From 7434b80c452eb8f7ac8200a6f693a9eb668421f0 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Mon, 14 Nov 2016 13:41:46 +0200
Subject: [PATCH] Further reduce overhead of applying ProgramCompiler visitors

---
 source/programcompiler.cpp | 32 +++++++++++++++++---------------
 source/programcompiler.h   | 16 ++++++++++++++--
 2 files changed, 31 insertions(+), 17 deletions(-)

diff --git a/source/programcompiler.cpp b/source/programcompiler.cpp
index a730f743..63939409 100644
--- a/source/programcompiler.cpp
+++ b/source/programcompiler.cpp
@@ -58,11 +58,11 @@ void ProgramCompiler::add_shaders(Program &program)
 	for(list<Stage>::iterator i=module->stages.begin(); i!=module->stages.end(); ++i)
 	{
 		if(i->type==VERTEX)
-			program.attach_shader_owned(new VertexShader(head+create_source(*i)));
+			program.attach_shader_owned(new VertexShader(head+apply<Formatter>(*i)));
 		else if(i->type==GEOMETRY)
-			program.attach_shader_owned(new GeometryShader(head+create_source(*i)));
+			program.attach_shader_owned(new GeometryShader(head+apply<Formatter>(*i)));
 		else if(i->type==FRAGMENT)
-			program.attach_shader_owned(new FragmentShader(head+create_source(*i)));
+			program.attach_shader_owned(new FragmentShader(head+apply<Formatter>(*i)));
 	}
 
 	program.bind_attribute(VERTEX4, "vertex");
@@ -125,14 +125,10 @@ void ProgramCompiler::generate(Stage &stage)
 
 bool ProgramCompiler::optimize(Stage &stage)
 {
-	UnusedVariableLocator unused_locator;
-	unused_locator.apply(stage);
+	set<Node *> unused = apply<UnusedVariableLocator>(stage);
+	apply<NodeRemover>(stage, unused);
 
-	NodeRemover remover;
-	remover.to_remove = unused_locator.unused_nodes;
-	remover.apply(stage);
-
-	return !unused_locator.unused_nodes.empty();
+	return !unused.empty();
 }
 
 void ProgramCompiler::inject_block(Block &target, const Block &source)
@@ -143,17 +139,19 @@ void ProgramCompiler::inject_block(Block &target, const Block &source)
 }
 
 template<typename T>
-void ProgramCompiler::apply(Stage &stage)
+typename T::ResultType ProgramCompiler::apply(Stage &stage)
 {
 	T visitor;
 	visitor.apply(stage);
+	return visitor.get_result();
 }
 
-string ProgramCompiler::create_source(Stage &stage)
+template<typename T, typename A>
+typename T::ResultType ProgramCompiler::apply(Stage &stage, const A &arg)
 {
-	Formatter formatter;
-	formatter.apply(stage);
-	return formatter.formatted;
+	T visitor(arg);
+	visitor.apply(stage);
+	return visitor.get_result();
 }
 
 
@@ -944,6 +942,10 @@ void ProgramCompiler::UnusedVariableLocator::visit(Iteration &iter)
 }
 
 
+ProgramCompiler::NodeRemover::NodeRemover(const set<Node *> &r):
+	to_remove(r)
+{ }
+
 void ProgramCompiler::NodeRemover::visit(Block &block)
 {
 	for(list<NodePtr<Node> >::iterator i=block.body.begin(); i!=block.body.end(); )
diff --git a/source/programcompiler.h b/source/programcompiler.h
index a2dd9401..2ef4aa7d 100644
--- a/source/programcompiler.h
+++ b/source/programcompiler.h
@@ -15,15 +15,20 @@ class ProgramCompiler
 private:
 	struct Visitor: ProgramSyntax::TraversingVisitor
 	{
+		typedef void ResultType;
+
 		ProgramSyntax::Stage *stage;
 
 		Visitor();
 
 		virtual void apply(ProgramSyntax::Stage &);
+		void get_result() const { }
 	};
 
 	struct Formatter: Visitor
 	{
+		typedef std::string ResultType;
+
 		std::string formatted;
 		unsigned indent;
 		bool parameter_list;
@@ -32,6 +37,7 @@ private:
 
 		Formatter();
 
+		const std::string &get_result() const { return formatted; }
 		virtual void visit(ProgramSyntax::Block &);
 		virtual void visit(ProgramSyntax::Literal &);
 		virtual void visit(ProgramSyntax::ParenthesizedExpression &);
@@ -112,6 +118,7 @@ private:
 			bool self_referencing;
 		};
 
+		typedef std::set<ProgramSyntax::Node *> ResultType;
 		typedef std::map<ProgramSyntax::VariableDeclaration *, AssignmentList> BlockAssignmentMap;
 
 		std::set<ProgramSyntax::Node *> unused_nodes;
@@ -124,6 +131,7 @@ private:
 		UnusedVariableLocator();
 
 		virtual void apply(ProgramSyntax::Stage &);
+		const ResultType &get_result() const { return unused_nodes; }
 		virtual void visit(ProgramSyntax::VariableReference &);
 		virtual void visit(ProgramSyntax::MemberAccess &);
 		virtual void visit(ProgramSyntax::BinaryExpression &);
@@ -143,6 +151,9 @@ private:
 	{
 		std::set<ProgramSyntax::Node *> to_remove;
 
+		NodeRemover() { }
+		NodeRemover(const std::set<ProgramSyntax::Node *> &);
+
 		virtual void visit(ProgramSyntax::Block &);
 		virtual void visit(ProgramSyntax::VariableDeclaration &);
 	};
@@ -166,8 +177,9 @@ private:
 	bool optimize(ProgramSyntax::Stage &);
 	static void inject_block(ProgramSyntax::Block &, const ProgramSyntax::Block &);
 	template<typename T>
-	static void apply(ProgramSyntax::Stage &);
-	std::string create_source(ProgramSyntax::Stage &);
+	static typename T::ResultType apply(ProgramSyntax::Stage &);
+	template<typename T, typename A>
+	static typename T::ResultType apply(ProgramSyntax::Stage &, const A &);
 };
 
 } // namespace GL
-- 
2.43.0