image.type);
		if (imgformat.basetype != SPIRType::Float)
		{
			SPIRV_CROSS_THROW("Sampling non-float textures is not supported in HLSL.");
		}

		if (options.shader_model >= 40)
		{
			texop += img_expr;

			if (imgtype.image.depth)
				texop += ".SampleCmp";
			else if (gather)
			{
				uint32_t comp_num = get<SPIRConstant>(comp).scalar();
				if (options.shader_model >= 50)
				{
					switch (comp_num)
					{
					case 0:
						texop += ".GatherRed";
						break;
					case 1:
						texop += ".GatherGreen";
						break;
					case 2:
						texop += ".GatherBlue";
						break;
					case 3:
						texop += ".GatherAlpha";
						break;
					default:
						SPIRV_CROSS_THROW("Invalid component.");
					}
				}
				else
				{
					if (comp_num == 0)
						texop += ".Gather";
					else
						SPIRV_CROSS_THROW("HLSL shader model 4 can only gather from the red component.");
				}
			}
			else if (bias)
				texop += ".SampleBias";
			else if (grad_x || grad_y)
				texop += ".SampleGrad";
			else if (lod)
				texop += ".SampleLevel";
			else
				texop += ".Sample";
		}
		else
		{
			switch (imgtype.image.dim)
			{
			case Dim1D:
				texop += "tex1D";
				break;
			case Dim2D:
				texop += "tex2D";
				break;
			case Dim3D:
				texop += "tex3D";
				break;
			case DimCube:
				texop += "texCUBE";
				break;
			case DimRect:
			case DimBuffer:
			case DimSubpassData:
				SPIRV_CROSS_THROW("Buffer texture support is not yet implemented for HLSL"); // TODO
			default:
				SPIRV_CROSS_THROW("Invalid dimension.");
			}

			if (gather)
				SPIRV_CROSS_THROW("textureGather is not supported in HLSL shader model 2/3.");
			if (offset || coffset)
				SPIRV_CROSS_THROW("textureOffset is not supported in HLSL shader model 2/3.");
			if (proj)
				texop += "proj";
			if (grad_x || grad_y)
				texop += "grad";
			if (lod)
				texop += "lod";
			if (bias)
				texop += "bias";
		}
	}

	expr += texop;
	expr += "(";
	if (options.shader_model < 40)
	{
		if (combined_image)
			SPIRV_CROSS_THROW("Separate images/samplers are not supported in HLSL shader model 2/3.");
		expr += to_expression(img);
	}
	else if (op != OpImageFetch)
	{
		string sampler_expr;
		if (combined_image)
			sampler_expr = to_expression(combined_image->sampler);
		else
			sampler_expr = to_sampler_expression(img);
		expr += sampler_expr;
	}

	auto swizzle = [](uint32_t comps, uint32_t in_comps) -> const char * {
		if (comps == in_comps)
			return "";

		switch (comps)
		{
		case 1:
			return ".x";
		case 2:
			return ".xy";
		case 3:
			return ".xyz";
		default:
			return "";
		}
	};

	bool forward = should_forward(coord);

	// The IR can give us more components than we need, so chop them off as needed.
	auto coord_expr = to_expression(coord) + swizzle(coord_components, expression_type(coord).vecsize);

	if (proj)
	{
		if (!requires_textureProj)
		{
			requires_textureProj = true;
			force_recompile = true;
		}
		coord_expr = "SPIRV_Cross_projectTextureCoordinate(" + coord_expr + ")";
	}

	if (options.shader_model < 40 && lod)
	{
		auto &coordtype = expression_type(coord);
		string coord_filler;
		for (uint32_t size = coordtype.vecsize; size < 3; ++size)
		{
			coord_filler += ", 0.0";
		}
		coord_expr = "float4(" + coord_expr + coord_filler + ", " + to_expression(lod) + ")";
	}

	if (options.shader_model < 40 && bias)
	{
		auto &coordtype = expression_type(coord);
		string coord_filler;
		for (uint32_t size = coordtype.vecsize; size < 3; ++size)
		{
			coord_filler += ", 0.0";
		}
		coord_expr = "float4(" + coord_expr + coord_filler + ", " + to_expression(bias) + ")";
	}

	if (op == OpImageFetch)
	{
		auto &coordtype = expression_type(coord);
		if (imgtype.image.dim != DimBuffer)
			coord_expr = join("int", coordtype.vecsize + 1, "(", coord_expr, ", ", to_expression(lod), ")");
	}

	if (op != OpImageFetch)
	{
		expr += ", ";
	}
	expr += coord_expr;

	if (dref)
	{
		forward = forward && should_forward(dref);
		expr += ", ";
		expr += to_expression(dref);
	}

	if (grad_x || grad_y)
	{
		forward = forward && should_forward(grad_x);
		forward = forward && should_forward(grad_y);
		expr += ", ";
		expr += to_expression(grad_x);
		expr += ", ";
		expr += to_expression(grad_y);
	}

	if (lod && options.shader_model >= 40 && op != OpImageFetch)
	{
		forward = forward && should_forward(lod);
		expr += ", ";
		expr += to_expression(lod);
	}

	if (bias && options.shader_model >= 40)
	{
		forward = forward && should_forward(bias);
		expr += ", ";
		expr += to_expression(bias);
	}

	if (coffset)
	{
		forward = forward && should_forward(coffset);
		expr += ", ";
		expr += to_expression(coffset);
	}
	else if (offset)
	{
		forward = forward && should_forward(offset);
		expr += ", ";
		expr += to_expression(offset);
	}

	if (sample)
	{
		expr += ", ";
		expr += to_expression(sample);
	}

	expr += ")";

	emit_op(result_type, id, expr, forward, false);
}

string CompilerHLSL::to_resource_binding(const SPIRVariable &var)
{
	// TODO: Basic implementation, might need special consideration for RW/RO structured buffers,
	// RW/RO images, and so on.

	if (!has_decoration(var.self, DecorationBinding))
		return "";

	auto &type = get<SPIRType>(var.basetype);
	const char *space = nullptr;

	switch (type.basetype)
	{
	case SPIRType::SampledImage:
		space = "t"; // SRV
		break;

	case SPIRType::Image:
		if (type.image.sampled == 2)
			space = "u"; // UAV
		else
			space = "t"; // SRV
		break;

	case SPIRType::Sampler:
		space = "s";
		break;

	case SPIRType::Struct:
	{
		auto storage = type.storage;
		if (storage == StorageClassUniform)
		{
			if (has_decoration(type.self, DecorationBufferBlock))
				space = "u"; // UAV
			else if (has_decoration(type.self, DecorationBlock))
				space = "b"; // Constant buffers
		}
		else if (storage == StorageClassPushConstant)
			space = "b"; // Constant buffers
		else if (storage == StorageClassStorageBuffer)
			space = "u"; // UAV

		break;
	}
	default:
		break;
	}

	if (!space)
		return "";

	// shader model 5.1 supports space
	if (options.shader_model >= 51)
		return join(" : register(", space, get_decoration(var.self, DecorationBinding), ", space",
		            get_decoration(var.self, DecorationDescriptorSet), ")");
	else
		return join(" : register(", space, get_decoration(var.self, DecorationBinding), ")");
}

string CompilerHLSL::to_resource_binding_sampler(const SPIRVariable &var)
{
	// For combined image samplers.
	if (!has_decoration(var.self, DecorationBinding))
		return "";

	if (options.shader_model >= 51)
		return join(" : register(s", get_decoration(var.self, DecorationBinding), ", space",
		            get_decoration(var.self, DecorationDescriptorSet), ")");
	else
		return join(" : register(s", get_decoration(var.self, DecorationBinding), ")");
}

void CompilerHLSL::emit_modern_uniform(const SPIRVariable &var)
{
	auto &type = get<SPIRType>(var.basetype);
	switch (type.basetype)
	{
	case SPIRType::SampledImage:
	case SPIRType::Image:
	{
		statement(image_type_hlsl_modern(type), " ", to_name(var.self), to_resource_binding(var), ";");

		if (type.basetype == SPIRType::SampledImage && type.image.dim != DimBuffer)
		{
			// For combined image samplers, also emit a combined image sampler.
			if (type.image.depth)
				statement("SamplerComparisonState ", to_sampler_expression(var.self), to_resource_binding_sampler(var),
				          ";");
			else
				statement("SamplerState ", to_sampler_expression(var.self), to_resource_binding_sampler(var), ";");
		}
		break;
	}

	case SPIRType::Sampler:
		if (comparison_samplers.count(var.self))
			statement("SamplerComparisonState ", to_name(var.self), to_resource_binding(var), ";");
		else
			statement("SamplerState ", to_name(var.self), to_resource_binding(var), ";");
		break;

	default:
		statement(variable_decl(var), to_resource_binding(var), ";");
		break;
	}
}

void CompilerHLSL::emit_legacy_uniform(const SPIRVariable &var)
{
	auto &type = get<SPIRType>(var.basetype);
	switch (type.basetype)
	{
	case SPIRType::Sampler:
	case SPIRType::Image:
		SPIRV_CROSS_THROW("Separate image and samplers not supported in legacy HLSL.");

	default:
		statement(variable_decl(var), ";");
		break;
	}
}

void CompilerHLSL::emit_uniform(const SPIRVariable &var)
{
	add_resource_name(var.self);
	if (options.shader_model >= 40)
		emit_modern_uniform(var);
	else
		emit_legacy_uniform(var);
}

string CompilerHLSL::bitcast_glsl_op(const SPIRType &out_type, const SPIRType &in_type)
{
	if (out_type.basetype == SPIRType::UInt && in_type.basetype == SPIRType::Int)
		return type_to_glsl(out_type);
	else if (out_type.basetype == SPIRType::UInt64 && in_type.basetype == SPIRType::Int64)
		return type_to_glsl(out_type);
	else if (out_type.basetype == SPIRType::UInt && in_type.basetype == SPIRType::Float)
		return "asuint";
	else if (out_type.basetype == SPIRType::Int && in_type.basetype == SPIRType::UInt)
		return type_to_glsl(out_type);
	else if (out_type.basetype == SPIRType::Int64 && in_type.basetype == SPIRType::UInt64)
		return type_to_glsl(out_type);
	else if (out_type.basetype == SPIRType::Int && in_type.basetype == SPIRType::Float)
		return "asint";
	else if (out_type.basetype == SPIRType::Float && in_type.basetype == SPIRType::UInt)
		return "asfloat";
	else if (out_type.basetype == SPIRType::Float && in_type.basetype == SPIRType::Int)
		return "asfloat";
	else if (out_type.basetype == SPIRType::Int64 && in_type.basetype == SPIRType::Double)
		SPIRV_CROSS_THROW("Double to Int64 is not supported in HLSL.");
	else if (out_type.basetype == SPIRType::UInt64 && in_type.basetype == SPIRType::Double)
		SPIRV_CROSS_THROW("Double to UInt64 is not supported in HLSL.");
	else if (out_type.basetype == SPIRType::Double && in_type.basetype == SPIRType::Int64)
		return "asdouble";
	else if (out_type.basetype == SPIRType::Double && in_type.basetype == SPIRType::UInt64)
		return "asdouble";
	else
		return "";
}

void CompilerHLSL::emit_glsl_op(uint32_t result_type, uint32_t id, uint32_t eop, const uint32_t *args, uint32_t count)
{
	GLSLstd450 op = static_cast<GLSLstd450>(eop);

	switch (op)
	{
	case GLSLstd450InverseSqrt:
		emit_unary_func_op(result_type, id, args[0], "rsqrt");
		break;

	case GLSLstd450Fract:
		emit_unary_func_op(result_type, id, args[0], "frac");
		break;

	case GLSLstd450FMix:
	case GLSLstd450IMix:
		emit_trinary_func_op(result_type, id, args[0], args[1], args[2], "lerp");
		break;

	case GLSLstd450Atan2:
		emit_binary_func_op(result_type, id, args[0], args[1], "atan2");
		break;

	case GLSLstd450Fma:
		emit_trinary_func_op(result_type, id, args[0], args[1], args[2], "mad");
		break;

	case GLSLstd450InterpolateAtCentroid:
		emit_unary_func_op(result_type, id, args[0], "EvaluateAttributeAtCentroid");
		break;
	case GLSLstd450InterpolateAtSample:
		emit_binary_func_op(result_type, id, args[0], args[1], "EvaluateAttributeAtSample");
		break;
	case GLSLstd450InterpolateAtOffset:
		emit_binary_func_op(result_type, id, args[0], args[1], "EvaluateAttributeSnapped");
		break;

	default:
		CompilerGLSL::emit_glsl_op(result_type, id, eop, args, count);
		break;
	}
}

string CompilerHLSL::read_access_chain(const SPIRAccessChain &chain)
{
	auto &type = get<SPIRType>(chain.basetype);

	SPIRType target_type;
	target_type.basetype = SPIRType::UInt;
	target_type.vecsize = type.vecsize;
	target_type.columns = type.columns;

	if (type.basetype == SPIRType::Struct)
		SPIRV_CROSS_THROW("Reading structs from ByteAddressBuffer not yet supported.");

	if (type.width != 32)
		SPIRV_CROSS_THROW("Reading types other than 32-bit from ByteAddressBuffer not yet supported.");

	if (!type.array.empty())
		SPIRV_CROSS_THROW("Reading arrays from ByteAddressBuffer not yet supported.");

	string load_expr;

	// Load a vector or scalar.
	if (type.columns == 1 && !chain.row_major_matrix)
	{
		const char *load_op = nullptr;
		switch (type.vecsize)
		{
		case 1:
			load_op = "Load";
			break;
		case 2:
			load_op = "Load2";
			break;
		case 3:
			load_op = "Load3";
			break;
		case 4:
			load_op = "Load4";
			break;
		default:
			SPIRV_CROSS_THROW("Unknown vector size.");
		}

		load_expr = join(chain.base, ".", load_op, "(", chain.dynamic_index, chain.static_index, ")");
	}
	else if (type.columns == 1)
	{
		// Strided load since we are loading a column from a row-major matrix.
		if (type.vecsize > 1)
		{
			load_expr = type_to_glsl(target_type);
			load_expr += "(";
		}

		for (uint32_t r = 0; r < type.vecsize; r++)
		{
			load_expr +=
			    join(chain.base, ".Load(", chain.dynamic_index, chain.static_index + r * chain.matrix_stride, ")");
			if (r + 1 < type.vecsize)
				load_expr += ", ";
		}

		if (type.vecsize > 1)
			load_expr += ")";
	}
	else if (!chain.row_major_matrix)
	{
		// Load a matrix, column-major, the easy case.
		const char *load_op = nullptr;
		switch (type.vecsize)
		{
		case 1:
			load_op = "Load";
			break;
		case 2:
			load_op = "Load2";
			break;
		case 3:
			load_op = "Load3";
			break;
		case 4:
			load_op = "Load4";
			break;
		default:
			SPIRV_CROSS_THROW("Unknown vector size.");
		}

		// Note, this loading style in HLSL is *actually* row-major, but we always treat matrices as transposed in this backend,
		// so row-major is technically column-major ...
		load_expr = type_to_glsl(target_type);
		load_expr += "(";
		for (uint32_t c = 0; c < type.columns; c++)
		{
			load_expr += join(chain.base, ".", load_op, "(", chain.dynamic_index,
			                  chain.static_index + c * chain.matrix_stride, ")");
			if (c + 1 < type.columns)
				load_expr += ", ";
		}
		load_expr += ")";
	}
	else
	{
		// Pick out elements one by one ... Hopefully compilers are smart enough to recognize this pattern
		// considering HLSL is "row-major decl", but "column-major" memory layout (basically implicit transpose model, ugh) ...

		load_expr = type_to_glsl(target_type);
		load_expr += "(";
		for (uint32_t c = 0; c < type.columns; c++)
		{
			for (uint32_t r = 0; r < type.vecsize; r++)
			{
				load_expr += join(chain.base, ".Load(", chain.dynamic_index,
				                  chain.static_index + c * (type.width / 8) + r * chain.matrix_stride, ")");

				if ((r + 1 < type.vecsize) || (c + 1 < type.columns))
					load_expr += ", ";
			}
		}
		load_expr += ")";
	}

	auto bitcast_op = bitcast_glsl_op(type, target_type);
	if (!bitcast_op.empty())
		load_expr = join(bitcast_op, "(", load_expr, ")");

	return load_expr;
}

void CompilerHLSL::emit_load(const Instruction &instruction)
{
	auto ops = stream(instruction);

	auto *chain = maybe_get<SPIRAccessChain>(ops[2]);
	if (chain)
	{
		uint32_t result_type = ops[0];
		uint32_t id = ops[1];
		uint32_t ptr = ops[2];

		auto load_expr = read_access_chain(*chain);

		bool forward = should_forward(ptr) && forced_temporaries.find(id) == end(forced_temporaries);

		// Do not forward complex load sequences like matrices, structs and arrays.
		auto &type = get<SPIRType>(result_type);
		if (type.columns > 1 || !type.array.empty() || type.basetype == SPIRType::Struct)
			forward = false;

		auto &e = emit_op(result_type, id, load_expr, forward, true);
		e.need_transpose = false;
		register_read(id, ptr, forward);
	}
	else
		CompilerGLSL::emit_instruction(instruction);
}

void CompilerHLSL::write_access_chain(const SPIRAccessChain &chain, uint32_t value)
{
	auto &type = get<SPIRType>(chain.basetype);

	SPIRType target_type;
	target_type.basetype = SPIRType::UInt;
	target_type.vecsize = type.vecsize;
	target_type.columns = type.columns;

	if (type.basetype == SPIRType::Struct)
		SPIRV_CROSS_THROW("Writing structs to RWByteAddressBuffer not yet supported.");
	if (type.width != 32)
		SPIRV_CROSS_THROW("Writing types other than 32-bit to RWByteAddressBuffer not yet supported.");
	if (!type.array.empty())
		SPIRV_CROSS_THROW("Reading arrays from ByteAddressBuffer not yet supported.");

	if (type.columns == 1 && !chain.row_major_matrix)
	{
		const char *store_op = nullptr;
		switch (type.vecsize)
		{
		case 1:
			store_op = "Store";
			break;
		case 2:
			store_op = "Store2";
			break;
		case 3:
			store_op = "Store3";
			break;
		case 4:
			store_op = "Store4";
			break;
		default:
			SPIRV_CROSS_THROW("Unknown vector size.");
		}

		auto store_expr = to_expression(value);
		auto bitcast_op = bitcast_glsl_op(target_type, type);
		if (!bitcast_op.empty())
			store_expr = join(bitcast_op, "(", store_expr, ")");
		statement(chain.base, ".", store_op, "(", chain.dynamic_index, chain.static_index, ", ", store_expr, ");");
	}
	else if (type.columns == 1)
	{
		// Strided store.
		for (uint32_t r = 0; r < type.vecsize; r++)
		{
			auto store_expr = to_enclosed_expression(value);
			if (type.vecsize > 1)
			{
				store_expr += ".";
				store_expr += index_to_swizzle(r);
			}

			auto bitcast_op = bitcast_glsl_op(target_type, type);
			if (!bitcast_op.empty())
				store_expr = join(bitcast_op, "(", store_expr, ")");
			statement(chain.base, ".Store(", chain.dynamic_index, chain.static_index + chain.matrix_stride * r, ", ",
			          store_expr, ");");
		}
	}
	else if (!chain.row_major_matrix)
	{
		const char *store_op = nullptr;
		switch (type.vecsize)
		{
		case 1:
			store_op = "Store";
			break;
		case 2:
			store_op = "Store2";
			break;
		case 3:
			store_op = "Store3";
			break;
		case 4:
			store_op = "Store4";
			break;
		default:
			SPIRV_CROSS_THROW("Unknown vector size.");
		}

		for (uint32_t c = 0; c < type.columns; c++)
		{
			auto store_expr = join(to_enclosed_expression(value), "[", c, "]");
			auto bitcast_op = bitcast_glsl_op(target_type, type);
			if (!bitcast_op.empty())
				store_expr = join(bitcast_op, "(", store_expr, ")");
			statement(chain.base, ".", store_op, "(", chain.dynamic_index, chain.static_index + c * chain.matrix_stride,
			          ", ", store_expr, ");");
		}
	}
	else
	{
		for (uint32_t r = 0; r < type.vecsize; r++)
		{
			for (uint32_t c = 0; c < type.columns; c++)
			{
				auto store_expr = join(to_enclosed_expression(value), "[", c, "].", index_to_swizzle(r));
				auto bitcast_op = bitcast_glsl_op(target_type, type);
				if (!bitcast_op.empty())
					store_expr = join(bitcast_op, "(", store_expr, ")");
				statement(chain.base, ".Store(", chain.dynamic_index,
				          chain.static_index + c * (type.width / 8) + r * chain.matrix_stride, ", ", store_expr, ");");
			}
		}
	}

	register_write(chain.self);
}

void CompilerHLSL::emit_store(const Instruction &instruction)
{
	auto ops = stream(instruction);
	auto *chain = maybe_get<SPIRAccessChain>(ops[0]);
	if (chain)
		write_access_chain(*chain, ops[1]);
	else
		CompilerGLSL::emit_instruction(instruction);
}

void CompilerHLSL::emit_access_chain(const Instruction &instruction)
{
	auto ops = stream(instruction);
	uint32_t length = instruction.length;

	bool need_byte_access_chain = false;
	auto &type = expression_type(ops[2]);
	const SPIRAccessChain *chain = nullptr;
	if (type.storage == StorageClassStorageBuffer || has_decoration(type.self, DecorationBufferBlock))
	{
		// If we are starting to poke into an SSBO, we are dealing with ByteAddressBuffers, and we need
		// to emit SPIRAccessChain rather than a plain SPIRExpression.
		uint32_t chain_arguments = length - 3;
		if (chain_arguments > type.array.size())
			need_byte_access_chain = true;
	}
	else
	{
		// Keep tacking on an existing access chain.
		chain = maybe_get<SPIRAccessChain>(ops[2]);
		if (chain)
			need_byte_access_chain = true;
	}

	if (need_byte_access_chain)
	{
		uint32_t to_plain_buffer_length = static_cast<uint32_t>(type.array.size());

		string base;
		if (to_plain_buffer_length != 0)
		{
			bool need_transpose;
			base = access_chain(ops[2], &ops[3], to_plain_buffer_length, get<SPIRType>(ops[0]), &need_transpose);
		}
		else
			base = to_expression(ops[2]);

		auto *basetype = &type;

		// Start traversing type hierarchy at the proper non-pointer types.
		while (basetype->pointer)
		{
			assert(basetype->parent_type);
			basetype = &get<SPIRType>(basetype->parent_type);
		}

		// Traverse the type hierarchy down to the actual buffer types.
		for (uint32_t i = 0; i < to_plain_buffer_length; i++)
		{
			assert(basetype->parent_type);
			basetype = &get<SPIRType>(basetype->parent_type);
		}

		uint32_t matrix_stride = 0;
		bool row_major_matrix = false;

		// Inherit matrix information.
		if (chain)
		{
			matrix_stride = chain->matrix_stride;
			row_major_matrix = chain->row_major_matrix;
		}

		auto offsets =
		    flattened_access_chain_offset(*basetype, &ops[3 + to_plain_buffer_length],
		                                  length - 3 - to_plain_buffer_length, 0, 1, &row_major_matrix, &matrix_stride);

		auto &e = set<SPIRAccessChain>(ops[1], ops[0], type.storage, base, offsets.first, offsets.second);
		e.row_major_matrix = row_major_matrix;
		e.matrix_stride = matrix_stride;
		e.immutable = should_forward(ops[2]);

		if (chain)
		{
			e.dynamic_index += chain->dynamic_index;
			e.static_index += chain->static_index;
		}
	}
	else
	{
		CompilerGLSL::emit_instruction(instruction);
	}
}

void CompilerHLSL::emit_atomic(const uint32_t *ops, uint32_t length, spv::Op op)
{
	const char *atomic_op = nullptr;
	auto value_expr = to_expression(ops[op == OpAtomicCompareExchange ? 6 : 5]);

	switch (op)
	{
	case OpAtomicISub:
		atomic_op = "InterlockedAdd";
		value_expr = join("-", enclose_expression(value_expr));
		break;

	case OpAtomicSMin:
	case OpAtomicUMin:
		atomic_op = "InterlockedMin";
		break;

	case OpAtomicSMax:
	case OpAtomicUMax:
		atomic_op = "InterlockedMax";
		break;

	case OpAtomicAnd:
		atomic_op = "InterlockedAnd";
		break;

	case OpAtomicOr:
		atomic_op = "InterlockedOr";
		break;

	case OpAtomicXor:
		atomic_op = "InterlockedXor";
		break;

	case OpAtomicIAdd:
		atomic_op = "InterlockedAdd";
		break;

	case OpAtomicExchange:
		atomic_op = "InterlockedExchange";
		break;

	case OpAtomicCompareExchange:
		if (length < 8)
			SPIRV_CROSS_THROW("Not enough data for opcode.");
		atomic_op = "InterlockedCompareExchange";
		value_expr = join(to_expression(ops[7]), ", ", value_expr);
		break;

	default:
		SPIRV_CROSS_THROW("Unknown atomic opcode.");
	}

	if (length < 6)
		SPIRV_CROSS_THROW("Not enough data for opcode.");

	uint32_t result_type = ops[0];
	uint32_t id = ops[1];
	forced_temporaries.insert(ops[1]);

	auto &type = get<SPIRType>(result_type);
	statement(variable_decl(type, to_name(id)), ";");

	auto &data_type = expression_type(ops[2]);
	auto *chain = maybe_get<SPIRAccessChain>(ops[2]);
	SPIRType::BaseType expr_type;
	if (data_type.storage == StorageClassImage || !chain)
	{
		statement(atomic_op, "(", to_expression(ops[2]), ", ", value_expr, ", ", to_name(id), ");");
		expr_type = data_type.basetype;
	}
	else
	{
		// RWByteAddress buffer is always uint in its underlying type.
		expr_type = SPIRType::UInt;
		statement(chain->base, ".", atomic_op, "(", chain->dynamic_index, chain->static_index, ", ", value_expr, ", ",
		          to_name(id), ");");
	}

	auto expr = bitcast_expression(type, expr_type, to_name(id));
	set<SPIRExpression>(id, expr, result_type, true);
	flush_all_atomic_capable_variables();
	register_read(ops[1], ops[2], should_forward(ops[2]));
}

const Instruction *CompilerHLSL::get_next_instruction_in_block(const Instruction &instr)
{
	// FIXME: This is kind of hacky. There should be a cleaner way.
	uint32_t offset = uint32_t(&instr - current_emitting_block->ops.data());
	if ((offset + 1) < current_emitting_block->ops.size())
		return &current_emitting_block->ops[offset + 1];
	else
		return nullptr;
}

void CompilerHLSL::emit_instruction(const Instruction &instruction)
{
	auto ops = stream(instruction);
	auto opcode = static_cast<Op>(instruction.op);

#define BOP(op) emit_binary_op(ops[0], ops[1], ops[2], ops[3], #op)
#define BOP_CAST(op, type) \
	emit_binary_op_cast(ops[0], ops[1], ops[2], ops[3], #op, type, opcode_is_sign_invariant(opcode))
#define UOP(op) emit_unary_op(ops[0], ops[1], ops[2], #op)
#define QFOP(op) emit_quaternary_func_op(ops[0], ops[1], ops[2], ops[3], ops[4], ops[5], #op)
#define TFOP(op) emit_trinary_func_op(ops[0], ops[1], ops[2], ops[3], ops[4], #op)
#define BFOP(op) emit_binary_func_op(ops[0], ops[1], ops[2], ops[3], #op)
#define BFOP_CAST(op, type) \
	emit_binary_func_op_cast(ops[0], ops[1], ops[2], ops[3], #op, type, opcode_is_sign_invariant(opcode))
#define BFOP(op) emit_binary_func_op(ops[0], ops[1], ops[2], ops[3], #op)
#define UFOP(op) emit_unary_func_op(ops[0], ops[1], ops[2], #op)

	switch (opcode)
	{
	case OpAccessChain:
	case OpInBoundsAccessChain:
	{
		emit_access_chain(instruction);
		break;
	}

	case OpStore:
	{
		emit_store(instruction);
		break;
	}

	case OpLoad:
	{
		emit_load(instruction);
		break;
	}

	case OpMatrixTimesVector:
	{
		emit_binary_func_op(ops[0], ops[1], ops[3], ops[2], "mul");
		break;
	}

	case OpVectorTimesMatrix:
	{
		emit_binary_func_op(ops[0], ops[1], ops[3], ops[2], "mul");
		break;
	}

	case OpMatrixTimesMatrix:
	{
		emit_binary_func_op(ops[0], ops[1], ops[3], ops[2], "mul");
		break;
	}

	case OpFMod:
	{
		if (!requires_op_fmod)
		{
			requires_op_fmod = true;
			force_recompile = true;
		}
		CompilerGLSL::emit_instruction(instruction);
		break;
	}

	case OpImage:
	{
		uint32_t result_type = ops[0];
		uint32_t id = ops[1];
		emit_op(result_type, id, to_expression(ops[2]), true, true);
		// TODO: Maybe change this when separate samplers/images are supported
		break;
	}

	case OpDPdx:
		UFOP(ddx);
		break;

	case OpDPdy:
		UFOP(ddy);
		break;

	case OpDPdxFine:
		UFOP(ddx_fine);
		break;

	case OpDPdyFine:
		UFOP(ddy_fine);
		break;

	case OpDPdxCoarse:
		UFOP(ddx_coarse);
		break;

	case OpDPdyCoarse:
		UFOP(ddy_coarse);
		break;

	case OpLogicalNot:
	{
		auto result_type = ops[0];
		auto id = ops[1];
		auto &type = get<SPIRType>(result_type);

		if (type.vecsize > 1)
			emit_unrolled_unary_op(result_type, id, ops[2], "!");
		else
			UOP(!);
		break;
	}

	case OpIEqual:
	{
		auto result_type = ops[0];
		auto id = ops[1];

		if (expression_type(ops[2]).vecsize > 1)
			emit_unrolled_binary_op(result_type, id, ops[2], ops[3], "==");
		else
			BOP_CAST(==, SPIRType::Int);
		break;
	}

	case OpLogicalEqual:
	case OpFOrdEqual:
	{
		auto result_type = ops[0];
		auto id = ops[1];

		if (expression_type(ops[2]).vecsize > 1)
			emit_unrolled_binary_op(result_type, id, ops[2], ops[3], "==");
		else
			BOP(==);
		break;
	}

	case OpINotEqual:
	{
		auto result_type = ops[0];
		auto id = ops[1];

		if (expression_type(ops[2]).vecsize > 1)
			emit_unrolled_binary_op(result_type, id, ops[2], ops[3], "!=");
		else
			BOP_CAST(!=, SPIRType::Int);
		break;
	}

	case OpLogicalNotEqual:
	case OpFOrdNotEqual:
	{
		auto result_type = ops[0];
		auto id = ops[1];

		if (expression_type(ops[2]).vecsize > 1)
			emit_unrolled_binary_op(result_type, id, ops[2], ops[3], "!=");
		else
			BOP(!=);
		break;
	}

	case OpUGreaterThan:
	case OpSGreaterThan:
	{
		auto result_type = ops[0];
		auto id = ops[1];
		auto type = opcode == OpUGreaterThan ? SPIRType::UInt : SPIRType::Int;

		if (expression_type(ops[2]).vecsize > 1)
			emit_unrolled_binary_op(result_type, id, ops[2], ops[3], ">");
		else
			BOP_CAST(>, type);
		break;
	}

	case OpFOrdGreaterThan:
	{
		auto result_type = ops[0];
		auto id = ops[1];

		if (expression_type(ops[2]).vecsize > 1)
			emit_unrolled_binary_op(result_type, id, ops[2], ops[3], ">");
		else
			BOP(>);
		break;
	}

	case OpUGreaterThanEqual:
	case OpSGreaterThanEqual:
	{
		auto result_type = ops[0];
		auto id = ops[1];

		auto type = opcode == OpUGreaterThanEqual ? SPIRType::UInt : SPIRType::Int;
		if (expression_type(ops[2]).vecsize > 1)
			emit_unrolled_binary_op(result_type, id, ops[2], ops[3], ">=");
		else
			BOP_CAST(>=, type);
		break;
	}

	case OpFOrdGreaterThanEqual:
	{
		auto result_type = ops[0];
		auto id = ops[1];

		if (expression_type(ops[2]).vecsize > 1)
			emit_unrolled_binary_op(result_type, id, ops[2], ops[3], ">=");
		else
			BOP(>=);
		break;
	}

	case OpULessThan:
	case OpSLessThan:
	{
		auto result_type = ops[0];
		auto id = ops[1];

		auto type = opcode == OpULessThan ? SPIRType::UInt : SPIRType::Int;
		if (expression_type(ops[2]).vecsize > 1)
			emit_unrolled_binary_op(result_type, id, ops[2], ops[3], "<");
		else
			BOP_CAST(<, type);
		break;
	}

	case OpFOrdLessThan:
	{
		auto result_type = ops[0];
		auto id = ops[1];

		if (expression_type(ops[2]).vecsize > 1)
			emit_unrolled_binary_op(result_type, id, ops[2], ops[3], "<");
		else
			BOP(<);
		break;
	}

	case OpULessThanEqual:
	case OpSLessThanEqual:
	{
		auto result_type = ops[0];
		auto id = ops[1];

		auto type = opcode == OpULessThanEqual ? SPIRType::UInt : SPIRType::Int;
		if (expression_type(ops[2]).vecsize > 1)
			emit_unrolled_binary_op(result_type, id, ops[2], ops[3], "<=");
		else
			BOP_CAST(<=, type);
		break;
	}

	case OpFOrdLessThanEqual:
	{
		auto result_type = ops[0];
		auto id = ops[1];

		if (expression_type(ops[2]).vecsize > 1)
			emit_unrolled_binary_op(result_type, id, ops[2], ops[3], "<=");
		else
			BOP(<=);
		break;
	}

	case OpImageQuerySizeLod:
	{
		auto result_type = ops[0];
		auto id = ops[1];

		require_texture_query_variant(expression_type(ops[2]));

		auto dummy_samples_levels = join(get_fallback_name(id), "_dummy_parameter");
		statement("uint ", dummy_samples_levels, ";");

		auto expr = join("SPIRV_Cross_textureSize(", to_expression(ops[2]), ", ",
		                 bitcast_expression(SPIRType::UInt, ops[3]), ", ", dummy_samples_levels, ")");

		auto &restype = get<SPIRType>(ops[0]);
		expr = bitcast_expression(restype, SPIRType::UInt, expr);
		emit_op(result_type, id, expr, true);
		break;
	}

	case OpImageQuerySize:
	{
		auto result_type = ops[0];
		auto id = ops[1];

		require_texture_query_variant(expression_type(ops[2]));

		auto dummy_samples_levels = join(get_fallback_name(id), "_dummy_parameter");
		statement("uint ", dummy_samples_levels, ";");

		auto expr = join("SPIRV_Cross_textureSize(", to_expression(ops[2]), ", 0u, ", dummy_samples_levels, ")");
		auto &restype = get<SPIRType>(ops[0]);
		expr = bitcast_expression(restype, SPIRType::UInt, expr);
		emit_op(result_type, id, expr, true);
		break;
	}

	case OpImageQuerySamples:
	case OpImageQueryLevels:
	{
		auto result_type = ops[0];
		auto id = ops[1];

		require_texture_query_variant(expression_type(ops[2]));

		// Keep it simple and do not emit special variants to make this look nicer ...
		// This stuff is barely, if ever, used.
		forced_temporaries.insert(id);
		auto &type = get<SPIRType>(result_type);
		statement(variable_decl(type, to_name(id)), ";");
		statement("SPIRV_Cross_textureSize(", to_expression(ops[2]), ", 0u, ", to_name(id), ");");

		auto &restype = get<SPIRType>(ops[0]);
		auto expr = bitcast_expression(restype, SPIRType::UInt, to_name(id));
		set<SPIRExpression>(id, expr, result_type, true);
		break;
	}

	case OpImageRead:
	{
		uint32_t result_type = ops[0];
		uint32_t id = ops[1];
		auto *var = maybe_get_backing_variable(ops[2]);
		auto imgexpr = join(to_expression(ops[2]), "[", to_expression(ops[3]), "]");

		// The underlying image type in HLSL depends on the image format, unlike GLSL, where all images are "vec4",
		// except that the underlying type changes how the data is interpreted.
		if (var)
			imgexpr = remap_swizzle(get<SPIRType>(result_type),
			                        image_format_to_components(get<SPIRType>(var->basetype).image.format), imgexpr);

		if (var && var->forwardable)
		{
			auto &e = emit_op(result_type, id, imgexpr, true);
			e.loaded_from = var->self;
			var->dependees.push_back(id);
		}
		else
			emit_op(result_type, id, imgexpr, false);
		break;
	}

	case OpImageWrite:
	{
		auto *var = maybe_get_backing_variable(ops[0]);

		// The underlying image type in HLSL depends on the image format, unlike GLSL, where all images are "vec4",
		// except that the underlying type changes how the data is interpreted.
		auto value_expr = to_expression(ops[2]);
		if (var)
		{
			auto &type = get<SPIRType>(var->basetype);
			auto narrowed_type = get<SPIRType>(type.image.type);
			narrowed_type.vecsize = image_format_to_components(type.image.format);
			value_expr = remap_swizzle(narrowed_type, expression_type(ops[2]).vecsize, value_expr);
		}

		statement(to_expression(ops[0]), "[", to_expression(ops[1]), "] = ", value_expr, ";");
		if (var && variable_storage_is_aliased(*var))
			flush_all_aliased_variables();
		break;
	}

	case OpImageTexelPointer:
	{
		uint32_t result_type = ops[0];
		uint32_t id = ops[1];
		auto &e =
		    set<SPIRExpression>(id, join(to_expression(ops[2]), "[", to_expression(ops[3]), "]"), result_type, true);

		// When using the pointer, we need to know which variable it is actually loaded from.
		auto *var = maybe_get_backing_variable(ops[2]);
		e.loaded_from = var ? var->self : 0;
		break;
	}

	case OpAtomicCompareExchange:
	case OpAtomicExchange:
	case OpAtomicISub:
	case OpAtomicSMin:
	case OpAtomicUMin:
	case OpAtomicSMax:
	case OpAtomicUMax:
	case OpAtomicAnd:
	case OpAtomicOr:
	case OpAtomicXor:
	case OpAtomicIAdd:
	{
		emit_atomic(ops, instruction.length, opcode);
		break;
	}

	case OpMemoryBarrier:
	{
		uint32_t mem = get<SPIRConstant>(ops[1]).scalar();

		// If the next instruction is OpControlBarrier and it does what we need, this opcode can be a noop.
		const Instruction *next = get_next_instruction_in_block(instruction);
		if (next && next->op == OpControlBarrier)
		{
			auto *next_ops = stream(*next);
			uint32_t next_mem = get<SPIRConstant>(next_ops[2]).scalar();
			next_mem |= MemorySemanticsWorkgroupMemoryMask; // Barrier in HLSL always implies GroupSync.
			if ((next_mem & mem) == mem)
				break;
		}

		// We cannot forward any loads beyond the memory barrier.
		if (mem)
			flush_all_active_variables();

		if (mem == MemorySemanticsWorkgroupMemoryMask)
			statement("GroupMemoryBarrier();");
		else if (mem)
			statement("DeviceMemoryBarrier();");
		break;
	}

	case OpControlBarrier:
	{
		uint32_t mem = get<SPIRConstant>(ops[2]).scalar();

		// We cannot forward any loads beyond the memory barrier.
		if (mem)
			flush_all_active_variables();

		if (mem == MemorySemanticsWorkgroupMemoryMask)
			statement("GroupMemoryBarrierWithGroupSync();");
		else if (mem)
			statement("DeviceMemoryBarrierWithGroupSync();");
		else
		{
			// There is no "GroupSync" standalone function.
			statement("GroupMemoryBarrierWithGroupSync();");
		}
		break;
	}

	default:
		CompilerGLSL::emit_instruction(instruction);
		break;
	}
}

void CompilerHLSL::require_texture_query_variant(const SPIRType &type)
{
	uint32_t bit = 0;
	switch (type.image.dim)
	{
	case Dim1D:
		bit = type.image.arrayed ? Query1DArray : Query1D;
		break;

	case Dim2D:
		if (type.image.ms)
			bit = type.image.arrayed ? Query2DMSArray : Query2DMS;
		else
			bit = type.image.arrayed ? Query2DArray : Query2D;
		break;

	case Dim3D:
		bit = Query3D;
		break;

	case DimCube:
		bit = type.image.arrayed ? QueryCubeArray : QueryCube;
		break;

	case DimBuffer:
		bit = QueryBuffer;
		break;

	default:
		SPIRV_CROSS_THROW("Unsupported query type.");
	}

	switch (get<SPIRType>(type.image.type).basetype)
	{
	case SPIRType::Float:
		bit += QueryTypeFloat;
		break;

	case SPIRType::Int:
		bit += QueryTypeInt;
		break;

	case SPIRType::UInt:
		bit += QueryTypeUInt;
		break;

	default:
		SPIRV_CROSS_THROW("Unsupported query type.");
	}

	uint64_t mask = 1ull << bit;
	if ((required_textureSizeVariants & mask) == 0)
	{
		force_recompile = true;
		required_textureSizeVariants |= mask;
	}
}

string CompilerHLSL::compile(std::vector<HLSLVertexAttributeRemap> vertex_attributes)
{
	remap_vertex_attributes = move(vertex_attributes);
	return compile();
}

string CompilerHLSL::compile()
{
	// Do not deal with ES-isms like precision, older extensions and such.
	CompilerGLSL::options.es = false;
	CompilerGLSL::options.version = 450;
	CompilerGLSL::options.vulkan_semantics = true;
	backend.float_literal_suffix = true;
	backend.double_literal_suffix = false;
	backend.long_long_literal_suffix = true;
	backend.uint32_t_literal_suffix = true;
	backend.basic_int_type = "int";
	backend.basic_uint_type = "uint";
	backend.swizzle_is_function = false;
	backend.shared_is_implied = true;
	backend.flexible_member_array_supported = false;
	backend.explicit_struct_type = false;
	backend.use_initializer_list = true;
	backend.use_constructor_splatting = false;
	backend.boolean_mix_support = false;

	update_active_builtins();
	analyze_sampler_comparison_states();

	uint32_t pass_count = 0;
	do
	{
		if (pass_count >= 3)
			SPIRV_CROSS_THROW("Over 3 compilation loops detected. Must be a bug!");

		reset();

		// Move constructor for this type is broken on GCC 4.9 ...
		buffer = unique_ptr<ostringstream>(new ostringstream());

		emit_header();
		emit_resources();

		emit_function(get<SPIRFunction>(entry_point), 0);
		emit_hlsl_entry_point();

		pass_count++;
	} while (force_recompile);

	// Entry point in HLSL is always main() for the time being.
	get_entry_point().name = "main";

	return buffer->str();
}