X-Git-Url: http://git.tdb.fi/?p=libs%2Fgl.git;a=blobdiff_plain;f=source%2Fglsl%2Foptimize.cpp;h=9ab8ef70ef94dfc235e08ecee479792f9ae9cf2b;hp=afa6394e19018a4766cb3c05252f97d18700bbbc;hb=7335009e18ecbf53ad9f59d64eed2ed5abbe7b8b;hpb=455fbb0b9c7d7c4b66cc969ad0e9915fe95e420f

diff --git a/source/glsl/optimize.cpp b/source/glsl/optimize.cpp
index afa6394e..9ab8ef70 100644
--- a/source/glsl/optimize.cpp
+++ b/source/glsl/optimize.cpp
@@ -23,6 +23,8 @@ void InlineableFunctionLocator::visit(FunctionCall &call)
 	{
 		unsigned &count = refcounts[def];
 		++count;
+		/* Don't inline functions which are called more than once or are called
+		recursively. */
 		if(count>1 || def==current_function)
 			inlineable.erase(def);
 	}
@@ -68,9 +70,9 @@ InlineContentInjector::InlineContentInjector():
 	deps_only(false)
 { }
 
-const string &InlineContentInjector::apply(Stage &stage, FunctionDeclaration &target_func, Block &tgtb, const NodeList<Statement>::iterator &ins_pt, FunctionDeclaration &src)
+const string &InlineContentInjector::apply(Stage &stage, FunctionDeclaration &target_func, Block &tgt_blk, const NodeList<Statement>::iterator &ins_pt, FunctionDeclaration &src)
 {
-	target_block = &tgtb;
+	target_block = &tgt_blk;
 	source_func = &src;
 	for(NodeList<Statement>::iterator i=src.body.body.begin(); i!=src.body.body.end(); ++i)
 	{
@@ -81,7 +83,7 @@ const string &InlineContentInjector::apply(Stage &stage, FunctionDeclaration &ta
 
 		SetFlag set_remap(remap_names);
 		r_inlined_statement->visit(*this);
-		tgtb.body.insert(ins_pt, r_inlined_statement);
+		tgt_blk.body.insert(ins_pt, r_inlined_statement);
 	}
 
 	NodeReorderer().apply(stage, target_func, dependencies);
@@ -163,6 +165,8 @@ void InlineContentInjector::visit(Return &ret)
 
 	if(ret.expression)
 	{
+		/* Create a new variable to hold the return value of the inlined
+		function. */
 		r_result_name = create_unused_name("return", true);
 		RefPtr<VariableDeclaration> var = new VariableDeclaration;
 		var->source = ret.source;
@@ -189,7 +193,7 @@ bool FunctionInliner::apply(Stage &s)
 	return r_any_inlined;
 }
 
-void FunctionInliner::visit_and_inline(RefPtr<Expression> &ptr)
+void FunctionInliner::visit(RefPtr<Expression> &ptr)
 {
 	r_inline_result = 0;
 	ptr->visit(*this);
@@ -198,6 +202,7 @@ void FunctionInliner::visit_and_inline(RefPtr<Expression> &ptr)
 		ptr = r_inline_result;
 		r_any_inlined = true;
 	}
+	r_inline_result = 0;
 }
 
 void FunctionInliner::visit(Block &block)
@@ -211,29 +216,10 @@ void FunctionInliner::visit(Block &block)
 	}
 }
 
-void FunctionInliner::visit(UnaryExpression &unary)
-{
-	visit_and_inline(unary.expression);
-	r_inline_result = 0;
-}
-
-void FunctionInliner::visit(BinaryExpression &binary)
-{
-	visit_and_inline(binary.left);
-	visit_and_inline(binary.right);
-	r_inline_result = 0;
-}
-
-void FunctionInliner::visit(MemberAccess &memacc)
-{
-	visit_and_inline(memacc.left);
-	r_inline_result = 0;
-}
-
 void FunctionInliner::visit(FunctionCall &call)
 {
 	for(NodeArray<Expression>::iterator i=call.arguments.begin(); i!=call.arguments.end(); ++i)
-		visit_and_inline(*i);
+		visit(*i);
 
 	FunctionDeclaration *def = call.declaration;
 	if(def)
@@ -243,7 +229,7 @@ void FunctionInliner::visit(FunctionCall &call)
 	{
 		string result_name = InlineContentInjector().apply(*stage, *current_function, *current_block, insert_point, *def);
 
-		// This will later get removed by UnusedVariableRemover
+		// This will later get removed by UnusedVariableRemover.
 		if(result_name.empty())
 			result_name = "msp_unused_from_inline";
 
@@ -255,209 +241,455 @@ void FunctionInliner::visit(FunctionCall &call)
 		inlined further. */
 		inlineable.erase(current_function);
 	}
-	else
-		r_inline_result = 0;
 }
 
-void FunctionInliner::visit(ExpressionStatement &expr)
+void FunctionInliner::visit(FunctionDeclaration &func)
 {
-	visit_and_inline(expr.expression);
+	SetForScope<FunctionDeclaration *> set_func(current_function, &func);
+	TraversingVisitor::visit(func);
 }
 
-void FunctionInliner::visit(VariableDeclaration &var)
+void FunctionInliner::visit(Iteration &iter)
 {
-	if(var.init_expression)
-		visit_and_inline(var.init_expression);
-	r_inline_result = 0;
+	/* Visit the initialization statement before entering the loop body so the
+	inlined statements get inserted outside. */
+	if(iter.init_statement)
+		iter.init_statement->visit(*this);
+
+	SetForScope<Block *> set_block(current_block, &iter.body);
+	/* Skip the condition and loop expression parts because they're not properly
+	inside the body block.  Inlining anything into them will require a more
+	comprehensive transformation. */
+	iter.body.visit(*this);
 }
 
-void FunctionInliner::visit(FunctionDeclaration &func)
+
+ExpressionInliner::ExpressionInfo::ExpressionInfo():
+	expression(0),
+	assign_scope(0),
+	inline_point(0),
+	inner_oper(0),
+	outer_oper(0),
+	inline_on_rhs(false),
+	trivial(false),
+	available(true)
+{ }
+
+
+ExpressionInliner::ExpressionInliner():
+	r_ref_info(0),
+	r_any_inlined(false),
+	r_trivial(false),
+	mutating(false),
+	iteration_init(false),
+	iteration_body(0),
+	r_oper(0)
+{ }
+
+bool ExpressionInliner::apply(Stage &s)
 {
-	SetForScope<FunctionDeclaration *> set_func(current_function, &func);
-	TraversingVisitor::visit(func);
+	s.content.visit(*this);
+	return r_any_inlined;
 }
 
-void FunctionInliner::visit(Conditional &cond)
+void ExpressionInliner::visit_and_record(RefPtr<Expression> &ptr, const Operator *outer_oper, bool on_rhs)
 {
-	visit_and_inline(cond.condition);
-	cond.body.visit(*this);
+	r_ref_info = 0;
+	ptr->visit(*this);
+	if(r_ref_info && r_ref_info->expression && r_ref_info->available)
+	{
+		if(iteration_body && !r_ref_info->trivial)
+		{
+			/* Don't inline non-trivial expressions which were assigned outside
+			an iteration statement.  The iteration may run multiple times, which
+			would cause the expression to also be evaluated multiple times. */
+			Block *i = r_ref_info->assign_scope;
+			for(; (i && i!=iteration_body); i=i->parent) ;
+			if(!i)
+				return;
+		}
+
+		r_ref_info->outer_oper = outer_oper;
+		if(r_ref_info->trivial)
+			inline_expression(*r_ref_info->expression, ptr, outer_oper, r_ref_info->inner_oper, on_rhs);
+		else
+		{
+			/* Record the inline point for a non-trivial expression but don't
+			inline it yet.  It might turn out it shouldn't be inlined after all. */
+			r_ref_info->inline_point = &ptr;
+			r_ref_info->inline_on_rhs = on_rhs;
+		}
+	}
+	r_ref_info = 0;
 }
 
-void FunctionInliner::visit(Iteration &iter)
+void ExpressionInliner::inline_expression(Expression &expr, RefPtr<Expression> &ptr, const Operator *outer_oper, const Operator *inner_oper, bool on_rhs)
 {
-	SetForScope<Block *> set_block(current_block, &iter.body);
-	if(iter.init_statement)
-		iter.init_statement->visit(*this);
-	/* Skip the condition and loop expression parts because they're executed on
-	every iteration of the loop */
-	iter.body.visit(*this);
+	unsigned outer_precedence = (outer_oper ? outer_oper->precedence : 20);
+	unsigned inner_precedence = (inner_oper ? inner_oper->precedence : 0);
+
+	bool needs_parentheses = (inner_precedence>=outer_precedence);
+	if(inner_oper && inner_oper==outer_oper)
+		// Omit parentheses if the operator's natural grouping works out.
+		needs_parentheses = (inner_oper->assoc!=Operator::ASSOCIATIVE && on_rhs!=(inner_oper->assoc==Operator::RIGHT_TO_LEFT));
+
+	if(needs_parentheses)
+	{
+		RefPtr<ParenthesizedExpression> parexpr = new ParenthesizedExpression;
+		parexpr->expression = expr.clone();
+		ptr = parexpr;
+	}
+	else
+		ptr = expr.clone();
+
+	r_any_inlined = true;
 }
 
-void FunctionInliner::visit(Return &ret)
+void ExpressionInliner::visit(Block &block)
 {
-	if(ret.expression)
-		visit_and_inline(ret.expression);
-}
+	TraversingVisitor::visit(block);
+
+	for(map<string, VariableDeclaration *>::iterator i=block.variables.begin(); i!=block.variables.end(); ++i)
+	{
+		map<Assignment::Target, ExpressionInfo>::iterator j = expressions.lower_bound(i->second);
+		for(; (j!=expressions.end() && j->first.declaration==i->second); )
+		{
+			if(j->second.expression && j->second.inline_point)
+				inline_expression(*j->second.expression, *j->second.inline_point, j->second.outer_oper, j->second.inner_oper, j->second.inline_on_rhs);
 
+			expressions.erase(j++);
+		}
+	}
 
-ConstantConditionEliminator::ConstantConditionEliminator():
-	record_only(false)
-{ }
+	/* Expressions assigned in this block may depend on local variables of the
+	block.  If this is a conditionally executed block, the assignments might not
+	always happen.  Mark the expressions as not available to any outer blocks. */
+	for(map<Assignment::Target, ExpressionInfo>::iterator i=expressions.begin(); i!=expressions.end(); ++i)
+		if(i->second.assign_scope==&block)
+			i->second.available = false;
+}
 
-void ConstantConditionEliminator::apply(Stage &stage)
+void ExpressionInliner::visit(RefPtr<Expression> &expr)
 {
-	stage.content.visit(*this);
-	NodeRemover().apply(stage, nodes_to_remove);
+	visit_and_record(expr, 0, false);
 }
 
-void ConstantConditionEliminator::visit(Block &block)
+void ExpressionInliner::visit(VariableReference &var)
 {
-	SetForScope<Block *> set_block(current_block, &block);
-	for(NodeList<Statement>::iterator i=block.body.begin(); i!=block.body.end(); ++i)
+	if(var.declaration)
 	{
-		insert_point = i;
-		(*i)->visit(*this);
+		map<Assignment::Target, ExpressionInfo>::iterator i = expressions.find(var.declaration);
+		if(i!=expressions.end())
+		{
+			/* If a non-trivial expression is referenced multiple times, don't
+			inline it. */
+			if(i->second.inline_point && !i->second.trivial)
+				i->second.expression = 0;
+			/* Mutating expressions are analogous to self-referencing assignments
+			and prevent inlining. */
+			if(mutating)
+				i->second.expression = 0;
+			r_ref_info = &i->second;
+		}
 	}
+}
 
-	for(map<string, VariableDeclaration *>::const_iterator i=block.variables.begin(); i!=block.variables.end(); ++i)
-		variable_values.erase(i->second);
+void ExpressionInliner::visit(MemberAccess &memacc)
+{
+	visit_and_record(memacc.left, memacc.oper, false);
+	r_oper = memacc.oper;
+	r_trivial = false;
+}
+
+void ExpressionInliner::visit(Swizzle &swizzle)
+{
+	visit_and_record(swizzle.left, swizzle.oper, false);
+	r_oper = swizzle.oper;
+	r_trivial = false;
 }
 
-void ConstantConditionEliminator::visit(UnaryExpression &unary)
+void ExpressionInliner::visit(UnaryExpression &unary)
 {
-	if(VariableReference *var = dynamic_cast<VariableReference *>(unary.expression.get()))
-		if(unary.oper->token[1]=='+' || unary.oper->token[1]=='-')
-			variable_values.erase(var->declaration);
+	SetFlag set_target(mutating, mutating || unary.oper->token[1]=='+' || unary.oper->token[1]=='-');
+	visit_and_record(unary.expression, unary.oper, false);
+	r_oper = unary.oper;
+	r_trivial = false;
+}
+
+void ExpressionInliner::visit(BinaryExpression &binary)
+{
+	visit_and_record(binary.left, binary.oper, false);
+	{
+		SetFlag clear_target(mutating, false);
+		visit_and_record(binary.right, binary.oper, true);
+	}
+	r_oper = binary.oper;
+	r_trivial = false;
+}
+
+void ExpressionInliner::visit(Assignment &assign)
+{
+	{
+		SetFlag set_target(mutating);
+		visit_and_record(assign.left, assign.oper, false);
+	}
+	r_oper = 0;
+	visit_and_record(assign.right, assign.oper, true);
+
+	map<Assignment::Target, ExpressionInfo>::iterator i = expressions.find(assign.target);
+	if(i!=expressions.end())
+	{
+		/* Self-referencing assignments can't be inlined without additional
+		work.  Just clear any previous expression. */
+		i->second.expression = (assign.self_referencing ? 0 : assign.right.get());
+		i->second.assign_scope = current_block;
+		i->second.inline_point = 0;
+		i->second.inner_oper = r_oper;
+		i->second.available = true;
+	}
+
+	r_oper = assign.oper;
+	r_trivial = false;
 }
 
-void ConstantConditionEliminator::visit(Assignment &assign)
+void ExpressionInliner::visit(FunctionCall &call)
 {
-	variable_values.erase(assign.target_declaration);
+	TraversingVisitor::visit(call);
+	r_oper = 0;
+	r_trivial = false;
 }
 
-void ConstantConditionEliminator::visit(VariableDeclaration &var)
+void ExpressionInliner::visit(VariableDeclaration &var)
 {
+	r_oper = 0;
+	r_trivial = true;
+	TraversingVisitor::visit(var);
+
 	bool constant = var.constant;
 	if(constant && var.layout)
 	{
 		for(vector<Layout::Qualifier>::const_iterator i=var.layout->qualifiers.begin(); (constant && i!=var.layout->qualifiers.end()); ++i)
 			constant = (i->name!="constant_id");
 	}
-	if((constant || current_block->parent) && var.init_expression)
-		variable_values[&var] = var.init_expression.get();
+
+	/* Only inline global variables if they're constant and have trivial
+	initializers.  Non-constant variables could change in ways which are hard to
+	analyze and non-trivial expressions could be expensive to inline.  */
+	if((current_block->parent || (constant && r_trivial)) && var.interface.empty())
+	{
+		ExpressionInfo &info = expressions[&var];
+		/* Assume variables declared in an iteration initialization statement
+		will have their values change throughout the iteration. */
+		info.expression = (iteration_init ? 0 : var.init_expression.get());
+		info.assign_scope = current_block;
+		info.inner_oper = r_oper;
+		info.trivial = r_trivial;
+	}
 }
 
-void ConstantConditionEliminator::visit(Conditional &cond)
+void ExpressionInliner::visit(Iteration &iter)
 {
-	if(!record_only)
+	SetForScope<Block *> set_block(current_block, &iter.body);
+	if(iter.init_statement)
 	{
-		ExpressionEvaluator eval(variable_values);
-		cond.condition->visit(eval);
-		if(eval.is_result_valid())
+		SetFlag set_init(iteration_init);
+		iter.init_statement->visit(*this);
+	}
+
+	SetForScope<Block *> set_body(iteration_body, &iter.body);
+	if(iter.condition)
+		visit(iter.condition);
+	iter.body.visit(*this);
+	if(iter.loop_expression)
+		visit(iter.loop_expression);
+}
+
+
+void ConstantConditionEliminator::apply(Stage &stage)
+{
+	stage.content.visit(*this);
+	NodeRemover().apply(stage, nodes_to_remove);
+}
+
+void ConstantConditionEliminator::visit(Block &block)
+{
+	SetForScope<Block *> set_block(current_block, &block);
+	for(NodeList<Statement>::iterator i=block.body.begin(); i!=block.body.end(); ++i)
+	{
+		insert_point = i;
+		(*i)->visit(*this);
+	}
+}
+
+void ConstantConditionEliminator::visit(Conditional &cond)
+{
+	if(Literal *literal = dynamic_cast<Literal *>(cond.condition.get()))
+		if(literal->value.check_type<bool>())
 		{
-			Block &block = (eval.get_result() ? cond.body : cond.else_body);
+			Block &block = (literal->value.value<bool>() ? cond.body : cond.else_body);
 			current_block->body.splice(insert_point, block.body);
 			nodes_to_remove.insert(&cond);
 			return;
 		}
-	}
 
 	TraversingVisitor::visit(cond);
 }
 
 void ConstantConditionEliminator::visit(Iteration &iter)
 {
-	if(!record_only)
+	if(iter.condition)
 	{
-		if(iter.condition)
+		/* If the loop condition is always false on the first iteration, the
+		entire loop can be removed */
+		ExpressionEvaluator::ValueMap values;
+		if(VariableDeclaration *var = dynamic_cast<VariableDeclaration *>(iter.init_statement.get()))
+			values[var] = var->init_expression.get();
+		ExpressionEvaluator eval(values);
+		iter.condition->visit(eval);
+		if(eval.is_result_valid() && !eval.get_result())
 		{
-			/* If the loop condition is always false on the first iteration, the
-			entire loop can be removed */
-			if(iter.init_statement)
-				iter.init_statement->visit(*this);
-			ExpressionEvaluator eval(variable_values);
-			iter.condition->visit(eval);
-			if(eval.is_result_valid() && !eval.get_result())
-			{
-				nodes_to_remove.insert(&iter);
-				return;
-			}
+			nodes_to_remove.insert(&iter);
+			return;
 		}
-
-		/* Record all assignments that occur inside the loop body so those
-		variables won't be considered as constant */
-		SetFlag set_record(record_only);
-		TraversingVisitor::visit(iter);
 	}
 
 	TraversingVisitor::visit(iter);
+}
+
 
-	if(VariableDeclaration *init_decl = dynamic_cast<VariableDeclaration *>(iter.init_statement.get()))
-		variable_values.erase(init_decl);
+bool UnusedTypeRemover::apply(Stage &stage)
+{
+	stage.content.visit(*this);
+	NodeRemover().apply(stage, unused_nodes);
+	return !unused_nodes.empty();
 }
 
+void UnusedTypeRemover::visit(Literal &literal)
+{
+	unused_nodes.erase(literal.type);
+}
 
-UnusedVariableRemover::VariableInfo::VariableInfo():
-	local(false),
-	conditionally_assigned(false),
-	referenced(false)
-{ }
+void UnusedTypeRemover::visit(UnaryExpression &unary)
+{
+	unused_nodes.erase(unary.type);
+	TraversingVisitor::visit(unary);
+}
+
+void UnusedTypeRemover::visit(BinaryExpression &binary)
+{
+	unused_nodes.erase(binary.type);
+	TraversingVisitor::visit(binary);
+}
+
+void UnusedTypeRemover::visit(FunctionCall &call)
+{
+	unused_nodes.erase(call.type);
+	TraversingVisitor::visit(call);
+}
+
+void UnusedTypeRemover::visit(BasicTypeDeclaration &type)
+{
+	if(type.base_type)
+		unused_nodes.erase(type.base_type);
+	unused_nodes.insert(&type);
+}
+
+void UnusedTypeRemover::visit(ImageTypeDeclaration &type)
+{
+	if(type.base_type)
+		unused_nodes.erase(type.base_type);
+	unused_nodes.insert(&type);
+}
+
+void UnusedTypeRemover::visit(StructDeclaration &strct)
+{
+	unused_nodes.insert(&strct);
+	TraversingVisitor::visit(strct);
+}
+
+void UnusedTypeRemover::visit(VariableDeclaration &var)
+{
+	unused_nodes.erase(var.type_declaration);
+}
+
+void UnusedTypeRemover::visit(InterfaceBlock &iface)
+{
+	unused_nodes.erase(iface.type_declaration);
+}
+
+void UnusedTypeRemover::visit(FunctionDeclaration &func)
+{
+	unused_nodes.erase(func.return_type_declaration);
+	TraversingVisitor::visit(func);
+}
 
 
 UnusedVariableRemover::UnusedVariableRemover():
-	aggregate(0),
+	stage(0),
+	interface_block(0),
 	r_assignment(0),
 	assignment_target(false),
-	r_assign_to_subfield(false),
 	r_side_effects(false)
 { }
 
-bool UnusedVariableRemover::apply(Stage &stage)
+bool UnusedVariableRemover::apply(Stage &s)
 {
-	variables.push_back(BlockVariableMap());
-	stage.content.visit(*this);
-	BlockVariableMap &global_variables = variables.back();
-	for(BlockVariableMap::iterator i=global_variables.begin(); i!=global_variables.end(); ++i)
+	stage = &s;
+	s.content.visit(*this);
+
+	for(list<AssignmentInfo>::const_iterator i=assignments.begin(); i!=assignments.end(); ++i)
+		if(i->used_by.empty())
+			unused_nodes.insert(i->node);
+
+	for(map<string, InterfaceBlock *>::const_iterator i=s.interface_blocks.begin(); i!=s.interface_blocks.end(); ++i)
+		if(i->second->instance_name.empty())
+			unused_nodes.insert(i->second);
+
+	for(BlockVariableMap::const_iterator i=variables.begin(); i!=variables.end(); ++i)
 	{
-		if(i->first->interface=="out" && (stage.type==Stage::FRAGMENT || i->first->linked_declaration || !i->first->name.compare(0, 3, "gl_")))
-			continue;
-		if(!i->second.referenced)
+		if(i->second.output)
 		{
-			unused_nodes.insert(i->first);
-			clear_assignments(i->second, true);
+			/* The last visible assignments of output variables are used by the
+			next stage or the API. */
+			for(vector<AssignmentInfo *>::const_iterator j=i->second.assignments.begin(); j!=i->second.assignments.end(); ++j)
+				unused_nodes.erase((*j)->node);
 		}
+
+		if(!i->second.output && !i->second.referenced)
+		{
+			// Don't remove variables from inside interface blocks.
+			if(!i->second.interface_block)
+				unused_nodes.insert(i->first);
+		}
+		else if(i->second.interface_block)
+			// Interface blocks are kept if even one member is used.
+			unused_nodes.erase(i->second.interface_block);
 	}
-	variables.pop_back();
 
-	NodeRemover().apply(stage, unused_nodes);
+	NodeRemover().apply(s, unused_nodes);
 
 	return !unused_nodes.empty();
 }
 
-void UnusedVariableRemover::visit(VariableReference &var)
+void UnusedVariableRemover::referenced(const Assignment::Target &target, Node &node)
 {
-	map<VariableDeclaration *, Node *>::iterator i = aggregates.find(var.declaration);
-	if(i!=aggregates.end())
-		unused_nodes.erase(i->second);
-
-	if(var.declaration && !assignment_target)
+	VariableInfo &var_info = variables[target.declaration];
+	var_info.referenced = true;
+	if(!assignment_target)
 	{
-		VariableInfo &var_info = variables.back()[var.declaration];
-		clear_assignments(var_info, false);
-		var_info.referenced = true;
+		for(vector<AssignmentInfo *>::const_iterator i=var_info.assignments.begin(); i!=var_info.assignments.end(); ++i)
+			(*i)->used_by.push_back(&node);
 	}
 }
 
-void UnusedVariableRemover::visit(InterfaceBlockReference &iface)
+void UnusedVariableRemover::visit(VariableReference &var)
 {
-	unused_nodes.erase(iface.declaration);
+	referenced(var.declaration, var);
 }
 
-void UnusedVariableRemover::visit(MemberAccess &memacc)
+void UnusedVariableRemover::visit(InterfaceBlockReference &iface)
 {
-	r_assign_to_subfield = true;
-	TraversingVisitor::visit(memacc);
-	unused_nodes.erase(memacc.declaration);
+	referenced(iface.declaration, iface);
 }
 
 void UnusedVariableRemover::visit(UnaryExpression &unary)
@@ -471,10 +703,8 @@ void UnusedVariableRemover::visit(BinaryExpression &binary)
 {
 	if(binary.oper->token[0]=='[')
 	{
-		if(assignment_target)
-			r_assign_to_subfield = true;
 		binary.left->visit(*this);
-		SetForScope<bool> set(assignment_target, false);
+		SetFlag set(assignment_target, false);
 		binary.right->visit(*this);
 	}
 	else
@@ -484,7 +714,7 @@ void UnusedVariableRemover::visit(BinaryExpression &binary)
 void UnusedVariableRemover::visit(Assignment &assign)
 {
 	{
-		SetForScope<bool> set(assignment_target, !assign.self_referencing);
+		SetFlag set(assignment_target, (assign.oper->token[0]=='='));
 		assign.left->visit(*this);
 	}
 	assign.right->visit(*this);
@@ -495,157 +725,159 @@ void UnusedVariableRemover::visit(Assignment &assign)
 void UnusedVariableRemover::visit(FunctionCall &call)
 {
 	TraversingVisitor::visit(call);
+	/* Treat function calls as having side effects so expression statements
+	consisting of nothing but a function call won't be optimized away. */
 	r_side_effects = true;
-}
 
-void UnusedVariableRemover::record_assignment(VariableDeclaration &var, Node &node, bool chained)
-{
-	VariableInfo &var_info = variables.back()[&var];
-	if(!chained)
-		clear_assignments(var_info, true);
-	var_info.assignments.push_back(&node);
-	var_info.conditionally_assigned = false;
+	if(stage->type==Stage::GEOMETRY && call.name=="EmitVertex")
+	{
+		for(map<Statement *, VariableInfo>::const_iterator i=variables.begin(); i!=variables.end(); ++i)
+			if(i->second.output)
+				referenced(i->first, call);
+	}
 }
 
-void UnusedVariableRemover::clear_assignments(VariableInfo &var_info, bool mark_unused)
+void UnusedVariableRemover::record_assignment(const Assignment::Target &target, Node &node)
 {
-	if(mark_unused)
+	assignments.push_back(AssignmentInfo());
+	AssignmentInfo &assign_info = assignments.back();
+	assign_info.node = &node;
+	assign_info.target = target;
+
+	/* An assignment to the target hides any assignments to the same target or
+	its subfields. */
+	VariableInfo &var_info = variables[target.declaration];
+	for(unsigned i=0; i<var_info.assignments.size(); ++i)
 	{
-		for(vector<Node *>::iterator i=var_info.assignments.begin(); i!=var_info.assignments.end(); ++i)
-			unused_nodes.insert(*i);
+		const Assignment::Target &t = var_info.assignments[i]->target;
+
+		bool subfield = (t.chain_len>=target.chain_len);
+		for(unsigned j=0; (subfield && j<target.chain_len); ++j)
+			subfield = (t.chain[j]==target.chain[j]);
+
+		if(subfield)
+			var_info.assignments.erase(var_info.assignments.begin()+i);
+		else
+			++i;
 	}
-	var_info.assignments.clear();
+
+	var_info.assignments.push_back(&assign_info);
 }
 
 void UnusedVariableRemover::visit(ExpressionStatement &expr)
 {
 	r_assignment = 0;
-	r_assign_to_subfield = false;
 	r_side_effects = false;
 	TraversingVisitor::visit(expr);
-	if(r_assignment && r_assignment->target_declaration)
-		record_assignment(*r_assignment->target_declaration, expr, (r_assignment->self_referencing || r_assign_to_subfield));
+	if(r_assignment && r_assignment->target.declaration)
+		record_assignment(r_assignment->target, expr);
 	if(!r_side_effects)
 		unused_nodes.insert(&expr);
 }
 
-void UnusedVariableRemover::visit(StructDeclaration &strct)
-{
-	SetForScope<Node *> set(aggregate, &strct);
-	unused_nodes.insert(&strct);
-	TraversingVisitor::visit(strct);
-}
-
 void UnusedVariableRemover::visit(VariableDeclaration &var)
 {
-	if(aggregate)
-		aggregates[&var] = aggregate;
+	VariableInfo &var_info = variables[&var];
+	var_info.interface_block = interface_block;
+
+	/* Mark variables as output if they're used by the next stage or the
+	graphics API. */
+	if(interface_block)
+		var_info.output = (interface_block->interface=="out" && (interface_block->linked_block || !interface_block->name.compare(0, 3, "gl_")));
 	else
+		var_info.output = (var.interface=="out" && (stage->type==Stage::FRAGMENT || var.linked_declaration || !var.name.compare(0, 3, "gl_")));
+
+	if(var.init_expression)
 	{
-		variables.back()[&var].local = true;
-		if(var.init_expression)
-			record_assignment(var, *var.init_expression, false);
+		var_info.initialized = true;
+		record_assignment(&var, *var.init_expression);
 	}
-	unused_nodes.erase(var.type_declaration);
 	TraversingVisitor::visit(var);
 }
 
 void UnusedVariableRemover::visit(InterfaceBlock &iface)
 {
-	SetForScope<Node *> set(aggregate, &iface);
-	unused_nodes.insert(&iface);
-	TraversingVisitor::visit(iface);
-}
-
-void UnusedVariableRemover::visit(FunctionDeclaration &func)
-{
-	variables.push_back(BlockVariableMap());
-
-	for(NodeArray<VariableDeclaration>::iterator i=func.parameters.begin(); i!=func.parameters.end(); ++i)
-		(*i)->visit(*this);
-	func.body.visit(*this);
-
-	BlockVariableMap &block_variables = variables.back();
-	for(BlockVariableMap::iterator i=block_variables.begin(); i!=block_variables.end(); ++i)
-		i->second.conditionally_assigned = true;
-	for(NodeArray<VariableDeclaration>::iterator i=func.parameters.begin(); i!=func.parameters.end(); ++i)
-		block_variables[i->get()].referenced = true;
-	merge_down_variables();
+	if(iface.instance_name.empty())
+	{
+		SetForScope<InterfaceBlock *> set_block(interface_block, &iface);
+		iface.struct_declaration->members.visit(*this);
+	}
+	else
+	{
+		VariableInfo &var_info = variables[&iface];
+		var_info.output = (iface.interface=="out" && (iface.linked_block || !iface.name.compare(0, 3, "gl_")));
+	}
 }
 
-void UnusedVariableRemover::merge_down_variables()
+void UnusedVariableRemover::merge_variables(const BlockVariableMap &other_vars)
 {
-	BlockVariableMap &parent_variables = variables[variables.size()-2];
-	BlockVariableMap &block_variables = variables.back();
-	for(BlockVariableMap::iterator i=block_variables.begin(); i!=block_variables.end(); ++i)
+	for(BlockVariableMap::const_iterator i=other_vars.begin(); i!=other_vars.end(); ++i)
 	{
-		if(i->second.local)
-		{
-			if(!i->second.referenced)
-				unused_nodes.insert(i->first);
-			clear_assignments(i->second, i->first->interface!="out");
-			continue;
-		}
-
-		BlockVariableMap::iterator j = parent_variables.find(i->first);
-		if(j==parent_variables.end())
-			parent_variables.insert(*i);
-		else
+		BlockVariableMap::iterator j = variables.find(i->first);
+		if(j!=variables.end())
 		{
-			if(i->second.referenced || !i->second.conditionally_assigned)
-				clear_assignments(j->second, !i->second.referenced);
-			j->second.conditionally_assigned = i->second.conditionally_assigned;
+			/* The merged blocks started as copies of each other so any common
+			assignments must be in the beginning. */
+			unsigned k = 0;
+			for(; (k<i->second.assignments.size() && k<j->second.assignments.size()); ++k)
+				if(i->second.assignments[k]!=j->second.assignments[k])
+					break;
+
+			// Remaining assignments are unique to each block; merge them.
+			j->second.assignments.insert(j->second.assignments.end(), i->second.assignments.begin()+k, i->second.assignments.end());
 			j->second.referenced |= i->second.referenced;
-			j->second.assignments.insert(j->second.assignments.end(), i->second.assignments.begin(), i->second.assignments.end());
 		}
+		else
+			variables.insert(*i);
 	}
-	variables.pop_back();
 }
 
-void UnusedVariableRemover::visit(Conditional &cond)
+void UnusedVariableRemover::visit(FunctionDeclaration &func)
 {
-	cond.condition->visit(*this);
-	variables.push_back(BlockVariableMap());
-	cond.body.visit(*this);
+	if(func.body.body.empty())
+		return;
 
-	BlockVariableMap if_variables;
-	swap(variables.back(), if_variables);
-	cond.else_body.visit(*this);
+	BlockVariableMap saved_vars = variables;
+	// Assignments from other functions should not be visible.
+	for(BlockVariableMap::iterator i=variables.begin(); i!=variables.end(); ++i)
+		i->second.assignments.resize(i->second.initialized);
+	TraversingVisitor::visit(func);
+	swap(variables, saved_vars);
+	merge_variables(saved_vars);
 
-	BlockVariableMap &else_variables = variables.back();
-	for(BlockVariableMap::iterator i=else_variables.begin(); i!=else_variables.end(); ++i)
+	/* Always treat function parameters as referenced.  Removing unused
+	parameters is not currently supported. */
+	for(NodeArray<VariableDeclaration>::iterator i=func.parameters.begin(); i!=func.parameters.end(); ++i)
 	{
-		BlockVariableMap::iterator j = if_variables.find(i->first);
-		if(j!=if_variables.end())
-		{
-			i->second.assignments.insert(i->second.assignments.end(), j->second.assignments.begin(), j->second.assignments.end());
-			i->second.conditionally_assigned |= j->second.conditionally_assigned;
-			if_variables.erase(j);
-		}
-		else
-			i->second.conditionally_assigned = true;
+		BlockVariableMap::iterator j = variables.find(i->get());
+		if(j!=variables.end())
+			j->second.referenced = true;
 	}
+}
 
-	for(BlockVariableMap::iterator i=if_variables.begin(); i!=if_variables.end(); ++i)
-	{
-		i->second.conditionally_assigned = true;
-		else_variables.insert(*i);
-	}
+void UnusedVariableRemover::visit(Conditional &cond)
+{
+	cond.condition->visit(*this);
+	BlockVariableMap saved_vars = variables;
+	cond.body.visit(*this);
+	swap(saved_vars, variables);
+	cond.else_body.visit(*this);
 
-	merge_down_variables();
+	/* Visible assignments after the conditional is the union of those visible
+	at the end of the if and else blocks.  If there was no else block, then it's
+	the union of the if block and the state before it. */
+	merge_variables(saved_vars);
 }
 
 void UnusedVariableRemover::visit(Iteration &iter)
 {
-	variables.push_back(BlockVariableMap());
+	BlockVariableMap saved_vars = variables;
 	TraversingVisitor::visit(iter);
 
-	BlockVariableMap &block_variables = variables.back();
-	for(BlockVariableMap::iterator i=block_variables.begin(); i!=block_variables.end(); ++i)
-		if(!i->second.local && i->second.referenced)
-			clear_assignments(i->second, false);
-
-	merge_down_variables();
+	/* Merge assignments from the iteration, without clearing previous state.
+	Further analysis is needed to determine which parts of the iteration body
+	are always executed, if any. */
+	merge_variables(saved_vars);
 }