source: src/AST/Util.cpp @ 5a1ae14

//
// Cforall Version 1.0.0 Copyright (C) 2019 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// Util.cpp -- General utilities for working with the AST.
//
// Author           : Andrew Beach
// Created On       : Wed Jan 19  9:46:00 2022
// Last Modified By : Andrew Beach
// Last Modified On : Wed May 11 16:16:00 2022
// Update Count     : 3
//

#include "Util.hpp"

#include "Node.hpp"
#include "ParseNode.hpp"
#include "Pass.hpp"
#include "TranslationUnit.hpp"
#include "Common/utility.h"
#include "GenPoly/ScopedSet.h"

#include <vector>

using GenPoly::ScopedSet;

namespace ast {

namespace {

/// Check that ast::ptr/strong references do not form a cycle.
struct NoStrongCyclesCore {
        std::vector<const Node *> parents;

        void previsit( const Node * node ) {
                for ( auto & parent : parents ) {
                        assert( parent != node );
                }
                parents.push_back( node );
        }

        void postvisit( const Node * node ) {
                assert( !parents.empty() );
                assert( parents.back() == node );
                parents.pop_back();
        }
};

/// Check that every note that can has a set CodeLocation.
void isCodeLocationSet( const ParseNode * node ) {
        assert( node->location.isSet() );
}

void areLabelLocationsSet( const Stmt * stmt ) {
        for ( const Label& label : stmt->labels ) {
                assert( label.location.isSet() );
        }
}

/// Make sure the reference counts are in a valid combination.
void isStable( const Node * node ) {
        assert( node->isStable() );
}

/// Check that a FunctionDecl is synchronized with it's FunctionType.
void functionDeclMatchesType( const FunctionDecl * decl ) {
        // The type is a cache of sorts, if it is missing that is only a
        // problem if isTypeFixed is set.
        if ( decl->isTypeFixed ) {
                assert( decl->type );
        } else if ( !decl->type ) {
                return;
        }

        const FunctionType * type = decl->type;

        // Check that `type->forall` corresponds with `decl->type_params`.
        assert( type->forall.size() == decl->type_params.size() );
        // Check that `type->assertions` corresponds with `decl->assertions`.
        assert( type->assertions.size() == decl->assertions.size() );
        // Check that `type->params` corresponds with `decl->params`.
        assert( type->params.size() == decl->params.size() );
        // Check that `type->returns` corresponds with `decl->returns`.
        assert( type->returns.size() == decl->returns.size() );
}

/// Check that the MemberExpr has an aggregate type and matching member.
void memberMatchesAggregate( const MemberExpr * expr ) {
        const Type * aggrType = expr->aggregate->result->stripReferences();
        const AggregateDecl * decl = nullptr;
        if ( auto inst = dynamic_cast<const StructInstType *>( aggrType ) ) {
                decl = inst->base;
        } else if ( auto inst = dynamic_cast<const UnionInstType *>( aggrType ) ) {
                decl = inst->base;
        }
        assertf( decl, "Aggregate of member not correct type." );

        for ( auto aggrMember : decl->members ) {
                if ( expr->member == aggrMember ) {
                        return;
                }
        }
        assertf( false, "Member not found." );
}

template<typename node_t>
void oneOfExprOrType( const node_t * node ) {
        if ( node->expr ) {
                assertf( node->expr && !node->type, "Exactly one of expr or type should be set." );
        } else {
                assertf( !node->expr && node->type, "Exactly one of expr or type should be set." );
        }
}

/// Check for Floating Nodes:
/// Every node should be reachable from a root (the TranslationUnit) via a
/// chain of structural references (tracked with ptr). This cannot check all
/// of that, it just checks if a given node's field has a strong reference.
template<typename node_t, typename field_t>
void noFloatingNode( const node_t * node, field_t node_t::*field_ptr ) {
        const field_t & field = node->*field_ptr;
        if ( nullptr == field ) return;
        assertf( field->isManaged(), "Floating node found." );
}

struct InvariantCore {
        // To save on the number of visits: this is a kind of composed core.
        // None of the passes should make changes so ordering doesn't matter.
        NoStrongCyclesCore no_strong_cycles;

        void previsit( const Node * node ) {
                no_strong_cycles.previsit( node );
                isStable( node );
        }

        void previsit( const ParseNode * node ) {
                previsit( (const Node *)node );
                isCodeLocationSet( node );
        }

        void previsit( const FunctionDecl * node ) {
                previsit( (const ParseNode *)node );
                functionDeclMatchesType( node );
        }

        void previsit( const Stmt * node ) {
                previsit( (const ParseNode *)node );
                areLabelLocationsSet( node );
        }

        void previsit( const VariableExpr * node ) {
                previsit( (const ParseNode *)node );
                noFloatingNode( node, &VariableExpr::var );
        }

        void previsit( const MemberExpr * node ) {
                previsit( (const ParseNode *)node );
                memberMatchesAggregate( node );
        }

        void previsit( const SizeofExpr * node ) {
                previsit( (const ParseNode *)node );
                oneOfExprOrType( node );
        }

        void previsit( const AlignofExpr * node ) {
                previsit( (const ParseNode *)node );
                oneOfExprOrType( node );
        }

        void previsit( const StructInstType * node ) {
                previsit( (const Node *)node );
                noFloatingNode( node, &StructInstType::base );
        }

        void previsit( const UnionInstType * node ) {
                previsit( (const Node *)node );
                noFloatingNode( node, &UnionInstType::base );
        }

        void previsit( const EnumInstType * node ) {
                previsit( (const Node *)node );
                noFloatingNode( node, &EnumInstType::base );
        }

        void previsit( const TypeInstType * node ) {
                previsit( (const Node *)node );
                noFloatingNode( node, &TypeInstType::base );
        }

        void postvisit( const Node * node ) {
                no_strong_cycles.postvisit( node );
        }
};

/// Checks that referred to nodes are in scope.
/// This checks many readonly pointers to see if the declaration they are
/// referring to is in scope by the structural rules of code.
// Any escapes marked with a bug should be removed once the bug is fixed.
// This is a separate pass because of it changes the visit pattern and
// must always be run on the entire translation unit.
struct InScopeCore : public ast::WithShortCircuiting {
        ScopedSet<DeclWithType const *> typedDecls;
        ScopedSet<TypeDecl const *> typeDecls;
        // These 3 are really hard to check, because uses that originally ref. at
        // a forward declaration can be rewired to point a later full definition.
        ScopedSet<StructDecl const *> structDecls;
        ScopedSet<UnionDecl const *> unionDecls;
        ScopedSet<EnumDecl const *> enumDecls;
        ScopedSet<TraitDecl const *> traitDecls;

        bool isInGlobal = false;

        void beginScope() {
                typedDecls.beginScope();
                typeDecls.beginScope();
                structDecls.beginScope();
                unionDecls.beginScope();
                enumDecls.beginScope();
                traitDecls.beginScope();
        }

        void endScope() {
                typedDecls.endScope();
                typeDecls.endScope();
                structDecls.endScope();
                unionDecls.endScope();
                enumDecls.endScope();
                traitDecls.endScope();
        }

        void previsit( ApplicationExpr const * expr ) {
                // All isInGlobal manipulation is just to isolate this check.
                // The invalid compound literals lead to bad ctor/dtors. [#280]
                VariableExpr const * func = nullptr;
                CastExpr const * cast = nullptr;
                VariableExpr const * arg = nullptr;
                if ( isInGlobal
                                && 1 == expr->args.size()
                                && ( func = expr->func.as<VariableExpr>() )
                                && ( "?{}" == func->var->name || "^?{}" == func->var->name )
                                && ( cast = expr->args[0].as<CastExpr>() )
                                && ( arg = cast->arg.as<VariableExpr>() )
                                && isPrefix( arg->var->name, "_compLit" ) ) {
                        visit_children = false;
                }
        }

        void previsit( VariableExpr const * expr ) {
                if ( !expr->var ) return;
                // bitwise assignment escape [#281]
                if ( expr->var->location.isUnset() ) return;
                assert( typedDecls.contains( expr->var ) );
        }

        void previsit( FunctionType const * type ) {
                // This is to avoid checking the assertions, which can point at the
                // function's declaration and not the enclosing function.
                for ( auto type_param : type->forall ) {
                        if ( type_param->formal_usage ) {
                                visit_children = false;
                                // We could check non-assertion fields here.
                        }
                }
        }

        void previsit( TypeInstType const * type ) {
                if ( !type->base ) return;
                assertf( type->base->isManaged(), "Floating Node" );

                // bitwise assignment escape [#281]
                if ( type->base->location.isUnset() ) return;
                // Formal types can actually look at out of scope variables.
                if ( type->formal_usage ) return;
                assert( typeDecls.contains( type->base ) );
        }

        void previsit( TraitInstType const * type ) {
                if ( !type->base ) return;
                assert( traitDecls.contains( type->base ) );
        }

        void previsit( ObjectDecl const * decl ) {
                typedDecls.insert( decl );
                // There are some ill-formed compound literals. [#280]
                // The only known problem cases are at the top level.
                if ( isPrefix( decl->name, "_compLit" ) ) {
                        visit_children = false;
                }
        }

        void previsit( FunctionDecl const * decl ) {
                typedDecls.insert( decl );
                beginScope();
                for ( auto & type_param : decl->type_params ) {
                        typeDecls.insert( type_param );
                }
                for ( auto & assertion : decl->assertions ) {
                        typedDecls.insert( assertion );
                }
                for ( auto & param : decl->params ) {
                        typedDecls.insert( param );
                }
                for ( auto & ret : decl->returns ) {
                        typedDecls.insert( ret );
                }
                // No special handling of withExprs.

                // Part of the compound literal escape. [#280]
                if ( "__global_init__" == decl->name
                                || "__global_destroy__" == decl->name ) {
                        assert( !isInGlobal );
                        isInGlobal = true;
                }
        }

        void postvisit( FunctionDecl const * decl ) {
                endScope();
                // Part of the compound literal escape. [#280]
                if ( isInGlobal && ( "__global_init__" == decl->name
                                || "__global_destroy__" == decl->name ) ) {
                        isInGlobal = false;
                }
        }

        void previsit( StructDecl const * decl ) {
                structDecls.insert( decl );
                beginScope();
                for ( auto & type_param : decl->params ) {
                        typeDecls.insert( type_param );
                }
        }

        void postvisit( StructDecl const * ) {
                endScope();
        }

        void previsit( UnionDecl const * decl ) {
                unionDecls.insert( decl );
                beginScope();
                for ( auto & type_param : decl->params ) {
                        typeDecls.insert( type_param );
                }
        }

        void postvisit( UnionDecl const * ) {
                endScope();
        }

        void previsit( EnumDecl const * decl ) {
                enumDecls.insert( decl );
                if ( ast::EnumDecl::EnumHiding::Visible == decl->hide ) {
                        for ( auto & member : decl->members ) {
                                typedDecls.insert( member.strict_as<ast::DeclWithType>() );
                        }
                }
                beginScope();
                for ( auto & type_param : decl->params ) {
                        typeDecls.insert( type_param );
                }
        }

        void postvisit( EnumDecl const * ) {
                endScope();
        }

        void previsit( TraitDecl const * decl ) {
                traitDecls.insert( decl );
                beginScope();
                for ( auto & type_param : decl->params ) {
                        typeDecls.insert( type_param );
                }
        }

        void postvisit( TraitDecl const * ) {
                endScope();
        }

        void previsit( Designation const * ) {
                visit_children = false;
        }
};

} // namespace

void checkInvariants( TranslationUnit & transUnit ) {
        Pass<InvariantCore>::run( transUnit );
        Pass<InScopeCore>::run( transUnit );
}

} // namespace ast