Optimizer - Refactored CFG construction

Split the control flow graph construction function into multiple
functions. Doesn't add anything to the code, but makes it slightly less
unreadable.

c-opopt.cc

@@ -149,52 +149,42 @@ T_OptData::P_CtrlFlowNode BCFGNewNode_(
 #define M_NODE_(i) \
 	ctrlFlowGraph[i]
 
-} // namespace <anon>
-
 /*----------------------------------------------------------------------------*/
 
-void T_OptData::buildControlFlowGraph(
+using T_BCFGFunctions_ = T_KeyValueTable< T_String , T_OptData::T_BasicBlock >;
-		T_OpsParserOutput& program ) noexcept
+
+inline void BCFGFuncEnter_(
+		A_Node&					node ,
+		T_Optional< uint32_t >&			cNode ,
+		T_Array< T_OptData::P_CtrlFlowNode >&	ctrlFlowGraph ,
+		T_Array< T_OptData::P_CtrlFlowNode >&	old ,
+		T_BCFGFunctions_&			cfgFunctions ,
+		F_OPLogger const&			logger
+		) noexcept
+{
+	auto& n{ dynamic_cast< A_FuncNode& >( node ) };
+	auto const& fn{ n.name( ) };
+	logger( [&](){
+		T_StringBuilder sb;
+		sb << "Starting function '" << fn << "' at "
+			<< ctrlFlowGraph.size( );
+		return sb;
+	} , LL1 );
+	cfgFunctions.add( fn , T_OptData::T_BasicBlock{
+			ctrlFlowGraph.size( ) } );
+	cNode = M_ADDNEW_( );
+}
+
+inline void BCFGFuncExit_(
+		A_Node&					node ,
+		T_Optional< uint32_t >&			cNode ,
+		T_Array< T_OptData::P_CtrlFlowNode >&	ctrlFlowGraph ,
+		T_BCFGFunctions_&			cfgFunctions ,
+		F_OPLogger const&			logger
+		) noexcept
 {
-	// Keep the old array, we'll reuse its contents
-	T_Array< P_CtrlFlowNode > old{ std::move( ctrlFlowGraph ) };
-	M_LOGSTR_( "Building control flow graph" , LL1 );
-
-	// Create special nodes
-	M_ADDNEW_( );
-	M_ADDNEW_( );
-	M_ADDNEW_( );
-	M_NODE_( CFG_MAINLOOP )->outbound.add( CFG_END );
-	M_NODE_( CFG_END )->inbound.add( CFG_MAINLOOP );
-
-	// Data structure to handle conditionals
-	struct T_StackEntry_ {
-		uint32_t condBlock;
-		bool hasDefault{ false };
-		T_AutoArray< uint32_t , 8 > caseBlocks;
-	};
-
-	// Data structure for call sites
-	struct T_CallSite_ {
-		T_String name;
-		uint32_t callBlock;
-		uint32_t retBlock;
-	};
-
-	// Generate control flow graph for each function
-	T_AutoArray< T_StackEntry_ , 8 > stack;
-	T_Array< T_CallSite_ > callSites;
-	T_Optional< uint32_t > cNode{ };
-	visitor.visit( program.root , [&]( A_Node& node , const bool exit ) {
-		const auto nt{ node.type( ) };
-
-		// Handle start/end of functions
-		if ( nt == A_Node::DECL_FN || nt == A_Node::DECL_INIT
-				|| nt == A_Node::DECL_FRAME ) {
 	auto& n{ dynamic_cast< A_FuncNode& >( node ) };
 	auto const& fn{ n.name( ) };
-			if ( exit ) {
-				assert( stack.empty( ) );
 	logger( [&](){
 		T_StringBuilder sb;
 		sb << "Function ended; last block had "
@@ -208,34 +198,47 @@ void T_OptData::buildControlFlowGraph(
 	assert( frec );
 	frec->count = ctrlFlowGraph.size( ) - frec->first;
 	cNode.clear( );
-			} else {
+}
+
+/*----------------------------------------------------------------------------*/
+
+// Data structure to handle conditionals
+struct T_BCFGStackEntry_ {
+	uint32_t condBlock;
+	bool hasDefault{ false };
+	T_AutoArray< uint32_t , 8 > caseBlocks;
+};
+using T_BCFGStack_ = T_AutoArray< T_BCFGStackEntry_ , 8 >;
+
+inline void BCFGCondEnter_(
+		T_BCFGStack_& stack ,
+		T_Optional< uint32_t >& cNode ,
+		T_Array< T_OptData::P_CtrlFlowNode >& ctrlFlowGraph ,
+		F_OPLogger const& logger ) noexcept
+{
+	auto& se{ stack.addNew( ) };
+	se.condBlock = *cNode;
+	cNode.clear( );
 	logger( [&](){
 		T_StringBuilder sb;
-					sb << "Starting function '" << fn << "' at "
+		sb << "Entering conditional instruction, stack size "
-						<< ctrlFlowGraph.size( );
+			<< stack.size( )
+			<< ", block had "
+			<< ( M_NODE_( se.condBlock )->instructions
+				? M_NODE_( se.condBlock )->instructions->count
+				: 0 )
+			<< " instructions";
 		return sb;
-				} , LL1 );
+	} , LL2 );
-				cfgFunctions.add( fn , T_BasicBlock{ ctrlFlowGraph.size( ) } );
-				cNode = M_ADDNEW_( );
-			}
-			return true;
 }
 
-		// All instructions: continue the current basic block
+inline void BCFGCondExit_(
-		auto* const iptr{ dynamic_cast< A_InstructionNode* >( &node ) };
+		T_BCFGStack_& stack ,
-		if ( iptr && !exit ) {
+		T_Optional< uint32_t >& cNode ,
-			assert( cNode );
+		T_Array< T_OptData::P_CtrlFlowNode >& ctrlFlowGraph ,
-			auto& n{ *M_NODE_( *cNode ) };
+		T_Array< T_OptData::P_CtrlFlowNode >& old ,
-			if ( n.instructions ) {
+		F_OPLogger const& logger ) noexcept
-				n.instructions->count ++;
+{
-			} else {
-				n.instructions = T_BasicBlock{ indexOf( *iptr ) };
-			}
-		}
-
-		// Handle conditionals
-		if ( nt == A_Node::OP_COND ) {
-			if ( exit ) {
 	auto& se{ stack.last( ) };
 	cNode = M_ADDNEW_( );
 
@@ -262,21 +265,57 @@ void T_OptData::buildControlFlowGraph(
 			<< stack.size( );
 		return sb;
 	} , LL2 );
+}
+
+/*----------------------------------------------------------------------------*/
+
+inline bool BCFGVisitor_(
+		A_Node&					node ,
+		const bool				exit ,
+		T_OptData&				data ,
+		T_BCFGStack_&				stack ,
+		T_Optional< uint32_t >&			cNode ,
+		T_Array< T_OptData::P_CtrlFlowNode >&	old
+		) noexcept
+{
+	const auto nt{ node.type( ) };
+
+	// Handle start/end of functions
+	if ( nt == A_Node::DECL_FN || nt == A_Node::DECL_INIT
+			|| nt == A_Node::DECL_FRAME ) {
+		if ( exit ) {
+			assert( stack.empty( ) );
+			BCFGFuncExit_( node , cNode , data.ctrlFlowGraph ,
+					data.cfgFunctions , data.logger );
 		} else {
-				auto& se{ stack.addNew( ) };
+			BCFGFuncEnter_( node , cNode , data.ctrlFlowGraph ,
-				se.condBlock = *cNode;
+					old , data.cfgFunctions ,
-				cNode.clear( );
+					data.logger );
-				logger( [&](){
+		}
-					T_StringBuilder sb;
+		return true;
-					sb << "Entering conditional instruction, stack size "
+	}
-						<< stack.size( )
+
-						<< ", block had "
+	// All instructions: continue the current basic block
-						<< ( M_NODE_( se.condBlock )->instructions
+	auto* const iptr{ dynamic_cast< A_InstructionNode* >( &node ) };
-							? M_NODE_( se.condBlock )->instructions->count
+	if ( iptr && !exit ) {
-							: 0 )
+		assert( cNode );
-						<< " instructions";
+		auto& n{ *data.ctrlFlowGraph[ *cNode ] };
-					return sb;
+		if ( n.instructions ) {
-				} , LL2 );
+			n.instructions->count ++;
+		} else {
+			n.instructions = T_OptData::T_BasicBlock{
+				data.indexOf( *iptr ) };
+		}
+	}
+
+	// Handle conditionals
+	if ( nt == A_Node::OP_COND ) {
+		if ( exit ) {
+			BCFGCondExit_( stack , cNode , data.ctrlFlowGraph ,
+					old , data.logger );
+		} else {
+			BCFGCondEnter_( stack , cNode , data.ctrlFlowGraph ,
+					data.logger );
 		}
 		return true;
 	}
@@ -284,31 +323,33 @@ void T_OptData::buildControlFlowGraph(
 	// Calls also break the flow
 	if ( nt == A_Node::OP_CALL && !exit ) {
 		T_CallInstrNode& ci{ *dynamic_cast< T_CallInstrNode* >( iptr ) };
-			logger( [&](){
+		data.logger( [&](){
 			T_StringBuilder sb;
+			auto const& node{ *data.ctrlFlowGraph[ *cNode ] };
 			sb << "Call to " << ci.id( ) << ", block had "
-					<< ( M_NODE_( *cNode )->instructions
+				<< ( node.instructions
-						? M_NODE_( *cNode )->instructions->count
+					? node.instructions->count
 					: 0 )
 				<< " instructions";
 			return sb;
 		} , LL2 );
 
-			auto& cs{ callSites.addNew( ) };
+		auto& cs{ data.callSites.addNew( ) };
 		cs.name = ci.id( );
 		cs.callBlock = *cNode;
-			cNode = cs.retBlock = M_ADDNEW_( );
+		cNode = cs.retBlock = data.ctrlFlowGraph.add( M_NEWNODE_( ) );
 		return true;
 	}
 
 	// Condition case nodes: create new basic block, add to stack's list
 	if ( nt == A_Node::TN_CASE || nt == A_Node::TN_DEFAULT ) {
 		if ( exit ) {
-				logger( [&](){
+			data.logger( [&](){
 				T_StringBuilder sb;
+				auto const& node{ *data.ctrlFlowGraph[ *cNode ] };
 				sb << "Case block added ("
-						<< ( M_NODE_( *cNode )->instructions
+					<< ( node.instructions
-							? M_NODE_( *cNode )->instructions->count
+						? node.instructions->count
 						: 0 )
 					<< " instructions)";
 				return sb;
@@ -317,53 +358,62 @@ void T_OptData::buildControlFlowGraph(
 		} else {
 			stack.last( ).hasDefault = stack.last( ).hasDefault
 				|| ( nt == A_Node::TN_DEFAULT );
-				cNode = M_ADDNEW_( );
+			cNode = data.ctrlFlowGraph.add( M_NEWNODE_( ) );
 			stack.last( ).caseBlocks.add( *cNode );
 		}
 	}
 
 	return !dynamic_cast< A_ExpressionNode* >( &node );
-	} );
+}
-	assert( cfgFunctions.contains( "*init*" ) && cfgFunctions.contains( "*frame*" ) );
 
+/*----------------------------------------------------------------------------*/
+
+inline void BCFGHandleCalls_(
+		T_OptData& data ) noexcept
+{
 	// Add fake call sites for *init* and *frame*
 	{
-		auto& cs{ callSites.addNew( ) };
+		auto& cs{ data.callSites.addNew( ) };
-		cs.callBlock = CFG_ENTER;
+		cs.callBlock = T_OptData::CFG_ENTER;
-		cs.retBlock = CFG_MAINLOOP;
+		cs.retBlock = T_OptData::CFG_MAINLOOP;
 		cs.name = "*init*";
 	}
 	{
-		auto& cs{ callSites.addNew( ) };
+		auto& cs{ data.callSites.addNew( ) };
-		cs.callBlock = CFG_MAINLOOP;
+		cs.callBlock = T_OptData::CFG_MAINLOOP;
-		cs.retBlock = CFG_MAINLOOP;
+		cs.retBlock = T_OptData::CFG_MAINLOOP;
 		cs.name = "*frame*";
 	}
 
 	// Handle calls
-	for ( auto const& cs : callSites ) {
+	for ( auto const& cs : data.callSites ) {
-		auto const* frec{ cfgFunctions.get( cs.name ) };
+		auto const* frec{ data.cfgFunctions.get( cs.name ) };
 		assert( frec );
 		{
-			auto& entry{ ctrlFlowGraph[ frec->first ] };
+			auto& entry{ data.ctrlFlowGraph[ frec->first ] };
 			entry->inbound.add( cs.callBlock );
-			M_NODE_( cs.callBlock )->outbound.add( frec->first );
+			data.ctrlFlowGraph[ cs.callBlock ]->outbound.add(
+					frec->first );
 		}
 		{
 			const auto n{ frec->first + frec->count - 1 };
-			auto& exit{ ctrlFlowGraph[ n ] };
+			auto& exit{ data.ctrlFlowGraph[ n ] };
 			exit->outbound.add( cs.retBlock );
-			M_NODE_( cs.retBlock )->inbound.add( n );
+			data.ctrlFlowGraph[ cs.retBlock ]->inbound.add( n );
+		}
 	}
 }
 
-	// Dump whole graph
+/*----------------------------------------------------------------------------*/
-	logger( [&](){
+
+inline T_StringBuilder BCFGDumpAll_(
+		T_OptData const& data ) noexcept
+{
 	T_StringBuilder dump;
 
 	int i{ 0 };
 	dump << "Control flow graph dump\n";
-		for ( auto const& p : ctrlFlowGraph ) {
+	for ( auto const& p : data.ctrlFlowGraph ) {
 		auto const& e{ *p };
 		dump << "\nNode " << i++ << "\n\t";
 		if ( e.instructions ) {
@@ -398,6 +448,40 @@ void T_OptData::buildControlFlowGraph(
 	dump << '\n';
 
 	return dump;
+}
+
+
+} // namespace <anon>
+/*----------------------------------------------------------------------------*/
+
+void T_OptData::buildControlFlowGraph(
+		T_OpsParserOutput& program ) noexcept
+{
+	// Keep the old array, we'll reuse its contents
+	T_Array< P_CtrlFlowNode > old{ std::move( ctrlFlowGraph ) };
+	M_LOGSTR_( "Building control flow graph" , LL1 );
+
+	// Create special nodes
+	M_ADDNEW_( );
+	M_ADDNEW_( );
+	M_ADDNEW_( );
+	M_NODE_( CFG_MAINLOOP )->outbound.add( CFG_END );
+	M_NODE_( CFG_END )->inbound.add( CFG_MAINLOOP );
+
+	// Generate control flow graph for each function
+	T_BCFGStack_ stack;
+	T_Optional< uint32_t > cNode{ };
+	callSites.clear( );
+	visitor.visit( program.root , [&]( A_Node& node , const bool exit ) {
+		return BCFGVisitor_( node , exit , *this ,
+				stack , cNode , old );
+	} );
+	assert( cfgFunctions.contains( "*init*" )
+			&& cfgFunctions.contains( "*frame*" ) );
+
+	BCFGHandleCalls_( *this );
+	logger( [this](){
+		return BCFGDumpAll_( *this );
 	} , LL2 );
 }
 

c-opopt.hh

@@ -75,6 +75,13 @@ struct T_OptData
 	};
 	using P_CtrlFlowNode = T_OwnPtr< T_CtrlFlowNode >;
 
+	// Data structure for call sites
+	struct T_CallSite {
+		T_String name;
+		uint32_t callBlock;
+		uint32_t retBlock;
+	};
+
 	// Special nodes in the graph
 	static constexpr uint32_t CFG_ENTER = 0;
 	static constexpr uint32_t CFG_MAINLOOP = 1;
@@ -82,6 +89,7 @@ struct T_OptData
 
 	// Control flow graph
 	T_Array< P_CtrlFlowNode > ctrlFlowGraph;
+	T_Array< T_CallSite > callSites;
 	T_KeyValueTable< T_String , T_BasicBlock > cfgFunctions;
 
 	// Build the control flow graph. Instruction numbering must be