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source: src/InitTweak/FixInit.cc @ c8dfcd3

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Last change on this file since c8dfcd3 was c8dfcd3, checked in by Rob Schluntz <rschlunt@…>, 8 years ago
insert implicit ctor/dtors if field is unhandled in a struct ctor/dtor
Property mode set to `100644`
File size: 39.0 KB

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1	//
2	// Cforall Version 1.0.0 Copyright (C) 2015 University of Waterloo
3	//
4	// The contents of this file are covered under the licence agreement in the
5	// file "LICENCE" distributed with Cforall.
6	//
7	// FixInit.h --
8	//
9	// Author : Rob Schluntz
10	// Created On : Wed Jan 13 16:29:30 2016
11	// Last Modified By : Peter A. Buhr
12	// Last Modified On : Tue Jul 12 17:41:15 2016
13	// Update Count : 34
14	//
15
16	#include <stack>
17	#include <list>
18	#include <iterator>
19	#include <algorithm>
20	#include "InitTweak.h"
21	#include "FixInit.h"
22	#include "FixGlobalInit.h"
23	#include "ResolvExpr/Resolver.h"
24	#include "ResolvExpr/typeops.h"
25	#include "SynTree/Declaration.h"
26	#include "SynTree/Type.h"
27	#include "SynTree/Expression.h"
28	#include "SynTree/Attribute.h"
29	#include "SynTree/Statement.h"
30	#include "SynTree/Initializer.h"
31	#include "SynTree/Mutator.h"
32	#include "SymTab/Indexer.h"
33	#include "SymTab/Autogen.h"
34	#include "GenPoly/PolyMutator.h"
35	#include "SynTree/AddStmtVisitor.h"
36	#include "CodeGen/GenType.h" // for warnings
37
38	bool ctordtorp = false;
39	bool ctorp = false;
40	bool cpctorp = false;
41	bool dtorp = false;
42	#define PRINT( text ) if ( ctordtorp ) { text }
43	#define CP_CTOR_PRINT( text ) if ( ctordtorp \|\| cpctorp ) { text }
44	#define DTOR_PRINT( text ) if ( ctordtorp \|\| dtorp ) { text }
45
46	namespace InitTweak {
47	namespace {
48	const std::list<Label> noLabels;
49	const std::list<Expression*> noDesignators;
50
51	class InsertImplicitCalls : public GenPoly::PolyMutator {
52	public:
53	/// wrap function application expressions as ImplicitCopyCtorExpr nodes so that it is easy to identify which
54	/// function calls need their parameters to be copy constructed
55	static void insert( std::list< Declaration * > & translationUnit );
56
57	virtual Expression * mutate( ApplicationExpr * appExpr );
58	};
59
60	class ResolveCopyCtors : public SymTab::Indexer {
61	public:
62	/// generate temporary ObjectDecls for each argument and return value of each ImplicitCopyCtorExpr,
63	/// generate/resolve copy construction expressions for each, and generate/resolve destructors for both
64	/// arguments and return value temporaries
65	static void resolveImplicitCalls( std::list< Declaration * > & translationUnit );
66
67	virtual void visit( ImplicitCopyCtorExpr * impCpCtorExpr );
68
69	/// create and resolve ctor/dtor expression: fname(var, [cpArg])
70	ApplicationExpr * makeCtorDtor( const std::string & fname, ObjectDecl * var, Expression * cpArg = NULL );
71	/// true if type does not need to be copy constructed to ensure correctness
72	bool skipCopyConstruct( Type * );
73	private:
74	TypeSubstitution * env;
75	};
76
77	/// collects constructed object decls - used as a base class
78	class ObjDeclCollector : public AddStmtVisitor {
79	public:
80	typedef AddStmtVisitor Parent;
81	using Parent::visit;
82	typedef std::set< ObjectDecl * > ObjectSet;
83	virtual void visit( CompoundStmt *compoundStmt );
84	virtual void visit( DeclStmt *stmt );
85	protected:
86	ObjectSet curVars;
87	};
88
89	// debug
90	struct printSet {
91	typedef ObjDeclCollector::ObjectSet ObjectSet;
92	printSet( const ObjectSet & objs ) : objs( objs ) {}
93	const ObjectSet & objs;
94	};
95	std::ostream & operator<<( std::ostream & out, const printSet & set) {
96	out << "{ ";
97	for ( ObjectDecl * obj : set.objs ) {
98	out << obj->get_name() << ", " ;
99	} // for
100	out << " }";
101	return out;
102	}
103
104	class LabelFinder : public ObjDeclCollector {
105	public:
106	typedef ObjDeclCollector Parent;
107	typedef std::map< Label, ObjectSet > LabelMap;
108	// map of Label -> live variables at that label
109	LabelMap vars;
110
111	void handleStmt( Statement * stmt );
112
113	// xxx - This needs to be done better.
114	// allow some generalization among different kinds of nodes with with similar parentage (e.g. all
115	// expressions, all statements, etc.) important to have this to provide a single entry point so that as new
116	// subclasses are added, there is only one place that the code has to be updated, rather than ensure that
117	// every specialized class knows about every new kind of statement that might be added.
118	virtual void visit( CompoundStmt *stmt ) { handleStmt( stmt ); return Parent::visit( stmt ); }
119	virtual void visit( ExprStmt *stmt ) { handleStmt( stmt ); return Parent::visit( stmt ); }
120	virtual void visit( AsmStmt *stmt ) { handleStmt( stmt ); return Parent::visit( stmt ); }
121	virtual void visit( IfStmt *stmt ) { handleStmt( stmt ); return Parent::visit( stmt ); }
122	virtual void visit( WhileStmt *stmt ) { handleStmt( stmt ); return Parent::visit( stmt ); }
123	virtual void visit( ForStmt *stmt ) { handleStmt( stmt ); return Parent::visit( stmt ); }
124	virtual void visit( SwitchStmt *stmt ) { handleStmt( stmt ); return Parent::visit( stmt ); }
125	virtual void visit( CaseStmt *stmt ) { handleStmt( stmt ); return Parent::visit( stmt ); }
126	virtual void visit( BranchStmt *stmt ) { handleStmt( stmt ); return Parent::visit( stmt ); }
127	virtual void visit( ReturnStmt *stmt ) { handleStmt( stmt ); return Parent::visit( stmt ); }
128	virtual void visit( TryStmt *stmt ) { handleStmt( stmt ); return Parent::visit( stmt ); }
129	virtual void visit( CatchStmt *stmt ) { handleStmt( stmt ); return Parent::visit( stmt ); }
130	virtual void visit( FinallyStmt *stmt ) { handleStmt( stmt ); return Parent::visit( stmt ); }
131	virtual void visit( NullStmt *stmt ) { handleStmt( stmt ); return Parent::visit( stmt ); }
132	virtual void visit( DeclStmt *stmt ) { handleStmt( stmt ); return Parent::visit( stmt ); }
133	virtual void visit( ImplicitCtorDtorStmt *stmt ) { handleStmt( stmt ); return Parent::visit( stmt ); }
134	};
135
136	class InsertDtors : public ObjDeclCollector {
137	public:
138	/// insert destructor calls at the appropriate places. must happen before CtorInit nodes are removed
139	/// (currently by FixInit)
140	static void insert( std::list< Declaration * > & translationUnit );
141
142	typedef ObjDeclCollector Parent;
143	typedef std::list< ObjectDecl * > OrderedDecls;
144	typedef std::list< OrderedDecls > OrderedDeclsStack;
145
146	InsertDtors( LabelFinder & finder ) : labelVars( finder.vars ) {}
147
148	virtual void visit( ObjectDecl * objDecl );
149
150	virtual void visit( CompoundStmt * compoundStmt );
151	virtual void visit( ReturnStmt * returnStmt );
152	virtual void visit( BranchStmt * stmt );
153	private:
154	void handleGoto( BranchStmt * stmt );
155
156	LabelFinder::LabelMap & labelVars;
157	OrderedDeclsStack reverseDeclOrder;
158	};
159
160	class FixInit : public GenPoly::PolyMutator {
161	public:
162	/// expand each object declaration to use its constructor after it is declared.
163	static void fixInitializers( std::list< Declaration * > &translationUnit );
164
165	virtual DeclarationWithType * mutate( ObjectDecl *objDecl );
166
167	std::list< Declaration * > staticDtorDecls;
168	};
169
170	class FixCopyCtors : public GenPoly::PolyMutator {
171	public:
172	/// expand ImplicitCopyCtorExpr nodes into the temporary declarations, copy constructors, call expression,
173	/// and destructors
174	static void fixCopyCtors( std::list< Declaration * > &translationUnit );
175
176	virtual Expression * mutate( ImplicitCopyCtorExpr * impCpCtorExpr );
177	};
178
179	class GenStructMemberCalls : public SymTab::Indexer {
180	public:
181	typedef Indexer Parent;
182	/// generate default/copy ctor and dtor calls for user-defined struct ctor/dtors
183	/// for any member that is missing a corresponding ctor/dtor call.
184	/// error if a member is used before constructed
185	static void generate( std::list< Declaration * > & translationUnit );
186
187	virtual void visit( FunctionDecl * funcDecl );
188
189	virtual void visit( MemberExpr * memberExpr );
190	virtual void visit( ApplicationExpr * appExpr );
191
192	SemanticError errors;
193	private:
194	void handleFirstParam( Expression * firstParam );
195	template< typename... Params >
196	void emit( const Params &... params );
197
198	FunctionDecl * function = 0;
199	std::set< DeclarationWithType * > unhandled, usedUninit;
200	ObjectDecl * thisParam = 0;
201	bool isCtor = false; // true if current function is a constructor
202	};
203
204	// very simple resolver-like mutator class - used to
205	// resolve UntypedExprs that are found within newly
206	// generated constructor/destructor calls
207	class MutatingResolver : public Mutator {
208	public:
209	MutatingResolver( SymTab::Indexer & indexer ) : indexer( indexer ) {}
210
211	virtual DeclarationWithType* mutate( ObjectDecl *objectDecl );
212
213	virtual Expression* mutate( UntypedExpr *untypedExpr );
214	private:
215	SymTab::Indexer & indexer;
216	};
217	} // namespace
218
219	void fix( std::list< Declaration * > & translationUnit, const std::string & filename, bool inLibrary ) {
220	// fixes ConstructorInit for global variables. should happen before fixInitializers.
221	InitTweak::fixGlobalInit( translationUnit, filename, inLibrary );
222
223	InsertImplicitCalls::insert( translationUnit );
224	ResolveCopyCtors::resolveImplicitCalls( translationUnit );
225	InsertDtors::insert( translationUnit );
226	FixInit::fixInitializers( translationUnit );
227
228	// FixCopyCtors must happen after FixInit, so that destructors are placed correctly
229	FixCopyCtors::fixCopyCtors( translationUnit );
230
231	GenStructMemberCalls::generate( translationUnit );
232	}
233
234	namespace {
235	void InsertImplicitCalls::insert( std::list< Declaration * > & translationUnit ) {
236	InsertImplicitCalls inserter;
237	mutateAll( translationUnit, inserter );
238	}
239
240	void ResolveCopyCtors::resolveImplicitCalls( std::list< Declaration * > & translationUnit ) {
241	ResolveCopyCtors resolver;
242	acceptAll( translationUnit, resolver );
243	}
244
245	void FixInit::fixInitializers( std::list< Declaration * > & translationUnit ) {
246	FixInit fixer;
247
248	// can't use mutateAll, because need to insert declarations at top-level
249	// can't use DeclMutator, because sometimes need to insert IfStmt, etc.
250	SemanticError errors;
251	for ( std::list< Declaration * >::iterator i = translationUnit.begin(); i != translationUnit.end(); ++i ) {
252	try {
253	i = maybeMutate( i, fixer );
254	translationUnit.splice( i, fixer.staticDtorDecls );
255	} catch( SemanticError &e ) {
256	errors.append( e );
257	} // try
258	} // for
259	if ( ! errors.isEmpty() ) {
260	throw errors;
261	} // if
262	}
263
264	void InsertDtors::insert( std::list< Declaration * > & translationUnit ) {
265	LabelFinder finder;
266	InsertDtors inserter( finder );
267	acceptAll( translationUnit, finder );
268	acceptAll( translationUnit, inserter );
269	}
270
271	void FixCopyCtors::fixCopyCtors( std::list< Declaration * > & translationUnit ) {
272	FixCopyCtors fixer;
273	mutateAll( translationUnit, fixer );
274	}
275
276	void GenStructMemberCalls::generate( std::list< Declaration * > & translationUnit ) {
277	GenStructMemberCalls warner;
278	acceptAll( translationUnit, warner );
279
280	// visitor doesn't throw so that it can collect all errors
281	if ( ! warner.errors.isEmpty() ) {
282	throw warner.errors;
283	}
284	}
285
286	Expression * InsertImplicitCalls::mutate( ApplicationExpr * appExpr ) {
287	appExpr = dynamic_cast< ApplicationExpr * >( Mutator::mutate( appExpr ) );
288	assert( appExpr );
289
290	if ( VariableExpr * function = dynamic_cast< VariableExpr * > ( appExpr->get_function() ) ) {
291	if ( function->get_var()->get_linkage() == LinkageSpec::Intrinsic ) {
292	// optimization: don't need to copy construct in order to call intrinsic functions
293	return appExpr;
294	} else if ( DeclarationWithType * funcDecl = dynamic_cast< DeclarationWithType * > ( function->get_var() ) ) {
295	FunctionType * ftype = dynamic_cast< FunctionType * >( GenPoly::getFunctionType( funcDecl->get_type() ) );
296	assert( ftype );
297	if ( (isConstructor( funcDecl->get_name() ) \|\| funcDecl->get_name() == "?=?") && ftype->get_parameters().size() == 2 ) {
298	Type * t1 = ftype->get_parameters().front()->get_type();
299	Type * t2 = ftype->get_parameters().back()->get_type();
300	PointerType * ptrType = dynamic_cast< PointerType * > ( t1 );
301	assert( ptrType );
302
303	if ( ResolvExpr::typesCompatible( ptrType->get_base(), t2, SymTab::Indexer() ) ) {
304	// optimization: don't need to copy construct in order to call a copy constructor or
305	// assignment operator
306	return appExpr;
307	} // if
308	} else if ( isDestructor( funcDecl->get_name() ) ) {
309	// correctness: never copy construct arguments to a destructor
310	return appExpr;
311	} // if
312	} // if
313	} // if
314	CP_CTOR_PRINT( std::cerr << "InsertImplicitCalls: adding a wrapper " << appExpr << std::endl; )
315
316	// wrap each function call so that it is easy to identify nodes that have to be copy constructed
317	ImplicitCopyCtorExpr * expr = new ImplicitCopyCtorExpr( appExpr );
318	// save the type substitution onto the new node so that it is easy to find.
319	// Ensure it is not deleted with the ImplicitCopyCtorExpr by removing it before deletion.
320	// The substitution is needed to obtain the type of temporary variables so that copy constructor
321	// calls can be resolved. Normally this is what PolyMutator is for, but the pass that resolves
322	// copy constructor calls must be an Indexer. We could alternatively make a PolyIndexer which
323	// saves the environment, or compute the types of temporaries here, but it's much simpler to
324	// save the environment here, and more cohesive to compute temporary variables and resolve copy
325	// constructor calls together.
326	assert( env );
327	expr->set_env( env );
328	return expr;
329	}
330
331	bool ResolveCopyCtors::skipCopyConstruct( Type * type ) {
332	return dynamic_cast< VarArgsType * >( type ) \|\| GenPoly::getFunctionType( type );
333	}
334
335	ApplicationExpr * ResolveCopyCtors::makeCtorDtor( const std::string & fname, ObjectDecl * var, Expression * cpArg ) {
336	assert( var );
337	UntypedExpr * untyped = new UntypedExpr( new NameExpr( fname ) );
338	untyped->get_args().push_back( new AddressExpr( new VariableExpr( var ) ) );
339	if (cpArg) untyped->get_args().push_back( cpArg->clone() );
340
341	// resolve copy constructor
342	// should only be one alternative for copy ctor and dtor expressions, since all arguments are fixed
343	// (VariableExpr and already resolved expression)
344	CP_CTOR_PRINT( std::cerr << "ResolvingCtorDtor " << untyped << std::endl; )
345	ApplicationExpr * resolved = dynamic_cast< ApplicationExpr * >( ResolvExpr::findVoidExpression( untyped, *this ) );
346	if ( resolved->get_env() ) {
347	env->add( *resolved->get_env() );
348	} // if
349
350	assert( resolved );
351	delete untyped;
352	return resolved;
353	}
354
355	void ResolveCopyCtors::visit( ImplicitCopyCtorExpr *impCpCtorExpr ) {
356	static UniqueName tempNamer("_tmp_cp");
357	static UniqueName retNamer("_tmp_cp_ret");
358
359	CP_CTOR_PRINT( std::cerr << "ResolveCopyCtors: " << impCpCtorExpr << std::endl; )
360	Visitor::visit( impCpCtorExpr );
361	env = impCpCtorExpr->get_env(); // xxx - maybe we really should just have a PolyIndexer...
362
363	ApplicationExpr * appExpr = impCpCtorExpr->get_callExpr();
364
365	// take each argument and attempt to copy construct it.
366	for ( Expression * & arg : appExpr->get_args() ) {
367	CP_CTOR_PRINT( std::cerr << "Type Substitution: " << *impCpCtorExpr->get_env() << std::endl; )
368	// xxx - need to handle tuple arguments
369	assert( ! arg->get_results().empty() );
370	Type * result = arg->get_results().front();
371	if ( skipCopyConstruct( result ) ) continue; // skip certain non-copyable types
372	// type may involve type variables, so apply type substitution to get temporary variable's actual type
373	result = result->clone();
374	impCpCtorExpr->get_env()->apply( result );
375	ObjectDecl * tmp = new ObjectDecl( tempNamer.newName(), DeclarationNode::NoStorageClass, LinkageSpec::C, 0, result, 0 );
376	tmp->get_type()->set_isConst( false );
377
378	// create and resolve copy constructor
379	CP_CTOR_PRINT( std::cerr << "makeCtorDtor for an argument" << std::endl; )
380	ApplicationExpr * cpCtor = makeCtorDtor( "?{}", tmp, arg );
381
382	// if the chosen constructor is intrinsic, the copy is unnecessary, so
383	// don't create the temporary and don't call the copy constructor
384	VariableExpr * function = dynamic_cast< VariableExpr * >( cpCtor->get_function() );
385	assert( function );
386	if ( function->get_var()->get_linkage() != LinkageSpec::Intrinsic ) {
387	// replace argument to function call with temporary
388	arg = new CommaExpr( cpCtor, new VariableExpr( tmp ) );
389	impCpCtorExpr->get_tempDecls().push_back( tmp );
390	impCpCtorExpr->get_dtors().push_front( makeCtorDtor( "^?{}", tmp ) );
391	} // if
392	} // for
393
394	// each return value from the call needs to be connected with an ObjectDecl at the call site, which is
395	// initialized with the return value and is destructed later
396	// xxx - handle multiple return values
397	ApplicationExpr * callExpr = impCpCtorExpr->get_callExpr();
398	// xxx - is this right? callExpr may not have the right environment, because it was attached at a higher
399	// level. Trying to pass that environment along.
400	callExpr->set_env( impCpCtorExpr->get_env()->clone() );
401	for ( Type * result : appExpr->get_results() ) {
402	result = result->clone();
403	impCpCtorExpr->get_env()->apply( result );
404	ObjectDecl * ret = new ObjectDecl( retNamer.newName(), DeclarationNode::NoStorageClass, LinkageSpec::C, 0, result, 0 );
405	ret->get_type()->set_isConst( false );
406	impCpCtorExpr->get_returnDecls().push_back( ret );
407	CP_CTOR_PRINT( std::cerr << "makeCtorDtor for a return" << std::endl; )
408	impCpCtorExpr->get_dtors().push_front( makeCtorDtor( "^?{}", ret ) );
409	} // for
410	CP_CTOR_PRINT( std::cerr << "after Resolving: " << impCpCtorExpr << std::endl; )
411	}
412
413
414	Expression * FixCopyCtors::mutate( ImplicitCopyCtorExpr * impCpCtorExpr ) {
415	CP_CTOR_PRINT( std::cerr << "FixCopyCtors: " << impCpCtorExpr << std::endl; )
416
417	impCpCtorExpr = dynamic_cast< ImplicitCopyCtorExpr * >( Mutator::mutate( impCpCtorExpr ) );
418	assert( impCpCtorExpr );
419
420	std::list< ObjectDecl * > & tempDecls = impCpCtorExpr->get_tempDecls();
421	std::list< ObjectDecl * > & returnDecls = impCpCtorExpr->get_returnDecls();
422	std::list< Expression * > & dtors = impCpCtorExpr->get_dtors();
423
424	// add all temporary declarations and their constructors
425	for ( ObjectDecl * obj : tempDecls ) {
426	stmtsToAdd.push_back( new DeclStmt( noLabels, obj ) );
427	} // for
428	for ( ObjectDecl * obj : returnDecls ) {
429	stmtsToAdd.push_back( new DeclStmt( noLabels, obj ) );
430	} // for
431
432	// add destructors after current statement
433	for ( Expression * dtor : dtors ) {
434	stmtsToAddAfter.push_back( new ExprStmt( noLabels, dtor ) );
435	} // for
436
437	// xxx - update to work with multiple return values
438	ObjectDecl * returnDecl = returnDecls.empty() ? NULL : returnDecls.front();
439	Expression * callExpr = impCpCtorExpr->get_callExpr();
440
441	CP_CTOR_PRINT( std::cerr << "Coming out the back..." << impCpCtorExpr << std::endl; )
442
443	// detach fields from wrapper node so that it can be deleted without deleting too much
444	dtors.clear();
445	tempDecls.clear();
446	returnDecls.clear();
447	impCpCtorExpr->set_callExpr( NULL );
448	impCpCtorExpr->set_env( NULL );
449	delete impCpCtorExpr;
450
451	if ( returnDecl ) {
452	UntypedExpr * assign = new UntypedExpr( new NameExpr( "?=?" ) );
453	assign->get_args().push_back( new VariableExpr( returnDecl ) );
454	assign->get_args().push_back( callExpr );
455	// know the result type of the assignment is the type of the LHS (minus the pointer), so
456	// add that onto the assignment expression so that later steps have the necessary information
457	assign->add_result( returnDecl->get_type()->clone() );
458
459	Expression * retExpr = new CommaExpr( assign, new VariableExpr( returnDecl ) );
460	if ( callExpr->get_results().front()->get_isLvalue() ) {
461	// lvalue returning functions are funny. Lvalue.cc inserts a *? in front of any lvalue returning
462	// non-intrinsic function. Add an AddressExpr to the call to negate the derefence and change the
463	// type of the return temporary from T to T* to properly capture the return value. Then dereference
464	// the result of the comma expression, since the lvalue returning call was originally wrapped with
465	// an AddressExpr. Effectively, this turns
466	// lvalue T f();
467	// &*f()
468	// into
469	// T * tmp_cp_retN;
470	// tmp_cp_ret_N = &(tmp_cp_ret_N = &f(), tmp_cp_ret);
471	// which work out in terms of types, but is pretty messy. It would be nice to find a better way.
472	assign->get_args().back() = new AddressExpr( assign->get_args().back() );
473
474	Type * resultType = returnDecl->get_type()->clone();
475	returnDecl->set_type( new PointerType( Type::Qualifiers(), returnDecl->get_type() ) );
476	UntypedExpr * deref = new UntypedExpr( new NameExpr( "*?" ) );
477	deref->get_args().push_back( retExpr );
478	deref->add_result( resultType );
479	retExpr = deref;
480	} // if
481	// xxx - might need to set env on retExpr...
482	// retExpr->set_env( env->clone() );
483	return retExpr;
484	} else {
485	return callExpr;
486	} // if
487	}
488
489	DeclarationWithType FixInit::mutate( ObjectDecl objDecl ) {
490	// first recursively handle pieces of ObjectDecl so that they aren't missed by other visitors when the init
491	// is removed from the ObjectDecl
492	objDecl = dynamic_cast< ObjectDecl * >( Mutator::mutate( objDecl ) );
493
494	if ( ConstructorInit * ctorInit = dynamic_cast< ConstructorInit * >( objDecl->get_init() ) ) {
495	// a decision should have been made by the resolver, so ctor and init are not both non-NULL
496	assert( ! ctorInit->get_ctor() \|\| ! ctorInit->get_init() );
497	if ( Statement * ctor = ctorInit->get_ctor() ) {
498	if ( objDecl->get_storageClass() == DeclarationNode::Static ) {
499	// originally wanted to take advantage of gcc nested functions, but
500	// we get memory errors with this approach. To remedy this, the static
501	// variable is hoisted when the destructor needs to be called.
502	//
503	// generate:
504	// static T __objName_static_varN;
505	// void __objName_dtor_atexitN() {
506	// __dtor__...;
507	// }
508	// int f(...) {
509	// ...
510	// static bool __objName_uninitialized = true;
511	// if (__objName_uninitialized) {
512	// __ctor(__objName);
513	// __objName_uninitialized = false;
514	// atexit(__objName_dtor_atexitN);
515	// }
516	// ...
517	// }
518
519	static UniqueName dtorCallerNamer( "_dtor_atexit" );
520
521	// static bool __objName_uninitialized = true
522	BasicType * boolType = new BasicType( Type::Qualifiers(), BasicType::Bool );
523	SingleInit * boolInitExpr = new SingleInit( new ConstantExpr( Constant( boolType->clone(), "1" ) ), noDesignators );
524	ObjectDecl * isUninitializedVar = new ObjectDecl( objDecl->get_mangleName() + "_uninitialized", DeclarationNode::Static, LinkageSpec::Cforall, 0, boolType, boolInitExpr );
525	isUninitializedVar->fixUniqueId();
526
527	// __objName_uninitialized = false;
528	UntypedExpr * setTrue = new UntypedExpr( new NameExpr( "?=?" ) );
529	setTrue->get_args().push_back( new VariableExpr( isUninitializedVar ) );
530	setTrue->get_args().push_back( new ConstantExpr( Constant( boolType->clone(), "0" ) ) );
531
532	// generate body of if
533	CompoundStmt * initStmts = new CompoundStmt( noLabels );
534	std::list< Statement * > & body = initStmts->get_kids();
535	body.push_back( ctor );
536	body.push_back( new ExprStmt( noLabels, setTrue ) );
537
538	// put it all together
539	IfStmt * ifStmt = new IfStmt( noLabels, new VariableExpr( isUninitializedVar ), initStmts, 0 );
540	stmtsToAddAfter.push_back( new DeclStmt( noLabels, isUninitializedVar ) );
541	stmtsToAddAfter.push_back( ifStmt );
542
543	if ( ctorInit->get_dtor() ) {
544	// if the object has a non-trivial destructor, have to
545	// hoist it and the object into the global space and
546	// call the destructor function with atexit.
547
548	Statement * dtorStmt = ctorInit->get_dtor()->clone();
549
550	// void __objName_dtor_atexitN(...) {...}
551	FunctionDecl * dtorCaller = new FunctionDecl( objDecl->get_mangleName() + dtorCallerNamer.newName(), DeclarationNode::Static, LinkageSpec::C, new FunctionType( Type::Qualifiers(), false ), new CompoundStmt( noLabels ), false, false );
552	dtorCaller->fixUniqueId();
553	dtorCaller->get_statements()->push_back( dtorStmt );
554
555	// atexit(dtor_atexit);
556	UntypedExpr * callAtexit = new UntypedExpr( new NameExpr( "atexit" ) );
557	callAtexit->get_args().push_back( new VariableExpr( dtorCaller ) );
558
559	body.push_back( new ExprStmt( noLabels, callAtexit ) );
560
561	// hoist variable and dtor caller decls to list of decls that will be added into global scope
562	staticDtorDecls.push_back( objDecl );
563	staticDtorDecls.push_back( dtorCaller );
564
565	// need to rename object uniquely since it now appears
566	// at global scope and there could be multiple function-scoped
567	// static variables with the same name in different functions.
568	// Note: it isn't sufficient to modify only the mangleName, because
569	// then subsequent Indexer passes can choke on seeing the object's name
570	// if another object has the same name and type. An unfortunate side-effect
571	// of renaming the object is that subsequent NameExprs may fail to resolve,
572	// but there shouldn't be any remaining past this point.
573	static UniqueName staticNamer( "_static_var" );
574	objDecl->set_name( objDecl->get_name() + staticNamer.newName() );
575	objDecl->set_mangleName( SymTab::Mangler::mangle( objDecl ) );
576
577	objDecl->set_init( NULL );
578	ctorInit->set_ctor( NULL );
579	delete ctorInit;
580
581	// xxx - temporary hack: need to return a declaration, but want to hoist the current object out of this scope
582	// create a new object which is never used
583	static UniqueName dummyNamer( "_dummy" );
584	ObjectDecl * dummy = new ObjectDecl( dummyNamer.newName(), DeclarationNode::Static, LinkageSpec::Cforall, 0, new PointerType( Type::Qualifiers(), new VoidType( Type::Qualifiers() ) ), 0, std::list< Attribute * >{ new Attribute("unused") } );
585	return dummy;
586	}
587	} else {
588	stmtsToAddAfter.push_back( ctor );
589	} // if
590	objDecl->set_init( NULL );
591	ctorInit->set_ctor( NULL );
592	} else if ( Initializer * init = ctorInit->get_init() ) {
593	objDecl->set_init( init );
594	ctorInit->set_init( NULL );
595	} else {
596	// no constructor and no initializer, which is okay
597	objDecl->set_init( NULL );
598	} // if
599	delete ctorInit;
600	} // if
601	return objDecl;
602	}
603
604	void ObjDeclCollector::visit( CompoundStmt *compoundStmt ) {
605	std::set< ObjectDecl * > prevVars = curVars;
606	Parent::visit( compoundStmt );
607	curVars = prevVars;
608	}
609
610	void ObjDeclCollector::visit( DeclStmt *stmt ) {
611	// keep track of all variables currently in scope
612	if ( ObjectDecl * objDecl = dynamic_cast< ObjectDecl * > ( stmt->get_decl() ) ) {
613	curVars.insert( objDecl );
614	} // if
615	Parent::visit( stmt );
616	}
617
618	void LabelFinder::handleStmt( Statement * stmt ) {
619	// for each label, remember the variables in scope at that label.
620	for ( Label l : stmt->get_labels() ) {
621	vars[l] = curVars;
622	} // for
623	}
624
625	template<typename Iterator, typename OutputIterator>
626	void insertDtors( Iterator begin, Iterator end, OutputIterator out ) {
627	for ( Iterator it = begin ; it != end ; ++it ) {
628	// extract destructor statement from the object decl and insert it into the output. Note that this is
629	// only called on lists of non-static objects with implicit non-intrinsic dtors, so if the user manually
630	// calls an intrinsic dtor then the call must (and will) still be generated since the argument may
631	// contain side effects.
632	ObjectDecl * objDecl = *it;
633	ConstructorInit * ctorInit = dynamic_cast< ConstructorInit * >( objDecl->get_init() );
634	assert( ctorInit && ctorInit->get_dtor() );
635	*out++ = ctorInit->get_dtor()->clone();
636	} // for
637	}
638
639	void InsertDtors::visit( ObjectDecl * objDecl ) {
640	// remember non-static destructed objects so that their destructors can be inserted later
641	if ( objDecl->get_storageClass() != DeclarationNode::Static ) {
642	if ( ConstructorInit * ctorInit = dynamic_cast< ConstructorInit * >( objDecl->get_init() ) ) {
643	// a decision should have been made by the resolver, so ctor and init are not both non-NULL
644	assert( ! ctorInit->get_ctor() \|\| ! ctorInit->get_init() );
645	Statement * dtor = ctorInit->get_dtor();
646	if ( dtor && ! isIntrinsicSingleArgCallStmt( dtor ) ) {
647	// don't need to call intrinsic dtor, because it does nothing, but
648	// non-intrinsic dtors must be called
649	reverseDeclOrder.front().push_front( objDecl );
650	} // if
651	} // if
652	} // if
653	Parent::visit( objDecl );
654	}
655
656	void InsertDtors::visit( CompoundStmt * compoundStmt ) {
657	// visit statements - this will also populate reverseDeclOrder list. don't want to dump all destructors
658	// when block is left, just the destructors associated with variables defined in this block, so push a new
659	// list to the top of the stack so that we can differentiate scopes
660	reverseDeclOrder.push_front( OrderedDecls() );
661	Parent::visit( compoundStmt );
662
663	// add destructors for the current scope that we're exiting
664	std::list< Statement * > & statements = compoundStmt->get_kids();
665	insertDtors( reverseDeclOrder.front().begin(), reverseDeclOrder.front().end(), back_inserter( statements ) );
666	reverseDeclOrder.pop_front();
667	}
668
669	void InsertDtors::visit( ReturnStmt * returnStmt ) {
670	// return exits all scopes, so dump destructors for all scopes
671	for ( OrderedDecls & od : reverseDeclOrder ) {
672	insertDtors( od.begin(), od.end(), back_inserter( stmtsToAdd ) );
673	} // for
674	}
675
676	// Handle break/continue/goto in the same manner as C++. Basic idea: any objects that are in scope at the
677	// BranchStmt but not at the labelled (target) statement must be destructed. If there are any objects in scope
678	// at the target location but not at the BranchStmt then those objects would be uninitialized so notify the user
679	// of the error. See C++ Reference 6.6 Jump Statements for details.
680	void InsertDtors::handleGoto( BranchStmt * stmt ) {
681	assert( stmt->get_target() != "" && "BranchStmt missing a label" );
682	// S_L = lvars = set of objects in scope at label definition
683	// S_G = curVars = set of objects in scope at goto statement
684	ObjectSet & lvars = labelVars[ stmt->get_target() ];
685
686	DTOR_PRINT(
687	std::cerr << "at goto label: " << stmt->get_target().get_name() << std::endl;
688	std::cerr << "S_G = " << printSet( curVars ) << std::endl;
689	std::cerr << "S_L = " << printSet( lvars ) << std::endl;
690	)
691
692	ObjectSet diff;
693	// S_L-S_G results in set of objects whose construction is skipped - it's an error if this set is non-empty
694	std::set_difference( lvars.begin(), lvars.end(), curVars.begin(), curVars.end(), std::inserter( diff, diff.begin() ) );
695	DTOR_PRINT(
696	std::cerr << "S_L-S_G = " << printSet( diff ) << std::endl;
697	)
698	if ( ! diff.empty() ) {
699	throw SemanticError( std::string("jump to label '") + stmt->get_target().get_name() + "' crosses initialization of " + (*diff.begin())->get_name() + " ", stmt );
700	} // if
701	// S_G-S_L results in set of objects that must be destructed
702	diff.clear();
703	std::set_difference( curVars.begin(), curVars.end(), lvars.begin(), lvars.end(), std::inserter( diff, diff.end() ) );
704	DTOR_PRINT(
705	std::cerr << "S_G-S_L = " << printSet( diff ) << std::endl;
706	)
707	if ( ! diff.empty() ) {
708	// go through decl ordered list of objectdecl. for each element that occurs in diff, output destructor
709	OrderedDecls ordered;
710	for ( OrderedDecls & rdo : reverseDeclOrder ) {
711	// add elements from reverseDeclOrder into ordered if they occur in diff - it is key that this happens in reverse declaration order.
712	copy_if( rdo.begin(), rdo.end(), back_inserter( ordered ), [&]( ObjectDecl * objDecl ) { return diff.count( objDecl ); } );
713	} // for
714	insertDtors( ordered.begin(), ordered.end(), back_inserter( stmtsToAdd ) );
715	} // if
716	}
717
718	void InsertDtors::visit( BranchStmt * stmt ) {
719	switch( stmt->get_type() ) {
720	case BranchStmt::Continue:
721	case BranchStmt::Break:
722	// could optimize the break/continue case, because the S_L-S_G check is unnecessary (this set should
723	// always be empty), but it serves as a small sanity check.
724	case BranchStmt::Goto:
725	handleGoto( stmt );
726	break;
727	default:
728	assert( false );
729	} // switch
730	}
731
732	bool checkWarnings( FunctionDecl * funcDecl ) {
733	// only check for warnings if the current function is a user-defined
734	// constructor or destructor
735	if ( ! funcDecl ) return false;
736	if ( ! funcDecl->get_statements() ) return false;
737	return isCtorDtor( funcDecl->get_name() ) && ! LinkageSpec::isOverridable( funcDecl->get_linkage() );
738	}
739
740	void GenStructMemberCalls::visit( FunctionDecl * funcDecl ) {
741	ValueGuard< FunctionDecl * > oldFunction( funcDecl );
742	ValueGuard< std::set< DeclarationWithType * > > oldUnhandled( unhandled );
743	ValueGuard< std::set< DeclarationWithType * > > oldUsedUninit( usedUninit );
744	ValueGuard< ObjectDecl * > oldThisParam( thisParam );
745	ValueGuard< bool > oldIsCtor( isCtor );
746
747	// need to start with fresh sets
748	unhandled.clear();
749	usedUninit.clear();
750
751	function = funcDecl;
752	isCtor = isConstructor( function->get_name() );
753	if ( checkWarnings( function ) ) {
754	FunctionType * type = function->get_functionType();
755	assert( ! type->get_parameters().empty() );
756	thisParam = safe_dynamic_cast< ObjectDecl * >( type->get_parameters().front() );
757	PointerType * ptrType = safe_dynamic_cast< PointerType * > ( thisParam->get_type() );
758	StructInstType * structType = dynamic_cast< StructInstType * >( ptrType->get_base() );
759	if ( structType ) {
760	StructDecl * structDecl = structType->get_baseStruct();
761	for ( Declaration * member : structDecl->get_members() ) {
762	if ( ObjectDecl * field = dynamic_cast< ObjectDecl * >( member ) ) {
763	// record all of the struct type's members that need to be constructed or
764	// destructed by the end of the function
765	unhandled.insert( field );
766	}
767	}
768	}
769	}
770	Parent::visit( function );
771
772	// remove the unhandled objects from usedUninit, because a call is inserted
773	// to handle them - only objects that are later constructed are used uninitialized.
774	std::set< DeclarationWithType * > diff;
775	std::set_difference( usedUninit.begin(), usedUninit.end(), unhandled.begin(), unhandled.end(), std::inserter( diff, diff.begin() ) );
776	for ( DeclarationWithType * member : diff ) {
777	emit( "in ", CodeGen::genType( function->get_functionType(), function->get_name(), false ), ", member ", member->get_name(), " used before being constructed" );
778	}
779
780	if ( ! unhandled.empty() ) {
781	// need to explicitly re-add function parameters in order to resolve copy constructors
782	enterScope();
783	// maybeAccept( function->get_functionType(), *this );
784	for ( DeclarationWithType * member : unhandled ) {
785	// insert and resolve default/copy constructor call for each member that's unhandled
786	std::list< Statement * > stmt;
787	UntypedExpr * deref = new UntypedExpr( new NameExpr( "*?" ) );
788	deref->get_args().push_back( new VariableExpr( thisParam ) );
789	InitExpander srcParam( (Initializer *)NULL ); // xxx - if copy ctor, need to pass appropriate argument - second param of this function dot member
790	SymTab::genImplicitCall( srcParam, new MemberExpr( member, deref ), function->get_name(), back_inserter( stmt ), member, isCtor );
791
792	assert( stmt.size() <= 1 );
793	if ( stmt.size() == 1 ) {
794	Statement * callStmt = stmt.front();
795
796	MutatingResolver resolver( *this );
797	try {
798	// xxx - these should be in field declaration order
799	callStmt->acceptMutator( resolver );
800	if ( isCtor ) {
801	function->get_statements()->push_front( callStmt );
802	} else {
803	// destructor statements should be added at the end
804	function->get_statements()->push_back( callStmt );
805	}
806	} catch ( SemanticError & error ) {
807	emit( "in ", CodeGen::genType( function->get_functionType(), function->get_name(), false ), ", member ", member->get_name(), " not explicitly ", isCtor ? "constructed" : "destructed", " and no ", isCtor ? "default constructor" : "destructor", " found" );
808	}
809	}
810	}
811	leaveScope();
812	}
813	}
814
815	void GenStructMemberCalls::visit( ApplicationExpr * appExpr ) {
816	if ( ! checkWarnings( function ) ) return;
817
818	std::string fname = getFunctionName( appExpr );
819	if ( fname == function->get_name() ) {
820	// call to same kind of function
821	Expression * firstParam = appExpr->get_args().front();
822
823	if ( VariableExpr * varExpr = dynamic_cast< VariableExpr * >( firstParam ) ) {
824	// if calling another constructor on thisParam, assume that function handles
825	// all members - if it doesn't a warning will appear in that function.
826	if ( varExpr->get_var() == thisParam ) {
827	unhandled.clear();
828	}
829	} else {
830	// if first parameter is a member expression then
831	// remove the member from unhandled set.
832	handleFirstParam( firstParam );
833	}
834	} else if ( fname == "?=?" && isIntrinsicCallExpr( appExpr ) ) {
835	// forgive use of intrinsic assignment to construct, since instrinsic constructors
836	// codegen as assignment anyway.
837	assert( appExpr->get_args().size() == 2 );
838	handleFirstParam( appExpr->get_args().front() );
839	}
840
841	Parent::visit( appExpr );
842	}
843
844	void GenStructMemberCalls::handleFirstParam( Expression * firstParam ) {
845	using namespace std;
846	if ( AddressExpr * addrExpr = dynamic_cast< AddressExpr * >( firstParam ) ) {
847	if ( MemberExpr * memberExpr = dynamic_cast< MemberExpr * >( addrExpr->get_arg() ) ) {
848	if ( ApplicationExpr * deref = dynamic_cast< ApplicationExpr * >( memberExpr->get_aggregate() ) ) {
849	if ( getFunctionName( deref ) == "*?" && deref->get_args().size() == 1 ) {
850	if ( VariableExpr * varExpr = dynamic_cast< VariableExpr * >( deref->get_args().front() ) ) {
851	if ( varExpr->get_var() == thisParam ) {
852	unhandled.erase( memberExpr->get_member() );
853	}
854	}
855	}
856	}
857	}
858	}
859	}
860
861	void GenStructMemberCalls::visit( MemberExpr * memberExpr ) {
862	if ( ! checkWarnings( function ) ) return;
863	if ( ! isCtor ) return;
864
865	if ( ApplicationExpr * deref = dynamic_cast< ApplicationExpr * >( memberExpr->get_aggregate() ) ) {
866	if ( getFunctionName( deref ) == "*?" && deref->get_args().size() == 1 ) {
867	if ( VariableExpr * varExpr = dynamic_cast< VariableExpr * >( deref->get_args().front() ) ) {
868	if ( varExpr->get_var() == thisParam ) {
869	if ( unhandled.count( memberExpr->get_member() ) ) {
870	// emit a warning because a member was used before it was constructed
871	usedUninit.insert( memberExpr->get_member() );
872	}
873	}
874	}
875	}
876	}
877	Parent::visit( memberExpr );
878	}
879
880	template< typename Visitor, typename... Params >
881	void error( Visitor & v, const Params &... params ) {
882	v.errors.append( toString( params... ) );
883	}
884
885	template< typename... Params >
886	void GenStructMemberCalls::emit( const Params &... params ) {
887	// toggle warnings vs. errors here.
888	// warn( params... );
889	error( *this, params... );
890	}
891
892	DeclarationWithType * MutatingResolver::mutate( ObjectDecl *objectDecl ) {
893	// add object to the indexer assumes that there will be no name collisions
894	// in generated code. If this changes, add mutate methods for entities with
895	// scope and call {enter,leave}Scope explicitly.
896	objectDecl->accept( indexer );
897	return objectDecl;
898	}
899
900	Expression* MutatingResolver::mutate( UntypedExpr *untypedExpr ) {
901	return safe_dynamic_cast< ApplicationExpr * >( ResolvExpr::findVoidExpression( untypedExpr, indexer ) );
902	}
903	} // namespace
904	} // namespace InitTweak
905
906	// Local Variables: //
907	// tab-width: 4 //
908	// mode: c++ //
909	// compile-command: "make install" //
910	// End: //

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