From 00be85f53c5bec0be00a7ed6271e1f5a38e0b534 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Fri, 2 Dec 2016 12:26:12 +0200
Subject: [PATCH] Reorder declarations in shaders

So that structs appear before variables and variables appear before
functions.  This ensures that the declarations stay visible if an
expression is moved to an earlier point while inlining functions.
---
 source/programcompiler.cpp | 40 ++++++++++++++++++++++++++++++++++++++
 source/programcompiler.h   | 23 ++++++++++++++++++++++
 2 files changed, 63 insertions(+)

diff --git a/source/programcompiler.cpp b/source/programcompiler.cpp
index fdb2576e..7224df1e 100644
--- a/source/programcompiler.cpp
+++ b/source/programcompiler.cpp
@@ -165,6 +165,7 @@ void ProgramCompiler::generate(Stage &stage)
 	apply<InterfaceGenerator>(stage);
 	apply<VariableResolver>(stage);
 	apply<VariableRenamer>(stage);
+	apply<DeclarationReorderer>(stage);
 	apply<LegacyConverter>(stage);
 }
 
@@ -917,6 +918,45 @@ void ProgramCompiler::VariableRenamer::visit(VariableDeclaration &var)
 }
 
 
+ProgramCompiler::DeclarationReorderer::DeclarationReorderer():
+	kind(NO_DECLARATION)
+{ }
+
+void ProgramCompiler::DeclarationReorderer::visit(Block &block)
+{
+	list<RefPtr<Node> >::iterator struct_insert_point = block.body.end();
+	list<RefPtr<Node> >::iterator variable_insert_point = block.body.end();
+
+	for(list<RefPtr<Node> >::iterator i=block.body.begin(); i!=block.body.end(); )
+	{
+		kind = NO_DECLARATION;
+		(*i)->visit(*this);
+
+		bool moved = false;
+		if(kind==STRUCT && struct_insert_point!=block.body.end())
+		{
+			block.body.insert(struct_insert_point, *i);
+			moved = true;
+		}
+		else if(kind>STRUCT && struct_insert_point==block.body.end())
+			struct_insert_point = i;
+
+		if(kind==VARIABLE && variable_insert_point!=block.body.end())
+		{
+			block.body.insert(variable_insert_point, *i);
+			moved = true;
+		}
+		else if(kind>VARIABLE && variable_insert_point==block.body.end())
+			variable_insert_point = i;
+
+		if(moved)
+			block.body.erase(i++);
+		else
+			++i;
+	}
+}
+
+
 ProgramCompiler::ExpressionEvaluator::ExpressionEvaluator():
 	variable_values(0),
 	result(0.0f),
diff --git a/source/programcompiler.h b/source/programcompiler.h
index 398bb214..8c4034d4 100644
--- a/source/programcompiler.h
+++ b/source/programcompiler.h
@@ -156,6 +156,29 @@ private:
 		virtual void visit(ProgramSyntax::VariableDeclaration &);
 	};
 
+	struct DeclarationReorderer: Visitor
+	{
+		enum DeclarationKind
+		{
+			NO_DECLARATION,
+			LAYOUT,
+			STRUCT,
+			VARIABLE,
+			FUNCTION
+		};
+
+		DeclarationKind kind;
+
+		DeclarationReorderer();
+
+		virtual void visit(ProgramSyntax::Block &);
+		virtual void visit(ProgramSyntax::InterfaceLayout &) { kind = LAYOUT; }
+		virtual void visit(ProgramSyntax::StructDeclaration &) { kind = STRUCT; }
+		virtual void visit(ProgramSyntax::VariableDeclaration &) { kind = VARIABLE; }
+		virtual void visit(ProgramSyntax::InterfaceBlock &) { kind = VARIABLE; }
+		virtual void visit(ProgramSyntax::FunctionDeclaration &) { kind = FUNCTION; }
+	};
+
 	struct ExpressionEvaluator: ProgramSyntax::NodeVisitor
 	{
 		typedef std::map<ProgramSyntax::VariableDeclaration *, ProgramSyntax::Expression *> ValueMap;
-- 
2.43.0