//
// Cforall Version 1.0.0 Copyright (C) 2015 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// LabelFixer.cc --
//
// Author           : Rodolfo G. Esteves
// Created On       : Mon May 18 07:44:20 2015
// Last Modified By : Andrew Beach
// Last Modified On : Tue Jan 21 10:32:00 2020
// Update Count     : 160
//

#include <cassert>                         // for assert
#include <list>                            // for list, _List_iterator, list...
#include <string>                          // for operator+, string, operator==
#include <utility>                         // for pair

#include "ControlStruct/LabelGenerator.h"  // for LabelGenerator
#include "LabelFixer.h"
#include "MLEMutator.h"                    // for MultiLevelExitMutator
#include "SynTree/Declaration.h"           // for FunctionDecl
#include "SynTree/Expression.h"            // for NameExpr, Expression, Unty...
#include "SynTree/Statement.h"             // for Statement, BranchStmt, Com...

namespace ControlStruct {
	bool LabelFixer::Entry::insideLoop() {
		return ( dynamic_cast< ForStmt * > ( definition ) ||
			dynamic_cast< WhileStmt * > ( definition )  );
	}

	LabelFixer::LabelFixer( LabelGenerator * gen ) : generator ( gen ) {
		if ( generator == 0 )
			generator = LabelGenerator::getGenerator();
	}

	void LabelFixer::previsit( FunctionDecl * ) {
		// need to go into a nested function in a fresh state
		GuardValue( labelTable );
		labelTable.clear();
	}

	void LabelFixer::postvisit( FunctionDecl * functionDecl ) {
		PassVisitor<MultiLevelExitMutator> mlem( resolveJumps(), generator );
		// We start in the body so we can stop when we hit another FunctionDecl.
		maybeMutate( functionDecl->statements, mlem );
	}

	// prune to at most one label definition for each statement
	void LabelFixer::previsit( Statement * stmt ) {
		std::list< Label > &labels = stmt->get_labels();

		if ( ! labels.empty() ) {
			// only remember one label for each statement
			Label current = setLabelsDef( labels, stmt );
		} // if
	}

	void LabelFixer::previsit( BranchStmt * branchStmt ) {
		previsit( ( Statement *)branchStmt );

		// for labeled branches, add an entry to the label table
		Label target = branchStmt->get_target();
		if ( target != "" ) {
			setLabelsUsg( target, branchStmt );
		}
	}

	void LabelFixer::previsit( LabelAddressExpr * addrExpr ) {
		Label & target = addrExpr->arg;
		assert( target != "" );
		setLabelsUsg( target, addrExpr );
	}


	// Sets the definition of the labelTable entry to be the provided statement for every label in
	// the list parameter. Happens for every kind of statement.
	Label LabelFixer::setLabelsDef( std::list< Label > & llabel, Statement * definition ) {
		assert( definition != 0 );
		assert( llabel.size() > 0 );

		for ( std::list< Label >::iterator i = llabel.begin(); i != llabel.end(); i++ ) {
			Label & l = *i;
			l.set_statement( definition ); // attach statement to the label to be used later
			if ( labelTable.find( l ) == labelTable.end() ) {
				// All labels on this statement need to use the same entry,
				// so this should only be created once.
				// undefined and unused until now, add an entry
				labelTable[ l ] = new Entry( definition );
			} else if ( labelTable[ l ]->defined() ) {
				// defined twice, error
				SemanticError( l.get_statement()->location,
					"Duplicate definition of label: " + l.get_name() );
			} else {
				// used previously, but undefined until now -> link with this entry
				// Question: Is changing objects important?
				delete labelTable[ l ];
				labelTable[ l ] = new Entry( definition );
			} // if
		} // for

		// Produce one of the labels attached to this statement to be temporarily used as the
		// canonical label.
		return labelTable[ llabel.front() ]->get_label();
	}

	// A label was used, add it to the table if it isn't already there
	template< typename UsageNode >
	void LabelFixer::setLabelsUsg( Label orgValue, UsageNode *use ) {
		assert( use != 0 );

		// add label with an unknown origin
		if ( labelTable.find( orgValue ) == labelTable.end() ) {
			labelTable[ orgValue ] = new Entry( 0 );
		}
	}

	// Builds a table that maps a label to its defining statement.
	std::map<Label, Statement * > * LabelFixer::resolveJumps() throw ( SemanticErrorException ) {
		std::map< Label, Statement * > *ret = new std::map< Label, Statement * >();
		for ( std::map< Label, Entry * >::iterator i = labelTable.begin(); i != labelTable.end(); ++i ) {
			if ( ! i->second->defined() ) {
				SemanticError( i->first.get_statement()->location, "Use of undefined label: " + i->first.get_name() );
			}
			(*ret)[ i->first ] = i->second->get_definition();
		}

		return ret;
	}
}  // namespace ControlStruct

// Local Variables: //
// tab-width: 4 //
// mode: c++ //
// compile-command: "make install" //
// End: //