//
// 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.
//
// Specialize.cc -- 
//
// Author           : Richard C. Bilson
// Created On       : Mon May 18 07:44:20 2015
// Last Modified By : Peter A. Buhr
// Last Modified On : Sat Jun 13 15:54:07 2015
// Update Count     : 6
//

#include <cassert>

#include "Specialize.h"
#include "PolyMutator.h"

#include "Parser/ParseNode.h"

#include "SynTree/Expression.h"
#include "SynTree/Statement.h"
#include "SynTree/Type.h"
#include "SynTree/TypeSubstitution.h"
#include "SynTree/Mutator.h"
#include "ResolvExpr/FindOpenVars.h"
#include "UniqueName.h"
#include "utility.h"

namespace GenPoly {
	const std::list<Label> noLabels;

	class Specialize : public PolyMutator {
	  public:
		Specialize( std::string paramPrefix = "_p" );

		virtual Expression * mutate( ApplicationExpr *applicationExpr );
		virtual Expression * mutate( AddressExpr *castExpr );
		virtual Expression * mutate( CastExpr *castExpr );
		virtual Expression * mutate( LogicalExpr *logicalExpr );
		virtual Expression * mutate( ConditionalExpr *conditionalExpr );
		virtual Expression * mutate( CommaExpr *commaExpr );

	  private:
		Expression *doSpecialization( Type *formalType, Expression *actual, InferredParams *inferParams = 0 );
		void handleExplicitParams( ApplicationExpr *appExpr );

		UniqueName thunkNamer;
		std::string paramPrefix;
	};

	void convertSpecializations( std::list< Declaration* >& translationUnit ) {
		Specialize specializer;
		mutateAll( translationUnit, specializer );
	}

	Specialize::Specialize( std::string paramPrefix )
		: thunkNamer( "_thunk" ), paramPrefix( paramPrefix ) {
	}

	bool needsSpecialization( Type *formalType, Type *actualType, TypeSubstitution *env ) {
		if ( env ) {
			using namespace ResolvExpr;
			OpenVarSet openVars, closedVars;
			AssertionSet need, have;
			findOpenVars( formalType, openVars, closedVars, need, have, false );
			findOpenVars( actualType, openVars, closedVars, need, have, true );
			for ( OpenVarSet::const_iterator openVar = openVars.begin(); openVar != openVars.end(); ++openVar ) {
				Type *boundType = env->lookup( openVar->first );
				if ( ! boundType ) continue;
				if ( TypeInstType *typeInst = dynamic_cast< TypeInstType* >( boundType ) ) {
					if ( closedVars.find( typeInst->get_name() ) == closedVars.end() ) {
						return true;
					} // if
				} else {
					return true;
				} // if
			} // for
			return false;
		} else {
			return false;
		} // if
	}

	Expression * Specialize::doSpecialization( Type *formalType, Expression *actual, InferredParams *inferParams ) {
		if ( needsSpecialization( formalType, actual->get_results().front(), env ) ) {
			PointerType *ptrType;
			FunctionType *funType;
			if ( ( ptrType = dynamic_cast< PointerType* >( formalType ) ) && ( funType = dynamic_cast< FunctionType* >( ptrType->get_base() ) ) ) {
				FunctionType *newType = funType->clone();
				if ( env ) {
					TypeSubstitution newEnv( *env );
					// it is important to replace only occurrences of type variables that occur free in the
					// thunk's type
					newEnv.applyFree( newType );
				} // if
				FunctionDecl *thunkFunc = new FunctionDecl( thunkNamer.newName(), DeclarationNode::NoStorageClass, LinkageSpec::C, newType, new CompoundStmt( std::list< std::string >() ), false, false );
				thunkFunc->fixUniqueId();

				UniqueName paramNamer( paramPrefix );
				ApplicationExpr *appExpr = new ApplicationExpr( actual );
				for ( std::list< DeclarationWithType* >::iterator param = thunkFunc->get_functionType()->get_parameters().begin(); param != thunkFunc->get_functionType()->get_parameters().end(); ++param ) {
					(*param )->set_name( paramNamer.newName() );
					appExpr->get_args().push_back( new VariableExpr( *param ) );
				} // for
				appExpr->set_env( maybeClone( env ) );
				if ( inferParams ) {
					appExpr->get_inferParams() = *inferParams;
				} // if

				// handle any specializations that may still be present
				std::string oldParamPrefix = paramPrefix;
				paramPrefix += "p";
				std::list< Statement* > oldStmts;
				oldStmts.splice( oldStmts.end(), stmtsToAdd );
				handleExplicitParams( appExpr );
				paramPrefix = oldParamPrefix;
				thunkFunc->get_statements()->get_kids().splice( thunkFunc->get_statements()->get_kids().end(), stmtsToAdd );
				stmtsToAdd.splice( stmtsToAdd.end(), oldStmts );

				Statement *appStmt;
				if ( funType->get_returnVals().empty() ) {
					appStmt = new ExprStmt( noLabels, appExpr );
				} else {
					appStmt = new ReturnStmt( noLabels, appExpr );
				} // if
				thunkFunc->get_statements()->get_kids().push_back( appStmt );
				stmtsToAdd.push_back( new DeclStmt( noLabels, thunkFunc ) );
				return new AddressExpr( new VariableExpr( thunkFunc ) );
			} else {
				return actual;
			} // if
		} else {
			return actual;
		} // if
	}

	void Specialize::handleExplicitParams( ApplicationExpr *appExpr ) {
		// create thunks for the explicit parameters
		assert( ! appExpr->get_function()->get_results().empty() );
		PointerType *pointer = dynamic_cast< PointerType* >( appExpr->get_function()->get_results().front() );
		assert( pointer );
		FunctionType *function = dynamic_cast< FunctionType* >( pointer->get_base() );
		std::list< DeclarationWithType* >::iterator formal;
		std::list< Expression* >::iterator actual;
		for ( formal = function->get_parameters().begin(), actual = appExpr->get_args().begin(); formal != function->get_parameters().end() && actual != appExpr->get_args().end(); ++formal, ++actual ) {
			*actual = doSpecialization( (*formal )->get_type(), *actual, &appExpr->get_inferParams() );
		}
	}

	Expression * Specialize::mutate( ApplicationExpr *appExpr ) {
		appExpr->get_function()->acceptMutator( *this );
		mutateAll( appExpr->get_args(), *this );

		// create thunks for the inferred parameters
		for ( InferredParams::iterator inferParam = appExpr->get_inferParams().begin(); inferParam != appExpr->get_inferParams().end(); ++inferParam ) {
			inferParam->second.expr = doSpecialization( inferParam->second.formalType, inferParam->second.expr, &appExpr->get_inferParams() );
		}

		handleExplicitParams( appExpr );

		return appExpr;
	}

	Expression * Specialize::mutate( AddressExpr *addrExpr ) {
		addrExpr->get_arg()->acceptMutator( *this );
		addrExpr->set_arg( doSpecialization( addrExpr->get_results().front(), addrExpr->get_arg() ) );
		return addrExpr;
	}

	Expression * Specialize::mutate( CastExpr *castExpr ) {
		castExpr->get_arg()->acceptMutator( *this );
		castExpr->set_arg( doSpecialization( castExpr->get_results().front(), castExpr->get_arg() ) );
		return castExpr;
	}

	Expression * Specialize::mutate( LogicalExpr *logicalExpr ) {
		return logicalExpr;
	}

	Expression * Specialize::mutate( ConditionalExpr *condExpr ) {
		return condExpr;
	}

	Expression * Specialize::mutate( CommaExpr *commaExpr ) {
		return commaExpr;
	}
} // namespace GenPoly

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