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source: src/ResolvExpr/TypeEnvironment.cc @ 28af389

ADTarm-ehast-experimentalenumforall-pointer-decayjacob/cs343-translationnew-astnew-ast-unique-exprpthread-emulationqualifiedEnum

Last change on this file since 28af389 was f474e91, checked in by Aaron Moss <a3moss@…>, 5 years ago
Port unification calculations to new AST
Property mode set to `100644`
File size: 16.2 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	// TypeEnvironment.cc --
8	//
9	// Author : Richard C. Bilson
10	// Created On : Sun May 17 12:19:47 2015
11	// Last Modified By : Aaron B. Moss
12	// Last Modified On : Mon Jun 18 11:58:00 2018
13	// Update Count : 4
14	//
15
16	#include <cassert> // for assert
17	#include <algorithm> // for copy, set_intersection
18	#include <iterator> // for ostream_iterator, insert_iterator
19	#include <memory> // for unique_ptr
20	#include <utility> // for pair, move
21
22	#include "Common/utility.h" // for maybeClone
23	#include "SynTree/Type.h" // for Type, FunctionType, Type::Fora...
24	#include "SynTree/TypeSubstitution.h" // for TypeSubstitution
25	#include "Tuples/Tuples.h" // for isTtype
26	#include "TypeEnvironment.h"
27	#include "typeops.h" // for occurs
28	#include "Unify.h" // for unifyInexact
29
30	namespace ResolvExpr {
31	void printAssertionSet( const AssertionSet &assertions, std::ostream &os, int indent ) {
32	for ( AssertionSet::const_iterator i = assertions.begin(); i != assertions.end(); ++i ) {
33	i->first->print( os, indent );
34	if ( i->second.isUsed ) {
35	os << "(used)";
36	} else {
37	os << "(not used)";
38	} // if
39	} // for
40	}
41
42	void printOpenVarSet( const OpenVarSet &openVars, std::ostream &os, int indent ) {
43	os << std::string( indent, ' ' );
44	for ( OpenVarSet::const_iterator i = openVars.begin(); i != openVars.end(); ++i ) {
45	os << i->first << "(" << i->second << ") ";
46	} // for
47	}
48
49	void EqvClass::initialize( const EqvClass &src, EqvClass &dest ) {
50	initialize( src, dest, src.type );
51	}
52
53	void EqvClass::initialize( const EqvClass &src, EqvClass &dest, const Type *ty ) {
54	dest.vars = src.vars;
55	dest.type = maybeClone( ty );
56	dest.allowWidening = src.allowWidening;
57	dest.data = src.data;
58	}
59
60	EqvClass::EqvClass() : type( nullptr ), allowWidening( true ) {
61	}
62
63	EqvClass::EqvClass( const EqvClass &other ) {
64	initialize( other, *this );
65	}
66
67	EqvClass::EqvClass( const EqvClass &other, const Type *ty ) {
68	initialize( other, *this, ty );
69	}
70
71	EqvClass::EqvClass( EqvClass &&other )
72	: vars{std::move(other.vars)}, type{other.type},
73	allowWidening{std::move(other.allowWidening)}, data{std::move(other.data)} {
74	other.type = nullptr;
75	}
76
77	EqvClass &EqvClass::operator=( const EqvClass &other ) {
78	if ( this == &other ) return *this;
79	delete type;
80	initialize( other, *this );
81	return *this;
82	}
83
84	EqvClass &EqvClass::operator=( EqvClass &&other ) {
85	if ( this == &other ) return *this;
86	delete type;
87
88	vars = std::move(other.vars);
89	type = other.type;
90	other.type = nullptr;
91	allowWidening = std::move(other.allowWidening);
92	data = std::move(other.data);
93
94	return *this;
95	}
96
97	EqvClass::~EqvClass() {
98	delete type;
99	}
100
101	void EqvClass::set_type( Type* ty ) {
102	if ( ty == type ) return;
103	delete type;
104	type = ty;
105	}
106
107	void EqvClass::print( std::ostream &os, Indenter indent ) const {
108	os << "( ";
109	std::copy( vars.begin(), vars.end(), std::ostream_iterator< std::string >( os, " " ) );
110	os << ")";
111	if ( type ) {
112	os << " -> ";
113	type->print( os, indent+1 );
114	} // if
115	if ( ! allowWidening ) {
116	os << " (no widening)";
117	} // if
118	os << std::endl;
119	}
120
121	const EqvClass* TypeEnvironment::lookup( const std::string &var ) const {
122	for ( ClassList::const_iterator i = env.begin(); i != env.end(); ++i ) {
123	if ( i->vars.find( var ) != i->vars.end() ) return &*i;
124	} // for
125	return nullptr;
126	}
127
128	/// Removes any class from env that intersects eqvClass
129	void filterOverlappingClasses( std::list<EqvClass> &env, const EqvClass &eqvClass ) {
130	for ( auto i = env.begin(); i != env.end(); ) {
131	auto next = i;
132	++next;
133	std::set<std::string> intersection;
134	std::set_intersection( i->vars.begin(), i->vars.end(), eqvClass.vars.begin(), eqvClass.vars.end(),
135	std::inserter( intersection, intersection.begin() ) );
136	if ( ! intersection.empty() ) { env.erase( i ); }
137	i = next;
138	}
139	}
140
141	void TypeEnvironment::add( EqvClass &&eqvClass ) {
142	filterOverlappingClasses( env, eqvClass );
143	env.push_back( std::move(eqvClass) );
144	}
145
146	void TypeEnvironment::add( const Type::ForallList &tyDecls ) {
147	for ( Type::ForallList::const_iterator i = tyDecls.begin(); i != tyDecls.end(); ++i ) {
148	EqvClass newClass;
149	newClass.vars.insert( (*i)->get_name() );
150	newClass.data = TypeDecl::Data{ (*i) };
151	env.push_back( std::move(newClass) );
152	} // for
153	}
154
155	void TypeEnvironment::add( const TypeSubstitution & sub ) {
156	EqvClass newClass;
157	for ( auto p : sub ) {
158	newClass.vars.insert( p.first );
159	newClass.type = p.second->clone();
160	newClass.allowWidening = false;
161	// Minimal assumptions. Not technically correct, but might be good enough, and
162	// is the best we can do at the moment since information is lost in the
163	// transition to TypeSubstitution
164	newClass.data = TypeDecl::Data{ TypeDecl::Dtype, false };
165	add( std::move(newClass) );
166	}
167	}
168
169	void TypeEnvironment::makeSubstitution( TypeSubstitution &sub ) const {
170	for ( ClassList::const_iterator theClass = env.begin(); theClass != env.end(); ++theClass ) {
171	for ( std::set< std::string >::const_iterator theVar = theClass->vars.begin(); theVar != theClass->vars.end(); ++theVar ) {
172	if ( theClass->type ) {
173	sub.add( *theVar, theClass->type );
174	} else if ( theVar != theClass->vars.begin() ) {
175	TypeInstType newTypeInst = new TypeInstType( Type::Qualifiers(), theClass->vars.begin(), theClass->data.kind == TypeDecl::Ftype );
176	sub.add( *theVar, newTypeInst );
177	delete newTypeInst;
178	} // if
179	} // for
180	} // for
181	sub.normalize();
182	}
183
184	void TypeEnvironment::print( std::ostream &os, Indenter indent ) const {
185	for ( const EqvClass & theClass : env ) {
186	theClass.print( os, indent );
187	} // for
188	}
189
190	TypeEnvironment::ClassList::iterator TypeEnvironment::internal_lookup( const std::string &var ) {
191	for ( ClassList::iterator i = env.begin(); i != env.end(); ++i ) {
192	if ( i->vars.count( var ) ) return i;
193	} // for
194	return env.end();
195	}
196
197	void TypeEnvironment::simpleCombine( const TypeEnvironment &second ) {
198	env.insert( env.end(), second.env.begin(), second.env.end() );
199	}
200
201	// xxx -- this should maybe be worrying about iterator invalidation (see resolv-proto)
202	bool TypeEnvironment::mergeBound( EqvClass& to, const EqvClass& from, OpenVarSet& openVars, const SymTab::Indexer& indexer ) {
203	if ( from.type ) {
204	if ( to.type ) {
205	// attempt to unify bound types
206	std::unique_ptr<Type> toType{ to.type->clone() }, fromType{ from.type->clone() };
207	WidenMode widen{ to.allowWidening, from.allowWidening };
208	Type* common = nullptr;
209	AssertionSet need, have;
210	if ( unifyInexact( toType.get(), fromType.get(), *this, need, have, openVars, widen, indexer, common ) ) {
211	// unifies, set common type if necessary
212	if ( common ) {
213	common->get_qualifiers() = Type::Qualifiers{};
214	to.set_type( common );
215	}
216	} else return false; // cannot unify
217	} else {
218	to.type = from.type->clone();
219	}
220	}
221
222	// unify widening if matches
223	to.allowWidening &= from.allowWidening;
224	return true;
225	}
226
227	// xxx -- this should maybe be worrying about iterator invalidation (see resolv-proto)
228	bool TypeEnvironment::mergeClasses( TypeEnvironment::ClassList::iterator to, TypeEnvironment::ClassList::iterator from, OpenVarSet& openVars, const SymTab::Indexer& indexer ) {
229	EqvClass& r = *to;
230	EqvClass& s = *from;
231
232	// ensure bounds match
233	if ( ! mergeBound( r, s, openVars, indexer ) ) return false;
234
235	// check safely bindable
236	if ( r.type && occursIn( r.type, s.vars.begin(), s.vars.end(), *this ) ) return false;
237
238	// merge classes in
239	r.vars.insert( s.vars.begin(), s.vars.end() );
240	r.allowWidening &= s.allowWidening;
241	env.erase( from );
242
243	return true;
244	}
245
246	bool TypeEnvironment::combine( const TypeEnvironment& o, OpenVarSet& openVars, const SymTab::Indexer& indexer ) {
247	// short-circuit easy cases
248	if ( o.isEmpty() ) return true;
249	if ( isEmpty() ) {
250	simpleCombine( o );
251	return true;
252	}
253
254	// merge classes
255	for ( auto ct = o.env.begin(); ct != o.env.end(); ++ct ) {
256	const EqvClass& c = *ct;
257
258	// typeclass in local environment bound to c
259	auto rt = env.end();
260
261	// look for first existing bound variable
262	auto vt = c.vars.begin();
263	for ( ; vt != c.vars.end(); ++vt ) {
264	rt = internal_lookup( *vt );
265	if ( rt != env.end() ) break;
266	}
267
268	if ( rt != env.end() ) { // c needs to be merged into *rt
269	EqvClass& r = *rt;
270	// merge bindings
271	if ( ! mergeBound( r, c, openVars, indexer ) ) return false;
272	// merge previous unbound variables into this class, checking occurs if needed
273	if ( r.type ) for ( auto ut = c.vars.begin(); ut != vt; ++ut ) {
274	if ( occurs( r.type, ut, this ) ) return false;
275	r.vars.insert( *ut );
276	} else { r.vars.insert( c.vars.begin(), vt ); }
277	// merge subsequent variables into this class (skipping *vt, already there)
278	while ( ++vt != c.vars.end() ) {
279	auto st = internal_lookup( *vt );
280	if ( st == env.end() ) {
281	// unbound, safe to add if passes occurs
282	if ( r.type && occurs( r.type, vt, this ) ) return false;
283	r.vars.insert( *vt );
284	} else if ( st != rt ) {
285	// bound, but not to the same class
286	if ( ! mergeClasses( rt, st, openVars, indexer ) ) return false;
287	} // ignore bound into the same class
288	}
289	} else { // no variables in c bound; just copy up
290	env.push_back( c );
291	}
292	}
293
294	// merged all classes
295	return true;
296	}
297
298	void TypeEnvironment::extractOpenVars( OpenVarSet &openVars ) const {
299	for ( ClassList::const_iterator eqvClass = env.begin(); eqvClass != env.end(); ++eqvClass ) {
300	for ( std::set< std::string >::const_iterator var = eqvClass->vars.begin(); var != eqvClass->vars.end(); ++var ) {
301	openVars[ *var ] = eqvClass->data;
302	} // for
303	} // for
304	}
305
306	void TypeEnvironment::addActual( const TypeEnvironment& actualEnv, OpenVarSet& openVars ) {
307	for ( const EqvClass& c : actualEnv ) {
308	EqvClass c2 = c;
309	c2.allowWidening = false;
310	for ( const std::string& var : c2.vars ) {
311	openVars[ var ] = c2.data;
312	}
313	env.push_back( std::move(c2) );
314	}
315	}
316
317	bool isFtype( Type *type ) {
318	if ( dynamic_cast< FunctionType* >( type ) ) {
319	return true;
320	} else if ( TypeInstType typeInst = dynamic_cast< TypeInstType >( type ) ) {
321	return typeInst->get_isFtype();
322	} // if
323	return false;
324	}
325
326	bool tyVarCompatible( const TypeDecl::Data & data, Type *type ) {
327	switch ( data.kind ) {
328	case TypeDecl::Dtype:
329	// to bind to an object type variable, the type must not be a function type.
330	// if the type variable is specified to be a complete type then the incoming
331	// type must also be complete
332	// xxx - should this also check that type is not a tuple type and that it's not a ttype?
333	return ! isFtype( type ) && (! data.isComplete \|\| type->isComplete() );
334	case TypeDecl::Ftype:
335	return isFtype( type );
336	case TypeDecl::Ttype:
337	// ttype unifies with any tuple type
338	return dynamic_cast< TupleType * >( type ) \|\| Tuples::isTtype( type );
339	default:
340	assertf(false, "Unhandled tyvar kind: %d", data.kind);
341	} // switch
342	return false;
343	}
344
345	bool TypeEnvironment::bindVar( TypeInstType typeInst, Type bindTo, const TypeDecl::Data & data, AssertionSet &need, AssertionSet &have, const OpenVarSet &openVars, WidenMode widen, const SymTab::Indexer &indexer ) {
346
347	// remove references from other, so that type variables can only bind to value types
348	bindTo = bindTo->stripReferences();
349	OpenVarSet::const_iterator tyvar = openVars.find( typeInst->get_name() );
350	assert( tyvar != openVars.end() );
351	if ( ! tyVarCompatible( tyvar->second, bindTo ) ) {
352	return false;
353	} // if
354	if ( occurs( bindTo, typeInst->get_name(), *this ) ) {
355	return false;
356	} // if
357	auto curClass = internal_lookup( typeInst->get_name() );
358	if ( curClass != env.end() ) {
359	if ( curClass->type ) {
360	Type *common = 0;
361	// attempt to unify equivalence class type (which has qualifiers stripped, so they must be restored) with the type to bind to
362	std::unique_ptr< Type > newType( curClass->type->clone() );
363	newType->get_qualifiers() = typeInst->get_qualifiers();
364	if ( unifyInexact( newType.get(), bindTo, *this, need, have, openVars, widen & WidenMode( curClass->allowWidening, true ), indexer, common ) ) {
365	if ( common ) {
366	common->get_qualifiers() = Type::Qualifiers{};
367	curClass->set_type( common );
368	} // if
369	} else return false;
370	} else {
371	Type* newType = bindTo->clone();
372	newType->get_qualifiers() = Type::Qualifiers{};
373	curClass->set_type( newType );
374	curClass->allowWidening = widen.first && widen.second;
375	} // if
376	} else {
377	EqvClass newClass;
378	newClass.vars.insert( typeInst->get_name() );
379	newClass.type = bindTo->clone();
380	newClass.type->get_qualifiers() = Type::Qualifiers();
381	newClass.allowWidening = widen.first && widen.second;
382	newClass.data = data;
383	env.push_back( std::move(newClass) );
384	} // if
385	return true;
386	}
387
388	bool TypeEnvironment::bindVarToVar( TypeInstType var1, TypeInstType var2,
389	TypeDecl::Data && data, AssertionSet &need, AssertionSet &have,
390	const OpenVarSet &openVars, WidenMode widen, const SymTab::Indexer &indexer ) {
391
392	auto class1 = internal_lookup( var1->get_name() );
393	auto class2 = internal_lookup( var2->get_name() );
394
395	// exit early if variables already bound together
396	if ( class1 != env.end() && class1 == class2 ) {
397	class1->allowWidening &= widen;
398	return true;
399	}
400
401	bool widen1 = false, widen2 = false;
402	const Type type1 = nullptr, type2 = nullptr;
403
404	// check for existing bindings, perform occurs check
405	if ( class1 != env.end() ) {
406	if ( class1->type ) {
407	if ( occurs( class1->type, var2->get_name(), *this ) ) return false;
408	type1 = class1->type;
409	} // if
410	widen1 = widen.first && class1->allowWidening;
411	} // if
412	if ( class2 != env.end() ) {
413	if ( class2->type ) {
414	if ( occurs( class2->type, var1->get_name(), *this ) ) return false;
415	type2 = class2->type;
416	} // if
417	widen2 = widen.second && class2->allowWidening;
418	} // if
419
420	if ( type1 && type2 ) {
421	// both classes bound, merge if bound types can be unified
422	std::unique_ptr<Type> newType1{ type1->clone() }, newType2{ type2->clone() };
423	WidenMode newWidenMode{ widen1, widen2 };
424	Type *common = 0;
425	if ( unifyInexact( newType1.get(), newType2.get(), *this, need, have, openVars, newWidenMode, indexer, common ) ) {
426	class1->vars.insert( class2->vars.begin(), class2->vars.end() );
427	class1->allowWidening = widen1 && widen2;
428	if ( common ) {
429	common->get_qualifiers() = Type::Qualifiers{};
430	class1->set_type( common );
431	}
432	class1->data.isComplete \|= data.isComplete;
433	env.erase( class2 );
434	} else return false;
435	} else if ( class1 != env.end() && class2 != env.end() ) {
436	// both classes exist, at least one unbound, merge unconditionally
437	if ( type1 ) {
438	class1->vars.insert( class2->vars.begin(), class2->vars.end() );
439	class1->allowWidening = widen1;
440	class1->data.isComplete \|= data.isComplete;
441	env.erase( class2 );
442	} else {
443	class2->vars.insert( class1->vars.begin(), class1->vars.end() );
444	class2->allowWidening = widen2;
445	class2->data.isComplete \|= data.isComplete;
446	env.erase( class1 );
447	} // if
448	} else if ( class1 != env.end() ) {
449	// var2 unbound, add to class1
450	class1->vars.insert( var2->get_name() );
451	class1->allowWidening = widen1;
452	class1->data.isComplete \|= data.isComplete;
453	} else if ( class2 != env.end() ) {
454	// var1 unbound, add to class2
455	class2->vars.insert( var1->get_name() );
456	class2->allowWidening = widen2;
457	class2->data.isComplete \|= data.isComplete;
458	} else {
459	// neither var bound, create new class
460	EqvClass newClass;
461	newClass.vars.insert( var1->get_name() );
462	newClass.vars.insert( var2->get_name() );
463	newClass.allowWidening = widen1 && widen2;
464	newClass.data = data;
465	env.push_back( std::move(newClass) );
466	} // if
467	return true;
468	}
469
470	void TypeEnvironment::forbidWidening() {
471	for ( EqvClass& c : env ) c.allowWidening = false;
472	}
473
474	std::ostream & operator<<( std::ostream & out, const TypeEnvironment & env ) {
475	env.print( out );
476	return out;
477	}
478	} // namespace ResolvExpr
479
480	// Local Variables: //
481	// tab-width: 4 //
482	// mode: c++ //
483	// compile-command: "make install" //
484	// End: //

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