source: src/ControlStruct/ExceptTranslateNew.cpp@ 56d711f

//
// 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.
//
// ExceptTranslateNew.cpp -- Conversion of exception control flow structures.
//
// Author           : Andrew Beach
// Created On       : Mon Nov  8 11:53:00 2021
// Last Modified By : Andrew Beach
// Last Modified On : Mon Nov  8 16:50:00 2021
// Update Count     : 0
//

#include "ExceptTranslate.h"

#include "AST/Expr.hpp"
#include "AST/Pass.hpp"
#include "AST/Stmt.hpp"
#include "AST/TranslationUnit.hpp"

namespace ControlStruct {

namespace {

class TranslateThrowsCore : public ast::WithGuards {
        const ast::ObjectDecl * terminateHandlerExcept;
        enum Context { NoHandler, TerHandler, ResHandler } currentContext;

        const ast::Stmt * createEitherThrow(
                const ast::ThrowStmt * throwStmt, const char * funcName );
        const ast::Stmt * createTerminateRethrow( const ast::ThrowStmt * );

public:
        TranslateThrowsCore() :
                terminateHandlerExcept( nullptr ), currentContext( NoHandler )
        {}

        void previsit( const ast::CatchStmt * stmt );
        const ast::Stmt * postvisit( const ast::ThrowStmt * stmt );
};

const ast::Stmt * TranslateThrowsCore::createEitherThrow(
                const ast::ThrowStmt * throwStmt, const char * funcName ) {
        // `throwFunc`( `throwStmt->name` );
        ast::UntypedExpr * call = new ast::UntypedExpr( throwStmt->location,
                new ast::NameExpr( throwStmt->location, funcName )
        );
        call->args.push_back( throwStmt->expr );
        return new ast::ExprStmt( throwStmt->location, call );
}

ast::VariableExpr * varOf( const ast::DeclWithType * decl ) {
        return new ast::VariableExpr( decl->location, decl );
}

const ast::Stmt * TranslateThrowsCore::createTerminateRethrow(
                const ast::ThrowStmt * stmt ) {
        // { `terminate_handler_except` = 0p; __rethrow_terminate(); }
        assert( nullptr == stmt->expr );
        assert( terminateHandlerExcept );

        ast::CompoundStmt * result = new ast::CompoundStmt(
                stmt->location, {}, std::vector<ast::Label>( stmt->labels ) );
        result->push_back( new ast::ExprStmt( stmt->location,
                ast::UntypedExpr::createAssign(
                        stmt->location,
                        varOf( terminateHandlerExcept ),
                        ast::ConstantExpr::null(
                                stmt->location,
                                terminateHandlerExcept->type
                        )
                )
        ) );
        result->push_back( new ast::ExprStmt( stmt->location, new ast::UntypedExpr(
                stmt->location,
                new ast::NameExpr( stmt->location, "__cfaehm_rethrow_terminate" )
        ) ) );
        return result;
}

void TranslateThrowsCore::previsit( const ast::CatchStmt * stmt ) {
        // Validate the statement's form.
        const ast::ObjectDecl * decl = stmt->decl.as<ast::ObjectDecl>();
        // Also checking the type would be nice.
        if ( !decl || !decl->type.as<ast::PointerType>() ) {
                std::string kind = (ast::Terminate == stmt->kind) ? "catch" : "catchResume";
                SemanticError( stmt->location, kind + " must have pointer to an exception type" );
        }

        // Track the handler context.
        if ( ast::Terminate == stmt->kind ) {
                GuardValue( currentContext ) = TerHandler;
                GuardValue( terminateHandlerExcept ) = decl;
        } else {
                GuardValue( currentContext ) = ResHandler;
        }
}

const ast::Stmt * TranslateThrowsCore::postvisit(
                const ast::ThrowStmt * stmt ) {
        // Ignoring ThrowStmt::target for now.
        // Handle Termination (Raise, Reraise, Error):
        if ( ast::Terminate == stmt->kind ) {
                if ( stmt->expr ) {
                        return createEitherThrow( stmt, "$throw" );
                } else if ( TerHandler == currentContext ) {
                        return createTerminateRethrow( stmt );
                } else {
                        abort( "Invalid throw in %s at %i\n",
                                stmt->location.filename.c_str(),
                                stmt->location.first_line);
                }
        // Handle Resumption (Raise, Reraise, Error):
        } else {
                if ( stmt->expr ) {
                        return createEitherThrow( stmt, "$throwResume" );
                } else if ( ResHandler == currentContext ) {
                        // This has to be handled later.
                        return stmt;
                } else {
                        abort( "Invalid throwResume in %s at %i\n",
                                stmt->location.filename.c_str(),
                                stmt->location.first_line);
                }
        }
}

} // namespace

void translateThrows( ast::TranslationUnit & transUnit ) {
        ast::Pass<TranslateThrowsCore>::run( transUnit );
}

} // namespace ControlStruct

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