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source: src/GenPoly/Lvalue.cc @ 6d267ca

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 6d267ca was 9191a8e, checked in by Rob Schluntz <rschlunt@…>, 7 years ago
Remove reference to rvalue cast on intrinsic results
Property mode set to `100644`
File size: 12.4 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	};
69
70	/// Intrinsic functions that take reference parameters don't REALLY take reference parameters -- their reference arguments must always be implicitly dereferenced.
71	struct FixIntrinsicArgs final {
72	Expression * postmutate( ApplicationExpr *appExpr );
73	};
74
75
76	/// Replace reference types with pointer types
77	struct ReferenceTypeElimination final {
78	Type * postmutate( ReferenceType * refType );
79	};
80
81	/// GCC-like Generalized Lvalues (which have since been removed from GCC)
82	/// https://gcc.gnu.org/onlinedocs/gcc-3.4.6/gcc/Lvalues.html#Lvalues
83	/// Replaces &(a,b) with (a, &b), &(a ? b : c) with (a ? &b : &c)
84	struct GeneralizedLvalue final {
85	Expression * postmutate( AddressExpr * addressExpr );
86	};
87
88	/// Removes redundant &/& pattern that this pass can generate
89	struct CollapseAddrDeref final {
90	Expression * postmutate( AddressExpr * addressExpr );
91	Expression * postmutate( ApplicationExpr * appExpr );
92	};
93	} // namespace
94
95	void convertLvalue( std::list< Declaration* >& translationUnit ) {
96	std::cerr << "convertLvalue" << std::endl;
97	PassVisitor<ReferenceConversions> refCvt;
98	PassVisitor<ReferenceTypeElimination> elim;
99	PassVisitor<GeneralizedLvalue> genLval;
100	PassVisitor<FixIntrinsicArgs> fixer;
101	PassVisitor<CollapseAddrDeref> collapser;
102	mutateAll( translationUnit, refCvt );
103	mutateAll( translationUnit, fixer );
104	mutateAll( translationUnit, elim );
105	mutateAll( translationUnit, genLval );
106	mutateAll( translationUnit, collapser );
107	}
108
109	namespace {
110	Type* isLvalueRet( FunctionType *function ) {
111	if ( function->get_returnVals().empty() ) return 0;
112	Type *ty = function->get_returnVals().front()->get_type();
113	return dynamic_cast< ReferenceType * >( ty ) ;
114	}
115
116	bool isIntrinsicApp( ApplicationExpr *appExpr ) {
117	if ( VariableExpr varExpr = dynamic_cast< VariableExpr >( appExpr->get_function() ) ) {
118	return varExpr->get_var()->get_linkage() == LinkageSpec::Intrinsic;
119	} else {
120	return false;
121	} // if
122	}
123
124	bool isDeref( Expression * expr ) {
125	if ( UntypedExpr * untyped = dynamic_cast< UntypedExpr * >( expr ) ) {
126	return InitTweak::getFunctionName( untyped ) == "*?";
127	} else if ( ApplicationExpr * appExpr = dynamic_cast< ApplicationExpr * > ( expr ) ) {
128	if ( DeclarationWithType * func = InitTweak::getFunction( appExpr ) ) {
129	return func->get_linkage() == LinkageSpec::Intrinsic && InitTweak::getFunctionName( appExpr ) == "*?";
130	}
131	}
132	return false;
133	}
134
135	bool isIntrinsicReference( Expression * expr ) {
136	if ( isDeref( expr ) ) return true;
137	else if ( UntypedExpr * untyped = dynamic_cast< UntypedExpr * >( expr ) ) {
138	return InitTweak::getFunctionName( untyped ) == "?[?]";
139	} else if ( ApplicationExpr * appExpr = dynamic_cast< ApplicationExpr * > ( expr ) ) {
140	if ( DeclarationWithType * func = InitTweak::getFunction( appExpr ) ) {
141	return func->get_linkage() == LinkageSpec::Intrinsic && InitTweak::getFunctionName( appExpr ) == "?[?]";
142	}
143	}
144	return false;
145	}
146
147	void fixArg( Expression & arg, Type formal ) {
148	if ( dynamic_cast<ReferenceType*>( formal ) ) {
149	// if the parameter is a reference, add a dereference to the reference-typed argument.
150	Type * baseType = InitTweak::getPointerBase( arg->get_result() );
151	assertf( baseType, "parameter is reference, arg must be pointer or reference: %s", toString( arg->get_result() ) );
152	PointerType * ptrType = new PointerType( Type::Qualifiers(), baseType->clone() );
153	delete arg->get_result();
154	arg->set_result( ptrType );
155	arg = mkDeref( arg );
156	}
157	}
158
159	// xxx - might need to & every * (or every * that is an arg to non-intrinsic function??)
160	Expression * FixIntrinsicArgs::postmutate( ApplicationExpr * appExpr ) {
161	// intrinsic functions don't really take reference-typed parameters, so they require an implicit dereference on their arguments.
162	if ( DeclarationWithType * function = InitTweak::getFunction( appExpr ) ) {
163	if ( function->get_linkage() == LinkageSpec::Intrinsic ) {
164	FunctionType * ftype = GenPoly::getFunctionType( function->get_type() );
165	assertf( ftype, "Function declaration does not have function type." );
166	for ( auto p : group_iterate( appExpr->get_args(), ftype->get_parameters() ) ) {
167	Expression *& arg = std::get<0>( p );
168	DeclarationWithType * formal = std::get<1>( p );
169	PRINT(
170	std::cerr << "pair<0>: " << arg << std::endl;
171	std::cerr << "pair<1>: " << formal->get_type() << std::endl;
172	)
173	if ( isIntrinsicReference( arg ) ) { // intrinsic functions that turn pointers into references
174	// if argument is dereference or array subscript, the result isn't REALLY a reference, so it's not necessary to fix the argument
175	PRINT( std::cerr << "skipping intrinsic reference" << std::endl; )
176	continue;
177	} else {
178	fixArg( arg, formal->get_type() );
179	}
180	}
181	}
182	}
183	return appExpr;
184	}
185
186	Expression * ReferenceConversions::postmutate( CastExpr * castExpr ) {
187	// xxx - is it possible to convert directly between reference types with a different base? E.g.,
188	// int x;
189	// (double&)x;
190	// At the moment, I am working off of the assumption that this is illegal, thus the cast becomes redundant
191	// after this pass, so trash the cast altogether. If that changes, care must be taken to insert the correct
192	// pointer casts in the right places.
193
194	// conversion to reference type
195	if ( ReferenceType * refType = dynamic_cast< ReferenceType * >( castExpr->get_result() ) ) {
196	(void)refType;
197	if ( ReferenceType * otherRef = dynamic_cast< ReferenceType * >( castExpr->get_arg()->get_result() ) ) {
198	// nothing to do if casting from reference to reference.
199	(void)otherRef;
200	PRINT( std::cerr << "convert reference to reference -- nop" << std::endl; )
201	if ( isIntrinsicReference( castExpr->get_arg() ) ) {
202	Expression * callExpr = castExpr->get_arg();
203	PRINT(
204	std::cerr << "but arg is deref -- &" << std::endl;
205	std::cerr << callExpr << std::endl;
206	)
207	// move environment out to new top-level
208	callExpr->set_env( castExpr->get_env() );
209	castExpr->set_arg( nullptr );
210	castExpr->set_env( nullptr );
211	delete castExpr;
212	return callExpr;
213	}
214	assertf( false, "non-intrinsic reference with cast of reference to reference not yet supported: ", toString( castExpr ) );
215	PRINT( std::cerr << castExpr << std::endl; )
216	return castExpr;
217	} else if ( castExpr->get_arg()->get_result()->get_lvalue() ) {
218	// conversion from lvalue to reference
219	// xxx - keep cast, but turn into pointer cast??
220	// xxx - memory
221	PRINT(
222	std::cerr << "convert lvalue to reference -- &" << std::endl;
223	std::cerr << castExpr->get_arg() << std::endl;
224	)
225	AddressExpr * ret = new AddressExpr( castExpr->get_arg() );
226	if ( refType->get_base()->get_qualifiers() != castExpr->get_arg()->get_result()->get_qualifiers() ) {
227	// must keep cast if cast-to type is different from the actual type
228	castExpr->set_arg( ret );
229
230	return castExpr;
231	}
232	ret->set_env( castExpr->get_env() );
233	castExpr->set_env( nullptr );
234	castExpr->set_arg( nullptr );
235	delete castExpr;
236	return ret;
237	} else {
238	// rvalue to reference conversion -- introduce temporary
239	}
240	assertf( false, "Only conversions to reference from lvalue are currently supported: %s", toString( castExpr ).c_str() );
241	} else if ( ReferenceType * refType = dynamic_cast< ReferenceType * >( castExpr->get_arg()->get_result() ) ) {
242	// conversion from reference to rvalue
243	PRINT( std::cerr << "convert reference to rvalue -- *" << std::endl; )
244	PRINT( std::cerr << "was = " << castExpr << std::endl; )
245	Expression * ret = castExpr->get_arg();
246	if ( ! isIntrinsicReference( ret ) ) {
247	// dereference if not already dereferenced
248	ret = mkDeref( ret );
249	}
250	ret->set_env( castExpr->get_env() );
251	castExpr->set_arg( nullptr );
252	castExpr->set_env( nullptr );
253	delete castExpr;
254	PRINT( std::cerr << "now: " << ret << std::endl; )
255	return ret;
256	}
257	return castExpr;
258	}
259
260	Type * ReferenceTypeElimination::postmutate( ReferenceType * refType ) {
261	Type * base = refType->get_base();
262	refType->set_base( nullptr );
263	delete refType;
264	return new PointerType( Type::Qualifiers(), base );
265	}
266
267	Expression * GeneralizedLvalue::postmutate( AddressExpr * addrExpr ) {
268	if ( CommaExpr * commaExpr = dynamic_cast< CommaExpr * >( addrExpr->get_arg() ) ) {
269	Expression * arg1 = commaExpr->get_arg1()->clone();
270	Expression * arg2 = commaExpr->get_arg2()->clone();
271	delete addrExpr;
272	return new CommaExpr( arg1, new AddressExpr( arg2 ) );
273	} else if ( ConditionalExpr * condExpr = dynamic_cast< ConditionalExpr * >( addrExpr->get_arg() ) ) {
274	Expression * arg1 = condExpr->get_arg1()->clone();
275	Expression * arg2 = condExpr->get_arg2()->clone();
276	Expression * arg3 = condExpr->get_arg3()->clone();
277	delete addrExpr;
278	return new ConditionalExpr( arg1, new AddressExpr( arg2 ), new AddressExpr( arg3 ) );
279	}
280	return addrExpr;
281	}
282
283	Expression * CollapseAddrDeref::postmutate( AddressExpr * addressExpr ) {
284	Expression * arg = addressExpr->get_arg();
285	if ( isIntrinsicReference( arg ) ) {
286	std::string fname = InitTweak::getFunctionName( arg );
287	if ( fname == "*?" ) {
288	Expression *& arg0 = InitTweak::getCallArg( arg, 0 );
289	Expression * ret = arg0;
290	ret->set_env( addressExpr->get_env() );
291	arg0 = nullptr;
292	addressExpr->set_env( nullptr );
293	delete addressExpr;
294	return ret;
295	}
296	}
297	return addressExpr;
298	}
299
300	Expression * CollapseAddrDeref::postmutate( ApplicationExpr * appExpr ) {
301	if ( isIntrinsicReference( appExpr ) ) {
302	std::string fname = InitTweak::getFunctionName( appExpr );
303	if ( fname == "*?" ) {
304	Expression * arg = InitTweak::getCallArg( appExpr, 0 );
305	// xxx - this isn't right, because it can remove casts that should be there...
306	// while ( CastExpr * castExpr = dynamic_cast< CastExpr * >( arg ) ) {
307	// arg = castExpr->get_arg();
308	// }
309	if ( AddressExpr * addrExpr = dynamic_cast< AddressExpr * >( arg ) ) {
310	Expression * ret = addrExpr->get_arg();
311	ret->set_env( appExpr->get_env() );
312	addrExpr->set_arg( nullptr );
313	appExpr->set_env( nullptr );
314	delete appExpr;
315	return ret;
316	}
317	}
318	}
319	return appExpr;
320	}
321	} // namespace
322	} // namespace GenPoly
323
324	// Local Variables: //
325	// tab-width: 4 //
326	// mode: c++ //
327	// compile-command: "make install" //
328	// End: //

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