Changeset ba417e2


Ignore:
Timestamp:
Aug 8, 2019, 11:51:16 AM (2 years ago)
Author:
Thierry Delisle <tdelisle@…>
Branches:
arm-eh, jacob/cs343-translation, master, new-ast, new-ast-unique-expr
Children:
92a6e02
Parents:
f49b3fc (diff), ae265b5 (diff)
Note: this is a merge changeset, the changes displayed below correspond to the merge itself.
Use the (diff) links above to see all the changes relative to each parent.
Message:

Merge branch 'new-ast' of plg.uwaterloo.ca:software/cfa/cfa-cc into new-ast

Location:
src/AST
Files:
3 edited

Legend:

Unmodified
Added
Removed
  • src/AST/Convert.cpp

    rf49b3fc rba417e2  
    21242124                                old->location,
    21252125                                GET_ACCEPT_1(member, DeclWithType),
    2126                                 GET_ACCEPT_1(aggregate, Expr)
     2126                                GET_ACCEPT_1(aggregate, Expr),
     2127                                ast::MemberExpr::NoOpConstructionChosen
    21272128                        )
    21282129                );
  • src/AST/Expr.cpp

    rf49b3fc rba417e2  
    158158        assert( aggregate->result );
    159159
    160         // take ownership of member type
    161         result = mem->get_type();
     160        // Deep copy on result type avoids mutation on transitively multiply referenced object.
     161        //
     162        // Example, adapted from parts of builtins and bootloader:
     163        //
     164        // forall(dtype T)
     165        // struct __Destructor {
     166        //   T * object;
     167        //   void (*dtor)(T *);
     168        // };
     169        //
     170        // forall(dtype S)
     171        // void foo(__Destructor(S) &d) {
     172        //   if (d.dtor) {  // here
     173        //   }
     174        // }
     175        //
     176        // Let e be the "d.dtor" guard espression, which is MemberExpr after resolve.  Let d be the
     177        // declaration of member __Destructor.dtor (an ObjectDecl), as accessed via the top-level
     178        // declaration of __Destructor.  Consider the types e.result and d.type.  In the old AST, one
     179        // is a clone of the other.  Ordinary new-AST use would set them up as a multiply-referenced
     180        // object.
     181        //
     182        // e.result: PointerType
     183        // .base: FunctionType
     184        // .params.front(): ObjectDecl, the anonymous parameter of type T*
     185        // .type: PointerType
     186        // .base: TypeInstType
     187        // let x = that
     188        // let y = similar, except start from d.type
     189        //
     190        // Consider two code lines down, genericSubstitution(...).apply(result).
     191        //
     192        // Applying this chosen-candidate's type substitution means modifying x, substituting
     193        // S for T.  This mutation should affect x and not y.
     194
     195        result = deepCopy(mem->get_type());
     196
    162197        // substitute aggregate generic parameters into member type
    163198        genericSubstitution( aggregate->result ).apply( result );
    164199        // ensure lvalue and appropriate restrictions from aggregate type
    165200        add_qualifiers( result, aggregate->result->qualifiers | CV::Lvalue );
     201}
     202
     203MemberExpr::MemberExpr( const CodeLocation & loc, const DeclWithType * mem, const Expr * agg,
     204    MemberExpr::NoOpConstruction overloadSelector )
     205: Expr( loc ), member( mem ), aggregate( agg ) {
     206        assert( member );
     207        assert( aggregate );
     208        assert( aggregate->result );
     209        (void) overloadSelector;
    166210}
    167211
  • src/AST/Expr.hpp

    rf49b3fc rba417e2  
    358358        MemberExpr * clone() const override { return new MemberExpr{ *this }; }
    359359        MUTATE_FRIEND
     360
     361        // Custructor overload meant only for AST conversion
     362        enum NoOpConstruction { NoOpConstructionChosen };
     363        MemberExpr( const CodeLocation & loc, const DeclWithType * mem, const Expr * agg,
     364            NoOpConstruction overloadSelector );
     365        friend class ::ConverterOldToNew;
     366        friend class ::ConverterNewToOld;
    360367};
    361368
Note: See TracChangeset for help on using the changeset viewer.