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;
 	};