Changes in src/GenPoly/Lvalue.cc [acd7c5dd:8499c707]

File:

• src/GenPoly/Lvalue.cc (modified) (2 diffs)

src/GenPoly/Lvalue.cc

@@ -27 +27 @@
 #include "SynTree/Mutator.h"
 #include "SymTab/Indexer.h"
+#include "SymTab/Autogen.h"
 
 #include "ResolvExpr/Resolver.h"
-#include "ResolvExpr/TypeEnvironment.h"
 #include "ResolvExpr/typeops.h"
-#include "ResolvExpr/Unify.h"
 
 #include "Common/UniqueName.h"
 #include "Common/utility.h"
+#include "Common/PassVisitor.h"
+
+#include "InitTweak/InitTweak.h"
+
+#if 0
+#define PRINT(x) x
+#else
+#define PRINT(x)
+#endif
 
 namespace GenPoly {
         namespace {
-                /// Replace uses of lvalue returns with appropriate pointers
-                class Pass1 : public Mutator {
-                  public:
-                        Pass1();
-
-                        virtual Expression *mutate( ApplicationExpr *appExpr );
-                        virtual Statement *mutate( ReturnStmt *appExpr );
-                        virtual DeclarationWithType *mutate( FunctionDecl *funDecl );
-                  private:
-                        DeclarationWithType* retval;
-                };
-
-                /// Replace declarations of lvalue returns with appropriate pointers
-                class Pass2 : public Visitor {
-                  public:
-                        virtual void visit( FunctionType *funType );
-                  private:
+                // TODO: fold this into the general createDeref function??
+                Expression * mkDeref( Expression * arg ) {
+                        if ( SymTab::dereferenceOperator ) {
+                                VariableExpr * deref = new VariableExpr( SymTab::dereferenceOperator );
+                                deref->set_result( new PointerType( Type::Qualifiers(), deref->get_result() ) );
+                                Type * base = InitTweak::getPointerBase( arg->get_result() );
+                                assertf( base, "expected pointer type in dereference (type was %s)", toString( arg->get_result() ).c_str() );
+                                ApplicationExpr * ret = new ApplicationExpr( deref, { arg } );
+                                delete ret->get_result();
+                                ret->set_result( base->clone() );
+                                ret->get_result()->set_lvalue( true );
+                                return ret;
+                        } else {
+                                return UntypedExpr::createDeref( arg );
+                        }
+                }
+
+                struct ReferenceConversions final {
+                        void premutate( AddressExpr * addrExpr );
+
+                        Expression * postmutate( CastExpr * castExpr );
+                        Expression * postmutate( AddressExpr * addrExpr );
+                };
+
+                /// Intrinsic functions that take reference parameters don't REALLY take reference parameters -- their reference arguments must always be implicitly dereferenced.
+                struct FixIntrinsicArgs final {
+                        Expression * postmutate( ApplicationExpr * appExpr );
+                };
+
+                struct FixIntrinsicResult final {
+                        Expression * postmutate( ApplicationExpr * appExpr );
+                };
+
+                /// Replace reference types with pointer types
+                struct ReferenceTypeElimination final {
+                        Type * postmutate( ReferenceType * refType );
                 };
 
@@ -60 +87 @@
                 /// https://gcc.gnu.org/onlinedocs/gcc-3.4.6/gcc/Lvalues.html#Lvalues
                 /// Replaces &(a,b) with (a, &b), &(a ? b : c) with (a ? &b : &c)
-                class GeneralizedLvalue : public Mutator {
-                        typedef Mutator Parent;
-
-                        virtual Expression * mutate( MemberExpr * memExpr );
-                        virtual Expression * mutate( AddressExpr * addressExpr );
-
-                        template<typename Func>
-                        Expression * applyTransformation( Expression * expr, Expression * arg, Func mkExpr );
+                struct GeneralizedLvalue final : public WithVisitorRef<GeneralizedLvalue> {
+                        Expression * postmutate( AddressExpr * addressExpr );
+                };
+
+                /// Removes redundant &*/*& pattern that this pass can generate
+                struct CollapseAddrDeref final {
+                        Expression * postmutate( AddressExpr * addressExpr );
+                        Expression * postmutate( ApplicationExpr * appExpr );
+                };
+
+                struct AddrRef final : public WithGuards {
+                        void premutate( AddressExpr * addrExpr );
+                        Expression * postmutate( AddressExpr * addrExpr );
+                        void premutate( Expression * expr );
+
+                        bool first = true;
+                        bool current = false;
+                        int refDepth = 0;
                 };
         } // namespace
 
+        static bool referencesEliminated = false;
+        // used by UntypedExpr::createDeref to determine whether result type of dereference should be ReferenceType or value type.
+        bool referencesPermissable() {
+                return ! referencesEliminated;
+        }
+
         void convertLvalue( std::list< Declaration* >& translationUnit ) {
-                Pass1 p1;
-                Pass2 p2;
-                GeneralizedLvalue genLval;
-                mutateAll( translationUnit, p1 );
-                acceptAll( translationUnit, p2 );
+                std::cerr << "convertLvalue" << std::endl;
+                PassVisitor<ReferenceConversions> refCvt;
+                PassVisitor<ReferenceTypeElimination> elim;
+                PassVisitor<GeneralizedLvalue> genLval;
+                PassVisitor<FixIntrinsicArgs> fixer;
+                PassVisitor<CollapseAddrDeref> collapser;
+                PassVisitor<AddrRef> addrRef;
+                PassVisitor<FixIntrinsicResult> intrinsicResults;
+                mutateAll( translationUnit, intrinsicResults );
+                mutateAll( translationUnit, addrRef );
+                mutateAll( translationUnit, refCvt );
+                mutateAll( translationUnit, fixer );
+                mutateAll( translationUnit, collapser );
                 mutateAll( translationUnit, genLval );
+                mutateAll( translationUnit, elim );  // last because other passes need reference types to work
+
+                // from this point forward, no other pass should create reference types.
+                referencesEliminated = true;
         }
 
-        Expression * generalizedLvalue( Expression * expr ) {
-                GeneralizedLvalue genLval;
-                return expr->acceptMutator( genLval );
-        }
-
         namespace {
-                Type* isLvalueRet( FunctionType *function ) {
-                        if ( function->get_returnVals().empty() ) return 0;
-                        Type *ty = function->get_returnVals().front()->get_type();
-                        return ty->get_lvalue() ? ty : 0;
-                }
-
-                bool isIntrinsicApp( ApplicationExpr *appExpr ) {
-                        if ( VariableExpr *varExpr = dynamic_cast< VariableExpr* >( appExpr->get_function() ) ) {
-                                return varExpr->get_var()->get_linkage() == LinkageSpec::Intrinsic;
-                        } else {
-                                return false;
-                        } // if
-                }
-
-                Pass1::Pass1() {
-                }
-
-                DeclarationWithType * Pass1::mutate( FunctionDecl *funcDecl ) {
-                        if ( funcDecl->get_statements() ) {
-                                DeclarationWithType* oldRetval = retval;
-                                retval = 0;
-                                if ( ! LinkageSpec::isBuiltin( funcDecl->get_linkage() ) && isLvalueRet( funcDecl->get_functionType() ) ) {
-                                        retval = funcDecl->get_functionType()->get_returnVals().front();
-                                }
-                                // fix expressions and return statements in this function
-                                funcDecl->set_statements( funcDecl->get_statements()->acceptMutator( *this ) );
-                                retval = oldRetval;
-                        } // if
-                        return funcDecl;
-                }
-
-                Expression * Pass1::mutate( ApplicationExpr *appExpr ) {
-                        appExpr->get_function()->acceptMutator( *this );
-                        mutateAll( appExpr->get_args(), *this );
-
-                        PointerType *pointer = safe_dynamic_cast< PointerType* >( appExpr->get_function()->get_result() );
-                        FunctionType *function = safe_dynamic_cast< FunctionType* >( pointer->get_base() );
-
-                        Type *funType = isLvalueRet( function );
-                        if ( funType && ! isIntrinsicApp( appExpr ) ) {
-                                Expression *expr = appExpr;
-                                Type *appType = appExpr->get_result();
-                                if ( isPolyType( funType ) && ! isPolyType( appType ) ) {
-                                        // make sure cast for polymorphic type is inside dereference
-                                        expr = new CastExpr( appExpr, new PointerType( Type::Qualifiers(), appType->clone() ) );
-                                }
-                                UntypedExpr *deref = new UntypedExpr( new NameExpr( "*?" ) );
-                                deref->set_result( appType->clone() );
-                                appExpr->set_result( new PointerType( Type::Qualifiers(), appType ) );
-                                deref->get_args().push_back( expr );
-                                return deref;
-                        } else {
-                                return appExpr;
-                        } // if
-                }
-
-                Statement * Pass1::mutate(ReturnStmt *retStmt) {
-                        if ( retval && retStmt->get_expr() ) {
-                                if ( retStmt->get_expr()->get_result()->get_lvalue() ) {
-                                        // ***** Code Removal ***** because casts may be stripped already
-
-                                        // strip casts because not allowed to take address of cast
-                                        // while ( CastExpr *castExpr = dynamic_cast< CastExpr* >( retStmt->get_expr() ) ) {
-                                        //      retStmt->set_expr( castExpr->get_arg() );
-                                        //      retStmt->get_expr()->set_env( castExpr->get_env() );
-                                        //      castExpr->set_env( 0 );
-                                        //      castExpr->set_arg( 0 );
-                                        //      delete castExpr;
-                                        // } // while
-                                        retStmt->set_expr( new AddressExpr( retStmt->get_expr()->acceptMutator( *this ) ) );
+                // true for intrinsic function calls that return a reference
+                bool isIntrinsicReference( Expression * expr ) {
+                        if ( UntypedExpr * untyped = dynamic_cast< UntypedExpr * >( expr ) ) {
+                                std::string fname = InitTweak::getFunctionName( untyped );
+                                // known intrinsic-reference prelude functions
+                                return fname == "*?" || fname == "?[?]";
+                        } else if ( ApplicationExpr * appExpr = dynamic_cast< ApplicationExpr * > ( expr ) ) {
+                                if ( DeclarationWithType * func = InitTweak::getFunction( appExpr ) ) {
+                                        // use type of return variable rather than expr result type, since it may have been changed to a pointer type
+                                        FunctionType * ftype = GenPoly::getFunctionType( func->get_type() );
+                                        Type * ret = ftype->get_returnVals().empty() ? nullptr : ftype->get_returnVals().front()->get_type();
+                                        return func->get_linkage() == LinkageSpec::Intrinsic && dynamic_cast<ReferenceType *>( ret );
+                                }
+                        }
+                        return false;
+                }
+
+                Expression * FixIntrinsicResult::postmutate( ApplicationExpr * appExpr ) {
+                        if ( isIntrinsicReference( appExpr ) ) {
+                                // eliminate reference types from intrinsic applications - now they return lvalues
+                                Type * result = appExpr->get_result();
+                                appExpr->set_result( result->stripReferences()->clone() );
+                                appExpr->get_result()->set_lvalue( true );
+                                Expression * ret = new CastExpr( appExpr, result );
+                                ret->set_env( appExpr->get_env() );
+                                appExpr->set_env( nullptr );
+                                return ret;
+                        }
+                        return appExpr;
+                }
+
+                Expression * FixIntrinsicArgs::postmutate( ApplicationExpr * appExpr ) {
+                        // intrinsic functions don't really take reference-typed parameters, so they require an implicit dereference on their arguments.
+                        if ( DeclarationWithType * function = InitTweak::getFunction( appExpr ) ) {
+                                FunctionType * ftype = GenPoly::getFunctionType( function->get_type() );
+                                assertf( ftype, "Function declaration does not have function type." );
+                                // can be of differing lengths only when function is variadic
+                                assertf( ftype->get_parameters().size() == appExpr->get_args().size() || ftype->get_isVarArgs(), "ApplicationExpr args do not match formal parameter type." );
+
+
+                                unsigned int i = 0;
+                                const unsigned int end = ftype->get_parameters().size();
+                                for ( auto p : unsafe_group_iterate( appExpr->get_args(), ftype->get_parameters() ) ) {
+                                        if (i == end) break;
+                                        Expression *& arg = std::get<0>( p );
+                                        Type * formal = std::get<1>( p )->get_type();
+                                        PRINT(
+                                                std::cerr << "pair<0>: " << arg << std::endl;
+                                                std::cerr << "pair<1>: " << formal << std::endl;
+                                        )
+                                        if ( dynamic_cast<ReferenceType*>( formal ) ) {
+                                                if ( isIntrinsicReference( arg ) ) { // do not combine conditions, because that changes the meaning of the else if
+                                                        if ( function->get_linkage() != LinkageSpec::Intrinsic ) { // intrinsic functions that turn pointers into references
+                                                                // if argument is dereference or array subscript, the result isn't REALLY a reference, so it's not necessary to fix the argument
+                                                                PRINT(
+                                                                        std::cerr << "===is intrinsic arg in non-intrinsic call - adding address" << std::endl;
+                                                                )
+                                                                arg = new AddressExpr( arg );
+                                                        }
+                                                } else if ( function->get_linkage() == LinkageSpec::Intrinsic ) {
+                                                        // std::cerr << "===adding deref to arg" << std::endl;
+                                                        // if the parameter is a reference, add a dereference to the reference-typed argument.
+                                                        Type * baseType = InitTweak::getPointerBase( arg->get_result() );
+                                                        assertf( baseType, "parameter is reference, arg must be pointer or reference: %s", toString( arg->get_result() ).c_str() );
+                                                        PointerType * ptrType = new PointerType( Type::Qualifiers(), baseType->clone() );
+                                                        delete arg->get_result();
+                                                        arg->set_result( ptrType );
+                                                        arg = mkDeref( arg );
+                                                }
+                                        }
+                                        ++i;
+                                }
+                        }
+                        return appExpr;
+                }
+
+                // idea: &&&E: get outer &, inner &
+                // at inner &, record depth D of reference type
+                // at outer &, add D derefs.
+                void AddrRef::premutate( Expression * expr ) {
+                        GuardValue( current );
+                        GuardValue( first );
+                        current = false;
+                        first = true;
+                }
+
+                void AddrRef::premutate( AddressExpr * addrExpr ) {
+                        GuardValue( current );
+                        GuardValue( first );
+                        current = first;
+                        first = false;
+                        if ( current ) {
+                                GuardValue( refDepth );
+                                refDepth = 0;
+                        }
+                }
+
+                Expression * AddrRef::postmutate( AddressExpr * addrExpr ) {
+                        if ( refDepth == 0 ) {
+                                if ( ! isIntrinsicReference( addrExpr->get_arg() ) ) {
+                                        // try to avoid ?[?]
+                                        refDepth = addrExpr->get_arg()->get_result()->referenceDepth();
+                                }
+                        }
+                        if ( current ) {
+                                Expression * ret = addrExpr;
+                                while ( refDepth ) {
+                                        ret = mkDeref( ret );
+                                        refDepth--;
+                                }
+                                return ret;
+                        }
+                        return addrExpr;
+                }
+
+                Expression * ReferenceConversions::postmutate( AddressExpr * addrExpr ) {
+                        // Inner expression may have been lvalue to reference conversion, which becomes an address expression.
+                        // In this case, remove the outer address expression and return the argument.
+                        // TODO: It's possible that this might catch too much and require a more sophisticated check.
+                        return addrExpr;
+                }
+
+                Expression * ReferenceConversions::postmutate( CastExpr * castExpr ) {
+                        // xxx - is it possible to convert directly between reference types with a different base? E.g.,
+                        //   int x;
+                        //   (double&)x;
+                        // At the moment, I am working off of the assumption that this is illegal, thus the cast becomes redundant
+                        // after this pass, so trash the cast altogether. If that changes, care must be taken to insert the correct
+                        // pointer casts in the right places.
+
+                        // conversion to reference type
+                        if ( ReferenceType * refType = dynamic_cast< ReferenceType * >( castExpr->get_result() ) ) {
+                                (void)refType;
+                                if ( ReferenceType * otherRef = dynamic_cast< ReferenceType * >( castExpr->get_arg()->get_result() ) ) {
+                                        // nothing to do if casting from reference to reference.
+                                        (void)otherRef;
+                                        PRINT( std::cerr << "convert reference to reference -- nop" << std::endl; )
+                                        if ( isIntrinsicReference( castExpr->get_arg() ) ) {
+                                                Expression * callExpr = castExpr->get_arg();
+                                                PRINT(
+                                                        std::cerr << "but arg is deref -- &" << std::endl;
+                                                        std::cerr << callExpr << std::endl;
+                                                )
+                                                callExpr = new AddressExpr( callExpr ); // this doesn't work properly for multiple casts
+                                                delete callExpr->get_result();
+                                                callExpr->set_result( refType->clone() );
+                                                // move environment out to new top-level
+                                                callExpr->set_env( castExpr->get_env() );
+                                                castExpr->set_arg( nullptr );
+                                                castExpr->set_env( nullptr );
+                                                delete castExpr;
+                                                return callExpr;
+                                        }
+                                        int depth1 = refType->referenceDepth();
+                                        int depth2 = otherRef->referenceDepth();
+                                        assertf( depth1 == depth2, "non-intrinsic reference with cast of reference to reference not yet supported: %d %d %s", depth1, depth2, toString( castExpr ).c_str() );
+                                        PRINT( std::cerr << castExpr << std::endl; )
+                                        return castExpr;
+                                } else if ( castExpr->get_arg()->get_result()->get_lvalue() ) {
+                                        // conversion from lvalue to reference
+                                        // xxx - keep cast, but turn into pointer cast??
+                                        // xxx - memory
+                                        PRINT(
+                                                std::cerr << "convert lvalue to reference -- &" << std::endl;
+                                                std::cerr << castExpr->get_arg() << std::endl;
+                                        )
+                                        AddressExpr * ret = new AddressExpr( castExpr->get_arg() );
+                                        if ( refType->get_base()->get_qualifiers() != castExpr->get_arg()->get_result()->get_qualifiers() ) {
+                                                // must keep cast if cast-to type is different from the actual type
+                                                castExpr->set_arg( ret );
+                                                return castExpr;
+                                        }
+                                        ret->set_env( castExpr->get_env() );
+                                        delete ret->get_result();
+                                        ret->set_result( castExpr->get_result() );
+                                        castExpr->set_env( nullptr );
+                                        castExpr->set_arg( nullptr );
+                                        castExpr->set_result( nullptr );
+                                        delete castExpr;
+                                        return ret;
                                 } else {
-                                        throw SemanticError( "Attempt to return non-lvalue from an lvalue-qualified function" );
-                                } // if
-                        } // if
-                        return retStmt;
-                }
-
-                void Pass2::visit( FunctionType *funType ) {
-                        std::string typeName;
-                        if ( isLvalueRet( funType ) ) {
-                                DeclarationWithType *retParm = funType->get_returnVals().front();
-
-                                // make a new parameter that is a pointer to the type of the old return value
-                                retParm->set_type( new PointerType( Type::Qualifiers(), retParm->get_type() ) );
-                        } // if
-
-                        Visitor::visit( funType );
-                }
-
-                template<typename Func>
-                Expression * GeneralizedLvalue::applyTransformation( Expression * expr, Expression * arg, Func mkExpr ) {
-                        if ( CommaExpr * commaExpr = dynamic_cast< CommaExpr * >( arg ) ) {
+                                        // rvalue to reference conversion -- introduce temporary
+                                }
+                                assertf( false, "Only conversions to reference from lvalue are currently supported: %s", toString( castExpr ).c_str() );
+                        } else if ( ReferenceType * refType = dynamic_cast< ReferenceType * >( castExpr->get_arg()->get_result() ) ) {
+                                (void)refType;
+                                // conversion from reference to rvalue
+                                PRINT(
+                                        std::cerr << "convert reference to rvalue -- *" << std::endl;
+                                        std::cerr << "was = " << castExpr << std::endl;
+                                )
+                                Expression * ret = castExpr->get_arg();
+                                TypeSubstitution * env = castExpr->get_env();
+                                castExpr->set_env( nullptr );
+                                if ( ! isIntrinsicReference( ret ) ) {
+                                        // dereference if not already dereferenced
+                                        ret = mkDeref( ret );
+                                }
+                                if ( ResolvExpr::typesCompatibleIgnoreQualifiers( castExpr->get_result(), castExpr->get_arg()->get_result()->stripReferences(), SymTab::Indexer() ) ) {
+                                        // can remove cast if types are compatible, changing expression type to value type
+                                        ret->set_result( castExpr->get_result()->clone() );
+                                        castExpr->set_arg( nullptr );
+                                        delete castExpr;
+                                } else {
+                                        // must keep cast if types are different
+                                        castExpr->set_arg( ret );
+                                        ret = castExpr;
+                                }
+                                ret->set_env( env );
+                                PRINT( std::cerr << "now: " << ret << std::endl; )
+                                return ret;
+                        }
+                        return castExpr;
+                }
+
+                Type * ReferenceTypeElimination::postmutate( ReferenceType * refType ) {
+                        Type * base = refType->get_base();
+                        Type::Qualifiers qualifiers = refType->get_qualifiers();
+                        refType->set_base( nullptr );
+                        delete refType;
+                        return new PointerType( qualifiers, base );
+                }
+
+                Expression * GeneralizedLvalue::postmutate( AddressExpr * addrExpr ) {
+                        if ( CommaExpr * commaExpr = dynamic_cast< CommaExpr * >( addrExpr->get_arg() ) ) {
                                 Expression * arg1 = commaExpr->get_arg1()->clone();
                                 Expression * arg2 = commaExpr->get_arg2()->clone();
-                                Expression * ret = new CommaExpr( arg1, mkExpr( arg2 ) );
-                                ret->set_env( expr->get_env() );
-                                expr->set_env( nullptr );
-                                delete expr;
-                                return ret->acceptMutator( *this );
-                        } else if ( ConditionalExpr * condExpr = dynamic_cast< ConditionalExpr * >( arg ) ) {
+                                Expression * ret = new CommaExpr( arg1, (new AddressExpr( arg2 ))->acceptMutator( *visitor ) );
+                                ret->set_env( addrExpr->get_env() );
+                                addrExpr->set_env( nullptr );
+                                delete addrExpr;
+                                return ret;
+                        } else if ( ConditionalExpr * condExpr = dynamic_cast< ConditionalExpr * >( addrExpr->get_arg() ) ) {
                                 Expression * arg1 = condExpr->get_arg1()->clone();
                                 Expression * arg2 = condExpr->get_arg2()->clone();
                                 Expression * arg3 = condExpr->get_arg3()->clone();
-                                ConditionalExpr * ret = new ConditionalExpr( arg1, mkExpr( arg2 ), mkExpr( arg3 ) );
-                                ret->set_env( expr->get_env() );
-                                expr->set_env( nullptr );
-                                delete expr;
-
-                                // conditional expr type may not be either of the argument types, need to unify
-                                using namespace ResolvExpr;
-                                Type* commonType = nullptr;
-                                TypeEnvironment newEnv;
-                                AssertionSet needAssertions, haveAssertions;
-                                OpenVarSet openVars;
-                                unify( ret->get_arg2()->get_result(), ret->get_arg3()->get_result(), newEnv, needAssertions, haveAssertions, openVars, SymTab::Indexer(), commonType );
-                                ret->set_result( commonType ? commonType : ret->get_arg2()->get_result()->clone() );
-                                return ret->acceptMutator( *this );
-                        }
-                        return expr;
-                }
-
-                Expression * GeneralizedLvalue::mutate( MemberExpr * memExpr ) {
-                        Parent::mutate( memExpr );
-                        return applyTransformation( memExpr, memExpr->get_aggregate(), [=]( Expression * aggr ) { return new MemberExpr( memExpr->get_member(), aggr ); } );
-                }
-
-                Expression * GeneralizedLvalue::mutate( AddressExpr * addrExpr ) {
-                        addrExpr = safe_dynamic_cast< AddressExpr * >( Parent::mutate( addrExpr ) );
-                        return applyTransformation( addrExpr, addrExpr->get_arg(), []( Expression * arg ) { return new AddressExpr( arg ); } );
+                                Expression * ret = new ConditionalExpr( arg1, (new AddressExpr( arg2 ))->acceptMutator( *visitor ), (new AddressExpr( arg3 ))->acceptMutator( *visitor ) );
+                                ret->set_env( addrExpr->get_env() );
+                                addrExpr->set_env( nullptr );
+                                delete addrExpr;
+                                return ret;
+                        }
+                        return addrExpr;
+                }
+
+                Expression * CollapseAddrDeref::postmutate( AddressExpr * addrExpr ) {
+                        Expression * arg = addrExpr->get_arg();
+                        if ( isIntrinsicReference( arg ) ) {
+                                std::string fname = InitTweak::getFunctionName( arg );
+                                if ( fname == "*?" ) {
+                                        Expression *& arg0 = InitTweak::getCallArg( arg, 0 );
+                                        Expression * ret = arg0;
+                                        ret->set_env( addrExpr->get_env() );
+                                        arg0 = nullptr;
+                                        addrExpr->set_env( nullptr );
+                                        delete addrExpr;
+                                        return ret;
+                                }
+                        }
+                        return addrExpr;
+                }
+
+                Expression * CollapseAddrDeref::postmutate( ApplicationExpr * appExpr ) {
+                        if ( isIntrinsicReference( appExpr ) ) {
+                                std::string fname = InitTweak::getFunctionName( appExpr );
+                                if ( fname == "*?" ) {
+                                        Expression * arg = InitTweak::getCallArg( appExpr, 0 );
+                                        // xxx - this isn't right, because it can remove casts that should be there...
+                                        // while ( CastExpr * castExpr = dynamic_cast< CastExpr * >( arg ) ) {
+                                        //      arg = castExpr->get_arg();
+                                        // }
+                                        if ( AddressExpr * addrExpr = dynamic_cast< AddressExpr * >( arg ) ) {
+                                                Expression * ret = addrExpr->get_arg();
+                                                ret->set_env( appExpr->get_env() );
+                                                addrExpr->set_arg( nullptr );
+                                                appExpr->set_env( nullptr );
+                                                delete appExpr;
+                                                return ret;
+                                        }
+                                }
+                        }
+                        return appExpr;
                 }
         } // namespace