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.
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35d3098917
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ddad981055
2 changed files with 319 additions and 227 deletions
292
c-opopt.cc
292
c-opopt.cc
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@ -149,52 +149,42 @@ T_OptData::P_CtrlFlowNode BCFGNewNode_(
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#define M_NODE_(i) \
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ctrlFlowGraph[i]
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} // namespace <anon>
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/*----------------------------------------------------------------------------*/
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void T_OptData::buildControlFlowGraph(
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T_OpsParserOutput& program ) noexcept
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using T_BCFGFunctions_ = T_KeyValueTable< T_String , T_OptData::T_BasicBlock >;
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inline void BCFGFuncEnter_(
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A_Node& node ,
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T_Optional< uint32_t >& cNode ,
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T_Array< T_OptData::P_CtrlFlowNode >& ctrlFlowGraph ,
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T_Array< T_OptData::P_CtrlFlowNode >& old ,
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T_BCFGFunctions_& cfgFunctions ,
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F_OPLogger const& logger
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) noexcept
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{
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auto& n{ dynamic_cast< A_FuncNode& >( node ) };
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auto const& fn{ n.name( ) };
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logger( [&](){
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T_StringBuilder sb;
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sb << "Starting function '" << fn << "' at "
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<< ctrlFlowGraph.size( );
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return sb;
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} , LL1 );
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cfgFunctions.add( fn , T_OptData::T_BasicBlock{
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ctrlFlowGraph.size( ) } );
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cNode = M_ADDNEW_( );
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}
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inline void BCFGFuncExit_(
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A_Node& node ,
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T_Optional< uint32_t >& cNode ,
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T_Array< T_OptData::P_CtrlFlowNode >& ctrlFlowGraph ,
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T_BCFGFunctions_& cfgFunctions ,
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F_OPLogger const& logger
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) noexcept
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{
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// Keep the old array, we'll reuse its contents
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T_Array< P_CtrlFlowNode > old{ std::move( ctrlFlowGraph ) };
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M_LOGSTR_( "Building control flow graph" , LL1 );
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// Create special nodes
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M_ADDNEW_( );
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M_ADDNEW_( );
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M_ADDNEW_( );
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M_NODE_( CFG_MAINLOOP )->outbound.add( CFG_END );
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M_NODE_( CFG_END )->inbound.add( CFG_MAINLOOP );
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// Data structure to handle conditionals
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struct T_StackEntry_ {
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uint32_t condBlock;
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bool hasDefault{ false };
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T_AutoArray< uint32_t , 8 > caseBlocks;
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};
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// Data structure for call sites
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struct T_CallSite_ {
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T_String name;
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uint32_t callBlock;
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uint32_t retBlock;
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};
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// Generate control flow graph for each function
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T_AutoArray< T_StackEntry_ , 8 > stack;
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T_Array< T_CallSite_ > callSites;
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T_Optional< uint32_t > cNode{ };
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visitor.visit( program.root , [&]( A_Node& node , const bool exit ) {
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const auto nt{ node.type( ) };
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// Handle start/end of functions
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if ( nt == A_Node::DECL_FN || nt == A_Node::DECL_INIT
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|| nt == A_Node::DECL_FRAME ) {
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auto& n{ dynamic_cast< A_FuncNode& >( node ) };
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auto const& fn{ n.name( ) };
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if ( exit ) {
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assert( stack.empty( ) );
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logger( [&](){
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T_StringBuilder sb;
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sb << "Function ended; last block had "
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@ -208,34 +198,47 @@ void T_OptData::buildControlFlowGraph(
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assert( frec );
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frec->count = ctrlFlowGraph.size( ) - frec->first;
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cNode.clear( );
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} else {
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}
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/*----------------------------------------------------------------------------*/
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// Data structure to handle conditionals
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struct T_BCFGStackEntry_ {
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uint32_t condBlock;
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bool hasDefault{ false };
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T_AutoArray< uint32_t , 8 > caseBlocks;
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};
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using T_BCFGStack_ = T_AutoArray< T_BCFGStackEntry_ , 8 >;
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inline void BCFGCondEnter_(
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T_BCFGStack_& stack ,
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T_Optional< uint32_t >& cNode ,
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T_Array< T_OptData::P_CtrlFlowNode >& ctrlFlowGraph ,
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F_OPLogger const& logger ) noexcept
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{
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auto& se{ stack.addNew( ) };
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se.condBlock = *cNode;
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cNode.clear( );
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logger( [&](){
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T_StringBuilder sb;
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sb << "Starting function '" << fn << "' at "
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<< ctrlFlowGraph.size( );
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sb << "Entering conditional instruction, stack size "
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<< stack.size( )
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<< ", block had "
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<< ( M_NODE_( se.condBlock )->instructions
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? M_NODE_( se.condBlock )->instructions->count
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: 0 )
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<< " instructions";
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return sb;
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} , LL1 );
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cfgFunctions.add( fn , T_BasicBlock{ ctrlFlowGraph.size( ) } );
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cNode = M_ADDNEW_( );
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}
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return true;
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} , LL2 );
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}
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// All instructions: continue the current basic block
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auto* const iptr{ dynamic_cast< A_InstructionNode* >( &node ) };
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if ( iptr && !exit ) {
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assert( cNode );
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auto& n{ *M_NODE_( *cNode ) };
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if ( n.instructions ) {
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n.instructions->count ++;
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} else {
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n.instructions = T_BasicBlock{ indexOf( *iptr ) };
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}
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}
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// Handle conditionals
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if ( nt == A_Node::OP_COND ) {
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if ( exit ) {
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inline void BCFGCondExit_(
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T_BCFGStack_& stack ,
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T_Optional< uint32_t >& cNode ,
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T_Array< T_OptData::P_CtrlFlowNode >& ctrlFlowGraph ,
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T_Array< T_OptData::P_CtrlFlowNode >& old ,
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F_OPLogger const& logger ) noexcept
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{
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auto& se{ stack.last( ) };
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cNode = M_ADDNEW_( );
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@ -262,21 +265,57 @@ void T_OptData::buildControlFlowGraph(
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<< stack.size( );
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return sb;
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} , LL2 );
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}
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/*----------------------------------------------------------------------------*/
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inline bool BCFGVisitor_(
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A_Node& node ,
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const bool exit ,
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T_OptData& data ,
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T_BCFGStack_& stack ,
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T_Optional< uint32_t >& cNode ,
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T_Array< T_OptData::P_CtrlFlowNode >& old
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) noexcept
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{
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const auto nt{ node.type( ) };
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// Handle start/end of functions
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if ( nt == A_Node::DECL_FN || nt == A_Node::DECL_INIT
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|| nt == A_Node::DECL_FRAME ) {
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if ( exit ) {
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assert( stack.empty( ) );
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BCFGFuncExit_( node , cNode , data.ctrlFlowGraph ,
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data.cfgFunctions , data.logger );
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} else {
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auto& se{ stack.addNew( ) };
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se.condBlock = *cNode;
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cNode.clear( );
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logger( [&](){
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T_StringBuilder sb;
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sb << "Entering conditional instruction, stack size "
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<< stack.size( )
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<< ", block had "
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<< ( M_NODE_( se.condBlock )->instructions
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? M_NODE_( se.condBlock )->instructions->count
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: 0 )
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<< " instructions";
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return sb;
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} , LL2 );
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BCFGFuncEnter_( node , cNode , data.ctrlFlowGraph ,
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old , data.cfgFunctions ,
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data.logger );
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}
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return true;
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}
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// All instructions: continue the current basic block
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auto* const iptr{ dynamic_cast< A_InstructionNode* >( &node ) };
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if ( iptr && !exit ) {
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assert( cNode );
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auto& n{ *data.ctrlFlowGraph[ *cNode ] };
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if ( n.instructions ) {
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n.instructions->count ++;
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} else {
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n.instructions = T_OptData::T_BasicBlock{
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data.indexOf( *iptr ) };
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}
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}
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// Handle conditionals
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if ( nt == A_Node::OP_COND ) {
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if ( exit ) {
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BCFGCondExit_( stack , cNode , data.ctrlFlowGraph ,
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old , data.logger );
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} else {
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BCFGCondEnter_( stack , cNode , data.ctrlFlowGraph ,
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data.logger );
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}
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return true;
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}
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@ -284,31 +323,33 @@ void T_OptData::buildControlFlowGraph(
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// Calls also break the flow
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if ( nt == A_Node::OP_CALL && !exit ) {
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T_CallInstrNode& ci{ *dynamic_cast< T_CallInstrNode* >( iptr ) };
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logger( [&](){
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data.logger( [&](){
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T_StringBuilder sb;
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auto const& node{ *data.ctrlFlowGraph[ *cNode ] };
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sb << "Call to " << ci.id( ) << ", block had "
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<< ( M_NODE_( *cNode )->instructions
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? M_NODE_( *cNode )->instructions->count
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<< ( node.instructions
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? node.instructions->count
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: 0 )
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<< " instructions";
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return sb;
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} , LL2 );
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auto& cs{ callSites.addNew( ) };
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auto& cs{ data.callSites.addNew( ) };
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cs.name = ci.id( );
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cs.callBlock = *cNode;
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cNode = cs.retBlock = M_ADDNEW_( );
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cNode = cs.retBlock = data.ctrlFlowGraph.add( M_NEWNODE_( ) );
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return true;
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}
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// Condition case nodes: create new basic block, add to stack's list
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if ( nt == A_Node::TN_CASE || nt == A_Node::TN_DEFAULT ) {
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if ( exit ) {
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logger( [&](){
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data.logger( [&](){
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T_StringBuilder sb;
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auto const& node{ *data.ctrlFlowGraph[ *cNode ] };
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sb << "Case block added ("
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<< ( M_NODE_( *cNode )->instructions
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? M_NODE_( *cNode )->instructions->count
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<< ( node.instructions
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? node.instructions->count
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: 0 )
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<< " instructions)";
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return sb;
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@ -317,53 +358,62 @@ void T_OptData::buildControlFlowGraph(
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} else {
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stack.last( ).hasDefault = stack.last( ).hasDefault
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|| ( nt == A_Node::TN_DEFAULT );
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cNode = M_ADDNEW_( );
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cNode = data.ctrlFlowGraph.add( M_NEWNODE_( ) );
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stack.last( ).caseBlocks.add( *cNode );
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}
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}
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return !dynamic_cast< A_ExpressionNode* >( &node );
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} );
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assert( cfgFunctions.contains( "*init*" ) && cfgFunctions.contains( "*frame*" ) );
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}
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/*----------------------------------------------------------------------------*/
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inline void BCFGHandleCalls_(
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T_OptData& data ) noexcept
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{
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// Add fake call sites for *init* and *frame*
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{
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auto& cs{ callSites.addNew( ) };
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cs.callBlock = CFG_ENTER;
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cs.retBlock = CFG_MAINLOOP;
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auto& cs{ data.callSites.addNew( ) };
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cs.callBlock = T_OptData::CFG_ENTER;
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cs.retBlock = T_OptData::CFG_MAINLOOP;
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cs.name = "*init*";
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}
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{
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auto& cs{ callSites.addNew( ) };
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cs.callBlock = CFG_MAINLOOP;
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cs.retBlock = CFG_MAINLOOP;
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auto& cs{ data.callSites.addNew( ) };
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cs.callBlock = T_OptData::CFG_MAINLOOP;
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cs.retBlock = T_OptData::CFG_MAINLOOP;
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cs.name = "*frame*";
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}
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// Handle calls
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for ( auto const& cs : callSites ) {
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auto const* frec{ cfgFunctions.get( cs.name ) };
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for ( auto const& cs : data.callSites ) {
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auto const* frec{ data.cfgFunctions.get( cs.name ) };
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assert( frec );
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{
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auto& entry{ ctrlFlowGraph[ frec->first ] };
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auto& entry{ data.ctrlFlowGraph[ frec->first ] };
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entry->inbound.add( cs.callBlock );
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M_NODE_( cs.callBlock )->outbound.add( frec->first );
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data.ctrlFlowGraph[ cs.callBlock ]->outbound.add(
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frec->first );
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}
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{
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const auto n{ frec->first + frec->count - 1 };
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auto& exit{ ctrlFlowGraph[ n ] };
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auto& exit{ data.ctrlFlowGraph[ n ] };
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exit->outbound.add( cs.retBlock );
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M_NODE_( cs.retBlock )->inbound.add( n );
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data.ctrlFlowGraph[ cs.retBlock ]->inbound.add( n );
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}
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}
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}
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// Dump whole graph
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logger( [&](){
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/*----------------------------------------------------------------------------*/
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inline T_StringBuilder BCFGDumpAll_(
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T_OptData const& data ) noexcept
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{
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T_StringBuilder dump;
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int i{ 0 };
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dump << "Control flow graph dump\n";
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for ( auto const& p : ctrlFlowGraph ) {
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for ( auto const& p : data.ctrlFlowGraph ) {
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auto const& e{ *p };
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dump << "\nNode " << i++ << "\n\t";
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if ( e.instructions ) {
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@ -398,6 +448,40 @@ void T_OptData::buildControlFlowGraph(
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dump << '\n';
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return dump;
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}
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} // namespace <anon>
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/*----------------------------------------------------------------------------*/
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void T_OptData::buildControlFlowGraph(
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T_OpsParserOutput& program ) noexcept
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{
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// Keep the old array, we'll reuse its contents
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T_Array< P_CtrlFlowNode > old{ std::move( ctrlFlowGraph ) };
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M_LOGSTR_( "Building control flow graph" , LL1 );
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// Create special nodes
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M_ADDNEW_( );
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M_ADDNEW_( );
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M_ADDNEW_( );
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M_NODE_( CFG_MAINLOOP )->outbound.add( CFG_END );
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M_NODE_( CFG_END )->inbound.add( CFG_MAINLOOP );
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// Generate control flow graph for each function
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T_BCFGStack_ stack;
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T_Optional< uint32_t > cNode{ };
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callSites.clear( );
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visitor.visit( program.root , [&]( A_Node& node , const bool exit ) {
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return BCFGVisitor_( node , exit , *this ,
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stack , cNode , old );
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} );
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assert( cfgFunctions.contains( "*init*" )
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&& cfgFunctions.contains( "*frame*" ) );
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BCFGHandleCalls_( *this );
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logger( [this](){
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return BCFGDumpAll_( *this );
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} , LL2 );
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}
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@ -75,6 +75,13 @@ struct T_OptData
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};
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using P_CtrlFlowNode = T_OwnPtr< T_CtrlFlowNode >;
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// Data structure for call sites
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struct T_CallSite {
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T_String name;
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uint32_t callBlock;
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uint32_t retBlock;
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};
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// Special nodes in the graph
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static constexpr uint32_t CFG_ENTER = 0;
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static constexpr uint32_t CFG_MAINLOOP = 1;
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@ -82,6 +89,7 @@ struct T_OptData
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// Control flow graph
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T_Array< P_CtrlFlowNode > ctrlFlowGraph;
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T_Array< T_CallSite > callSites;
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T_KeyValueTable< T_String , T_BasicBlock > cfgFunctions;
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// Build the control flow graph. Instruction numbering must be
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