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source: src/GenPoly/Lvalue.cc @ b0440b7

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 b0440b7 was b0440b7, checked in by Rob Schluntz <rschlunt@…>, 7 years ago
Prevent reference types from being added in Box through createDeref
Property mode set to `100644`
File size: 14.1 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>
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	#include "ResolvExpr/Resolver.h"
31	#include "ResolvExpr/typeops.h"
32
33	#include "Common/UniqueName.h"
34	#include "Common/utility.h"
35	#include "InitTweak/InitTweak.h"
36
37	#include "Common/PassVisitor.h"
38
39	// need to be careful about polymorphic references... e.g. in *? (___operator_deref__A0_1_0_0__Fd0_Pd0_intrinsic___1)
40	// the variable is automatically dereferenced and this causes errors dereferencing void*.
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( new ReferenceType( Type::Qualifiers(), base->clone() ) );
60	return ret;
61	} else {
62	return UntypedExpr::createDeref( arg );
63	}
64	}
65
66	struct ReferenceConversions final {
67	Expression * postmutate( CastExpr * castExpr );
68	Expression * postmutate( AddressExpr * addrExpr );
69	};
70
71	/// Intrinsic functions that take reference parameters don't REALLY take reference parameters -- their reference arguments must always be implicitly dereferenced.
72	struct FixIntrinsicArgs final {
73	Expression * postmutate( ApplicationExpr *appExpr );
74	};
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	};
88
89	/// Removes redundant &/& pattern that this pass can generate
90	struct CollapseAddrDeref final {
91	Expression * postmutate( AddressExpr * addressExpr );
92	Expression * postmutate( ApplicationExpr * appExpr );
93	};
94	} // namespace
95
96	static bool referencesEliminated = false;
97	// used by UntypedExpr::createDeref to determine whether result type of dereference should be ReferenceType or value type.
98	bool referencesPermissable() {
99	return ! referencesEliminated;
100	}
101
102	void convertLvalue( std::list< Declaration* >& translationUnit ) {
103	std::cerr << "convertLvalue" << std::endl;
104	PassVisitor<ReferenceConversions> refCvt;
105	PassVisitor<ReferenceTypeElimination> elim;
106	PassVisitor<GeneralizedLvalue> genLval;
107	PassVisitor<FixIntrinsicArgs> fixer;
108	PassVisitor<CollapseAddrDeref> collapser;
109	mutateAll( translationUnit, refCvt );
110	mutateAll( translationUnit, fixer );
111	mutateAll( translationUnit, genLval );
112	mutateAll( translationUnit, collapser );
113	mutateAll( translationUnit, elim ); // last because other passes need reference types to work
114
115	// from this point forward, no other pass should create reference types.
116	referencesEliminated = true;
117	}
118
119	namespace {
120	// true for intrinsic function calls that return a reference
121	bool isIntrinsicReference( Expression * expr ) {
122	if ( UntypedExpr * untyped = dynamic_cast< UntypedExpr * >( expr ) ) {
123	std::string fname = InitTweak::getFunctionName( untyped );
124	// known intrinsic-reference prelude functions
125	return fname == "*?" \|\| fname == "?[?]";
126	} else if ( ApplicationExpr * appExpr = dynamic_cast< ApplicationExpr * > ( expr ) ) {
127	if ( DeclarationWithType * func = InitTweak::getFunction( appExpr ) ) {
128	// use type of return variable rather than expr result type, since it may have been changed to a pointer type
129	FunctionType * ftype = GenPoly::getFunctionType( func->get_type() );
130	Type * ret = ftype->get_returnVals().empty() ? nullptr : ftype->get_returnVals().front()->get_type();
131	return func->get_linkage() == LinkageSpec::Intrinsic && dynamic_cast<ReferenceType *>( ret );
132	}
133	}
134	return false;
135	}
136
137	// xxx - might need to & every * (or every * that is an arg to non-intrinsic function??)
138	Expression * FixIntrinsicArgs::postmutate( ApplicationExpr * appExpr ) {
139	// intrinsic functions don't really take reference-typed parameters, so they require an implicit dereference on their arguments.
140	if ( DeclarationWithType * function = InitTweak::getFunction( appExpr ) ) {
141	FunctionType * ftype = GenPoly::getFunctionType( function->get_type() );
142	assertf( ftype, "Function declaration does not have function type." );
143	// can be of differing lengths only when function is variadic
144	assertf( ftype->get_parameters().size() == appExpr->get_args().size() \|\| ftype->get_isVarArgs(), "ApplicationExpr args do not match formal parameter type." );
145
146	if ( isIntrinsicReference( appExpr ) ) {
147	// eliminate reference types from intrinsic applications - now they return lvalues
148	appExpr->set_result( appExpr->get_result()->stripReferences() );
149	appExpr->get_result()->set_lvalue( true );
150	}
151
152	unsigned int i = 0;
153	const unsigned int end = ftype->get_parameters().size();
154	for ( auto p : unsafe_group_iterate( appExpr->get_args(), ftype->get_parameters() ) ) {
155	if (i == end) break;
156	Expression *& arg = std::get<0>( p );
157	Type * formal = std::get<1>( p )->get_type();
158	PRINT(
159	std::cerr << "pair<0>: " << arg << std::endl;
160	std::cerr << "pair<1>: " << formal << std::endl;
161	)
162	if ( dynamic_cast<ReferenceType*>( formal ) ) {
163	if ( isIntrinsicReference( arg ) ) {
164	if ( function->get_linkage() != LinkageSpec::Intrinsic ) { // intrinsic functions that turn pointers into references
165	// if argument is dereference or array subscript, the result isn't REALLY a reference, so it's not necessary to fix the argument
166	PRINT( std::cerr << "is intrinsic arg in non-intrinsic call - adding address" << std::endl; )
167	arg = new AddressExpr( arg );
168	}
169	} else if ( function->get_linkage() == LinkageSpec::Intrinsic ) {
170	// if the parameter is a reference, add a dereference to the reference-typed argument.
171	Type * baseType = InitTweak::getPointerBase( arg->get_result() );
172	assertf( baseType, "parameter is reference, arg must be pointer or reference: %s", toString( arg->get_result() ) );
173	PointerType * ptrType = new PointerType( Type::Qualifiers(), baseType->clone() );
174	delete arg->get_result();
175	arg->set_result( ptrType );
176	arg = mkDeref( arg );
177	}
178	}
179	++i;
180	}
181	}
182	return appExpr;
183	}
184
185	Expression * ReferenceConversions::postmutate( AddressExpr * addrExpr ) {
186	// Inner expression may have been lvalue to reference conversion, which becomes an address expression.
187	// In this case, remove the outer address expression and return the argument.
188	// TODO: It's possible that this might catch too much and require a more sophisticated check.
189	if ( dynamic_cast<AddressExpr*>( addrExpr->get_arg() ) ) {
190	Expression * arg = addrExpr->get_arg();
191	arg->set_env( addrExpr->get_env() );
192	addrExpr->set_arg( nullptr );
193	addrExpr->set_env( nullptr );
194	delete addrExpr;
195	return arg;
196	}
197	return addrExpr;
198	}
199
200	Expression * ReferenceConversions::postmutate( CastExpr * castExpr ) {
201	// xxx - is it possible to convert directly between reference types with a different base? E.g.,
202	// int x;
203	// (double&)x;
204	// At the moment, I am working off of the assumption that this is illegal, thus the cast becomes redundant
205	// after this pass, so trash the cast altogether. If that changes, care must be taken to insert the correct
206	// pointer casts in the right places.
207
208	// conversion to reference type
209	if ( ReferenceType * refType = dynamic_cast< ReferenceType * >( castExpr->get_result() ) ) {
210	(void)refType;
211	if ( ReferenceType * otherRef = dynamic_cast< ReferenceType * >( castExpr->get_arg()->get_result() ) ) {
212	// nothing to do if casting from reference to reference.
213	(void)otherRef;
214	PRINT( std::cerr << "convert reference to reference -- nop" << std::endl; )
215	if ( isIntrinsicReference( castExpr->get_arg() ) ) {
216	Expression * callExpr = castExpr->get_arg();
217	PRINT(
218	std::cerr << "but arg is deref -- &" << std::endl;
219	std::cerr << callExpr << std::endl;
220	)
221	// move environment out to new top-level
222	callExpr->set_env( castExpr->get_env() );
223	castExpr->set_arg( nullptr );
224	castExpr->set_env( nullptr );
225	delete castExpr;
226	return callExpr;
227	}
228	assertf( false, "non-intrinsic reference with cast of reference to reference not yet supported: ", toString( castExpr ) );
229	PRINT( std::cerr << castExpr << std::endl; )
230	return castExpr;
231	} else if ( castExpr->get_arg()->get_result()->get_lvalue() ) {
232	// conversion from lvalue to reference
233	// xxx - keep cast, but turn into pointer cast??
234	// xxx - memory
235	PRINT(
236	std::cerr << "convert lvalue to reference -- &" << std::endl;
237	std::cerr << castExpr->get_arg() << std::endl;
238	)
239	AddressExpr * ret = new AddressExpr( castExpr->get_arg() );
240	if ( refType->get_base()->get_qualifiers() != castExpr->get_arg()->get_result()->get_qualifiers() ) {
241	// must keep cast if cast-to type is different from the actual type
242	castExpr->set_arg( ret );
243
244	return castExpr;
245	}
246	ret->set_env( castExpr->get_env() );
247	castExpr->set_env( nullptr );
248	castExpr->set_arg( nullptr );
249	delete castExpr;
250	return ret;
251	} else {
252	// rvalue to reference conversion -- introduce temporary
253	}
254	assertf( false, "Only conversions to reference from lvalue are currently supported: %s", toString( castExpr ).c_str() );
255	} else if ( ReferenceType * refType = dynamic_cast< ReferenceType * >( castExpr->get_arg()->get_result() ) ) {
256	(void)refType;
257	// conversion from reference to rvalue
258	PRINT(
259	std::cerr << "convert reference to rvalue -- *" << std::endl;
260	std::cerr << "was = " << castExpr << std::endl;
261	)
262	Expression * ret = castExpr->get_arg();
263	TypeSubstitution * env = castExpr->get_env();
264	castExpr->set_env( nullptr );
265	if ( ! isIntrinsicReference( ret ) ) {
266	// dereference if not already dereferenced
267	ret = mkDeref( ret );
268	}
269	if ( ResolvExpr::typesCompatibleIgnoreQualifiers( castExpr->get_result(), castExpr->get_arg()->get_result()->stripReferences(), SymTab::Indexer() ) ) {
270	// can remove cast if types are compatible, changing expression type to value type
271	ret->set_result( castExpr->get_result()->clone() );
272	castExpr->set_arg( nullptr );
273	delete castExpr;
274	} else {
275	// must keep cast if types are different
276	castExpr->set_arg( ret );
277	ret = castExpr;
278	}
279	ret->set_env( env );
280	PRINT( std::cerr << "now: " << ret << std::endl; )
281	return ret;
282	}
283	return castExpr;
284	}
285
286	Type * ReferenceTypeElimination::postmutate( ReferenceType * refType ) {
287	Type * base = refType->get_base();
288	Type::Qualifiers qualifiers = refType->get_qualifiers();
289	refType->set_base( nullptr );
290	delete refType;
291	return new PointerType( qualifiers, base );
292	}
293
294	Expression * GeneralizedLvalue::postmutate( AddressExpr * addrExpr ) {
295	if ( CommaExpr * commaExpr = dynamic_cast< CommaExpr * >( addrExpr->get_arg() ) ) {
296	Expression * arg1 = commaExpr->get_arg1()->clone();
297	Expression * arg2 = commaExpr->get_arg2()->clone();
298	delete addrExpr;
299	return new CommaExpr( arg1, (new AddressExpr( arg2 ))->acceptMutator( *visitor ) );
300	} else if ( ConditionalExpr * condExpr = dynamic_cast< ConditionalExpr * >( addrExpr->get_arg() ) ) {
301	Expression * arg1 = condExpr->get_arg1()->clone();
302	Expression * arg2 = condExpr->get_arg2()->clone();
303	Expression * arg3 = condExpr->get_arg3()->clone();
304	delete addrExpr;
305	return new ConditionalExpr( arg1, (new AddressExpr( arg2 ))->acceptMutator( visitor ), (new AddressExpr( arg3 ))->acceptMutator( visitor ) );
306	}
307	return addrExpr;
308	}
309
310	Expression * CollapseAddrDeref::postmutate( AddressExpr * addressExpr ) {
311	Expression * arg = addressExpr->get_arg();
312	if ( isIntrinsicReference( arg ) ) {
313	std::string fname = InitTweak::getFunctionName( arg );
314	if ( fname == "*?" ) {
315	Expression *& arg0 = InitTweak::getCallArg( arg, 0 );
316	Expression * ret = arg0;
317	ret->set_env( addressExpr->get_env() );
318	arg0 = nullptr;
319	addressExpr->set_env( nullptr );
320	delete addressExpr;
321	return ret;
322	}
323	}
324	return addressExpr;
325	}
326
327	Expression * CollapseAddrDeref::postmutate( ApplicationExpr * appExpr ) {
328	if ( isIntrinsicReference( appExpr ) ) {
329	std::string fname = InitTweak::getFunctionName( appExpr );
330	if ( fname == "*?" ) {
331	Expression * arg = InitTweak::getCallArg( appExpr, 0 );
332	// xxx - this isn't right, because it can remove casts that should be there...
333	// while ( CastExpr * castExpr = dynamic_cast< CastExpr * >( arg ) ) {
334	// arg = castExpr->get_arg();
335	// }
336	if ( AddressExpr * addrExpr = dynamic_cast< AddressExpr * >( arg ) ) {
337	Expression * ret = addrExpr->get_arg();
338	ret->set_env( appExpr->get_env() );
339	addrExpr->set_arg( nullptr );
340	appExpr->set_env( nullptr );
341	delete appExpr;
342	return ret;
343	}
344	}
345	}
346	return appExpr;
347	}
348	} // namespace
349	} // namespace GenPoly
350
351	// Local Variables: //
352	// tab-width: 4 //
353	// mode: c++ //
354	// compile-command: "make install" //
355	// End: //

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