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source: src/GenPoly/Lvalue.cc @ d16d159

ADTaaron-thesisarm-ehast-experimentalcleanup-dtorsdeferred_resndemanglerenumforall-pointer-decayjacob/cs343-translationjenkins-sandboxnew-astnew-ast-unique-exprnew-envno_listpersistent-indexerpthread-emulationqualifiedEnumresolv-newwith_gc

Last change on this file since d16d159 was e3e16bc, checked in by Thierry Delisle <tdelisle@…>, 7 years ago
Renamed safe_dynamic_cast to strict_dynamic_cast
Property mode set to `100644`
File size: 19.3 KB

Line
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	// Lvalue.cc --
8	//
9	// Author : Richard C. Bilson
10	// Created On : Mon May 18 07:44:20 2015
11	// Last Modified By : Peter A. Buhr
12	// Last Modified On : Fri Mar 17 09:11:18 2017
13	// Update Count : 5
14	//
15
16	#include <cassert> // for strict_dynamic_cast
17	#include <string> // for string
18
19	#include "Common/PassVisitor.h"
20	#include "Common/SemanticError.h" // for SemanticError
21	#include "GenPoly.h" // for isPolyType
22	#include "Lvalue.h"
23
24	#include "Parser/LinkageSpec.h" // for Spec, isBuiltin, Intrinsic
25	#include "ResolvExpr/TypeEnvironment.h" // for AssertionSet, OpenVarSet
26	#include "ResolvExpr/Unify.h" // for unify
27	#include "ResolvExpr/typeops.h"
28	#include "SymTab/Autogen.h"
29	#include "SymTab/Indexer.h" // for Indexer
30	#include "SynTree/Declaration.h" // for Declaration, FunctionDecl
31	#include "SynTree/Expression.h" // for Expression, ConditionalExpr
32	#include "SynTree/Mutator.h" // for mutateAll, Mutator
33	#include "SynTree/Statement.h" // for ReturnStmt, Statement (ptr o...
34	#include "SynTree/Type.h" // for PointerType, Type, FunctionType
35	#include "SynTree/Visitor.h" // for Visitor, acceptAll
36
37	#if 0
38	#define PRINT(x) x
39	#else
40	#define PRINT(x)
41	#endif
42
43	namespace GenPoly {
44	namespace {
45	// TODO: fold this into the general createDeref function??
46	Expression * mkDeref( Expression * arg ) {
47	if ( SymTab::dereferenceOperator ) {
48	VariableExpr * deref = new VariableExpr( SymTab::dereferenceOperator );
49	deref->set_result( new PointerType( Type::Qualifiers(), deref->get_result() ) );
50	Type * base = InitTweak::getPointerBase( arg->get_result() );
51	assertf( base, "expected pointer type in dereference (type was %s)", toString( arg->get_result() ).c_str() );
52	ApplicationExpr * ret = new ApplicationExpr( deref, { arg } );
53	delete ret->get_result();
54	ret->set_result( base->clone() );
55	ret->get_result()->set_lvalue( true );
56	return ret;
57	} else {
58	return UntypedExpr::createDeref( arg );
59	}
60	}
61
62	struct ReferenceConversions final {
63	Expression * postmutate( CastExpr * castExpr );
64	Expression * postmutate( AddressExpr * addrExpr );
65	};
66
67	/// Intrinsic functions that take reference parameters don't REALLY take reference parameters -- their reference arguments must always be implicitly dereferenced.
68	struct FixIntrinsicArgs final {
69	Expression * postmutate( ApplicationExpr * appExpr );
70	};
71
72	struct FixIntrinsicResult final : public WithGuards {
73	Expression * postmutate( ApplicationExpr * appExpr );
74	void premutate( FunctionDecl * funcDecl );
75	bool inIntrinsic = false;
76	};
77
78	/// Replace reference types with pointer types
79	struct ReferenceTypeElimination final {
80	Type * postmutate( ReferenceType * refType );
81	};
82
83	/// GCC-like Generalized Lvalues (which have since been removed from GCC)
84	/// https://gcc.gnu.org/onlinedocs/gcc-3.4.6/gcc/Lvalues.html#Lvalues
85	/// Replaces &(a,b) with (a, &b), &(a ? b : c) with (a ? &b : &c)
86	struct GeneralizedLvalue final : public WithVisitorRef<GeneralizedLvalue> {
87	Expression * postmutate( AddressExpr * addressExpr );
88	Expression * postmutate( MemberExpr * memExpr );
89
90	template<typename Func>
91	Expression * applyTransformation( Expression * expr, Expression * arg, Func mkExpr );
92	};
93
94	/// Removes redundant &/& pattern that this pass can generate
95	struct CollapseAddrDeref final {
96	Expression * postmutate( AddressExpr * addressExpr );
97	Expression * postmutate( ApplicationExpr * appExpr );
98	};
99
100	struct AddrRef final : public WithGuards {
101	void premutate( AddressExpr * addrExpr );
102	Expression * postmutate( AddressExpr * addrExpr );
103	void premutate( Expression * expr );
104
105	bool first = true;
106	bool current = false;
107	int refDepth = 0;
108	};
109	} // namespace
110
111	static bool referencesEliminated = false;
112	// used by UntypedExpr::createDeref to determine whether result type of dereference should be ReferenceType or value type.
113	bool referencesPermissable() {
114	return ! referencesEliminated;
115	}
116
117	void convertLvalue( std::list< Declaration* >& translationUnit ) {
118	PassVisitor<ReferenceConversions> refCvt;
119	PassVisitor<ReferenceTypeElimination> elim;
120	PassVisitor<GeneralizedLvalue> genLval;
121	PassVisitor<FixIntrinsicArgs> fixer;
122	PassVisitor<CollapseAddrDeref> collapser;
123	PassVisitor<AddrRef> addrRef;
124	PassVisitor<FixIntrinsicResult> intrinsicResults;
125	mutateAll( translationUnit, intrinsicResults );
126	mutateAll( translationUnit, addrRef );
127	mutateAll( translationUnit, refCvt );
128	mutateAll( translationUnit, fixer );
129	mutateAll( translationUnit, collapser );
130	mutateAll( translationUnit, genLval );
131	mutateAll( translationUnit, elim ); // last because other passes need reference types to work
132
133	// from this point forward, no other pass should create reference types.
134	referencesEliminated = true;
135	}
136
137	Expression * generalizedLvalue( Expression * expr ) {
138	PassVisitor<GeneralizedLvalue> genLval;
139	return expr->acceptMutator( genLval );
140	}
141
142	namespace {
143	// true for intrinsic function calls that return a reference
144	bool isIntrinsicReference( Expression * expr ) {
145	if ( UntypedExpr * untyped = dynamic_cast< UntypedExpr * >( expr ) ) {
146	std::string fname = InitTweak::getFunctionName( untyped );
147	// known intrinsic-reference prelude functions
148	return fname == "*?" \|\| fname == "?[?]";
149	} else if ( ApplicationExpr * appExpr = dynamic_cast< ApplicationExpr * > ( expr ) ) {
150	if ( DeclarationWithType * func = InitTweak::getFunction( appExpr ) ) {
151	// use type of return variable rather than expr result type, since it may have been changed to a pointer type
152	FunctionType * ftype = GenPoly::getFunctionType( func->get_type() );
153	Type * ret = ftype->get_returnVals().empty() ? nullptr : ftype->get_returnVals().front()->get_type();
154	return func->get_linkage() == LinkageSpec::Intrinsic && dynamic_cast<ReferenceType *>( ret );
155	}
156	}
157	return false;
158	}
159
160	Expression * FixIntrinsicResult::postmutate( ApplicationExpr * appExpr ) {
161	if ( isIntrinsicReference( appExpr ) ) {
162	// eliminate reference types from intrinsic applications - now they return lvalues
163	Type * result = appExpr->get_result();
164	appExpr->set_result( result->stripReferences()->clone() );
165	appExpr->get_result()->set_lvalue( true );
166	if ( ! inIntrinsic ) {
167	// when not in an intrinsic function, add a cast to
168	// don't add cast when in an intrinsic function, since they already have the cast
169	Expression * ret = new CastExpr( appExpr, result );
170	ret->set_env( appExpr->get_env() );
171	appExpr->set_env( nullptr );
172	return ret;
173	}
174	delete result;
175	}
176	return appExpr;
177	}
178
179	void FixIntrinsicResult::premutate( FunctionDecl * funcDecl ) {
180	GuardValue( inIntrinsic );
181	inIntrinsic = funcDecl->linkage == LinkageSpec::Intrinsic;
182	}
183
184	Expression * FixIntrinsicArgs::postmutate( ApplicationExpr * appExpr ) {
185	// intrinsic functions don't really take reference-typed parameters, so they require an implicit dereference on their arguments.
186	if ( DeclarationWithType * function = InitTweak::getFunction( appExpr ) ) {
187	FunctionType * ftype = GenPoly::getFunctionType( function->get_type() );
188	assertf( ftype, "Function declaration does not have function type." );
189	// can be of differing lengths only when function is variadic
190	assertf( ftype->get_parameters().size() == appExpr->get_args().size() \|\| ftype->get_isVarArgs(), "ApplicationExpr args do not match formal parameter type." );
191
192
193	unsigned int i = 0;
194	const unsigned int end = ftype->get_parameters().size();
195	for ( auto p : unsafe_group_iterate( appExpr->get_args(), ftype->get_parameters() ) ) {
196	if (i == end) break;
197	Expression *& arg = std::get<0>( p );
198	Type * formal = std::get<1>( p )->get_type();
199	PRINT(
200	std::cerr << "pair<0>: " << arg << std::endl;
201	std::cerr << "pair<1>: " << formal << std::endl;
202	)
203	if ( dynamic_cast<ReferenceType*>( formal ) ) {
204	if ( isIntrinsicReference( arg ) ) { // do not combine conditions, because that changes the meaning of the else if
205	if ( function->get_linkage() != LinkageSpec::Intrinsic ) { // intrinsic functions that turn pointers into references
206	// if argument is dereference or array subscript, the result isn't REALLY a reference, so it's not necessary to fix the argument
207	PRINT(
208	std::cerr << "===is intrinsic arg in non-intrinsic call - adding address" << std::endl;
209	)
210	arg = new AddressExpr( arg );
211	}
212	} else if ( function->get_linkage() == LinkageSpec::Intrinsic ) {
213	// std::cerr << "===adding deref to arg" << std::endl;
214	// if the parameter is a reference, add a dereference to the reference-typed argument.
215	Type * baseType = InitTweak::getPointerBase( arg->get_result() );
216	assertf( baseType, "parameter is reference, arg must be pointer or reference: %s", toString( arg->get_result() ).c_str() );
217	PointerType * ptrType = new PointerType( Type::Qualifiers(), baseType->clone() );
218	delete arg->get_result();
219	arg->set_result( ptrType );
220	arg = mkDeref( arg );
221	}
222	}
223	++i;
224	}
225	}
226	return appExpr;
227	}
228
229	// idea: &&&E: get outer &, inner &
230	// at inner &, record depth D of reference type
231	// at outer &, add D derefs.
232	void AddrRef::premutate( Expression * ) {
233	GuardValue( current );
234	GuardValue( first );
235	current = false;
236	first = true;
237	}
238
239	void AddrRef::premutate( AddressExpr * ) {
240	GuardValue( current );
241	GuardValue( first );
242	current = first;
243	first = false;
244	if ( current ) {
245	GuardValue( refDepth );
246	refDepth = 0;
247	}
248	}
249
250	Expression * AddrRef::postmutate( AddressExpr * addrExpr ) {
251	if ( refDepth == 0 ) {
252	if ( ! isIntrinsicReference( addrExpr->get_arg() ) ) {
253	// try to avoid ?[?]
254	refDepth = addrExpr->get_arg()->get_result()->referenceDepth();
255	}
256	}
257	if ( current ) {
258	Expression * ret = addrExpr;
259	while ( refDepth ) {
260	ret = mkDeref( ret );
261	refDepth--;
262	}
263	return ret;
264	}
265	return addrExpr;
266	}
267
268	Expression * ReferenceConversions::postmutate( AddressExpr * addrExpr ) {
269	// Inner expression may have been lvalue to reference conversion, which becomes an address expression.
270	// In this case, remove the outer address expression and return the argument.
271	// TODO: It's possible that this might catch too much and require a more sophisticated check.
272	return addrExpr;
273	}
274
275	Expression * ReferenceConversions::postmutate( CastExpr * castExpr ) {
276	// xxx - is it possible to convert directly between reference types with a different base? E.g.,
277	// int x;
278	// (double&)x;
279	// At the moment, I am working off of the assumption that this is illegal, thus the cast becomes redundant
280	// after this pass, so trash the cast altogether. If that changes, care must be taken to insert the correct
281	// pointer casts in the right places.
282
283	// conversion to reference type
284	if ( ReferenceType * refType = dynamic_cast< ReferenceType * >( castExpr->get_result() ) ) {
285	(void)refType;
286	if ( ReferenceType * otherRef = dynamic_cast< ReferenceType * >( castExpr->get_arg()->get_result() ) ) {
287	// nothing to do if casting from reference to reference.
288	(void)otherRef;
289	PRINT( std::cerr << "convert reference to reference -- nop" << std::endl; )
290	if ( isIntrinsicReference( castExpr->get_arg() ) ) {
291	Expression * callExpr = castExpr->get_arg();
292	PRINT(
293	std::cerr << "but arg is deref -- &" << std::endl;
294	std::cerr << callExpr << std::endl;
295	)
296	callExpr = new AddressExpr( callExpr ); // this doesn't work properly for multiple casts
297	delete callExpr->get_result();
298	callExpr->set_result( refType->clone() );
299	// move environment out to new top-level
300	callExpr->set_env( castExpr->get_env() );
301	castExpr->set_arg( nullptr );
302	castExpr->set_env( nullptr );
303	delete castExpr;
304	return callExpr;
305	}
306	int depth1 = refType->referenceDepth();
307	int depth2 = otherRef->referenceDepth();
308	int diff = depth1-depth2;
309	if ( diff == 0 ) {
310	assertf( depth1 == depth2, "non-intrinsic reference with cast of reference to reference not yet supported: %d %d %s", depth1, depth2, toString( castExpr ).c_str() );
311	PRINT( std::cerr << castExpr << std::endl; )
312	return castExpr;
313	} else if ( diff < 0 ) {
314	Expression * ret = castExpr->get_arg();
315	for ( int i = 0; i < diff; ++i ) {
316	ret = mkDeref( ret );
317	}
318	ret->set_env( castExpr->get_env() );
319	delete ret->get_result();
320	ret->set_result( castExpr->get_result() );
321	castExpr->set_env( nullptr );
322	castExpr->set_arg( nullptr );
323	castExpr->set_result( nullptr );
324	delete castExpr;
325	return ret;
326	} else if ( diff > 0 ) {
327	Expression * ret = castExpr->get_arg();
328	for ( int i = 0; i < diff; ++i ) {
329	ret = new AddressExpr( ret );
330	}
331	ret->set_env( castExpr->get_env() );
332	delete ret->get_result();
333	ret->set_result( castExpr->get_result() );
334	castExpr->set_env( nullptr );
335	castExpr->set_arg( nullptr );
336	castExpr->set_result( nullptr );
337	delete castExpr;
338	return ret;
339	}
340
341	assertf( depth1 == depth2, "non-intrinsic reference with cast of reference to reference not yet supported: %d %d %s", depth1, depth2, toString( castExpr ).c_str() );
342	PRINT( std::cerr << castExpr << std::endl; )
343	return castExpr;
344	} else if ( castExpr->get_arg()->get_result()->get_lvalue() ) {
345	// conversion from lvalue to reference
346	// xxx - keep cast, but turn into pointer cast??
347	// xxx - memory
348	PRINT(
349	std::cerr << "convert lvalue to reference -- &" << std::endl;
350	std::cerr << castExpr->get_arg() << std::endl;
351	)
352	AddressExpr * ret = new AddressExpr( castExpr->get_arg() );
353	if ( refType->get_base()->get_qualifiers() != castExpr->get_arg()->get_result()->get_qualifiers() ) {
354	// must keep cast if cast-to type is different from the actual type
355	castExpr->set_arg( ret );
356	return castExpr;
357	}
358	ret->set_env( castExpr->get_env() );
359	delete ret->get_result();
360	ret->set_result( castExpr->get_result() );
361	castExpr->set_env( nullptr );
362	castExpr->set_arg( nullptr );
363	castExpr->set_result( nullptr );
364	delete castExpr;
365	return ret;
366	} else {
367	// rvalue to reference conversion -- introduce temporary
368	}
369	assertf( false, "Only conversions to reference from lvalue are currently supported: %s", toString( castExpr ).c_str() );
370	} else if ( ReferenceType * refType = dynamic_cast< ReferenceType * >( castExpr->get_arg()->get_result() ) ) {
371	(void)refType;
372	// conversion from reference to rvalue
373	PRINT(
374	std::cerr << "convert reference to rvalue -- *" << std::endl;
375	std::cerr << "was = " << castExpr << std::endl;
376	)
377	Expression * ret = castExpr->get_arg();
378	TypeSubstitution * env = castExpr->get_env();
379	castExpr->set_env( nullptr );
380	if ( ! isIntrinsicReference( ret ) ) {
381	// dereference if not already dereferenced
382	ret = mkDeref( ret );
383	}
384	if ( ResolvExpr::typesCompatibleIgnoreQualifiers( castExpr->get_result(), castExpr->get_arg()->get_result()->stripReferences(), SymTab::Indexer() ) ) {
385	// can remove cast if types are compatible, changing expression type to value type
386	ret->set_result( castExpr->get_result()->clone() );
387	castExpr->set_arg( nullptr );
388	delete castExpr;
389	} else {
390	// must keep cast if types are different
391	castExpr->set_arg( ret );
392	ret = castExpr;
393	}
394	ret->set_env( env );
395	PRINT( std::cerr << "now: " << ret << std::endl; )
396	return ret;
397	}
398	return castExpr;
399	}
400
401	Type * ReferenceTypeElimination::postmutate( ReferenceType * refType ) {
402	Type * base = refType->get_base();
403	Type::Qualifiers qualifiers = refType->get_qualifiers();
404	refType->set_base( nullptr );
405	delete refType;
406	return new PointerType( qualifiers, base );
407	}
408
409	template<typename Func>
410	Expression * GeneralizedLvalue::applyTransformation( Expression * expr, Expression * arg, Func mkExpr ) {
411	if ( CommaExpr * commaExpr = dynamic_cast< CommaExpr * >( arg ) ) {
412	Expression * arg1 = commaExpr->get_arg1()->clone();
413	Expression * arg2 = commaExpr->get_arg2()->clone();
414	Expression * ret = new CommaExpr( arg1, mkExpr( arg2 )->acceptMutator( *visitor ) );
415	ret->set_env( expr->get_env() );
416	expr->set_env( nullptr );
417	delete expr;
418	return ret;
419	} else if ( ConditionalExpr * condExpr = dynamic_cast< ConditionalExpr * >( arg ) ) {
420	Expression * arg1 = condExpr->get_arg1()->clone();
421	Expression * arg2 = condExpr->get_arg2()->clone();
422	Expression * arg3 = condExpr->get_arg3()->clone();
423	ConditionalExpr * ret = new ConditionalExpr( arg1, mkExpr( arg2 )->acceptMutator( visitor ), mkExpr( arg3 )->acceptMutator( visitor ) );
424	ret->set_env( expr->get_env() );
425	expr->set_env( nullptr );
426	delete expr;
427
428	// conditional expr type may not be either of the argument types, need to unify
429	using namespace ResolvExpr;
430	Type* commonType = nullptr;
431	TypeEnvironment newEnv;
432	AssertionSet needAssertions, haveAssertions;
433	OpenVarSet openVars;
434	unify( ret->get_arg2()->get_result(), ret->get_arg3()->get_result(), newEnv, needAssertions, haveAssertions, openVars, SymTab::Indexer(), commonType );
435	ret->set_result( commonType ? commonType : ret->get_arg2()->get_result()->clone() );
436	return ret;
437	}
438	return expr;
439	}
440
441	Expression * GeneralizedLvalue::postmutate( MemberExpr * memExpr ) {
442	return applyTransformation( memExpr, memExpr->get_aggregate(), [=]( Expression * aggr ) { return new MemberExpr( memExpr->get_member(), aggr ); } );
443	}
444
445	Expression * GeneralizedLvalue::postmutate( AddressExpr * addrExpr ) {
446	return applyTransformation( addrExpr, addrExpr->get_arg(), []( Expression * arg ) { return new AddressExpr( arg ); } );
447	}
448
449	Expression * CollapseAddrDeref::postmutate( AddressExpr * addrExpr ) {
450	Expression * arg = addrExpr->get_arg();
451	if ( isIntrinsicReference( arg ) ) {
452	std::string fname = InitTweak::getFunctionName( arg );
453	if ( fname == "*?" ) {
454	Expression *& arg0 = InitTweak::getCallArg( arg, 0 );
455	Expression * ret = arg0;
456	ret->set_env( addrExpr->get_env() );
457	arg0 = nullptr;
458	addrExpr->set_env( nullptr );
459	delete addrExpr;
460	return ret;
461	}
462	}
463	return addrExpr;
464	}
465
466	Expression * CollapseAddrDeref::postmutate( ApplicationExpr * appExpr ) {
467	if ( isIntrinsicReference( appExpr ) ) {
468	std::string fname = InitTweak::getFunctionName( appExpr );
469	if ( fname == "*?" ) {
470	Expression * arg = InitTweak::getCallArg( appExpr, 0 );
471	// xxx - this isn't right, because it can remove casts that should be there...
472	// while ( CastExpr * castExpr = dynamic_cast< CastExpr * >( arg ) ) {
473	// arg = castExpr->get_arg();
474	// }
475	if ( AddressExpr * addrExpr = dynamic_cast< AddressExpr * >( arg ) ) {
476	Expression * ret = addrExpr->get_arg();
477	ret->set_env( appExpr->get_env() );
478	addrExpr->set_arg( nullptr );
479	appExpr->set_env( nullptr );
480	delete appExpr;
481	return ret;
482	}
483	}
484	}
485	return appExpr;
486	}
487	} // namespace
488	} // namespace GenPoly
489
490	// Local Variables: //
491	// tab-width: 4 //
492	// mode: c++ //
493	// compile-command: "make install" //
494	// End: //

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