Shader: Add EliminateUnusedPassVisitor and use it when optimizing

include/Nazara/Shader/Ast/EliminateUnusedPassVisitor.hpp

@@ -0,0 +1,50 @@
+// Copyright (C) 2022 Jérôme "Lynix" Leclercq (lynix680@gmail.com)
+// This file is part of the "Nazara Engine - Shader module"
+// For conditions of distribution and use, see copyright notice in Config.hpp
+
+#pragma once
+
+#ifndef NAZARA_SHADER_AST_ELIMINATEUNUSEDPASSVISITOR_HPP
+#define NAZARA_SHADER_AST_ELIMINATEUNUSEDPASSVISITOR_HPP
+
+#include <Nazara/Prerequisites.hpp>
+#include <Nazara/Core/Bitset.hpp>
+#include <Nazara/Shader/Config.hpp>
+#include <Nazara/Shader/Ast/AstCloner.hpp>
+
+namespace Nz::ShaderAst
+{
+	class NAZARA_SHADER_API EliminateUnusedPassVisitor : AstCloner
+	{
+		public:
+			EliminateUnusedPassVisitor() = default;
+			EliminateUnusedPassVisitor(const EliminateUnusedPassVisitor&) = delete;
+			EliminateUnusedPassVisitor(EliminateUnusedPassVisitor&&) = delete;
+			~EliminateUnusedPassVisitor() = default;
+
+			StatementPtr Process(Statement& statement);
+
+			EliminateUnusedPassVisitor& operator=(const EliminateUnusedPassVisitor&) = delete;
+			EliminateUnusedPassVisitor& operator=(EliminateUnusedPassVisitor&&) = delete;
+
+		private:
+			using AstCloner::Clone;
+			StatementPtr Clone(DeclareExternalStatement& node) override;
+			StatementPtr Clone(DeclareFunctionStatement& node) override;
+			StatementPtr Clone(DeclareStructStatement& node) override;
+			StatementPtr Clone(DeclareVariableStatement& node) override;
+
+			bool IsFunctionUsed(std::size_t varIndex) const;
+			bool IsStructUsed(std::size_t varIndex) const;
+			bool IsVariableUsed(std::size_t varIndex) const;
+
+			struct Context;
+			Context* m_context;
+	};
+
+	inline StatementPtr EliminateUnusedPass(Statement& ast);
+}
+
+#include <Nazara/Shader/Ast/EliminateUnusedPassVisitor.inl>
+
+#endif // NAZARA_SHADER_AST_ELIMINATEUNUSEDPASSVISITOR_HPP

include/Nazara/Shader/Ast/EliminateUnusedPassVisitor.inl

@@ -0,0 +1,17 @@
+// Copyright (C) 2022 Jérôme "Lynix" Leclercq (lynix680@gmail.com)
+// This file is part of the "Nazara Engine - Shader module"
+// For conditions of distribution and use, see copyright notice in Config.hpp
+
+#include <Nazara/Shader/Ast/EliminateUnusedPassVisitor.hpp>
+#include <Nazara/Shader/Debug.hpp>
+
+namespace Nz::ShaderAst
+{
+	inline StatementPtr EliminateUnusedPass(Statement& ast)
+	{
+		EliminateUnusedPassVisitor visitor;
+		return visitor.Process(ast);
+	}
+}
+
+#include <Nazara/Shader/DebugOff.hpp>

include/Nazara/Shader/Ast/Nodes.hpp

@@ -265,11 +265,11 @@ namespace Nz::ShaderAst
 			ExpressionValue<UInt32> bindingIndex;
 			ExpressionValue<UInt32> bindingSet;
 			ExpressionValue<ExpressionType> type;
+			std::optional<std::size_t> varIndex;
 			std::string name;
 		};
 
 		ExpressionValue<UInt32> bindingSet;
-		std::optional<std::size_t> varIndex;
 		std::vector<ExternalVar> externalVars;
 	};
 

src/Nazara/Shader/Ast/AstCloner.cpp

@@ -91,8 +91,6 @@ namespace Nz::ShaderAst
 	StatementPtr AstCloner::Clone(DeclareExternalStatement& node)
 	{
 		auto clone = std::make_unique<DeclareExternalStatement>();
-		clone->varIndex = node.varIndex;
-
 		clone->bindingSet = Clone(node.bindingSet);
 
 		clone->externalVars.reserve(node.externalVars.size());
@@ -100,6 +98,7 @@ namespace Nz::ShaderAst
 		{
 			auto& cloneVar = clone->externalVars.emplace_back();
 			cloneVar.name = var.name;
+			cloneVar.varIndex = var.varIndex;
 			cloneVar.type = Clone(var.type);
 			cloneVar.bindingIndex = Clone(var.bindingIndex);
 			cloneVar.bindingSet = Clone(var.bindingSet);

src/Nazara/Shader/Ast/AstSerializer.cpp

@@ -193,14 +193,13 @@ namespace Nz::ShaderAst
 
 	void AstSerializerBase::Serialize(DeclareExternalStatement& node)
 	{
-		OptVal(node.varIndex);
-
 		ExprValue(node.bindingSet);
 
 		Container(node.externalVars);
 		for (auto& extVar : node.externalVars)
 		{
 			Value(extVar.name);
+			OptVal(extVar.varIndex);
 			ExprValue(extVar.type);
 			ExprValue(extVar.bindingIndex);
 			ExprValue(extVar.bindingSet);

src/Nazara/Shader/Ast/EliminateUnusedPassVisitor.cpp

@@ -0,0 +1,308 @@
+// Copyright (C) 2022 Jérôme "Lynix" Leclercq (lynix680@gmail.com)
+// This file is part of the "Nazara Engine - Shader module"
+// For conditions of distribution and use, see copyright notice in Config.hpp
+
+#include <Nazara/Shader/Ast/EliminateUnusedPassVisitor.hpp>
+#include <Nazara/Core/CallOnExit.hpp>
+#include <Nazara/Shader/ShaderBuilder.hpp>
+#include <Nazara/Shader/Ast/AstRecursiveVisitor.hpp>
+#include <unordered_map>
+#include <Nazara/Shader/Debug.hpp>
+
+namespace Nz::ShaderAst
+{
+	namespace
+	{
+		template<typename T> T& Retrieve(std::unordered_map<std::size_t, T>& map, std::size_t id)
+		{
+			auto it = map.find(id);
+			assert(it != map.end());
+			return it->second;
+		}
+
+		template<typename T> const T& Retrieve(const std::unordered_map<std::size_t, T>& map, std::size_t id)
+		{
+			auto it = map.find(id);
+			assert(it != map.end());
+			return it->second;
+		}
+
+		struct UsageChecker : AstRecursiveVisitor
+		{
+			struct UsageSet;
+
+			void Resolve()
+			{
+				Resolve(globalUsage);
+			}
+
+			void Resolve(const UsageSet& usageSet)
+			{
+				resolvedUsage.usedFunctions |= usageSet.usedFunctions;
+				resolvedUsage.usedStructs |= usageSet.usedStructs;
+				resolvedUsage.usedVariables |= usageSet.usedVariables;
+
+				for (std::size_t funcIndex = usageSet.usedFunctions.FindFirst(); funcIndex != usageSet.usedFunctions.npos; funcIndex = usageSet.usedFunctions.FindNext(funcIndex))
+					Resolve(Retrieve(functionUsages, funcIndex));
+
+				for (std::size_t structIndex = usageSet.usedStructs.FindFirst(); structIndex != usageSet.usedStructs.npos; structIndex = usageSet.usedStructs.FindNext(structIndex))
+					Resolve(Retrieve(structUsages, structIndex));
+
+				for (std::size_t varIndex = usageSet.usedVariables.FindFirst(); varIndex != usageSet.usedVariables.npos; varIndex = usageSet.usedVariables.FindNext(varIndex))
+					Resolve(Retrieve(variableUsages, varIndex));
+			}
+
+			using AstRecursiveVisitor::Visit;
+
+			void Visit(CallFunctionExpression& node) override
+			{
+				const auto& targetFuncType = GetExpressionType(node);
+				assert(std::holds_alternative<FunctionType>(targetFuncType));
+
+				const auto& funcType = std::get<FunctionType>(targetFuncType);
+
+				assert(currentFunctionIndex);
+				UsageSet& usageSet = Retrieve(functionUsages, *currentFunctionIndex);
+				usageSet.usedFunctions.UnboundedSet(funcType.funcIndex);
+			}
+
+			void Visit(DeclareExternalStatement& node) override
+			{
+				for (const auto& externalVar : node.externalVars)
+				{
+					assert(externalVar.varIndex);
+					std::size_t varIndex = *externalVar.varIndex;
+
+					assert(variableUsages.find(varIndex) == variableUsages.end());
+					UsageSet& usageSet = variableUsages[varIndex];
+
+					const auto& exprType = externalVar.type.GetResultingValue();
+
+					if (IsUniformType(exprType))
+					{
+						const UniformType& uniformType = std::get<UniformType>(exprType);
+						usageSet.usedStructs.UnboundedSet(uniformType.containedType.structIndex);
+					}
+
+					++varIndex;
+				}
+
+				AstRecursiveVisitor::Visit(node);
+			}
+
+			void Visit(DeclareFunctionStatement& node) override
+			{
+				assert(node.funcIndex);
+				assert(functionUsages.find(*node.funcIndex) == functionUsages.end());
+				UsageSet& usageSet = functionUsages[*node.funcIndex];
+
+				// Register struct used in parameters or return type
+				if (!node.parameters.empty())
+				{
+					assert(node.varIndex);
+					std::size_t parameterVarIndex = *node.varIndex;
+					for (auto& parameter : node.parameters)
+					{
+						// Since parameters must always be defined, their type isn't a dependency of parameter variables
+						assert(variableUsages.find(parameterVarIndex) == variableUsages.end());
+						variableUsages.emplace(parameterVarIndex, UsageSet{});
+
+						const auto& exprType = parameter.type.GetResultingValue();
+						if (IsStructType(exprType))
+						{
+							std::size_t structIndex = std::get<ShaderAst::StructType>(exprType).structIndex;
+							usageSet.usedStructs.UnboundedSet(structIndex);
+						}
+
+						++parameterVarIndex;
+					}
+				}
+
+				if (node.returnType.HasValue())
+				{
+					const auto& returnExprType = node.returnType.GetResultingValue();
+					if (IsStructType(returnExprType))
+					{
+						std::size_t structIndex = std::get<ShaderAst::StructType>(returnExprType).structIndex;
+						usageSet.usedStructs.UnboundedSet(structIndex);
+					}
+				}
+
+				if (node.entryStage.HasValue())
+					globalUsage.usedFunctions.UnboundedSet(*node.funcIndex);
+
+				currentFunctionIndex = node.funcIndex;
+				AstRecursiveVisitor::Visit(node);
+				currentFunctionIndex = {};
+			}
+
+			void Visit(DeclareStructStatement& node) override
+			{
+				assert(node.structIndex);
+				assert(structUsages.find(*node.structIndex) == structUsages.end());
+				UsageSet& usageSet = structUsages[*node.structIndex];
+
+				for (const auto& structMember : node.description.members)
+				{
+					const auto& memberExprType = structMember.type.GetResultingValue();
+					if (IsStructType(memberExprType))
+					{
+						std::size_t structIndex = std::get<ShaderAst::StructType>(memberExprType).structIndex;
+						usageSet.usedStructs.UnboundedSet(structIndex);
+					}
+				}
+
+				AstRecursiveVisitor::Visit(node);
+			}
+
+			void Visit(DeclareVariableStatement& node) override
+			{
+				assert(node.varIndex);
+				assert(variableUsages.find(*node.varIndex) == variableUsages.end());
+				UsageSet& usageSet = variableUsages[*node.varIndex];
+
+				const auto& varType = node.varType.GetResultingValue();
+				if (IsStructType(varType))
+				{
+					const auto& structType = std::get<StructType>(varType);
+					usageSet.usedStructs.UnboundedSet(structType.structIndex);
+				}
+
+				currentVariableDeclIndex = node.varIndex;
+				AstRecursiveVisitor::Visit(node);
+				currentVariableDeclIndex = {};
+			}
+
+			void Visit(VariableExpression& node) override
+			{
+				assert(currentFunctionIndex);
+				if (currentVariableDeclIndex)
+				{
+					UsageSet& usageSet = Retrieve(variableUsages, *currentVariableDeclIndex);
+					usageSet.usedVariables.UnboundedSet(node.variableId);
+				}
+				else
+				{
+					UsageSet& usageSet = Retrieve(functionUsages, *currentFunctionIndex);
+					usageSet.usedVariables.UnboundedSet(node.variableId);
+				}
+			}
+
+			struct UsageSet
+			{
+				Bitset<> usedFunctions;
+				Bitset<> usedStructs;
+				Bitset<> usedVariables;
+			};
+
+			std::optional<std::size_t> currentFunctionIndex;
+			std::optional<std::size_t> currentVariableDeclIndex;
+			std::unordered_map<std::size_t, UsageSet> functionUsages;
+			std::unordered_map<std::size_t, UsageSet> structUsages;
+			std::unordered_map<std::size_t, UsageSet> variableUsages;
+			UsageSet globalUsage;
+			UsageSet resolvedUsage;
+		};
+	}
+
+	struct EliminateUnusedPassVisitor::Context
+	{
+		UsageChecker usageChecker;
+	};
+
+	StatementPtr EliminateUnusedPassVisitor::Process(Statement& statement)
+	{
+		Context context;
+		statement.Visit(context.usageChecker);
+		context.usageChecker.Resolve();
+
+		m_context = &context;
+		CallOnExit onExit([this]()
+		{
+			m_context = nullptr;
+		});
+
+		return Clone(statement);
+	}
+
+	StatementPtr EliminateUnusedPassVisitor::Clone(DeclareExternalStatement& node)
+	{
+		bool isUsed = false;
+		for (const auto& externalVar : node.externalVars)
+		{
+			assert(externalVar.varIndex);
+			std::size_t varIndex = *externalVar.varIndex;
+
+			if (IsVariableUsed(varIndex))
+			{
+				isUsed = true;
+				break;
+			}
+		}
+
+		if (!isUsed)
+			return ShaderBuilder::NoOp();
+
+		auto clonedNode = AstCloner::Clone(node);
+
+		auto& externalStatement = static_cast<DeclareExternalStatement&>(*clonedNode);
+		for (auto it = externalStatement.externalVars.begin(); it != externalStatement.externalVars.end(); )
+		{
+			const auto& externalVar = *it;
+			assert(externalVar.varIndex);
+			std::size_t varIndex = *externalVar.varIndex;
+
+			if (!IsVariableUsed(varIndex))
+				it = externalStatement.externalVars.erase(it);
+			else
+				++it;
+		}
+
+		return clonedNode;
+	}
+
+	StatementPtr EliminateUnusedPassVisitor::Clone(DeclareFunctionStatement& node)
+	{
+		assert(node.funcIndex);
+		if (!IsFunctionUsed(*node.funcIndex))
+			return ShaderBuilder::NoOp();
+
+		return AstCloner::Clone(node);
+	}
+
+	StatementPtr EliminateUnusedPassVisitor::Clone(DeclareStructStatement& node)
+	{
+		assert(node.structIndex);
+		if (!IsStructUsed(*node.structIndex))
+			return ShaderBuilder::NoOp();
+
+		return AstCloner::Clone(node);
+	}
+
+	StatementPtr EliminateUnusedPassVisitor::Clone(DeclareVariableStatement& node)
+	{
+		assert(node.varIndex);
+		if (!IsVariableUsed(*node.varIndex))
+			return ShaderBuilder::NoOp();
+
+		return AstCloner::Clone(node);
+	}
+
+	bool EliminateUnusedPassVisitor::IsFunctionUsed(std::size_t varIndex) const
+	{
+		assert(m_context);
+		return m_context->usageChecker.resolvedUsage.usedFunctions.UnboundedTest(varIndex);
+	}
+
+	bool EliminateUnusedPassVisitor::IsStructUsed(std::size_t varIndex) const
+	{
+		assert(m_context);
+		return m_context->usageChecker.resolvedUsage.usedStructs.UnboundedTest(varIndex);
+	}
+
+	bool EliminateUnusedPassVisitor::IsVariableUsed(std::size_t varIndex) const
+	{
+		assert(m_context);
+		return m_context->usageChecker.resolvedUsage.usedVariables.UnboundedTest(varIndex);
+	}
+}

src/Nazara/Shader/Ast/SanitizeVisitor.cpp

@@ -786,10 +786,7 @@ namespace Nz::ShaderAst
 				throw AstError{ "external variable " + extVar.name + " is of wrong type: only uniform and sampler are allowed in external blocks" };
 
 			extVar.type = std::move(resolvedType);
-
+			extVar.varIndex = RegisterVariable(extVar.name, std::move(varType));
-			std::size_t varIndex = RegisterVariable(extVar.name, std::move(varType));
-			if (!clone->varIndex)
-				clone->varIndex = varIndex; //< First external variable index is node variable index
 
 			SanitizeIdentifier(extVar.name);
 		}

src/Nazara/Shader/GlslWriter.cpp

@@ -12,6 +12,7 @@
 #include <Nazara/Shader/Ast/AstOptimizer.hpp>
 #include <Nazara/Shader/Ast/AstRecursiveVisitor.hpp>
 #include <Nazara/Shader/Ast/AstUtils.hpp>
+#include <Nazara/Shader/Ast/EliminateUnusedPassVisitor.hpp>
 #include <Nazara/Shader/Ast/SanitizeVisitor.hpp>
 #include <optional>
 #include <set>
@@ -177,7 +178,11 @@ namespace Nz
 		ShaderAst::StatementPtr optimizedAst;
 		if (states.optimize)
 		{
-			optimizedAst = ShaderAst::Optimize(*targetAst);
+			ShaderAst::StatementPtr tempAst;
+
+			tempAst = ShaderAst::Optimize(*targetAst);
+			optimizedAst = ShaderAst::EliminateUnusedPass(*tempAst);
+
 			targetAst = optimizedAst.get();
 		}
 
@@ -992,9 +997,6 @@ namespace Nz
 
 	void GlslWriter::Visit(ShaderAst::DeclareExternalStatement& node)
 	{
-		assert(node.varIndex);
-		std::size_t varIndex = *node.varIndex;
-
 		for (const auto& externalVar : node.externalVars)
 		{
 			bool isStd140 = false;
@@ -1075,7 +1077,8 @@ namespace Nz
 			if (IsUniformType(externalVar.type.GetResultingValue()))
 				AppendLine();
 
-			RegisterVariable(varIndex++, externalVar.name);
+			assert(externalVar.varIndex);
+			RegisterVariable(*externalVar.varIndex, externalVar.name);
 		}
 	}
 

src/Nazara/Shader/LangWriter.cpp

@@ -787,9 +787,6 @@ namespace Nz
 
 	void LangWriter::Visit(ShaderAst::DeclareExternalStatement& node)
 	{
-		assert(node.varIndex);
-		std::size_t varIndex = *node.varIndex;
-
 		AppendLine("external");
 		EnterScope();
 
@@ -804,7 +801,8 @@ namespace Nz
 			AppendAttributes(false, SetAttribute{ externalVar.bindingSet }, BindingAttribute{ externalVar.bindingIndex });
 			Append(externalVar.name, ": ", externalVar.type);
 
-			RegisterVariable(varIndex++, externalVar.name);
+			assert(externalVar.varIndex);
+			RegisterVariable(*externalVar.varIndex, externalVar.name);
 		}
 
 		LeaveScope();

src/Nazara/Shader/SpirvAstVisitor.cpp

@@ -579,11 +579,11 @@ namespace Nz
 
 	void SpirvAstVisitor::Visit(ShaderAst::DeclareExternalStatement& node)
 	{
-		assert(node.varIndex);
-
-		std::size_t varIndex = *node.varIndex;
 		for (auto&& extVar : node.externalVars)
-			RegisterExternalVariable(varIndex++, extVar.type.GetResultingValue());
+		{
+			assert(extVar.varIndex);
+			RegisterExternalVariable(*extVar.varIndex, extVar.type.GetResultingValue());
+		}
 	}
 
 	void SpirvAstVisitor::Visit(ShaderAst::DeclareFunctionStatement& node)

src/Nazara/Shader/SpirvWriter.cpp

@@ -13,6 +13,7 @@
 #include <Nazara/Shader/Ast/AstCloner.hpp>
 #include <Nazara/Shader/Ast/AstOptimizer.hpp>
 #include <Nazara/Shader/Ast/AstRecursiveVisitor.hpp>
+#include <Nazara/Shader/Ast/EliminateUnusedPassVisitor.hpp>
 #include <Nazara/Shader/Ast/SanitizeVisitor.hpp>
 #include <SpirV/GLSL.std.450.h>
 #include <tsl/ordered_map.h>
@@ -137,8 +138,6 @@ namespace Nz
 
 				void Visit(ShaderAst::DeclareExternalStatement& node) override
 				{
-					assert(node.varIndex);
-					std::size_t varIndex = *node.varIndex;
 					for (auto& extVar : node.externalVars)
 					{
 						SpirvConstantCache::Variable variable;
@@ -165,7 +164,8 @@ namespace Nz
 
 						assert(extVar.bindingIndex.IsResultingValue());
 
-						UniformVar& uniformVar = extVars[varIndex++];
+						assert(extVar.varIndex);
+						UniformVar& uniformVar = extVars[*extVar.varIndex];
 						uniformVar.pointerId = m_constantCache.Register(variable);
 						uniformVar.bindingIndex = extVar.bindingIndex.GetResultingValue();
 						uniformVar.descriptorSet = (extVar.bindingSet.HasValue()) ? extVar.bindingSet.GetResultingValue() : 0;
@@ -519,7 +519,11 @@ namespace Nz
 		ShaderAst::StatementPtr optimizedAst;
 		if (states.optimize)
 		{
-			optimizedAst = ShaderAst::Optimize(*targetAst);
+			ShaderAst::StatementPtr tempAst;
+
+			tempAst = ShaderAst::Optimize(*targetAst);
+			optimizedAst = ShaderAst::EliminateUnusedPass(*tempAst);
+
 			targetAst = optimizedAst.get();
 		}
 

src/ShaderNode/Widgets/CodeOutputWidget.cpp

@@ -2,6 +2,7 @@
 #include <Nazara/Shader/GlslWriter.hpp>
 #include <Nazara/Shader/LangWriter.hpp>
 #include <Nazara/Shader/Ast/AstOptimizer.hpp>
+#include <Nazara/Shader/Ast/EliminateUnusedPassVisitor.hpp>
 #include <Nazara/Shader/Ast/SanitizeVisitor.hpp>
 #include <Nazara/Shader/SpirvPrinter.hpp>
 #include <Nazara/Shader/SpirvWriter.hpp>
@@ -16,7 +17,7 @@
 enum class OutputLanguage
 {
 	GLSL,
-	Nazalang,
+	NZSL,
 	SpirV
 };
 
@@ -27,7 +28,7 @@ m_shaderGraph(shaderGraph)
 
 	m_outputLang = new QComboBox;
 	m_outputLang->addItem("GLSL", int(OutputLanguage::GLSL));
-	m_outputLang->addItem("Nazalang", int(OutputLanguage::Nazalang));
+	m_outputLang->addItem("NZSL", int(OutputLanguage::NZSL));
 	m_outputLang->addItem("SPIR-V", int(OutputLanguage::SpirV));
 	connect(m_outputLang, qOverload<int>(&QComboBox::currentIndexChanged), [this](int)
 	{
@@ -70,7 +71,8 @@ void CodeOutputWidget::Refresh()
 			shaderAst = Nz::ShaderAst::Sanitize(*shaderAst, sanitizeOptions);
 
 			Nz::ShaderAst::AstOptimizer optimiser;
-			shaderAst = optimiser.Optimise(*shaderAst);
+			shaderAst = Nz::ShaderAst::Optimize(*shaderAst);
+			shaderAst = Nz::ShaderAst::EliminateUnusedPass(*shaderAst);
 		}
 
 		std::string output;
@@ -91,7 +93,7 @@ void CodeOutputWidget::Refresh()
 				break;
 			}
 
-			case OutputLanguage::Nazalang:
+			case OutputLanguage::NZSL:
 			{
 				Nz::LangWriter writer;
 				output = writer.Generate(*shaderAst, states);