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source: src/GenPoly/Lvalue.cc @ 8573729

resolv-new

Last change on this file since 8573729 was a16764a6, checked in by Thierry Delisle <tdelisle@…>, 7 years ago
Changed warning system to prepare for toggling warnings
Property mode set to `100644`
File size: 19.8 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	// 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 "GenPoly.h" // for isPolyType
21	#include "Lvalue.h"
22
23	#include "Parser/LinkageSpec.h" // for Spec, isBuiltin, Intrinsic
24	#include "ResolvExpr/TypeEnvironment.h" // for AssertionSet, OpenVarSet
25	#include "ResolvExpr/Unify.h" // for unify
26	#include "ResolvExpr/typeops.h"
27	#include "SymTab/Autogen.h"
28	#include "SymTab/Indexer.h" // for Indexer
29	#include "SynTree/Declaration.h" // for Declaration, FunctionDecl
30	#include "SynTree/Expression.h" // for Expression, ConditionalExpr
31	#include "SynTree/Mutator.h" // for mutateAll, Mutator
32	#include "SynTree/Statement.h" // for ReturnStmt, Statement (ptr o...
33	#include "SynTree/Type.h" // for PointerType, Type, FunctionType
34	#include "SynTree/Visitor.h" // for Visitor, acceptAll
35
36	#if 0
37	#define PRINT(x) x
38	#else
39	#define PRINT(x)
40	#endif
41
42	namespace GenPoly {
43	namespace {
44	// TODO: fold this into the general createDeref function??
45	Expression * mkDeref( Expression * arg ) {
46	if ( SymTab::dereferenceOperator ) {
47	VariableExpr * deref = new VariableExpr( SymTab::dereferenceOperator );
48	deref->result = new PointerType( Type::Qualifiers(), deref->result );
49	Type * base = InitTweak::getPointerBase( arg->result );
50	assertf( base, "expected pointer type in dereference (type was %s)", toString( arg->result ).c_str() );
51	ApplicationExpr * ret = new ApplicationExpr( deref, { arg } );
52	delete ret->result;
53	ret->result = base->clone();
54	ret->result->set_lvalue( true );
55	return ret;
56	} else {
57	return UntypedExpr::createDeref( arg );
58	}
59	}
60
61	struct ReferenceConversions final {
62	Expression * postmutate( CastExpr * castExpr );
63	Expression * postmutate( AddressExpr * addrExpr );
64	};
65
66	/// Intrinsic functions that take reference parameters don't REALLY take reference parameters -- their reference arguments must always be implicitly dereferenced.
67	struct FixIntrinsicArgs final {
68	Expression * postmutate( ApplicationExpr * appExpr );
69	};
70
71	struct FixIntrinsicResult final : public WithGuards {
72	Expression * postmutate( ApplicationExpr * appExpr );
73	void premutate( FunctionDecl * funcDecl );
74	bool inIntrinsic = false;
75	};
76
77	/// Replace reference types with pointer types
78	struct ReferenceTypeElimination final {
79	Type * postmutate( ReferenceType * refType );
80	};
81
82	/// GCC-like Generalized Lvalues (which have since been removed from GCC)
83	/// https://gcc.gnu.org/onlinedocs/gcc-3.4.6/gcc/Lvalues.html#Lvalues
84	/// Replaces &(a,b) with (a, &b), &(a ? b : c) with (a ? &b : &c)
85	struct GeneralizedLvalue final : public WithVisitorRef<GeneralizedLvalue> {
86	Expression * postmutate( AddressExpr * addressExpr );
87	Expression * postmutate( MemberExpr * memExpr );
88
89	template<typename Func>
90	Expression * applyTransformation( Expression * expr, Expression * arg, Func mkExpr );
91	};
92
93	/// Removes redundant &/& pattern that this pass can generate
94	struct CollapseAddrDeref final {
95	Expression * postmutate( AddressExpr * addressExpr );
96	Expression * postmutate( ApplicationExpr * appExpr );
97	};
98
99	struct AddrRef final : public WithGuards {
100	void premutate( AddressExpr * addrExpr );
101	Expression * postmutate( AddressExpr * addrExpr );
102	void premutate( Expression * expr );
103
104	bool first = true;
105	bool current = false;
106	int refDepth = 0;
107	};
108	} // namespace
109
110	static bool referencesEliminated = false;
111	// used by UntypedExpr::createDeref to determine whether result type of dereference should be ReferenceType or value type.
112	bool referencesPermissable() {
113	return ! referencesEliminated;
114	}
115
116	void convertLvalue( std::list< Declaration* >& translationUnit ) {
117	PassVisitor<ReferenceConversions> refCvt;
118	PassVisitor<ReferenceTypeElimination> elim;
119	PassVisitor<GeneralizedLvalue> genLval;
120	PassVisitor<FixIntrinsicArgs> fixer;
121	PassVisitor<CollapseAddrDeref> collapser;
122	PassVisitor<AddrRef> addrRef;
123	PassVisitor<FixIntrinsicResult> intrinsicResults;
124	mutateAll( translationUnit, intrinsicResults );
125	mutateAll( translationUnit, addrRef );
126	mutateAll( translationUnit, refCvt );
127	mutateAll( translationUnit, fixer );
128	mutateAll( translationUnit, collapser );
129	mutateAll( translationUnit, genLval );
130	mutateAll( translationUnit, elim ); // last because other passes need reference types to work
131
132	// from this point forward, no other pass should create reference types.
133	referencesEliminated = true;
134	}
135
136	Expression * generalizedLvalue( Expression * expr ) {
137	PassVisitor<GeneralizedLvalue> genLval;
138	return expr->acceptMutator( genLval );
139	}
140
141	namespace {
142	// true for intrinsic function calls that return a reference
143	bool isIntrinsicReference( Expression * expr ) {
144	if ( UntypedExpr * untyped = dynamic_cast< UntypedExpr * >( expr ) ) {
145	std::string fname = InitTweak::getFunctionName( untyped );
146	// known intrinsic-reference prelude functions
147	return fname == "*?" \|\| fname == "?[?]";
148	} else if ( ApplicationExpr * appExpr = dynamic_cast< ApplicationExpr * > ( expr ) ) {
149	if ( DeclarationWithType * func = InitTweak::getFunction( appExpr ) ) {
150	// use type of return variable rather than expr result type, since it may have been changed to a pointer type
151	FunctionType * ftype = GenPoly::getFunctionType( func->get_type() );
152	Type * ret = ftype->get_returnVals().empty() ? nullptr : ftype->get_returnVals().front()->get_type();
153	return func->get_linkage() == LinkageSpec::Intrinsic && dynamic_cast<ReferenceType *>( ret );
154	}
155	}
156	return false;
157	}
158
159	Expression * FixIntrinsicResult::postmutate( ApplicationExpr * appExpr ) {
160	if ( isIntrinsicReference( appExpr ) ) {
161	// eliminate reference types from intrinsic applications - now they return lvalues
162	Type * result = appExpr->get_result();
163	appExpr->set_result( result->stripReferences()->clone() );
164	appExpr->get_result()->set_lvalue( true );
165	if ( ! inIntrinsic ) {
166	// when not in an intrinsic function, add a cast to
167	// don't add cast when in an intrinsic function, since they already have the cast
168	Expression * ret = new CastExpr( appExpr, result );
169	ret->set_env( appExpr->get_env() );
170	appExpr->set_env( nullptr );
171	return ret;
172	}
173	delete result;
174	}
175	return appExpr;
176	}
177
178	void FixIntrinsicResult::premutate( FunctionDecl * funcDecl ) {
179	GuardValue( inIntrinsic );
180	inIntrinsic = funcDecl->linkage == LinkageSpec::Intrinsic;
181	}
182
183	Expression * FixIntrinsicArgs::postmutate( ApplicationExpr * appExpr ) {
184	// intrinsic functions don't really take reference-typed parameters, so they require an implicit dereference on their arguments.
185	if ( DeclarationWithType * function = InitTweak::getFunction( appExpr ) ) {
186	FunctionType * ftype = GenPoly::getFunctionType( function->get_type() );
187	assertf( ftype, "Function declaration does not have function type." );
188	// can be of differing lengths only when function is variadic
189	assertf( ftype->get_parameters().size() == appExpr->get_args().size() \|\| ftype->get_isVarArgs(), "ApplicationExpr args do not match formal parameter type." );
190
191
192	unsigned int i = 0;
193	const unsigned int end = ftype->get_parameters().size();
194	for ( auto p : unsafe_group_iterate( appExpr->get_args(), ftype->get_parameters() ) ) {
195	if (i == end) break;
196	Expression *& arg = std::get<0>( p );
197	Type * formal = std::get<1>( p )->get_type();
198	PRINT(
199	std::cerr << "pair<0>: " << arg << std::endl;
200	std::cerr << "pair<1>: " << formal << std::endl;
201	)
202	if ( dynamic_cast<ReferenceType*>( formal ) ) {
203	if ( isIntrinsicReference( arg ) ) { // do not combine conditions, because that changes the meaning of the else if
204	if ( function->get_linkage() != LinkageSpec::Intrinsic ) { // intrinsic functions that turn pointers into references
205	// if argument is dereference or array subscript, the result isn't REALLY a reference, so it's not necessary to fix the argument
206	PRINT(
207	std::cerr << "===is intrinsic arg in non-intrinsic call - adding address" << std::endl;
208	)
209	arg = new AddressExpr( arg );
210	}
211	} else if ( function->get_linkage() == LinkageSpec::Intrinsic ) {
212	// std::cerr << "===adding deref to arg" << std::endl;
213	// if the parameter is a reference, add a dereference to the reference-typed argument.
214	Type * baseType = InitTweak::getPointerBase( arg->get_result() );
215	assertf( baseType, "parameter is reference, arg must be pointer or reference: %s", toString( arg->get_result() ).c_str() );
216	PointerType * ptrType = new PointerType( Type::Qualifiers(), baseType->clone() );
217	delete arg->get_result();
218	arg->set_result( ptrType );
219	arg = mkDeref( arg );
220	}
221	}
222	++i;
223	}
224	}
225	return appExpr;
226	}
227
228	// idea: &&&E: get outer &, inner &
229	// at inner &, record depth D of reference type
230	// at outer &, add D derefs.
231	void AddrRef::premutate( Expression * ) {
232	GuardValue( current );
233	GuardValue( first );
234	current = false;
235	first = true;
236	}
237
238	void AddrRef::premutate( AddressExpr * ) {
239	GuardValue( current );
240	GuardValue( first );
241	current = first;
242	first = false;
243	if ( current ) {
244	GuardValue( refDepth );
245	refDepth = 0;
246	}
247	}
248
249	Expression * AddrRef::postmutate( AddressExpr * addrExpr ) {
250	if ( refDepth == 0 ) {
251	if ( ! isIntrinsicReference( addrExpr->get_arg() ) ) {
252	// try to avoid ?[?]
253	refDepth = addrExpr->get_arg()->get_result()->referenceDepth();
254	}
255	}
256	if ( current ) {
257	Expression * ret = addrExpr;
258	while ( refDepth ) {
259	ret = mkDeref( ret );
260	refDepth--;
261	}
262	return ret;
263	}
264	return addrExpr;
265	}
266
267	Expression * ReferenceConversions::postmutate( AddressExpr * addrExpr ) {
268	// Inner expression may have been lvalue to reference conversion, which becomes an address expression.
269	// In this case, remove the outer address expression and return the argument.
270	// TODO: It's possible that this might catch too much and require a more sophisticated check.
271	return addrExpr;
272	}
273
274	Expression * ReferenceConversions::postmutate( CastExpr * castExpr ) {
275	// xxx - is it possible to convert directly between reference types with a different base? E.g.,
276	// int x;
277	// (double&)x;
278	// At the moment, I am working off of the assumption that this is illegal, thus the cast becomes redundant
279	// after this pass, so trash the cast altogether. If that changes, care must be taken to insert the correct
280	// pointer casts in the right places.
281
282	// conversion to reference type
283	if ( ReferenceType * refType = dynamic_cast< ReferenceType * >( castExpr->get_result() ) ) {
284	(void)refType;
285	if ( ReferenceType * otherRef = dynamic_cast< ReferenceType * >( castExpr->get_arg()->get_result() ) ) {
286	// nothing to do if casting from reference to reference.
287	(void)otherRef;
288	PRINT( std::cerr << "convert reference to reference -- nop" << std::endl; )
289	if ( isIntrinsicReference( castExpr->get_arg() ) ) {
290	Expression * callExpr = castExpr->get_arg();
291	PRINT(
292	std::cerr << "but arg is deref -- &" << std::endl;
293	std::cerr << callExpr << std::endl;
294	)
295	callExpr = new AddressExpr( callExpr ); // this doesn't work properly for multiple casts
296	delete callExpr->get_result();
297	callExpr->set_result( refType->clone() );
298	// move environment out to new top-level
299	callExpr->set_env( castExpr->get_env() );
300	castExpr->set_arg( nullptr );
301	castExpr->set_env( nullptr );
302	delete castExpr;
303	return callExpr;
304	}
305	int depth1 = refType->referenceDepth();
306	int depth2 = otherRef->referenceDepth();
307	int diff = depth1-depth2;
308	if ( diff == 0 ) {
309	// conversion between references of the same depth
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	// conversion from reference to reference with less depth (e.g. int && -> int &): add dereferences
315	Expression * ret = castExpr->arg;
316	for ( int i = 0; i < diff; ++i ) {
317	ret = mkDeref( ret );
318	}
319	ret->env = castExpr->env;
320	delete ret->result;
321	ret->result = castExpr->result;
322	ret->result->set_lvalue( true ); // ensure result is lvalue
323	castExpr->env = nullptr;
324	castExpr->arg = nullptr;
325	castExpr->result = nullptr;
326	delete castExpr;
327	return ret;
328	} else if ( diff > 0 ) {
329	// conversion from reference to reference with more depth (e.g. int & -> int &&): add address-of
330	Expression * ret = castExpr->arg;
331	for ( int i = 0; i < diff; ++i ) {
332	ret = new AddressExpr( ret );
333	}
334	ret->env = castExpr->env;
335	delete ret->result;
336	ret->result = castExpr->result;
337	castExpr->env = nullptr;
338	castExpr->arg = nullptr;
339	castExpr->result = nullptr;
340	delete castExpr;
341	return ret;
342	}
343
344	assertf( depth1 == depth2, "non-intrinsic reference with cast of reference to reference not yet supported: %d %d %s", depth1, depth2, toString( castExpr ).c_str() );
345	PRINT( std::cerr << castExpr << std::endl; )
346	return castExpr;
347	} else if ( castExpr->arg->result->get_lvalue() ) {
348	// conversion from lvalue to reference
349	// xxx - keep cast, but turn into pointer cast??
350	// xxx - memory
351	PRINT(
352	std::cerr << "convert lvalue to reference -- &" << std::endl;
353	std::cerr << castExpr->arg << std::endl;
354	)
355	AddressExpr * ret = new AddressExpr( castExpr->arg );
356	if ( refType->base->get_qualifiers() != castExpr->arg->result->get_qualifiers() ) {
357	// must keep cast if cast-to type is different from the actual type
358	castExpr->arg = ret;
359	return castExpr;
360	}
361	ret->env = castExpr->env;
362	delete ret->result;
363	ret->result = castExpr->result;
364	castExpr->env = nullptr;
365	castExpr->arg = nullptr;
366	castExpr->result = nullptr;
367	delete castExpr;
368	return ret;
369	} else {
370	// rvalue to reference conversion -- introduce temporary
371	}
372	assertf( false, "Only conversions to reference from lvalue are currently supported: %s", toString( castExpr ).c_str() );
373	} else if ( ReferenceType * refType = dynamic_cast< ReferenceType * >( castExpr->arg->result ) ) {
374	(void)refType;
375	// conversion from reference to rvalue
376	PRINT(
377	std::cerr << "convert reference to rvalue -- *" << std::endl;
378	std::cerr << "was = " << castExpr << std::endl;
379	)
380	Expression * ret = castExpr->arg;
381	TypeSubstitution * env = castExpr->env;
382	castExpr->set_env( nullptr );
383	if ( ! isIntrinsicReference( ret ) ) {
384	// dereference if not already dereferenced
385	ret = mkDeref( ret );
386	}
387	if ( ResolvExpr::typesCompatibleIgnoreQualifiers( castExpr->result, castExpr->arg->result->stripReferences(), SymTab::Indexer() ) ) {
388	// can remove cast if types are compatible, changing expression type to value type
389	ret->result = castExpr->result->clone();
390	ret->result->set_lvalue( true ); // ensure result is lvalue
391	castExpr->arg = nullptr;
392	delete castExpr;
393	} else {
394	// must keep cast if types are different
395	castExpr->arg = ret;
396	ret = castExpr;
397	}
398	ret->set_env( env );
399	PRINT( std::cerr << "now: " << ret << std::endl; )
400	return ret;
401	}
402	return castExpr;
403	}
404
405	Type * ReferenceTypeElimination::postmutate( ReferenceType * refType ) {
406	Type * base = refType->get_base();
407	Type::Qualifiers qualifiers = refType->get_qualifiers();
408	refType->set_base( nullptr );
409	delete refType;
410	return new PointerType( qualifiers, base );
411	}
412
413	template<typename Func>
414	Expression * GeneralizedLvalue::applyTransformation( Expression * expr, Expression * arg, Func mkExpr ) {
415	if ( CommaExpr * commaExpr = dynamic_cast< CommaExpr * >( arg ) ) {
416	Expression * arg1 = commaExpr->get_arg1()->clone();
417	Expression * arg2 = commaExpr->get_arg2()->clone();
418	Expression * ret = new CommaExpr( arg1, mkExpr( arg2 )->acceptMutator( *visitor ) );
419	ret->set_env( expr->get_env() );
420	expr->set_env( nullptr );
421	delete expr;
422	return ret;
423	} else if ( ConditionalExpr * condExpr = dynamic_cast< ConditionalExpr * >( arg ) ) {
424	Expression * arg1 = condExpr->get_arg1()->clone();
425	Expression * arg2 = condExpr->get_arg2()->clone();
426	Expression * arg3 = condExpr->get_arg3()->clone();
427	ConditionalExpr * ret = new ConditionalExpr( arg1, mkExpr( arg2 )->acceptMutator( visitor ), mkExpr( arg3 )->acceptMutator( visitor ) );
428	ret->set_env( expr->get_env() );
429	expr->set_env( nullptr );
430	delete expr;
431
432	// conditional expr type may not be either of the argument types, need to unify
433	using namespace ResolvExpr;
434	Type* commonType = nullptr;
435	TypeEnvironment newEnv;
436	AssertionSet needAssertions, haveAssertions;
437	OpenVarSet openVars;
438	unify( ret->get_arg2()->get_result(), ret->get_arg3()->get_result(), newEnv, needAssertions, haveAssertions, openVars, SymTab::Indexer(), commonType );
439	ret->set_result( commonType ? commonType : ret->get_arg2()->get_result()->clone() );
440	return ret;
441	}
442	return expr;
443	}
444
445	Expression * GeneralizedLvalue::postmutate( MemberExpr * memExpr ) {
446	return applyTransformation( memExpr, memExpr->get_aggregate(), [=]( Expression * aggr ) { return new MemberExpr( memExpr->get_member(), aggr ); } );
447	}
448
449	Expression * GeneralizedLvalue::postmutate( AddressExpr * addrExpr ) {
450	return applyTransformation( addrExpr, addrExpr->get_arg(), []( Expression * arg ) { return new AddressExpr( arg ); } );
451	}
452
453	Expression * CollapseAddrDeref::postmutate( AddressExpr * addrExpr ) {
454	Expression * arg = addrExpr->get_arg();
455	if ( isIntrinsicReference( arg ) ) {
456	std::string fname = InitTweak::getFunctionName( arg );
457	if ( fname == "*?" ) {
458	Expression *& arg0 = InitTweak::getCallArg( arg, 0 );
459	Expression * ret = arg0;
460	ret->set_env( addrExpr->get_env() );
461	arg0 = nullptr;
462	addrExpr->set_env( nullptr );
463	delete addrExpr;
464	return ret;
465	}
466	} else if ( CastExpr * castExpr = dynamic_cast< CastExpr * > ( arg ) ) {
467	// need to move cast to pointer type out a level since address of pointer
468	// is not valid C code (can be introduced in prior passes, e.g., InstantiateGeneric)
469	if ( InitTweak::getPointerBase( castExpr->result ) ) {
470	addrExpr->arg = castExpr->arg;
471	castExpr->arg = addrExpr;
472	castExpr->result = new PointerType( Type::Qualifiers(), castExpr->result );
473	return castExpr;
474	}
475	}
476	return addrExpr;
477	}
478
479	Expression * CollapseAddrDeref::postmutate( ApplicationExpr * appExpr ) {
480	if ( isIntrinsicReference( appExpr ) ) {
481	std::string fname = InitTweak::getFunctionName( appExpr );
482	if ( fname == "*?" ) {
483	Expression * arg = InitTweak::getCallArg( appExpr, 0 );
484	// xxx - this isn't right, because it can remove casts that should be there...
485	// while ( CastExpr * castExpr = dynamic_cast< CastExpr * >( arg ) ) {
486	// arg = castExpr->get_arg();
487	// }
488	if ( AddressExpr * addrExpr = dynamic_cast< AddressExpr * >( arg ) ) {
489	Expression * ret = addrExpr->get_arg();
490	ret->set_env( appExpr->get_env() );
491	addrExpr->set_arg( nullptr );
492	appExpr->set_env( nullptr );
493	delete appExpr;
494	return ret;
495	}
496	}
497	}
498	return appExpr;
499	}
500	} // namespace
501	} // namespace GenPoly
502
503	// Local Variables: //
504	// tab-width: 4 //
505	// mode: c++ //
506	// compile-command: "make install" //
507	// End: //

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