spirv_cross.cpp

/*
 * Copyright 2015-2021 Arm Limited
 * SPDX-License-Identifier: Apache-2.0 OR MIT
 *
 * 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.
 */

/*
 * At your option, you may choose to accept this material under either:
 *  1. The Apache License, Version 2.0, found at <http://www.apache.org/licenses/LICENSE-2.0>, or
 *  2. The MIT License, found at <http://opensource.org/licenses/MIT>.
 */

#include "spirv_cross.hpp"
#include "GLSL.std.450.h"
#include "spirv_cfg.hpp"
#include "spirv_common.hpp"
#include "spirv_parser.hpp"
#include <algorithm>
#include <cstring>
#include <utility>

using namespace std;
using namespace spv;
using namespace SPIRV_CROSS_NAMESPACE;

Compiler::Compiler(vector<uint32_t> ir_)
{
	Parser parser(std::move(ir_));
	parser.parse();
	set_ir(std::move(parser.get_parsed_ir()));
}

Compiler::Compiler(const uint32_t *ir_, size_t word_count)
{
	Parser parser(ir_, word_count);
	parser.parse();
	set_ir(std::move(parser.get_parsed_ir()));
}

Compiler::Compiler(const ParsedIR &ir_)
{
	set_ir(ir_);
}

Compiler::Compiler(ParsedIR &&ir_)
{
	set_ir(std::move(ir_));
}

void Compiler::set_ir(ParsedIR &&ir_)
{
	ir = std::move(ir_);
	parse_fixup();
}

void Compiler::set_ir(const ParsedIR &ir_)
{
	ir = ir_;
	parse_fixup();
}

string Compiler::compile()
{
	return "";
}

bool Compiler::variable_storage_is_aliased(const SPIRVariable &v)
{
	auto &type = get<SPIRType>(v.basetype);
	bool ssbo = v.storage == StorageClassStorageBuffer ||
	            ir.meta[type.self].decoration.decoration_flags.get(DecorationBufferBlock);
	bool image = type.basetype == SPIRType::Image;
	bool counter = type.basetype == SPIRType::AtomicCounter;
	bool buffer_reference = type.storage == StorageClassPhysicalStorageBufferEXT;

	bool is_restrict;
	if (ssbo)
		is_restrict = ir.get_buffer_block_flags(v).get(DecorationRestrict);
	else
		is_restrict = has_decoration(v.self, DecorationRestrict);

	return !is_restrict && (ssbo || image || counter || buffer_reference);
}

bool Compiler::block_is_pure(const SPIRBlock &block)
{
	// This is a global side effect of the function.
	if (block.terminator == SPIRBlock::Kill ||
	    block.terminator == SPIRBlock::TerminateRay ||
	    block.terminator == SPIRBlock::IgnoreIntersection ||
	    block.terminator == SPIRBlock::EmitMeshTasks)
		return false;

	for (auto &i : block.ops)
	{
		auto ops = stream(i);
		auto op = static_cast<Op>(i.op);

		switch (op)
		{
		case OpFunctionCall:
		{
			uint32_t func = ops[2];
			if (!function_is_pure(get<SPIRFunction>(func)))
				return false;
			break;
		}

		case OpCopyMemory:
		case OpStore:
		{
			auto &type = expression_type(ops[0]);
			if (type.storage != StorageClassFunction)
				return false;
			break;
		}

		case OpImageWrite:
			return false;

		// Atomics are impure.
		case OpAtomicLoad:
		case OpAtomicStore:
		case OpAtomicExchange:
		case OpAtomicCompareExchange:
		case OpAtomicCompareExchangeWeak:
		case OpAtomicIIncrement:
		case OpAtomicIDecrement:
		case OpAtomicIAdd:
		case OpAtomicISub:
		case OpAtomicSMin:
		case OpAtomicUMin:
		case OpAtomicSMax:
		case OpAtomicUMax:
		case OpAtomicAnd:
		case OpAtomicOr:
		case OpAtomicXor:
			return false;

		// Geometry shader builtins modify global state.
		case OpEndPrimitive:
		case OpEmitStreamVertex:
		case OpEndStreamPrimitive:
		case OpEmitVertex:
			return false;

		// Mesh shader functions modify global state.
		// (EmitMeshTasks is a terminator).
		case OpSetMeshOutputsEXT:
			return false;

		// Barriers disallow any reordering, so we should treat blocks with barrier as writing.
		case OpControlBarrier:
		case OpMemoryBarrier:
			return false;

		// Ray tracing builtins are impure.
		case OpReportIntersectionKHR:
		case OpIgnoreIntersectionNV:
		case OpTerminateRayNV:
		case OpTraceNV:
		case OpTraceRayKHR:
		case OpExecuteCallableNV:
		case OpExecuteCallableKHR:
		case OpRayQueryInitializeKHR:
		case OpRayQueryTerminateKHR:
		case OpRayQueryGenerateIntersectionKHR:
		case OpRayQueryConfirmIntersectionKHR:
		case OpRayQueryProceedKHR:
			// There are various getters in ray query, but they are considered pure.
			return false;

			// OpExtInst is potentially impure depending on extension, but GLSL builtins are at least pure.

		case OpDemoteToHelperInvocationEXT:
			// This is a global side effect of the function.
			return false;

		case OpExtInst:
		{
			uint32_t extension_set = ops[2];
			if (get<SPIRExtension>(extension_set).ext == SPIRExtension::GLSL)
			{
				auto op_450 = static_cast<GLSLstd450>(ops[3]);
				switch (op_450)
				{
				case GLSLstd450Modf:
				case GLSLstd450Frexp:
				{
					auto &type = expression_type(ops[5]);
					if (type.storage != StorageClassFunction)
						return false;
					break;
				}

				default:
					break;
				}
			}
			break;
		}

		default:
			break;
		}
	}

	return true;
}

string Compiler::to_name(uint32_t id, bool allow_alias) const
{
	if (allow_alias && ir.ids[id].get_type() == TypeType)
	{
		// If this type is a simple alias, emit the
		// name of the original type instead.
		// We don't want to override the meta alias
		// as that can be overridden by the reflection APIs after parse.
		auto &type = get<SPIRType>(id);
		if (type.type_alias)
		{
			// If the alias master has been specially packed, we will have emitted a clean variant as well,
			// so skip the name aliasing here.
			if (!has_extended_decoration(type.type_alias, SPIRVCrossDecorationBufferBlockRepacked))
				return to_name(type.type_alias);
		}
	}

	auto &alias = ir.get_name(id);
	if (alias.empty())
		return join("_", id);
	else
		return alias;
}

bool Compiler::function_is_pure(const SPIRFunction &func)
{
	for (auto block : func.blocks)
	{
		if (!block_is_pure(get<SPIRBlock>(block)))
		{
			//fprintf(stderr, "Function %s is impure!\n", to_name(func.self).c_str());
			return false;
		}
	}

	//fprintf(stderr, "Function %s is pure!\n", to_name(func.self).c_str());
	return true;
}

void Compiler::register_global_read_dependencies(const SPIRBlock &block, uint32_t id)
{
	for (auto &i : block.ops)
	{
		auto ops = stream(i);
		auto op = static_cast<Op>(i.op);

		switch (op)
		{
		case OpFunctionCall:
		{
			uint32_t func = ops[2];
			register_global_read_dependencies(get<SPIRFunction>(func), id);
			break;
		}

		case OpLoad:
		case OpImageRead:
		{
			// If we're in a storage class which does not get invalidated, adding dependencies here is no big deal.
			auto *var = maybe_get_backing_variable(ops[2]);
			if (var && var->storage != StorageClassFunction)
			{
				auto &type = get<SPIRType>(var->basetype);

				// InputTargets are immutable.
				if (type.basetype != SPIRType::Image && type.image.dim != DimSubpassData)
					var->dependees.push_back(id);
			}
			break;
		}

		default:
			break;
		}
	}
}

void Compiler::register_global_read_dependencies(const SPIRFunction &func, uint32_t id)
{
	for (auto block : func.blocks)
		register_global_read_dependencies(get<SPIRBlock>(block), id);
}

SPIRVariable *Compiler::maybe_get_backing_variable(uint32_t chain)
{
	auto *var = maybe_get<SPIRVariable>(chain);
	if (!var)
	{
		auto *cexpr = maybe_get<SPIRExpression>(chain);
		if (cexpr)
			var = maybe_get<SPIRVariable>(cexpr->loaded_from);

		auto *access_chain = maybe_get<SPIRAccessChain>(chain);
		if (access_chain)
			var = maybe_get<SPIRVariable>(access_chain->loaded_from);
	}

	return var;
}

void Compiler::register_read(uint32_t expr, uint32_t chain, bool forwarded)
{
	auto &e = get<SPIRExpression>(expr);
	auto *var = maybe_get_backing_variable(chain);

	if (var)
	{
		e.loaded_from = var->self;

		// If the backing variable is immutable, we do not need to depend on the variable.
		if (forwarded && !is_immutable(var->self))
			var->dependees.push_back(e.self);

		// If we load from a parameter, make sure we create "inout" if we also write to the parameter.
		// The default is "in" however, so we never invalidate our compilation by reading.
		if (var && var->parameter)
			var->parameter->read_count++;
	}
}

void Compiler::register_write(uint32_t chain)
{
	auto *var = maybe_get<SPIRVariable>(chain);
	if (!var)
	{
		// If we're storing through an access chain, invalidate the backing variable instead.
		auto *expr = maybe_get<SPIRExpression>(chain);
		if (expr && expr->loaded_from)
			var = maybe_get<SPIRVariable>(expr->loaded_from);

		auto *access_chain = maybe_get<SPIRAccessChain>(chain);
		if (access_chain && access_chain->loaded_from)
			var = maybe_get<SPIRVariable>(access_chain->loaded_from);
	}

	auto &chain_type = expression_type(chain);

	if (var)
	{
		bool check_argument_storage_qualifier = true;
		auto &type = expression_type(chain);

		// If our variable is in a storage class which can alias with other buffers,
		// invalidate all variables which depend on aliased variables. And if this is a
		// variable pointer, then invalidate all variables regardless.
		if (get_variable_data_type(*var).pointer)
		{
			flush_all_active_variables();

			if (type.pointer_depth == 1)
			{
				// We have a backing variable which is a pointer-to-pointer type.
				// We are storing some data through a pointer acquired through that variable,
				// but we are not writing to the value of the variable itself,
				// i.e., we are not modifying the pointer directly.
				// If we are storing a non-pointer type (pointer_depth == 1),
				// we know that we are storing some unrelated data.
				// A case here would be
				// void foo(Foo * const *arg) {
				//   Foo *bar = *arg;
				//   bar->unrelated = 42;
				// }
				// arg, the argument is constant.
				check_argument_storage_qualifier = false;
			}
		}

		if (type.storage == StorageClassPhysicalStorageBufferEXT || variable_storage_is_aliased(*var))
			flush_all_aliased_variables();
		else if (var)
			flush_dependees(*var);

		// We tried to write to a parameter which is not marked with out qualifier, force a recompile.
		if (check_argument_storage_qualifier && var->parameter && var->parameter->write_count == 0)
		{
			var->parameter->write_count++;
			force_recompile();
		}
	}
	else if (chain_type.pointer)
	{
		// If we stored through a variable pointer, then we don't know which
		// variable we stored to. So *all* expressions after this point need to
		// be invalidated.
		// FIXME: If we can prove that the variable pointer will point to
		// only certain variables, we can invalidate only those.
		flush_all_active_variables();
	}

	// If chain_type.pointer is false, we're not writing to memory backed variables, but temporaries instead.
	// This can happen in copy_logical_type where we unroll complex reads and writes to temporaries.
}

void Compiler::flush_dependees(SPIRVariable &var)
{
	for (auto expr : var.dependees)
		invalid_expressions.insert(expr);
	var.dependees.clear();
}

void Compiler::flush_all_aliased_variables()
{
	for (auto aliased : aliased_variables)
		flush_dependees(get<SPIRVariable>(aliased));
}

void Compiler::flush_all_atomic_capable_variables()
{
	for (auto global : global_variables)
		flush_dependees(get<SPIRVariable>(global));
	flush_all_aliased_variables();
}

void Compiler::flush_control_dependent_expressions(uint32_t block_id)
{
	auto &block = get<SPIRBlock>(block_id);
	for (auto &expr : block.invalidate_expressions)
		invalid_expressions.insert(expr);
	block.invalidate_expressions.clear();
}

void Compiler::flush_all_active_variables()
{
	// Invalidate all temporaries we read from variables in this block since they were forwarded.
	// Invalidate all temporaries we read from globals.
	for (auto &v : current_function->local_variables)
		flush_dependees(get<SPIRVariable>(v));
	for (auto &arg : current_function->arguments)
		flush_dependees(get<SPIRVariable>(arg.id));
	for (auto global : global_variables)
		flush_dependees(get<SPIRVariable>(global));

	flush_all_aliased_variables();
}

uint32_t Compiler::expression_type_id(uint32_t id) const
{
	switch (ir.ids[id].get_type())
	{
	case TypeVariable:
		return get<SPIRVariable>(id).basetype;

	case TypeExpression:
		return get<SPIRExpression>(id).expression_type;

	case TypeConstant:
		return get<SPIRConstant>(id).constant_type;

	case TypeConstantOp:
		return get<SPIRConstantOp>(id).basetype;

	case TypeUndef:
		return get<SPIRUndef>(id).basetype;

	case TypeCombinedImageSampler:
		return get<SPIRCombinedImageSampler>(id).combined_type;

	case TypeAccessChain:
		return get<SPIRAccessChain>(id).basetype;

	default:
		SPIRV_CROSS_THROW("Cannot resolve expression type.");
	}
}

const SPIRType &Compiler::expression_type(uint32_t id) const
{
	return get<SPIRType>(expression_type_id(id));
}

bool Compiler::expression_is_lvalue(uint32_t id) const
{
	auto &type = expression_type(id);
	switch (type.basetype)
	{
	case SPIRType::SampledImage:
	case SPIRType::Image:
	case SPIRType::Sampler:
		return false;

	default:
		return true;
	}
}

bool Compiler::is_immutable(uint32_t id) const
{
	if (ir.ids[id].get_type() == TypeVariable)
	{
		auto &var = get<SPIRVariable>(id);

		// Anything we load from the UniformConstant address space is guaranteed to be immutable.
		bool pointer_to_const = var.storage == StorageClassUniformConstant;
		return pointer_to_const || var.phi_variable || !expression_is_lvalue(id);
	}
	else if (ir.ids[id].get_type() == TypeAccessChain)
		return get<SPIRAccessChain>(id).immutable;
	else if (ir.ids[id].get_type() == TypeExpression)
		return get<SPIRExpression>(id).immutable;
	else if (ir.ids[id].get_type() == TypeConstant || ir.ids[id].get_type() == TypeConstantOp ||
	         ir.ids[id].get_type() == TypeUndef)
		return true;
	else
		return false;
}

static inline bool storage_class_is_interface(spv::StorageClass storage)
{
	switch (storage)
	{
	case StorageClassInput:
	case StorageClassOutput:
	case StorageClassUniform:
	case StorageClassUniformConstant:
	case StorageClassAtomicCounter:
	case StorageClassPushConstant:
	case StorageClassStorageBuffer:
		return true;

	default:
		return false;
	}
}

bool Compiler::is_hidden_variable(const SPIRVariable &var, bool include_builtins) const
{
	if ((is_builtin_variable(var) && !include_builtins) || var.remapped_variable)
		return true;

	// Combined image samplers are always considered active as they are "magic" variables.
	if (find_if(begin(combined_image_samplers), end(combined_image_samplers), [&var](const CombinedImageSampler &samp) {
		    return samp.combined_id == var.self;
	    }) != end(combined_image_samplers))
	{
		return false;
	}

	// In SPIR-V 1.4 and up we must also use the active variable interface to disable global variables
	// which are not part of the entry point.
	if (ir.get_spirv_version() >= 0x10400 && var.storage != spv::StorageClassGeneric &&
	    var.storage != spv::StorageClassFunction && !interface_variable_exists_in_entry_point(var.self))
	{
		return true;
	}

	return check_active_interface_variables && storage_class_is_interface(var.storage) &&
	       active_interface_variables.find(var.self) == end(active_interface_variables);
}

bool Compiler::is_builtin_type(const SPIRType &type) const
{
	auto *type_meta = ir.find_meta(type.self);

	// We can have builtin structs as well. If one member of a struct is builtin, the struct must also be builtin.
	if (type_meta)
		for (auto &m : type_meta->members)
			if (m.builtin)
				return true;

	return false;
}

bool Compiler::is_builtin_variable(const SPIRVariable &var) const
{
	auto *m = ir.find_meta(var.self);

	if (var.compat_builtin || (m && m->decoration.builtin))
		return true;
	else
		return is_builtin_type(get<SPIRType>(var.basetype));
}

bool Compiler::is_member_builtin(const SPIRType &type, uint32_t index, BuiltIn *builtin) const
{
	auto *type_meta = ir.find_meta(type.self);

	if (type_meta)
	{
		auto &memb = type_meta->members;
		if (index < memb.size() && memb[index].builtin)
		{
			if (builtin)
				*builtin = memb[index].builtin_type;
			return true;
		}
	}

	return false;
}

bool Compiler::is_scalar(const SPIRType &type) const
{
	return type.basetype != SPIRType::Struct && type.vecsize == 1 && type.columns == 1;
}

bool Compiler::is_vector(const SPIRType &type) const
{
	return type.vecsize > 1 && type.columns == 1;
}

bool Compiler::is_matrix(const SPIRType &type) const
{
	return type.vecsize > 1 && type.columns > 1;
}

bool Compiler::is_array(const SPIRType &type) const
{
	return !type.array.empty();
}

ShaderResources Compiler::get_shader_resources() const
{
	return get_shader_resources(nullptr);
}

ShaderResources Compiler::get_shader_resources(const unordered_set<VariableID> &active_variables) const
{
	return get_shader_resources(&active_variables);
}

bool Compiler::InterfaceVariableAccessHandler::handle(Op opcode, const uint32_t *args, uint32_t length)
{
	uint32_t variable = 0;
	switch (opcode)
	{
	// Need this first, otherwise, GCC complains about unhandled switch statements.
	default:
		break;

	case OpFunctionCall:
	{
		// Invalid SPIR-V.
		if (length < 3)
			return false;

		uint32_t count = length - 3;
		args += 3;
		for (uint32_t i = 0; i < count; i++)
		{
			auto *var = compiler.maybe_get<SPIRVariable>(args[i]);
			if (var && storage_class_is_interface(var->storage))
				variables.insert(args[i]);
		}
		break;
	}

	case OpSelect:
	{
		// Invalid SPIR-V.
		if (length < 5)
			return false;

		uint32_t count = length - 3;
		args += 3;
		for (uint32_t i = 0; i < count; i++)
		{
			auto *var = compiler.maybe_get<SPIRVariable>(args[i]);
			if (var && storage_class_is_interface(var->storage))
				variables.insert(args[i]);
		}
		break;
	}

	case OpPhi:
	{
		// Invalid SPIR-V.
		if (length < 2)
			return false;

		uint32_t count = length - 2;
		args += 2;
		for (uint32_t i = 0; i < count; i += 2)
		{
			auto *var = compiler.maybe_get<SPIRVariable>(args[i]);
			if (var && storage_class_is_interface(var->storage))
				variables.insert(args[i]);
		}
		break;
	}

	case OpAtomicStore:
	case OpStore:
		// Invalid SPIR-V.
		if (length < 1)
			return false;
		variable = args[0];
		break;

	case OpCopyMemory:
	{
		if (length < 2)
			return false;

		auto *var = compiler.maybe_get<SPIRVariable>(args[0]);
		if (var && storage_class_is_interface(var->storage))
			variables.insert(args[0]);

		var = compiler.maybe_get<SPIRVariable>(args[1]);
		if (var && storage_class_is_interface(var->storage))
			variables.insert(args[1]);
		break;
	}

	case OpExtInst:
	{
		if (length < 3)
			return false;
		auto &extension_set = compiler.get<SPIRExtension>(args[2]);
		switch (extension_set.ext)
		{
		case SPIRExtension::GLSL:
		{
			auto op = static_cast<GLSLstd450>(args[3]);

			switch (op)
			{
			case GLSLstd450InterpolateAtCentroid:
			case GLSLstd450InterpolateAtSample:
			case GLSLstd450InterpolateAtOffset:
			{
				auto *var = compiler.maybe_get<SPIRVariable>(args[4]);
				if (var && storage_class_is_interface(var->storage))
					variables.insert(args[4]);
				break;
			}

			case GLSLstd450Modf:
			case GLSLstd450Fract:
			{
				auto *var = compiler.maybe_get<SPIRVariable>(args[5]);
				if (var && storage_class_is_interface(var->storage))
					variables.insert(args[5]);
				break;
			}

			default:
				break;
			}
			break;
		}
		case SPIRExtension::SPV_AMD_shader_explicit_vertex_parameter:
		{
			enum AMDShaderExplicitVertexParameter
			{
				InterpolateAtVertexAMD = 1
			};

			auto op = static_cast<AMDShaderExplicitVertexParameter>(args[3]);

			switch (op)
			{
			case InterpolateAtVertexAMD:
			{
				auto *var = compiler.maybe_get<SPIRVariable>(args[4]);
				if (var && storage_class_is_interface(var->storage))
					variables.insert(args[4]);
				break;
			}

			default:
				break;
			}
			break;
		}
		default:
			break;
		}
		break;
	}

	case OpAccessChain:
	case OpInBoundsAccessChain:
	case OpPtrAccessChain:
	case OpLoad:
	case OpCopyObject:
	case OpImageTexelPointer:
	case OpAtomicLoad:
	case OpAtomicExchange:
	case OpAtomicCompareExchange:
	case OpAtomicCompareExchangeWeak:
	case OpAtomicIIncrement:
	case OpAtomicIDecrement:
	case OpAtomicIAdd:
	case OpAtomicISub:
	case OpAtomicSMin:
	case OpAtomicUMin:
	case OpAtomicSMax:
	case OpAtomicUMax:
	case OpAtomicAnd:
	case OpAtomicOr:
	case OpAtomicXor:
	case OpArrayLength:
		// Invalid SPIR-V.
		if (length < 3)
			return false;
		variable = args[2];
		break;
	}

	if (variable)
	{
		auto *var = compiler.maybe_get<SPIRVariable>(variable);
		if (var && storage_class_is_interface(var->storage))
			variables.insert(variable);
	}
	return true;
}

unordered_set<VariableID> Compiler::get_active_interface_variables() const
{
	// Traverse the call graph and find all interface variables which are in use.
	unordered_set<VariableID> variables;
	InterfaceVariableAccessHandler handler(*this, variables);
	traverse_all_reachable_opcodes(get<SPIRFunction>(ir.default_entry_point), handler);

	ir.for_each_typed_id<SPIRVariable>([&](uint32_t, const SPIRVariable &var) {
		if (var.storage != StorageClassOutput)
			return;
		if (!interface_variable_exists_in_entry_point(var.self))
			return;

		// An output variable which is just declared (but uninitialized) might be read by subsequent stages
		// so we should force-enable these outputs,
		// since compilation will fail if a subsequent stage attempts to read from the variable in question.
		// Also, make sure we preserve output variables which are only initialized, but never accessed by any code.
		if (var.initializer != ID(0) || get_execution_model() != ExecutionModelFragment)
			variables.insert(var.self);
	});

	// If we needed to create one, we'll need it.
	if (dummy_sampler_id)
		variables.insert(dummy_sampler_id);

	return variables;
}

void Compiler::set_enabled_interface_variables(std::unordered_set<VariableID> active_variables)
{
	active_interface_variables = std::move(active_variables);
	check_active_interface_variables = true;
}

ShaderResources Compiler::get_shader_resources(const unordered_set<VariableID> *active_variables) const
{
	ShaderResources res;

	bool ssbo_instance_name = reflection_ssbo_instance_name_is_significant();

	ir.for_each_typed_id<SPIRVariable>([&](uint32_t, const SPIRVariable &var) {
		auto &type = this->get<SPIRType>(var.basetype);

		// It is possible for uniform storage classes to be passed as function parameters, so detect
		// that. To detect function parameters, check of StorageClass of variable is function scope.
		if (var.storage == StorageClassFunction || !type.pointer)
			return;

		if (active_variables && active_variables->find(var.self) == end(*active_variables))
			return;

		// In SPIR-V 1.4 and up, every global must be present in the entry point interface list,
		// not just IO variables.
		bool active_in_entry_point = true;
		if (ir.get_spirv_version() < 0x10400)
		{
			if (var.storage == StorageClassInput || var.storage == StorageClassOutput)
				active_in_entry_point = interface_variable_exists_in_entry_point(var.self);
		}
		else
			active_in_entry_point = interface_variable_exists_in_entry_point(var.self);

		if (!active_in_entry_point)
			return;

		bool is_builtin = is_builtin_variable(var);

		if (is_builtin)
		{
			if (var.storage != StorageClassInput && var.storage != StorageClassOutput)
				return;

			auto &list = var.storage == StorageClassInput ? res.builtin_inputs : res.builtin_outputs;
			BuiltInResource resource;

			if (has_decoration(type.self, DecorationBlock))
			{
				resource.resource = { var.self, var.basetype, type.self,
				                      get_remapped_declared_block_name(var.self, false) };

				for (uint32_t i = 0; i < uint32_t(type.member_types.size()); i++)
				{
					resource.value_type_id = type.member_types[i];
					resource.builtin = BuiltIn(get_member_decoration(type.self, i, DecorationBuiltIn));
					list.push_back(resource);
				}
			}
			else
			{
				bool strip_array =
						!has_decoration(var.self, DecorationPatch) && (
								get_execution_model() == ExecutionModelTessellationControl ||
								(get_execution_model() == ExecutionModelTessellationEvaluation &&
								 var.storage == StorageClassInput));

				resource.resource = { var.self, var.basetype, type.self, get_name(var.self) };

				if (strip_array && !type.array.empty())
					resource.value_type_id = get_variable_data_type(var).parent_type;
				else
					resource.value_type_id = get_variable_data_type_id(var);

				assert(resource.value_type_id);

				resource.builtin = BuiltIn(get_decoration(var.self, DecorationBuiltIn));
				list.push_back(std::move(resource));
			}
			return;
		}

		// Input
		if (var.storage == StorageClassInput)
		{
			if (has_decoration(type.self, DecorationBlock))
			{
				res.stage_inputs.push_back(
						{ var.self, var.basetype, type.self,
						  get_remapped_declared_block_name(var.self, false) });
			}
			else
				res.stage_inputs.push_back({ var.self, var.basetype, type.self, get_name(var.self) });
		}
		// Subpass inputs
		else if (var.storage == StorageClassUniformConstant && type.image.dim == DimSubpassData)
		{
			res.subpass_inputs.push_back({ var.self, var.basetype, type.self, get_name(var.self) });
		}
		// Outputs
		else if (var.storage == StorageClassOutput)
		{
			if (has_decoration(type.self, DecorationBlock))
			{
				res.stage_outputs.push_back(
						{ var.self, var.basetype, type.self, get_remapped_declared_block_name(var.self, false) });
			}
			else
				res.stage_outputs.push_back({ var.self, var.basetype, type.self, get_name(var.self) });
		}
		// UBOs
		else if (type.storage == StorageClassUniform && has_decoration(type.self, DecorationBlock))
		{
			res.uniform_buffers.push_back(
			    { var.self, var.basetype, type.self, get_remapped_declared_block_name(var.self, false) });
		}
		// Old way to declare SSBOs.
		else if (type.storage == StorageClassUniform && has_decoration(type.self, DecorationBufferBlock))
		{
			res.storage_buffers.push_back(
			    { var.self, var.basetype, type.self, get_remapped_declared_block_name(var.self, ssbo_instance_name) });
		}
		// Modern way to declare SSBOs.
		else if (type.storage == StorageClassStorageBuffer)
		{
			res.storage_buffers.push_back(
			    { var.self, var.basetype, type.self, get_remapped_declared_block_name(var.self, ssbo_instance_name) });
		}
		// Push constant blocks
		else if (type.storage == StorageClassPushConstant)
		{
			// There can only be one push constant block, but keep the vector in case this restriction is lifted
			// in the future.
			res.push_constant_buffers.push_back({ var.self, var.basetype, type.self, get_name(var.self) });
		}
		else if (type.storage == StorageClassShaderRecordBufferKHR)
		{
			res.shader_record_buffers.push_back({ var.self, var.basetype, type.self, get_remapped_declared_block_name(var.self, ssbo_instance_name) });
		}
		// Images
		else if (type.storage == StorageClassUniformConstant && type.basetype == SPIRType::Image &&
		         type.image.sampled == 2)
		{
			res.storage_images.push_back({ var.self, var.basetype, type.self, get_name(var.self) });
		}
		// Separate images
		else if (type.storage == StorageClassUniformConstant && type.basetype == SPIRType::Image &&
		         type.image.sampled == 1)
		{
			res.separate_images.push_back({ var.self, var.basetype, type.self, get_name(var.self) });
		}
		// Separate samplers
		else if (type.storage == StorageClassUniformConstant && type.basetype == SPIRType::Sampler)
		{
			res.separate_samplers.push_back({ var.self, var.basetype, type.self, get_name(var.self) });
		}
		// Textures
		else if (type.storage == StorageClassUniformConstant && type.basetype == SPIRType::SampledImage)
		{
			res.sampled_images.push_back({ var.self, var.basetype, type.self, get_name(var.self) });
		}
		// Atomic counters
		else if (type.storage == StorageClassAtomicCounter)
		{
			res.atomic_counters.push_back({ var.self, var.basetype, type.self, get_name(var.self) });
		}
		// Acceleration structures
		else if (type.storage == StorageClassUniformConstant && type.basetype == SPIRType::AccelerationStructure)
		{
			res.acceleration_structures.push_back({ var.self, var.basetype, type.self, get_name(var.self) });
		}
	});

	return res;
}

bool Compiler::type_is_block_like(const SPIRType &type) const
{
	if (type.basetype != SPIRType::Struct)
		return false;

	if (has_decoration(type.self, DecorationBlock) || has_decoration(type.self, DecorationBufferBlock))
	{
		return true;
	}

	// Block-like types may have Offset decorations.
	for (uint32_t i = 0; i < uint32_t(type.member_types.size()); i++)
		if (has_member_decoration(type.self, i, DecorationOffset))
			return true;

	return false;
}

void Compiler::parse_fixup()
{
	// Figure out specialization constants for work group sizes.
	for (auto id_ : ir.ids_for_constant_or_variable)
	{
		auto &id = ir.ids[id_];

		if (id.get_type() == TypeConstant)
		{
			auto &c = id.get<SPIRConstant>();
			if (has_decoration(c.self, DecorationBuiltIn) &&
			    BuiltIn(get_decoration(c.self, DecorationBuiltIn)) == BuiltInWorkgroupSize)
			{
				// In current SPIR-V, there can be just one constant like this.
				// All entry points will receive the constant value.
				// WorkgroupSize take precedence over LocalSizeId.
				for (auto &entry : ir.entry_points)
				{
					entry.second.workgroup_size.constant = c.self;
					entry.second.workgroup_size.x = c.scalar(0, 0);
					entry.second.workgroup_size.y = c.scalar(0, 1);
					entry.second.workgroup_size.z = c.scalar(0, 2);
				}
			}
		}
		else if (id.get_type() == TypeVariable)
		{
			auto &var = id.get<SPIRVariable>();
			if (var.storage == StorageClassPrivate || var.storage == StorageClassWorkgroup ||
			    var.storage == StorageClassTaskPayloadWorkgroupEXT ||
			    var.storage == StorageClassOutput)
			{
				global_variables.push_back(var.self);
			}
			if (variable_storage_is_aliased(var))
				aliased_variables.push_back(var.self);
		}
	}
}

void Compiler::update_name_cache(unordered_set<string> &cache_primary, const unordered_set<string> &cache_secondary,
                                 string &name)
{
	if (name.empty())
		return;

	const auto find_name = [&](const string &n) -> bool {
		if (cache_primary.find(n) != end(cache_primary))
			return true;

		if (&cache_primary != &cache_secondary)
			if (cache_secondary.find(n) != end(cache_secondary))
				return true;

		return false;
	};

	const auto insert_name = [&](const string &n) { cache_primary.insert(n); };

	if (!find_name(name))
	{
		insert_name(name);
		return;
	}

	uint32_t counter = 0;
	auto tmpname = name;

	bool use_linked_underscore = true;

	if (tmpname == "_")
	{
		// We cannot just append numbers, as we will end up creating internally reserved names.
		// Make it like _0_<counter> instead.
		tmpname += "0";
	}
	else if (tmpname.back() == '_')
	{
		// The last_character is an underscore, so we don't need to link in underscore.
		// This would violate double underscore rules.
		use_linked_underscore = false;
	}

	// If there is a collision (very rare),
	// keep tacking on extra identifier until it's unique.
	do
	{
		counter++;
		name = tmpname + (use_linked_underscore ? "_" : "") + convert_to_string(counter);
	} while (find_name(name));
	insert_name(name);
}

void Compiler::update_name_cache(unordered_set<string> &cache, string &name)
{
	update_name_cache(cache, cache, name);
}

void Compiler::set_name(ID id, const std::string &name)
{
	ir.set_name(id, name);
}

const SPIRType &Compiler::get_type(TypeID id) const
{
	return get<SPIRType>(id);
}

const SPIRType &Compiler::get_type_from_variable(VariableID id) const
{
	return get<SPIRType>(get<SPIRVariable>(id).basetype);
}

uint32_t Compiler::get_pointee_type_id(uint32_t type_id) const
{
	auto *p_type = &get<SPIRType>(type_id);
	if (p_type->pointer)
	{
		assert(p_type->parent_type);
		type_id = p_type->parent_type;
	}
	return type_id;
}

const SPIRType &Compiler::get_pointee_type(const SPIRType &type) const
{
	auto *p_type = &type;
	if (p_type->pointer)
	{
		assert(p_type->parent_type);
		p_type = &get<SPIRType>(p_type->parent_type);
	}
	return *p_type;
}

const SPIRType &Compiler::get_pointee_type(uint32_t type_id) const
{
	return get_pointee_type(get<SPIRType>(type_id));
}

uint32_t Compiler::get_variable_data_type_id(const SPIRVariable &var) const
{
	if (var.phi_variable)
		return var.basetype;
	return get_pointee_type_id(var.basetype);
}

SPIRType &Compiler::get_variable_data_type(const SPIRVariable &var)
{
	return get<SPIRType>(get_variable_data_type_id(var));
}

const SPIRType &Compiler::get_variable_data_type(const SPIRVariable &var) const
{
	return get<SPIRType>(get_variable_data_type_id(var));
}

SPIRType &Compiler::get_variable_element_type(const SPIRVariable &var)
{
	SPIRType *type = &get_variable_data_type(var);
	if (is_array(*type))
		type = &get<SPIRType>(type->parent_type);
	return *type;
}

const SPIRType &Compiler::get_variable_element_type(const SPIRVariable &var) const
{
	const SPIRType *type = &get_variable_data_type(var);
	if (is_array(*type))
		type = &get<SPIRType>(type->parent_type);
	return *type;
}

bool Compiler::is_sampled_image_type(const SPIRType &type)
{
	return (type.basetype == SPIRType::Image || type.basetype == SPIRType::SampledImage) && type.image.sampled == 1 &&
	       type.image.dim != DimBuffer;
}

void Compiler::set_member_decoration_string(TypeID id, uint32_t index, spv::Decoration decoration,
                                            const std::string &argument)
{
	ir.set_member_decoration_string(id, index, decoration, argument);
}

void Compiler::set_member_decoration(TypeID id, uint32_t index, Decoration decoration, uint32_t argument)
{
	ir.set_member_decoration(id, index, decoration, argument);
}

void Compiler::set_member_name(TypeID id, uint32_t index, const std::string &name)
{
	ir.set_member_name(id, index, name);
}

const std::string &Compiler::get_member_name(TypeID id, uint32_t index) const
{
	return ir.get_member_name(id, index);
}

void Compiler::set_qualified_name(uint32_t id, const string &name)
{
	ir.meta[id].decoration.qualified_alias = name;
}

void Compiler::set_member_qualified_name(uint32_t type_id, uint32_t index, const std::string &name)
{
	ir.meta[type_id].members.resize(max(ir.meta[type_id].members.size(), size_t(index) + 1));
	ir.meta[type_id].members[index].qualified_alias = name;
}

const string &Compiler::get_member_qualified_name(TypeID type_id, uint32_t index) const
{
	auto *m = ir.find_meta(type_id);
	if (m && index < m->members.size())
		return m->members[index].qualified_alias;
	else
		return ir.get_empty_string();
}

uint32_t Compiler::get_member_decoration(TypeID id, uint32_t index, Decoration decoration) const
{
	return ir.get_member_decoration(id, index, decoration);
}

const Bitset &Compiler::get_member_decoration_bitset(TypeID id, uint32_t index) const
{
	return ir.get_member_decoration_bitset(id, index);
}

bool Compiler::has_member_decoration(TypeID id, uint32_t index, Decoration decoration) const
{
	return ir.has_member_decoration(id, index, decoration);
}

void Compiler::unset_member_decoration(TypeID id, uint32_t index, Decoration decoration)
{
	ir.unset_member_decoration(id, index, decoration);
}

void Compiler::set_decoration_string(ID id, spv::Decoration decoration, const std::string &argument)
{
	ir.set_decoration_string(id, decoration, argument);
}

void Compiler::set_decoration(ID id, Decoration decoration, uint32_t argument)
{
	ir.set_decoration(id, decoration, argument);
}

void Compiler::set_extended_decoration(uint32_t id, ExtendedDecorations decoration, uint32_t value)
{
	auto &dec = ir.meta[id].decoration;
	dec.extended.flags.set(decoration);
	dec.extended.values[decoration] = value;
}

void Compiler::set_extended_member_decoration(uint32_t type, uint32_t index, ExtendedDecorations decoration,
                                              uint32_t value)
{
	ir.meta[type].members.resize(max(ir.meta[type].members.size(), size_t(index) + 1));
	auto &dec = ir.meta[type].members[index];
	dec.extended.flags.set(decoration);
	dec.extended.values[decoration] = value;
}

static uint32_t get_default_extended_decoration(ExtendedDecorations decoration)
{
	switch (decoration)
	{
	case SPIRVCrossDecorationResourceIndexPrimary:
	case SPIRVCrossDecorationResourceIndexSecondary:
	case SPIRVCrossDecorationResourceIndexTertiary:
	case SPIRVCrossDecorationResourceIndexQuaternary:
	case SPIRVCrossDecorationInterfaceMemberIndex:
		return ~(0u);

	default:
		return 0;
	}
}

uint32_t Compiler::get_extended_decoration(uint32_t id, ExtendedDecorations decoration) const
{
	auto *m = ir.find_meta(id);
	if (!m)
		return 0;

	auto &dec = m->decoration;

	if (!dec.extended.flags.get(decoration))
		return get_default_extended_decoration(decoration);

	return dec.extended.values[decoration];
}

uint32_t Compiler::get_extended_member_decoration(uint32_t type, uint32_t index, ExtendedDecorations decoration) const
{
	auto *m = ir.find_meta(type);
	if (!m)
		return 0;

	if (index >= m->members.size())
		return 0;

	auto &dec = m->members[index];
	if (!dec.extended.flags.get(decoration))
		return get_default_extended_decoration(decoration);
	return dec.extended.values[decoration];
}

bool Compiler::has_extended_decoration(uint32_t id, ExtendedDecorations decoration) const
{
	auto *m = ir.find_meta(id);
	if (!m)
		return false;

	auto &dec = m->decoration;
	return dec.extended.flags.get(decoration);
}

bool Compiler::has_extended_member_decoration(uint32_t type, uint32_t index, ExtendedDecorations decoration) const
{
	auto *m = ir.find_meta(type);
	if (!m)
		return false;

	if (index >= m->members.size())
		return false;

	auto &dec = m->members[index];
	return dec.extended.flags.get(decoration);
}

void Compiler::unset_extended_decoration(uint32_t id, ExtendedDecorations decoration)
{
	auto &dec = ir.meta[id].decoration;
	dec.extended.flags.clear(decoration);
	dec.extended.values[decoration] = 0;
}

void Compiler::unset_extended_member_decoration(uint32_t type, uint32_t index, ExtendedDecorations decoration)
{
	ir.meta[type].members.resize(max(ir.meta[type].members.size(), size_t(index) + 1));
	auto &dec = ir.meta[type].members[index];
	dec.extended.flags.clear(decoration);
	dec.extended.values[decoration] = 0;
}

StorageClass Compiler::get_storage_class(VariableID id) const
{
	return get<SPIRVariable>(id).storage;
}

const std::string &Compiler::get_name(ID id) const
{
	return ir.get_name(id);
}

const std::string Compiler::get_fallback_name(ID id) const
{
	return join("_", id);
}

const std::string Compiler::get_block_fallback_name(VariableID id) const
{
	auto &var = get<SPIRVariable>(id);
	if (get_name(id).empty())
		return join("_", get<SPIRType>(var.basetype).self, "_", id);
	else
		return get_name(id);
}

const Bitset &Compiler::get_decoration_bitset(ID id) const
{
	return ir.get_decoration_bitset(id);
}

bool Compiler::has_decoration(ID id, Decoration decoration) const
{
	return ir.has_decoration(id, decoration);
}

const string &Compiler::get_decoration_string(ID id, Decoration decoration) const
{
	return ir.get_decoration_string(id, decoration);
}

const string &Compiler::get_member_decoration_string(TypeID id, uint32_t index, Decoration decoration) const
{
	return ir.get_member_decoration_string(id, index, decoration);
}

uint32_t Compiler::get_decoration(ID id, Decoration decoration) const
{
	return ir.get_decoration(id, decoration);
}

void Compiler::unset_decoration(ID id, Decoration decoration)
{
	ir.unset_decoration(id, decoration);
}

bool Compiler::get_binary_offset_for_decoration(VariableID id, spv::Decoration decoration, uint32_t &word_offset) const
{
	auto *m = ir.find_meta(id);
	if (!m)
		return false;

	auto &word_offsets = m->decoration_word_offset;
	auto itr = word_offsets.find(decoration);
	if (itr == end(word_offsets))
		return false;

	word_offset = itr->second;
	return true;
}

bool Compiler::block_is_noop(const SPIRBlock &block) const
{
	if (block.terminator != SPIRBlock::Direct)
		return false;

	auto &child = get<SPIRBlock>(block.next_block);

	// If this block participates in PHI, the block isn't really noop.
	for (auto &phi : block.phi_variables)
		if (phi.parent == block.self || phi.parent == child.self)
			return false;

	for (auto &phi : child.phi_variables)
		if (phi.parent == block.self)
			return false;

	// Verify all instructions have no semantic impact.
	for (auto &i : block.ops)
	{
		auto op = static_cast<Op>(i.op);

		switch (op)
		{
		// Non-Semantic instructions.
		case OpLine:
		case OpNoLine:
			break;

		case OpExtInst:
		{
			auto *ops = stream(i);
			auto ext = get<SPIRExtension>(ops[2]).ext;

			bool ext_is_nonsemantic_only =
				ext == SPIRExtension::NonSemanticShaderDebugInfo ||
				ext == SPIRExtension::SPV_debug_info ||
				ext == SPIRExtension::NonSemanticGeneric;

			if (!ext_is_nonsemantic_only)
				return false;

			break;
		}

		default:
			return false;
		}
	}

	return true;
}

bool Compiler::block_is_loop_candidate(const SPIRBlock &block, SPIRBlock::Method method) const
{
	// Tried and failed.
	if (block.disable_block_optimization || block.complex_continue)
		return false;

	if (method == SPIRBlock::MergeToSelectForLoop || method == SPIRBlock::MergeToSelectContinueForLoop)
	{
		// Try to detect common for loop pattern
		// which the code backend can use to create cleaner code.
		// for(;;) { if (cond) { some_body; } else { break; } }
		// is the pattern we're looking for.
		const auto *false_block = maybe_get<SPIRBlock>(block.false_block);
		const auto *true_block = maybe_get<SPIRBlock>(block.true_block);
		const auto *merge_block = maybe_get<SPIRBlock>(block.merge_block);

		bool false_block_is_merge = block.false_block == block.merge_block ||
		                            (false_block && merge_block && execution_is_noop(*false_block, *merge_block));

		bool true_block_is_merge = block.true_block == block.merge_block ||
		                           (true_block && merge_block && execution_is_noop(*true_block, *merge_block));

		bool positive_candidate =
		    block.true_block != block.merge_block && block.true_block != block.self && false_block_is_merge;

		bool negative_candidate =
		    block.false_block != block.merge_block && block.false_block != block.self && true_block_is_merge;

		bool ret = block.terminator == SPIRBlock::Select && block.merge == SPIRBlock::MergeLoop &&
		           (positive_candidate || negative_candidate);

		if (ret && positive_candidate && method == SPIRBlock::MergeToSelectContinueForLoop)
			ret = block.true_block == block.continue_block;
		else if (ret && negative_candidate && method == SPIRBlock::MergeToSelectContinueForLoop)
			ret = block.false_block == block.continue_block;

		// If we have OpPhi which depends on branches which came from our own block,
		// we need to flush phi variables in else block instead of a trivial break,
		// so we cannot assume this is a for loop candidate.
		if (ret)
		{
			for (auto &phi : block.phi_variables)
				if (phi.parent == block.self)
					return false;

			auto *merge = maybe_get<SPIRBlock>(block.merge_block);
			if (merge)
				for (auto &phi : merge->phi_variables)
					if (phi.parent == block.self)
						return false;
		}
		return ret;
	}
	else if (method == SPIRBlock::MergeToDirectForLoop)
	{
		// Empty loop header that just sets up merge target
		// and branches to loop body.
		bool ret = block.terminator == SPIRBlock::Direct && block.merge == SPIRBlock::MergeLoop && block_is_noop(block);

		if (!ret)
			return false;

		auto &child = get<SPIRBlock>(block.next_block);

		const auto *false_block = maybe_get<SPIRBlock>(child.false_block);
		const auto *true_block = maybe_get<SPIRBlock>(child.true_block);
		const auto *merge_block = maybe_get<SPIRBlock>(block.merge_block);

		bool false_block_is_merge = child.false_block == block.merge_block ||
		                            (false_block && merge_block && execution_is_noop(*false_block, *merge_block));

		bool true_block_is_merge = child.true_block == block.merge_block ||
		                           (true_block && merge_block && execution_is_noop(*true_block, *merge_block));

		bool positive_candidate =
		    child.true_block != block.merge_block && child.true_block != block.self && false_block_is_merge;

		bool negative_candidate =
		    child.false_block != block.merge_block && child.false_block != block.self && true_block_is_merge;

		ret = child.terminator == SPIRBlock::Select && child.merge == SPIRBlock::MergeNone &&
		      (positive_candidate || negative_candidate);

		if (ret)
		{
			auto *merge = maybe_get<SPIRBlock>(block.merge_block);
			if (merge)
				for (auto &phi : merge->phi_variables)
					if (phi.parent == block.self || phi.parent == child.false_block)
						return false;
		}

		return ret;
	}
	else
		return false;
}

bool Compiler::execution_is_noop(const SPIRBlock &from, const SPIRBlock &to) const
{
	if (!execution_is_branchless(from, to))
		return false;

	auto *start = &from;
	for (;;)
	{
		if (start->self == to.self)
			return true;

		if (!block_is_noop(*start))
			return false;

		auto &next = get<SPIRBlock>(start->next_block);
		start = &next;
	}
}

bool Compiler::execution_is_branchless(const SPIRBlock &from, const SPIRBlock &to) const
{
	auto *start = &from;
	for (;;)
	{
		if (start->self == to.self)
			return true;

		if (start->terminator == SPIRBlock::Direct && start->merge == SPIRBlock::MergeNone)
			start = &get<SPIRBlock>(start->next_block);
		else
			return false;
	}
}

bool Compiler::execution_is_direct_branch(const SPIRBlock &from, const SPIRBlock &to) const
{
	return from.terminator == SPIRBlock::Direct && from.merge == SPIRBlock::MergeNone && from.next_block == to.self;
}

SPIRBlock::ContinueBlockType Compiler::continue_block_type(const SPIRBlock &block) const
{
	// The block was deemed too complex during code emit, pick conservative fallback paths.
	if (block.complex_continue)
		return SPIRBlock::ComplexLoop;

	// In older glslang output continue block can be equal to the loop header.
	// In this case, execution is clearly branchless, so just assume a while loop header here.
	if (block.merge == SPIRBlock::MergeLoop)
		return SPIRBlock::WhileLoop;

	if (block.loop_dominator == BlockID(SPIRBlock::NoDominator))
	{
		// Continue block is never reached from CFG.
		return SPIRBlock::ComplexLoop;
	}

	auto &dominator = get<SPIRBlock>(block.loop_dominator);

	if (execution_is_noop(block, dominator))
		return SPIRBlock::WhileLoop;
	else if (execution_is_branchless(block, dominator))
		return SPIRBlock::ForLoop;
	else
	{
		const auto *false_block = maybe_get<SPIRBlock>(block.false_block);
		const auto *true_block = maybe_get<SPIRBlock>(block.true_block);
		const auto *merge_block = maybe_get<SPIRBlock>(dominator.merge_block);

		// If we need to flush Phi in this block, we cannot have a DoWhile loop.
		bool flush_phi_to_false = false_block && flush_phi_required(block.self, block.false_block);
		bool flush_phi_to_true = true_block && flush_phi_required(block.self, block.true_block);
		if (flush_phi_to_false || flush_phi_to_true)
			return SPIRBlock::ComplexLoop;

		bool positive_do_while = block.true_block == dominator.self &&
		                         (block.false_block == dominator.merge_block ||
		                          (false_block && merge_block && execution_is_noop(*false_block, *merge_block)));

		bool negative_do_while = block.false_block == dominator.self &&
		                         (block.true_block == dominator.merge_block ||
		                          (true_block && merge_block && execution_is_noop(*true_block, *merge_block)));

		if (block.merge == SPIRBlock::MergeNone && block.terminator == SPIRBlock::Select &&
		    (positive_do_while || negative_do_while))
		{
			return SPIRBlock::DoWhileLoop;
		}
		else
			return SPIRBlock::ComplexLoop;
	}
}

const SmallVector<SPIRBlock::Case> &Compiler::get_case_list(const SPIRBlock &block) const
{
	uint32_t width = 0;

	// First we check if we can get the type directly from the block.condition
	// since it can be a SPIRConstant or a SPIRVariable.
	if (const auto *constant = maybe_get<SPIRConstant>(block.condition))
	{
		const auto &type = get<SPIRType>(constant->constant_type);
		width = type.width;
	}
	else if (const auto *var = maybe_get<SPIRVariable>(block.condition))
	{
		const auto &type = get<SPIRType>(var->basetype);
		width = type.width;
	}
	else if (const auto *undef = maybe_get<SPIRUndef>(block.condition))
	{
		const auto &type = get<SPIRType>(undef->basetype);
		width = type.width;
	}
	else
	{
		auto search = ir.load_type_width.find(block.condition);
		if (search == ir.load_type_width.end())
		{
			SPIRV_CROSS_THROW("Use of undeclared variable on a switch statement.");
		}

		width = search->second;
	}

	if (width > 32)
		return block.cases_64bit;

	return block.cases_32bit;
}

bool Compiler::traverse_all_reachable_opcodes(const SPIRBlock &block, OpcodeHandler &handler) const
{
	handler.set_current_block(block);
	handler.rearm_current_block(block);

	// Ideally, perhaps traverse the CFG instead of all blocks in order to eliminate dead blocks,
	// but this shouldn't be a problem in practice unless the SPIR-V is doing insane things like recursing
	// inside dead blocks ...
	for (auto &i : block.ops)
	{
		auto ops = stream(i);
		auto op = static_cast<Op>(i.op);

		if (!handler.handle(op, ops, i.length))
			return false;

		if (op == OpFunctionCall)
		{
			auto &func = get<SPIRFunction>(ops[2]);
			if (handler.follow_function_call(func))
			{
				if (!handler.begin_function_scope(ops, i.length))
					return false;
				if (!traverse_all_reachable_opcodes(get<SPIRFunction>(ops[2]), handler))
					return false;
				if (!handler.end_function_scope(ops, i.length))
					return false;

				handler.rearm_current_block(block);
			}
		}
	}

	if (!handler.handle_terminator(block))
		return false;

	return true;
}

bool Compiler::traverse_all_reachable_opcodes(const SPIRFunction &func, OpcodeHandler &handler) const
{
	for (auto block : func.blocks)
		if (!traverse_all_reachable_opcodes(get<SPIRBlock>(block), handler))
			return false;

	return true;
}

uint32_t Compiler::type_struct_member_offset(const SPIRType &type, uint32_t index) const
{
	auto *type_meta = ir.find_meta(type.self);
	if (type_meta)
	{
		// Decoration must be set in valid SPIR-V, otherwise throw.
		auto &dec = type_meta->members[index];
		if (dec.decoration_flags.get(DecorationOffset))
			return dec.offset;
		else
			SPIRV_CROSS_THROW("Struct member does not have Offset set.");
	}
	else
		SPIRV_CROSS_THROW("Struct member does not have Offset set.");
}

uint32_t Compiler::type_struct_member_array_stride(const SPIRType &type, uint32_t index) const
{
	auto *type_meta = ir.find_meta(type.member_types[index]);
	if (type_meta)
	{
		// Decoration must be set in valid SPIR-V, otherwise throw.
		// ArrayStride is part of the array type not OpMemberDecorate.
		auto &dec = type_meta->decoration;
		if (dec.decoration_flags.get(DecorationArrayStride))
			return dec.array_stride;
		else
			SPIRV_CROSS_THROW("Struct member does not have ArrayStride set.");
	}
	else
		SPIRV_CROSS_THROW("Struct member does not have ArrayStride set.");
}

uint32_t Compiler::type_struct_member_matrix_stride(const SPIRType &type, uint32_t index) const
{
	auto *type_meta = ir.find_meta(type.self);
	if (type_meta)
	{
		// Decoration must be set in valid SPIR-V, otherwise throw.
		// MatrixStride is part of OpMemberDecorate.
		auto &dec = type_meta->members[index];
		if (dec.decoration_flags.get(DecorationMatrixStride))
			return dec.matrix_stride;
		else
			SPIRV_CROSS_THROW("Struct member does not have MatrixStride set.");
	}
	else
		SPIRV_CROSS_THROW("Struct member does not have MatrixStride set.");
}

size_t Compiler::get_declared_struct_size(const SPIRType &type) const
{
	if (type.member_types.empty())
		SPIRV_CROSS_THROW("Declared struct in block cannot be empty.");

	// Offsets can be declared out of order, so we need to deduce the actual size
	// based on last member instead.
	uint32_t member_index = 0;
	size_t highest_offset = 0;
	for (uint32_t i = 0; i < uint32_t(type.member_types.size()); i++)
	{
		size_t offset = type_struct_member_offset(type, i);
		if (offset > highest_offset)
		{
			highest_offset = offset;
			member_index = i;
		}
	}

	size_t size = get_declared_struct_member_size(type, member_index);
	return highest_offset + size;
}

size_t Compiler::get_declared_struct_size_runtime_array(const SPIRType &type, size_t array_size) const
{
	if (type.member_types.empty())
		SPIRV_CROSS_THROW("Declared struct in block cannot be empty.");

	size_t size = get_declared_struct_size(type);
	auto &last_type = get<SPIRType>(type.member_types.back());
	if (!last_type.array.empty() && last_type.array_size_literal[0] && last_type.array[0] == 0) // Runtime array
		size += array_size * type_struct_member_array_stride(type, uint32_t(type.member_types.size() - 1));

	return size;
}

uint32_t Compiler::evaluate_spec_constant_u32(const SPIRConstantOp &spec) const
{
	auto &result_type = get<SPIRType>(spec.basetype);
	if (result_type.basetype != SPIRType::UInt && result_type.basetype != SPIRType::Int &&
	    result_type.basetype != SPIRType::Boolean)
	{
		SPIRV_CROSS_THROW(
		    "Only 32-bit integers and booleans are currently supported when evaluating specialization constants.\n");
	}

	if (!is_scalar(result_type))
		SPIRV_CROSS_THROW("Spec constant evaluation must be a scalar.\n");

	uint32_t value = 0;

	const auto eval_u32 = [&](uint32_t id) -> uint32_t {
		auto &type = expression_type(id);
		if (type.basetype != SPIRType::UInt && type.basetype != SPIRType::Int && type.basetype != SPIRType::Boolean)
		{
			SPIRV_CROSS_THROW("Only 32-bit integers and booleans are currently supported when evaluating "
			                  "specialization constants.\n");
		}

		if (!is_scalar(type))
			SPIRV_CROSS_THROW("Spec constant evaluation must be a scalar.\n");
		if (const auto *c = this->maybe_get<SPIRConstant>(id))
			return c->scalar();
		else
			return evaluate_spec_constant_u32(this->get<SPIRConstantOp>(id));
	};

#define binary_spec_op(op, binary_op)                                              \
	case Op##op:                                                                   \
		value = eval_u32(spec.arguments[0]) binary_op eval_u32(spec.arguments[1]); \
		break
#define binary_spec_op_cast(op, binary_op, type)                                                         \
	case Op##op:                                                                                         \
		value = uint32_t(type(eval_u32(spec.arguments[0])) binary_op type(eval_u32(spec.arguments[1]))); \
		break

	// Support the basic opcodes which are typically used when computing array sizes.
	switch (spec.opcode)
	{
		binary_spec_op(IAdd, +);
		binary_spec_op(ISub, -);
		binary_spec_op(IMul, *);
		binary_spec_op(BitwiseAnd, &);
		binary_spec_op(BitwiseOr, |);
		binary_spec_op(BitwiseXor, ^);
		binary_spec_op(LogicalAnd, &);
		binary_spec_op(LogicalOr, |);
		binary_spec_op(ShiftLeftLogical, <<);
		binary_spec_op(ShiftRightLogical, >>);
		binary_spec_op_cast(ShiftRightArithmetic, >>, int32_t);
		binary_spec_op(LogicalEqual, ==);
		binary_spec_op(LogicalNotEqual, !=);
		binary_spec_op(IEqual, ==);
		binary_spec_op(INotEqual, !=);
		binary_spec_op(ULessThan, <);
		binary_spec_op(ULessThanEqual, <=);
		binary_spec_op(UGreaterThan, >);
		binary_spec_op(UGreaterThanEqual, >=);
		binary_spec_op_cast(SLessThan, <, int32_t);
		binary_spec_op_cast(SLessThanEqual, <=, int32_t);
		binary_spec_op_cast(SGreaterThan, >, int32_t);
		binary_spec_op_cast(SGreaterThanEqual, >=, int32_t);
#undef binary_spec_op
#undef binary_spec_op_cast

	case OpLogicalNot:
		value = uint32_t(!eval_u32(spec.arguments[0]));
		break;

	case OpNot:
		value = ~eval_u32(spec.arguments[0]);
		break;

	case OpSNegate:
		value = uint32_t(-int32_t(eval_u32(spec.arguments[0])));
		break;

	case OpSelect:
		value = eval_u32(spec.arguments[0]) ? eval_u32(spec.arguments[1]) : eval_u32(spec.arguments[2]);
		break;

	case OpUMod:
	{
		uint32_t a = eval_u32(spec.arguments[0]);
		uint32_t b = eval_u32(spec.arguments[1]);
		if (b == 0)
			SPIRV_CROSS_THROW("Undefined behavior in UMod, b == 0.\n");
		value = a % b;
		break;
	}

	case OpSRem:
	{
		auto a = int32_t(eval_u32(spec.arguments[0]));
		auto b = int32_t(eval_u32(spec.arguments[1]));
		if (b == 0)
			SPIRV_CROSS_THROW("Undefined behavior in SRem, b == 0.\n");
		value = a % b;
		break;
	}

	case OpSMod:
	{
		auto a = int32_t(eval_u32(spec.arguments[0]));
		auto b = int32_t(eval_u32(spec.arguments[1]));
		if (b == 0)
			SPIRV_CROSS_THROW("Undefined behavior in SMod, b == 0.\n");
		auto v = a % b;

		// Makes sure we match the sign of b, not a.
		if ((b < 0 && v > 0) || (b > 0 && v < 0))
			v += b;
		value = v;
		break;
	}

	case OpUDiv:
	{
		uint32_t a = eval_u32(spec.arguments[0]);
		uint32_t b = eval_u32(spec.arguments[1]);
		if (b == 0)
			SPIRV_CROSS_THROW("Undefined behavior in UDiv, b == 0.\n");
		value = a / b;
		break;
	}

	case OpSDiv:
	{
		auto a = int32_t(eval_u32(spec.arguments[0]));
		auto b = int32_t(eval_u32(spec.arguments[1]));
		if (b == 0)
			SPIRV_CROSS_THROW("Undefined behavior in SDiv, b == 0.\n");
		value = a / b;
		break;
	}

	default:
		SPIRV_CROSS_THROW("Unsupported spec constant opcode for evaluation.\n");
	}

	return value;
}

uint32_t Compiler::evaluate_constant_u32(uint32_t id) const
{
	if (const auto *c = maybe_get<SPIRConstant>(id))
		return c->scalar();
	else
		return evaluate_spec_constant_u32(get<SPIRConstantOp>(id));
}

size_t Compiler::get_declared_struct_member_size(const SPIRType &struct_type, uint32_t index) const
{
	if (struct_type.member_types.empty())
		SPIRV_CROSS_THROW("Declared struct in block cannot be empty.");

	auto &flags = get_member_decoration_bitset(struct_type.self, index);
	auto &type = get<SPIRType>(struct_type.member_types[index]);

	switch (type.basetype)
	{
	case SPIRType::Unknown:
	case SPIRType::Void:
	case SPIRType::Boolean: // Bools are purely logical, and cannot be used for externally visible types.
	case SPIRType::AtomicCounter:
	case SPIRType::Image:
	case SPIRType::SampledImage:
	case SPIRType::Sampler:
		SPIRV_CROSS_THROW("Querying size for object with opaque size.");

	default:
		break;
	}

	if (type.pointer && type.storage == StorageClassPhysicalStorageBuffer)
	{
		// Check if this is a top-level pointer type, and not an array of pointers.
		if (type.pointer_depth > get<SPIRType>(type.parent_type).pointer_depth)
			return 8;
	}

	if (!type.array.empty())
	{
		// For arrays, we can use ArrayStride to get an easy check.
		bool array_size_literal = type.array_size_literal.back();
		uint32_t array_size = array_size_literal ? type.array.back() : evaluate_constant_u32(type.array.back());
		return type_struct_member_array_stride(struct_type, index) * array_size;
	}
	else if (type.basetype == SPIRType::Struct)
	{
		return get_declared_struct_size(type);
	}
	else
	{
		unsigned vecsize = type.vecsize;
		unsigned columns = type.columns;

		// Vectors.
		if (columns == 1)
		{
			size_t component_size = type.width / 8;
			return vecsize * component_size;
		}
		else
		{
			uint32_t matrix_stride = type_struct_member_matrix_stride(struct_type, index);

			// Per SPIR-V spec, matrices must be tightly packed and aligned up for vec3 accesses.
			if (flags.get(DecorationRowMajor))
				return matrix_stride * vecsize;
			else if (flags.get(DecorationColMajor))
				return matrix_stride * columns;
			else
				SPIRV_CROSS_THROW("Either row-major or column-major must be declared for matrices.");
		}
	}
}

bool Compiler::BufferAccessHandler::handle(Op opcode, const uint32_t *args, uint32_t length)
{
	if (opcode != OpAccessChain && opcode != OpInBoundsAccessChain && opcode != OpPtrAccessChain)
		return true;

	bool ptr_chain = (opcode == OpPtrAccessChain);

	// Invalid SPIR-V.
	if (length < (ptr_chain ? 5u : 4u))
		return false;

	if (args[2] != id)
		return true;

	// Don't bother traversing the entire access chain tree yet.
	// If we access a struct member, assume we access the entire member.
	uint32_t index = compiler.get<SPIRConstant>(args[ptr_chain ? 4 : 3]).scalar();

	// Seen this index already.
	if (seen.find(index) != end(seen))
		return true;
	seen.insert(index);

	auto &type = compiler.expression_type(id);
	uint32_t offset = compiler.type_struct_member_offset(type, index);

	size_t range;
	// If we have another member in the struct, deduce the range by looking at the next member.
	// This is okay since structs in SPIR-V can have padding, but Offset decoration must be
	// monotonically increasing.
	// Of course, this doesn't take into account if the SPIR-V for some reason decided to add
	// very large amounts of padding, but that's not really a big deal.
	if (index + 1 < type.member_types.size())
	{
		range = compiler.type_struct_member_offset(type, index + 1) - offset;
	}
	else
	{
		// No padding, so just deduce it from the size of the member directly.
		range = compiler.get_declared_struct_member_size(type, index);
	}

	ranges.push_back({ index, offset, range });
	return true;
}

SmallVector<BufferRange> Compiler::get_active_buffer_ranges(VariableID id) const
{
	SmallVector<BufferRange> ranges;
	BufferAccessHandler handler(*this, ranges, id);
	traverse_all_reachable_opcodes(get<SPIRFunction>(ir.default_entry_point), handler);
	return ranges;
}

bool Compiler::types_are_logically_equivalent(const SPIRType &a, const SPIRType &b) const
{
	if (a.basetype != b.basetype)
		return false;
	if (a.width != b.width)
		return false;
	if (a.vecsize != b.vecsize)
		return false;
	if (a.columns != b.columns)
		return false;
	if (a.array.size() != b.array.size())
		return false;

	size_t array_count = a.array.size();
	if (array_count && memcmp(a.array.data(), b.array.data(), array_count * sizeof(uint32_t)) != 0)
		return false;

	if (a.basetype == SPIRType::Image || a.basetype == SPIRType::SampledImage)
	{
		if (memcmp(&a.image, &b.image, sizeof(SPIRType::Image)) != 0)
			return false;
	}

	if (a.member_types.size() != b.member_types.size())
		return false;

	size_t member_types = a.member_types.size();
	for (size_t i = 0; i < member_types; i++)
	{
		if (!types_are_logically_equivalent(get<SPIRType>(a.member_types[i]), get<SPIRType>(b.member_types[i])))
			return false;
	}

	return true;
}

const Bitset &Compiler::get_execution_mode_bitset() const
{
	return get_entry_point().flags;
}

void Compiler::set_execution_mode(ExecutionMode mode, uint32_t arg0, uint32_t arg1, uint32_t arg2)
{
	auto &execution = get_entry_point();

	execution.flags.set(mode);
	switch (mode)
	{
	case ExecutionModeLocalSize:
		execution.workgroup_size.x = arg0;
		execution.workgroup_size.y = arg1;
		execution.workgroup_size.z = arg2;
		break;

	case ExecutionModeLocalSizeId:
		execution.workgroup_size.id_x = arg0;
		execution.workgroup_size.id_y = arg1;
		execution.workgroup_size.id_z = arg2;
		break;

	case ExecutionModeInvocations:
		execution.invocations = arg0;
		break;

	case ExecutionModeOutputVertices:
		execution.output_vertices = arg0;
		break;

	case ExecutionModeOutputPrimitivesEXT:
		execution.output_primitives = arg0;
		break;

	default:
		break;
	}
}

void Compiler::unset_execution_mode(ExecutionMode mode)
{
	auto &execution = get_entry_point();
	execution.flags.clear(mode);
}

uint32_t Compiler::get_work_group_size_specialization_constants(SpecializationConstant &x, SpecializationConstant &y,
                                                                SpecializationConstant &z) const
{
	auto &execution = get_entry_point();
	x = { 0, 0 };
	y = { 0, 0 };
	z = { 0, 0 };

	// WorkgroupSize builtin takes precedence over LocalSize / LocalSizeId.
	if (execution.workgroup_size.constant != 0)
	{
		auto &c = get<SPIRConstant>(execution.workgroup_size.constant);

		if (c.m.c[0].id[0] != ID(0))
		{
			x.id = c.m.c[0].id[0];
			x.constant_id = get_decoration(c.m.c[0].id[0], DecorationSpecId);
		}

		if (c.m.c[0].id[1] != ID(0))
		{
			y.id = c.m.c[0].id[1];
			y.constant_id = get_decoration(c.m.c[0].id[1], DecorationSpecId);
		}

		if (c.m.c[0].id[2] != ID(0))
		{
			z.id = c.m.c[0].id[2];
			z.constant_id = get_decoration(c.m.c[0].id[2], DecorationSpecId);
		}
	}
	else if (execution.flags.get(ExecutionModeLocalSizeId))
	{
		auto &cx = get<SPIRConstant>(execution.workgroup_size.id_x);
		if (cx.specialization)
		{
			x.id = execution.workgroup_size.id_x;
			x.constant_id = get_decoration(execution.workgroup_size.id_x, DecorationSpecId);
		}

		auto &cy = get<SPIRConstant>(execution.workgroup_size.id_y);
		if (cy.specialization)
		{
			y.id = execution.workgroup_size.id_y;
			y.constant_id = get_decoration(execution.workgroup_size.id_y, DecorationSpecId);
		}

		auto &cz = get<SPIRConstant>(execution.workgroup_size.id_z);
		if (cz.specialization)
		{
			z.id = execution.workgroup_size.id_z;
			z.constant_id = get_decoration(execution.workgroup_size.id_z, DecorationSpecId);
		}
	}

	return execution.workgroup_size.constant;
}

uint32_t Compiler::get_execution_mode_argument(spv::ExecutionMode mode, uint32_t index) const
{
	auto &execution = get_entry_point();
	switch (mode)
	{
	case ExecutionModeLocalSizeId:
		if (execution.flags.get(ExecutionModeLocalSizeId))
		{
			switch (index)
			{
			case 0:
				return execution.workgroup_size.id_x;
			case 1:
				return execution.workgroup_size.id_y;
			case 2:
				return execution.workgroup_size.id_z;
			default:
				return 0;
			}
		}
		else
			return 0;

	case ExecutionModeLocalSize:
		switch (index)
		{
		case 0:
			if (execution.flags.get(ExecutionModeLocalSizeId) && execution.workgroup_size.id_x != 0)
				return get<SPIRConstant>(execution.workgroup_size.id_x).scalar();
			else
				return execution.workgroup_size.x;
		case 1:
			if (execution.flags.get(ExecutionModeLocalSizeId) && execution.workgroup_size.id_y != 0)
				return get<SPIRConstant>(execution.workgroup_size.id_y).scalar();
			else
				return execution.workgroup_size.y;
		case 2:
			if (execution.flags.get(ExecutionModeLocalSizeId) && execution.workgroup_size.id_z != 0)
				return get<SPIRConstant>(execution.workgroup_size.id_z).scalar();
			else
				return execution.workgroup_size.z;
		default:
			return 0;
		}

	case ExecutionModeInvocations:
		return execution.invocations;

	case ExecutionModeOutputVertices:
		return execution.output_vertices;

	case ExecutionModeOutputPrimitivesEXT:
		return execution.output_primitives;

	default:
		return 0;
	}
}

ExecutionModel Compiler::get_execution_model() const
{
	auto &execution = get_entry_point();
	return execution.model;
}

bool Compiler::is_tessellation_shader(ExecutionModel model)
{
	return model == ExecutionModelTessellationControl || model == ExecutionModelTessellationEvaluation;
}

bool Compiler::is_vertex_like_shader() const
{
	auto model = get_execution_model();
	return model == ExecutionModelVertex || model == ExecutionModelGeometry ||
	       model == ExecutionModelTessellationControl || model == ExecutionModelTessellationEvaluation;
}

bool Compiler::is_tessellation_shader() const
{
	return is_tessellation_shader(get_execution_model());
}

bool Compiler::is_tessellating_triangles() const
{
	return get_execution_mode_bitset().get(ExecutionModeTriangles);
}

void Compiler::set_remapped_variable_state(VariableID id, bool remap_enable)
{
	get<SPIRVariable>(id).remapped_variable = remap_enable;
}

bool Compiler::get_remapped_variable_state(VariableID id) const
{
	return get<SPIRVariable>(id).remapped_variable;
}

void Compiler::set_subpass_input_remapped_components(VariableID id, uint32_t components)
{
	get<SPIRVariable>(id).remapped_components = components;
}

uint32_t Compiler::get_subpass_input_remapped_components(VariableID id) const
{
	return get<SPIRVariable>(id).remapped_components;
}

void Compiler::add_implied_read_expression(SPIRExpression &e, uint32_t source)
{
	auto itr = find(begin(e.implied_read_expressions), end(e.implied_read_expressions), ID(source));
	if (itr == end(e.implied_read_expressions))
		e.implied_read_expressions.push_back(source);
}

void Compiler::add_implied_read_expression(SPIRAccessChain &e, uint32_t source)
{
	auto itr = find(begin(e.implied_read_expressions), end(e.implied_read_expressions), ID(source));
	if (itr == end(e.implied_read_expressions))
		e.implied_read_expressions.push_back(source);
}

void Compiler::add_active_interface_variable(uint32_t var_id)
{
	active_interface_variables.insert(var_id);

	// In SPIR-V 1.4 and up we must also track the interface variable in the entry point.
	if (ir.get_spirv_version() >= 0x10400)
	{
		auto &vars = get_entry_point().interface_variables;
		if (find(begin(vars), end(vars), VariableID(var_id)) == end(vars))
			vars.push_back(var_id);
	}
}

void Compiler::inherit_expression_dependencies(uint32_t dst, uint32_t source_expression)
{
	// Don't inherit any expression dependencies if the expression in dst
	// is not a forwarded temporary.
	if (forwarded_temporaries.find(dst) == end(forwarded_temporaries) ||
	    forced_temporaries.find(dst) != end(forced_temporaries))
	{
		return;
	}

	auto &e = get<SPIRExpression>(dst);
	auto *phi = maybe_get<SPIRVariable>(source_expression);
	if (phi && phi->phi_variable)
	{
		// We have used a phi variable, which can change at the end of the block,
		// so make sure we take a dependency on this phi variable.
		phi->dependees.push_back(dst);
	}

	auto *s = maybe_get<SPIRExpression>(source_expression);
	if (!s)
		return;

	auto &e_deps = e.expression_dependencies;
	auto &s_deps = s->expression_dependencies;

	// If we depend on a expression, we also depend on all sub-dependencies from source.
	e_deps.push_back(source_expression);
	e_deps.insert(end(e_deps), begin(s_deps), end(s_deps));

	// Eliminate duplicated dependencies.
	sort(begin(e_deps), end(e_deps));
	e_deps.erase(unique(begin(e_deps), end(e_deps)), end(e_deps));
}

SmallVector<EntryPoint> Compiler::get_entry_points_and_stages() const
{
	SmallVector<EntryPoint> entries;
	for (auto &entry : ir.entry_points)
		entries.push_back({ entry.second.orig_name, entry.second.model });
	return entries;
}

void Compiler::rename_entry_point(const std::string &old_name, const std::string &new_name, spv::ExecutionModel model)
{
	auto &entry = get_entry_point(old_name, model);
	entry.orig_name = new_name;
	entry.name = new_name;
}

void Compiler::set_entry_point(const std::string &name, spv::ExecutionModel model)
{
	auto &entry = get_entry_point(name, model);
	ir.default_entry_point = entry.self;
}

SPIREntryPoint &Compiler::get_first_entry_point(const std::string &name)
{
	auto itr = find_if(
	    begin(ir.entry_points), end(ir.entry_points),
	    [&](const std::pair<uint32_t, SPIREntryPoint> &entry) -> bool { return entry.second.orig_name == name; });

	if (itr == end(ir.entry_points))
		SPIRV_CROSS_THROW("Entry point does not exist.");

	return itr->second;
}

const SPIREntryPoint &Compiler::get_first_entry_point(const std::string &name) const
{
	auto itr = find_if(
	    begin(ir.entry_points), end(ir.entry_points),
	    [&](const std::pair<uint32_t, SPIREntryPoint> &entry) -> bool { return entry.second.orig_name == name; });

	if (itr == end(ir.entry_points))
		SPIRV_CROSS_THROW("Entry point does not exist.");

	return itr->second;
}

SPIREntryPoint &Compiler::get_entry_point(const std::string &name, ExecutionModel model)
{
	auto itr = find_if(begin(ir.entry_points), end(ir.entry_points),
	                   [&](const std::pair<uint32_t, SPIREntryPoint> &entry) -> bool {
		                   return entry.second.orig_name == name && entry.second.model == model;
	                   });

	if (itr == end(ir.entry_points))
		SPIRV_CROSS_THROW("Entry point does not exist.");

	return itr->second;
}

const SPIREntryPoint &Compiler::get_entry_point(const std::string &name, ExecutionModel model) const
{
	auto itr = find_if(begin(ir.entry_points), end(ir.entry_points),
	                   [&](const std::pair<uint32_t, SPIREntryPoint> &entry) -> bool {
		                   return entry.second.orig_name == name && entry.second.model == model;
	                   });

	if (itr == end(ir.entry_points))
		SPIRV_CROSS_THROW("Entry point does not exist.");

	return itr->second;
}

const string &Compiler::get_cleansed_entry_point_name(const std::string &name, ExecutionModel model) const
{
	return get_entry_point(name, model).name;
}

const SPIREntryPoint &Compiler::get_entry_point() const
{
	return ir.entry_points.find(ir.default_entry_point)->second;
}

SPIREntryPoint &Compiler::get_entry_point()
{
	return ir.entry_points.find(ir.default_entry_point)->second;
}

bool Compiler::interface_variable_exists_in_entry_point(uint32_t id) const
{
	auto &var = get<SPIRVariable>(id);

	if (ir.get_spirv_version() < 0x10400)
	{
		if (var.storage != StorageClassInput && var.storage != StorageClassOutput &&
		    var.storage != StorageClassUniformConstant)
			SPIRV_CROSS_THROW("Only Input, Output variables and Uniform constants are part of a shader linking interface.");

		// This is to avoid potential problems with very old glslang versions which did
		// not emit input/output interfaces properly.
		// We can assume they only had a single entry point, and single entry point
		// shaders could easily be assumed to use every interface variable anyways.
		if (ir.entry_points.size() <= 1)
			return true;
	}

	// In SPIR-V 1.4 and later, all global resource variables must be present.

	auto &execution = get_entry_point();
	return find(begin(execution.interface_variables), end(execution.interface_variables), VariableID(id)) !=
	       end(execution.interface_variables);
}

void Compiler::CombinedImageSamplerHandler::push_remap_parameters(const SPIRFunction &func, const uint32_t *args,
                                                                  uint32_t length)
{
	// If possible, pipe through a remapping table so that parameters know
	// which variables they actually bind to in this scope.
	unordered_map<uint32_t, uint32_t> remapping;
	for (uint32_t i = 0; i < length; i++)
		remapping[func.arguments[i].id] = remap_parameter(args[i]);
	parameter_remapping.push(std::move(remapping));
}

void Compiler::CombinedImageSamplerHandler::pop_remap_parameters()
{
	parameter_remapping.pop();
}

uint32_t Compiler::CombinedImageSamplerHandler::remap_parameter(uint32_t id)
{
	auto *var = compiler.maybe_get_backing_variable(id);
	if (var)
		id = var->self;

	if (parameter_remapping.empty())
		return id;

	auto &remapping = parameter_remapping.top();
	auto itr = remapping.find(id);
	if (itr != end(remapping))
		return itr->second;
	else
		return id;
}

bool Compiler::CombinedImageSamplerHandler::begin_function_scope(const uint32_t *args, uint32_t length)
{
	if (length < 3)
		return false;

	auto &callee = compiler.get<SPIRFunction>(args[2]);
	args += 3;
	length -= 3;
	push_remap_parameters(callee, args, length);
	functions.push(&callee);
	return true;
}

bool Compiler::CombinedImageSamplerHandler::end_function_scope(const uint32_t *args, uint32_t length)
{
	if (length < 3)
		return false;

	auto &callee = compiler.get<SPIRFunction>(args[2]);
	args += 3;

	// There are two types of cases we have to handle,
	// a callee might call sampler2D(texture2D, sampler) directly where
	// one or more parameters originate from parameters.
	// Alternatively, we need to provide combined image samplers to our callees,
	// and in this case we need to add those as well.

	pop_remap_parameters();

	// Our callee has now been processed at least once.
	// No point in doing it again.
	callee.do_combined_parameters = false;

	auto &params = functions.top()->combined_parameters;
	functions.pop();
	if (functions.empty())
		return true;

	auto &caller = *functions.top();
	if (caller.do_combined_parameters)
	{
		for (auto &param : params)
		{
			VariableID image_id = param.global_image ? param.image_id : VariableID(args[param.image_id]);
			VariableID sampler_id = param.global_sampler ? param.sampler_id : VariableID(args[param.sampler_id]);

			auto *i = compiler.maybe_get_backing_variable(image_id);
			auto *s = compiler.maybe_get_backing_variable(sampler_id);
			if (i)
				image_id = i->self;
			if (s)
				sampler_id = s->self;

			register_combined_image_sampler(caller, 0, image_id, sampler_id, param.depth);
		}
	}

	return true;
}

void Compiler::CombinedImageSamplerHandler::register_combined_image_sampler(SPIRFunction &caller,
                                                                            VariableID combined_module_id,
                                                                            VariableID image_id, VariableID sampler_id,
                                                                            bool depth)
{
	// We now have a texture ID and a sampler ID which will either be found as a global
	// or a parameter in our own function. If both are global, they will not need a parameter,
	// otherwise, add it to our list.
	SPIRFunction::CombinedImageSamplerParameter param = {
		0u, image_id, sampler_id, true, true, depth,
	};

	auto texture_itr = find_if(begin(caller.arguments), end(caller.arguments),
	                           [image_id](const SPIRFunction::Parameter &p) { return p.id == image_id; });
	auto sampler_itr = find_if(begin(caller.arguments), end(caller.arguments),
	                           [sampler_id](const SPIRFunction::Parameter &p) { return p.id == sampler_id; });

	if (texture_itr != end(caller.arguments))
	{
		param.global_image = false;
		param.image_id = uint32_t(texture_itr - begin(caller.arguments));
	}

	if (sampler_itr != end(caller.arguments))
	{
		param.global_sampler = false;
		param.sampler_id = uint32_t(sampler_itr - begin(caller.arguments));
	}

	if (param.global_image && param.global_sampler)
		return;

	auto itr = find_if(begin(caller.combined_parameters), end(caller.combined_parameters),
	                   [&param](const SPIRFunction::CombinedImageSamplerParameter &p) {
		                   return param.image_id == p.image_id && param.sampler_id == p.sampler_id &&
		                          param.global_image == p.global_image && param.global_sampler == p.global_sampler;
	                   });

	if (itr == end(caller.combined_parameters))
	{
		uint32_t id = compiler.ir.increase_bound_by(3);
		auto type_id = id + 0;
		auto ptr_type_id = id + 1;
		auto combined_id = id + 2;
		auto &base = compiler.expression_type(image_id);
		auto &type = compiler.set<SPIRType>(type_id);
		auto &ptr_type = compiler.set<SPIRType>(ptr_type_id);

		type = base;
		type.self = type_id;
		type.basetype = SPIRType::SampledImage;
		type.pointer = false;
		type.storage = StorageClassGeneric;
		type.image.depth = depth;

		ptr_type = type;
		ptr_type.pointer = true;
		ptr_type.storage = StorageClassUniformConstant;
		ptr_type.parent_type = type_id;

		// Build new variable.
		compiler.set<SPIRVariable>(combined_id, ptr_type_id, StorageClassFunction, 0);

		// Inherit RelaxedPrecision.
		// If any of OpSampledImage, underlying image or sampler are marked, inherit the decoration.
		bool relaxed_precision =
		    compiler.has_decoration(sampler_id, DecorationRelaxedPrecision) ||
		    compiler.has_decoration(image_id, DecorationRelaxedPrecision) ||
		    (combined_module_id && compiler.has_decoration(combined_module_id, DecorationRelaxedPrecision));

		if (relaxed_precision)
			compiler.set_decoration(combined_id, DecorationRelaxedPrecision);

		param.id = combined_id;

		compiler.set_name(combined_id,
		                  join("SPIRV_Cross_Combined", compiler.to_name(image_id), compiler.to_name(sampler_id)));

		caller.combined_parameters.push_back(param);
		caller.shadow_arguments.push_back({ ptr_type_id, combined_id, 0u, 0u, true });
	}
}

bool Compiler::DummySamplerForCombinedImageHandler::handle(Op opcode, const uint32_t *args, uint32_t length)
{
	if (need_dummy_sampler)
	{
		// No need to traverse further, we know the result.
		return false;
	}

	switch (opcode)
	{
	case OpLoad:
	{
		if (length < 3)
			return false;

		uint32_t result_type = args[0];

		auto &type = compiler.get<SPIRType>(result_type);
		bool separate_image =
		    type.basetype == SPIRType::Image && type.image.sampled == 1 && type.image.dim != DimBuffer;

		// If not separate image, don't bother.
		if (!separate_image)
			return true;

		uint32_t id = args[1];
		uint32_t ptr = args[2];
		compiler.set<SPIRExpression>(id, "", result_type, true);
		compiler.register_read(id, ptr, true);
		break;
	}

	case OpImageFetch:
	case OpImageQuerySizeLod:
	case OpImageQuerySize:
	case OpImageQueryLevels:
	case OpImageQuerySamples:
	{
		// If we are fetching or querying LOD from a plain OpTypeImage, we must pre-combine with our dummy sampler.
		auto *var = compiler.maybe_get_backing_variable(args[2]);
		if (var)
		{
			auto &type = compiler.get<SPIRType>(var->basetype);
			if (type.basetype == SPIRType::Image && type.image.sampled == 1 && type.image.dim != DimBuffer)
				need_dummy_sampler = true;
		}

		break;
	}

	case OpInBoundsAccessChain:
	case OpAccessChain:
	case OpPtrAccessChain:
	{
		if (length < 3)
			return false;

		uint32_t result_type = args[0];
		auto &type = compiler.get<SPIRType>(result_type);
		bool separate_image =
		    type.basetype == SPIRType::Image && type.image.sampled == 1 && type.image.dim != DimBuffer;
		if (!separate_image)
			return true;

		uint32_t id = args[1];
		uint32_t ptr = args[2];
		compiler.set<SPIRExpression>(id, "", result_type, true);
		compiler.register_read(id, ptr, true);

		// Other backends might use SPIRAccessChain for this later.
		compiler.ir.ids[id].set_allow_type_rewrite();
		break;
	}

	default:
		break;
	}

	return true;
}

bool Compiler::CombinedImageSamplerHandler::handle(Op opcode, const uint32_t *args, uint32_t length)
{
	// We need to figure out where samplers and images are loaded from, so do only the bare bones compilation we need.
	bool is_fetch = false;

	switch (opcode)
	{
	case OpLoad:
	{
		if (length < 3)
			return false;