Context Navigation

source: src/GenPoly/Lvalue.cc @ 9236060

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 9236060 was 9236060, checked in by Rob Schluntz <rschlunt@…>, 7 years ago
Merge branch 'master' into references
Property mode set to `100644`
File size: 17.3 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>
17
18	#include "Lvalue.h"
19
20	#include "GenPoly.h"
21
22	#include "SynTree/Declaration.h"
23	#include "SynTree/Type.h"
24	#include "SynTree/Expression.h"
25	#include "SynTree/Statement.h"
26	#include "SynTree/Visitor.h"
27	#include "SynTree/Mutator.h"
28	#include "SymTab/Indexer.h"
29	#include "SymTab/Autogen.h"
30
31	#include "ResolvExpr/Resolver.h"
32	#include "ResolvExpr/TypeEnvironment.h"
33	#include "ResolvExpr/typeops.h"
34	#include "ResolvExpr/Unify.h"
35
36	#include "Common/UniqueName.h"
37	#include "Common/utility.h"
38	#include "Common/PassVisitor.h"
39
40	#include "InitTweak/InitTweak.h"
41
42	#if 0
43	#define PRINT(x) x
44	#else
45	#define PRINT(x)
46	#endif
47
48	namespace GenPoly {
49	namespace {
50	// TODO: fold this into the general createDeref function??
51	Expression * mkDeref( Expression * arg ) {
52	if ( SymTab::dereferenceOperator ) {
53	VariableExpr * deref = new VariableExpr( SymTab::dereferenceOperator );
54	deref->set_result( new PointerType( Type::Qualifiers(), deref->get_result() ) );
55	Type * base = InitTweak::getPointerBase( arg->get_result() );
56	assertf( base, "expected pointer type in dereference (type was %s)", toString( arg->get_result() ).c_str() );
57	ApplicationExpr * ret = new ApplicationExpr( deref, { arg } );
58	delete ret->get_result();
59	ret->set_result( base->clone() );
60	ret->get_result()->set_lvalue( true );
61	return ret;
62	} else {
63	return UntypedExpr::createDeref( arg );
64	}
65	}
66
67	struct ReferenceConversions final {
68	Expression * postmutate( CastExpr * castExpr );
69	Expression * postmutate( AddressExpr * addrExpr );
70	};
71
72	/// Intrinsic functions that take reference parameters don't REALLY take reference parameters -- their reference arguments must always be implicitly dereferenced.
73	struct FixIntrinsicArgs final {
74	Expression * postmutate( ApplicationExpr * appExpr );
75	};
76
77	struct FixIntrinsicResult final {
78	Expression * postmutate( ApplicationExpr * appExpr );
79	};
80
81	/// Replace reference types with pointer types
82	struct ReferenceTypeElimination final {
83	Type * postmutate( ReferenceType * refType );
84	};
85
86	/// GCC-like Generalized Lvalues (which have since been removed from GCC)
87	/// https://gcc.gnu.org/onlinedocs/gcc-3.4.6/gcc/Lvalues.html#Lvalues
88	/// Replaces &(a,b) with (a, &b), &(a ? b : c) with (a ? &b : &c)
89	struct GeneralizedLvalue final : public WithVisitorRef<GeneralizedLvalue> {
90	Expression * postmutate( AddressExpr * addressExpr );
91	Expression * postmutate( MemberExpr * memExpr );
92
93	template<typename Func>
94	Expression * applyTransformation( Expression * expr, Expression * arg, Func mkExpr );
95	};
96
97	/// Removes redundant &/& pattern that this pass can generate
98	struct CollapseAddrDeref final {
99	Expression * postmutate( AddressExpr * addressExpr );
100	Expression * postmutate( ApplicationExpr * appExpr );
101	};
102
103	struct AddrRef final : public WithGuards {
104	void premutate( AddressExpr * addrExpr );
105	Expression * postmutate( AddressExpr * addrExpr );
106	void premutate( Expression * expr );
107
108	bool first = true;
109	bool current = false;
110	int refDepth = 0;
111	};
112	} // namespace
113
114	static bool referencesEliminated = false;
115	// used by UntypedExpr::createDeref to determine whether result type of dereference should be ReferenceType or value type.
116	bool referencesPermissable() {
117	return ! referencesEliminated;
118	}
119
120	void convertLvalue( std::list< Declaration* >& translationUnit ) {
121	std::cerr << "convertLvalue" << std::endl;
122	PassVisitor<ReferenceConversions> refCvt;
123	PassVisitor<ReferenceTypeElimination> elim;
124	PassVisitor<GeneralizedLvalue> genLval;
125	PassVisitor<FixIntrinsicArgs> fixer;
126	PassVisitor<CollapseAddrDeref> collapser;
127	PassVisitor<AddrRef> addrRef;
128	PassVisitor<FixIntrinsicResult> intrinsicResults;
129	mutateAll( translationUnit, intrinsicResults );
130	mutateAll( translationUnit, addrRef );
131	mutateAll( translationUnit, refCvt );
132	mutateAll( translationUnit, fixer );
133	mutateAll( translationUnit, collapser );
134	mutateAll( translationUnit, genLval );
135	mutateAll( translationUnit, elim ); // last because other passes need reference types to work
136
137	// from this point forward, no other pass should create reference types.
138	referencesEliminated = true;
139	}
140
141	Expression * generalizedLvalue( Expression * expr ) {
142	PassVisitor<GeneralizedLvalue> genLval;
143	return expr->acceptMutator( genLval );
144	}
145
146	namespace {
147	// true for intrinsic function calls that return a reference
148	bool isIntrinsicReference( Expression * expr ) {
149	if ( UntypedExpr * untyped = dynamic_cast< UntypedExpr * >( expr ) ) {
150	std::string fname = InitTweak::getFunctionName( untyped );
151	// known intrinsic-reference prelude functions
152	return fname == "*?" \|\| fname == "?[?]";
153	} else if ( ApplicationExpr * appExpr = dynamic_cast< ApplicationExpr * > ( expr ) ) {
154	if ( DeclarationWithType * func = InitTweak::getFunction( appExpr ) ) {
155	// use type of return variable rather than expr result type, since it may have been changed to a pointer type
156	FunctionType * ftype = GenPoly::getFunctionType( func->get_type() );
157	Type * ret = ftype->get_returnVals().empty() ? nullptr : ftype->get_returnVals().front()->get_type();
158	return func->get_linkage() == LinkageSpec::Intrinsic && dynamic_cast<ReferenceType *>( ret );
159	}
160	}
161	return false;
162	}
163
164	Expression * FixIntrinsicResult::postmutate( ApplicationExpr * appExpr ) {
165	if ( isIntrinsicReference( appExpr ) ) {
166	// eliminate reference types from intrinsic applications - now they return lvalues
167	Type * result = appExpr->get_result();
168	appExpr->set_result( result->stripReferences()->clone() );
169	appExpr->get_result()->set_lvalue( true );
170	Expression * ret = new CastExpr( appExpr, result );
171	ret->set_env( appExpr->get_env() );
172	appExpr->set_env( nullptr );
173	return ret;
174	}
175	return appExpr;
176	}
177
178	Expression * FixIntrinsicArgs::postmutate( ApplicationExpr * appExpr ) {
179	// intrinsic functions don't really take reference-typed parameters, so they require an implicit dereference on their arguments.
180	if ( DeclarationWithType * function = InitTweak::getFunction( appExpr ) ) {
181	FunctionType * ftype = GenPoly::getFunctionType( function->get_type() );
182	assertf( ftype, "Function declaration does not have function type." );
183	// can be of differing lengths only when function is variadic
184	assertf( ftype->get_parameters().size() == appExpr->get_args().size() \|\| ftype->get_isVarArgs(), "ApplicationExpr args do not match formal parameter type." );
185
186
187	unsigned int i = 0;
188	const unsigned int end = ftype->get_parameters().size();
189	for ( auto p : unsafe_group_iterate( appExpr->get_args(), ftype->get_parameters() ) ) {
190	if (i == end) break;
191	Expression *& arg = std::get<0>( p );
192	Type * formal = std::get<1>( p )->get_type();
193	PRINT(
194	std::cerr << "pair<0>: " << arg << std::endl;
195	std::cerr << "pair<1>: " << formal << std::endl;
196	)
197	if ( dynamic_cast<ReferenceType*>( formal ) ) {
198	if ( isIntrinsicReference( arg ) ) { // do not combine conditions, because that changes the meaning of the else if
199	if ( function->get_linkage() != LinkageSpec::Intrinsic ) { // intrinsic functions that turn pointers into references
200	// if argument is dereference or array subscript, the result isn't REALLY a reference, so it's not necessary to fix the argument
201	PRINT(
202	std::cerr << "===is intrinsic arg in non-intrinsic call - adding address" << std::endl;
203	)
204	arg = new AddressExpr( arg );
205	}
206	} else if ( function->get_linkage() == LinkageSpec::Intrinsic ) {
207	// std::cerr << "===adding deref to arg" << std::endl;
208	// if the parameter is a reference, add a dereference to the reference-typed argument.
209	Type * baseType = InitTweak::getPointerBase( arg->get_result() );
210	assertf( baseType, "parameter is reference, arg must be pointer or reference: %s", toString( arg->get_result() ).c_str() );
211	PointerType * ptrType = new PointerType( Type::Qualifiers(), baseType->clone() );
212	delete arg->get_result();
213	arg->set_result( ptrType );
214	arg = mkDeref( arg );
215	}
216	}
217	++i;
218	}
219	}
220	return appExpr;
221	}
222
223	// idea: &&&E: get outer &, inner &
224	// at inner &, record depth D of reference type
225	// at outer &, add D derefs.
226	void AddrRef::premutate( Expression * expr ) {
227	GuardValue( current );
228	GuardValue( first );
229	current = false;
230	first = true;
231	}
232
233	void AddrRef::premutate( AddressExpr * addrExpr ) {
234	GuardValue( current );
235	GuardValue( first );
236	current = first;
237	first = false;
238	if ( current ) {
239	GuardValue( refDepth );
240	refDepth = 0;
241	}
242	}
243
244	Expression * AddrRef::postmutate( AddressExpr * addrExpr ) {
245	if ( refDepth == 0 ) {
246	if ( ! isIntrinsicReference( addrExpr->get_arg() ) ) {
247	// try to avoid ?[?]
248	refDepth = addrExpr->get_arg()->get_result()->referenceDepth();
249	}
250	}
251	if ( current ) {
252	Expression * ret = addrExpr;
253	while ( refDepth ) {
254	ret = mkDeref( ret );
255	refDepth--;
256	}
257	return ret;
258	}
259	return addrExpr;
260	}
261
262	Expression * ReferenceConversions::postmutate( AddressExpr * addrExpr ) {
263	// Inner expression may have been lvalue to reference conversion, which becomes an address expression.
264	// In this case, remove the outer address expression and return the argument.
265	// TODO: It's possible that this might catch too much and require a more sophisticated check.
266	return addrExpr;
267	}
268
269	Expression * ReferenceConversions::postmutate( CastExpr * castExpr ) {
270	// xxx - is it possible to convert directly between reference types with a different base? E.g.,
271	// int x;
272	// (double&)x;
273	// At the moment, I am working off of the assumption that this is illegal, thus the cast becomes redundant
274	// after this pass, so trash the cast altogether. If that changes, care must be taken to insert the correct
275	// pointer casts in the right places.
276
277	// conversion to reference type
278	if ( ReferenceType * refType = dynamic_cast< ReferenceType * >( castExpr->get_result() ) ) {
279	(void)refType;
280	if ( ReferenceType * otherRef = dynamic_cast< ReferenceType * >( castExpr->get_arg()->get_result() ) ) {
281	// nothing to do if casting from reference to reference.
282	(void)otherRef;
283	PRINT( std::cerr << "convert reference to reference -- nop" << std::endl; )
284	if ( isIntrinsicReference( castExpr->get_arg() ) ) {
285	Expression * callExpr = castExpr->get_arg();
286	PRINT(
287	std::cerr << "but arg is deref -- &" << std::endl;
288	std::cerr << callExpr << std::endl;
289	)
290	callExpr = new AddressExpr( callExpr ); // this doesn't work properly for multiple casts
291	delete callExpr->get_result();
292	callExpr->set_result( refType->clone() );
293	// move environment out to new top-level
294	callExpr->set_env( castExpr->get_env() );
295	castExpr->set_arg( nullptr );
296	castExpr->set_env( nullptr );
297	delete castExpr;
298	return callExpr;
299	}
300	int depth1 = refType->referenceDepth();
301	int depth2 = otherRef->referenceDepth();
302	assertf( depth1 == depth2, "non-intrinsic reference with cast of reference to reference not yet supported: %d %d %s", depth1, depth2, toString( castExpr ).c_str() );
303	PRINT( std::cerr << castExpr << std::endl; )
304	return castExpr;
305	} else if ( castExpr->get_arg()->get_result()->get_lvalue() ) {
306	// conversion from lvalue to reference
307	// xxx - keep cast, but turn into pointer cast??
308	// xxx - memory
309	PRINT(
310	std::cerr << "convert lvalue to reference -- &" << std::endl;
311	std::cerr << castExpr->get_arg() << std::endl;
312	)
313	AddressExpr * ret = new AddressExpr( castExpr->get_arg() );
314	if ( refType->get_base()->get_qualifiers() != castExpr->get_arg()->get_result()->get_qualifiers() ) {
315	// must keep cast if cast-to type is different from the actual type
316	castExpr->set_arg( ret );
317	return castExpr;
318	}
319	ret->set_env( castExpr->get_env() );
320	delete ret->get_result();
321	ret->set_result( castExpr->get_result() );
322	castExpr->set_env( nullptr );
323	castExpr->set_arg( nullptr );
324	castExpr->set_result( nullptr );
325	delete castExpr;
326	return ret;
327	} else {
328	// rvalue to reference conversion -- introduce temporary
329	}
330	assertf( false, "Only conversions to reference from lvalue are currently supported: %s", toString( castExpr ).c_str() );
331	} else if ( ReferenceType * refType = dynamic_cast< ReferenceType * >( castExpr->get_arg()->get_result() ) ) {
332	(void)refType;
333	// conversion from reference to rvalue
334	PRINT(
335	std::cerr << "convert reference to rvalue -- *" << std::endl;
336	std::cerr << "was = " << castExpr << std::endl;
337	)
338	Expression * ret = castExpr->get_arg();
339	TypeSubstitution * env = castExpr->get_env();
340	castExpr->set_env( nullptr );
341	if ( ! isIntrinsicReference( ret ) ) {
342	// dereference if not already dereferenced
343	ret = mkDeref( ret );
344	}
345	if ( ResolvExpr::typesCompatibleIgnoreQualifiers( castExpr->get_result(), castExpr->get_arg()->get_result()->stripReferences(), SymTab::Indexer() ) ) {
346	// can remove cast if types are compatible, changing expression type to value type
347	ret->set_result( castExpr->get_result()->clone() );
348	castExpr->set_arg( nullptr );
349	delete castExpr;
350	} else {
351	// must keep cast if types are different
352	castExpr->set_arg( ret );
353	ret = castExpr;
354	}
355	ret->set_env( env );
356	PRINT( std::cerr << "now: " << ret << std::endl; )
357	return ret;
358	}
359	return castExpr;
360	}
361
362	Type * ReferenceTypeElimination::postmutate( ReferenceType * refType ) {
363	Type * base = refType->get_base();
364	Type::Qualifiers qualifiers = refType->get_qualifiers();
365	refType->set_base( nullptr );
366	delete refType;
367	return new PointerType( qualifiers, base );
368	}
369
370	template<typename Func>
371	Expression * GeneralizedLvalue::applyTransformation( Expression * expr, Expression * arg, Func mkExpr ) {
372	if ( CommaExpr * commaExpr = dynamic_cast< CommaExpr * >( arg ) ) {
373	Expression * arg1 = commaExpr->get_arg1()->clone();
374	Expression * arg2 = commaExpr->get_arg2()->clone();
375	Expression * ret = new CommaExpr( arg1, mkExpr( arg2 )->acceptMutator( *visitor ) );
376	ret->set_env( expr->get_env() );
377	expr->set_env( nullptr );
378	delete expr;
379	return ret;
380	} else if ( ConditionalExpr * condExpr = dynamic_cast< ConditionalExpr * >( arg ) ) {
381	Expression * arg1 = condExpr->get_arg1()->clone();
382	Expression * arg2 = condExpr->get_arg2()->clone();
383	Expression * arg3 = condExpr->get_arg3()->clone();
384	ConditionalExpr * ret = new ConditionalExpr( arg1, mkExpr( arg2 )->acceptMutator( visitor ), mkExpr( arg3 )->acceptMutator( visitor ) );
385	ret->set_env( expr->get_env() );
386	expr->set_env( nullptr );
387	delete expr;
388
389	// conditional expr type may not be either of the argument types, need to unify
390	using namespace ResolvExpr;
391	Type* commonType = nullptr;
392	TypeEnvironment newEnv;
393	AssertionSet needAssertions, haveAssertions;
394	OpenVarSet openVars;
395	unify( ret->get_arg2()->get_result(), ret->get_arg3()->get_result(), newEnv, needAssertions, haveAssertions, openVars, SymTab::Indexer(), commonType );
396	ret->set_result( commonType ? commonType : ret->get_arg2()->get_result()->clone() );
397	return ret;
398	}
399	return expr;
400	}
401
402	Expression * GeneralizedLvalue::postmutate( MemberExpr * memExpr ) {
403	return applyTransformation( memExpr, memExpr->get_aggregate(), [=]( Expression * aggr ) { return new MemberExpr( memExpr->get_member(), aggr ); } );
404	}
405
406	Expression * GeneralizedLvalue::postmutate( AddressExpr * addrExpr ) {
407	return applyTransformation( addrExpr, addrExpr->get_arg(), []( Expression * arg ) { return new AddressExpr( arg ); } );
408	}
409
410	Expression * CollapseAddrDeref::postmutate( AddressExpr * addrExpr ) {
411	Expression * arg = addrExpr->get_arg();
412	if ( isIntrinsicReference( arg ) ) {
413	std::string fname = InitTweak::getFunctionName( arg );
414	if ( fname == "*?" ) {
415	Expression *& arg0 = InitTweak::getCallArg( arg, 0 );
416	Expression * ret = arg0;
417	ret->set_env( addrExpr->get_env() );
418	arg0 = nullptr;
419	addrExpr->set_env( nullptr );
420	delete addrExpr;
421	return ret;
422	}
423	}
424	return addrExpr;
425	}
426
427	Expression * CollapseAddrDeref::postmutate( ApplicationExpr * appExpr ) {
428	if ( isIntrinsicReference( appExpr ) ) {
429	std::string fname = InitTweak::getFunctionName( appExpr );
430	if ( fname == "*?" ) {
431	Expression * arg = InitTweak::getCallArg( appExpr, 0 );
432	// xxx - this isn't right, because it can remove casts that should be there...
433	// while ( CastExpr * castExpr = dynamic_cast< CastExpr * >( arg ) ) {
434	// arg = castExpr->get_arg();
435	// }
436	if ( AddressExpr * addrExpr = dynamic_cast< AddressExpr * >( arg ) ) {
437	Expression * ret = addrExpr->get_arg();
438	ret->set_env( appExpr->get_env() );
439	addrExpr->set_arg( nullptr );
440	appExpr->set_env( nullptr );
441	delete appExpr;
442	return ret;
443	}
444	}
445	}
446	return appExpr;
447	}
448	} // namespace
449	} // namespace GenPoly
450
451	// Local Variables: //
452	// tab-width: 4 //
453	// mode: c++ //
454	// compile-command: "make install" //
455	// End: //

Note: See TracBrowser for help on using the repository browser.

Download in other formats: