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source: src/ResolvExpr/ConversionCost.cc @ 97397a26

new-env

Last change on this file since 97397a26 was 97397a26, checked in by Aaron Moss <a3moss@…>, 6 years ago
Merge branch 'with_gc' into new-env
Property mode set to `100644`
File size: 18.4 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	// ConversionCost.cc --
8	//
9	// Author : Richard C. Bilson
10	// Created On : Sun May 17 07:06:19 2015
11	// Last Modified By : Peter A. Buhr
12	// Last Modified On : Mon Sep 25 15:43:34 2017
13	// Update Count : 10
14	//
15
16	#include "ConversionCost.h"
17
18	#include <cassert> // for assert
19	#include <list> // for list, list<>::const_iterator
20	#include <string> // for operator==, string
21
22	#include "Common/GC.h" // for new_static_root
23	#include "ResolvExpr/Cost.h" // for Cost
24	#include "ResolvExpr/TypeEnvironment.h" // for ClassRef, TypeEnvironment
25	#include "SymTab/Indexer.h" // for Indexer
26	#include "SynTree/Declaration.h" // for TypeDecl, NamedTypeDecl
27	#include "SynTree/Type.h" // for Type, BasicType, TypeInstType
28	#include "typeops.h" // for typesCompatibleIgnoreQualifiers
29
30	namespace ResolvExpr {
31	const Cost Cost::zero = Cost{ 0, 0, 0, 0, 0, 0 };
32	const Cost Cost::infinity = Cost{ -1, -1, -1, 1, -1, -1 };
33	const Cost Cost::unsafe = Cost{ 1, 0, 0, 0, 0, 0 };
34	const Cost Cost::poly = Cost{ 0, 1, 0, 0, 0, 0 };
35	const Cost Cost::var = Cost{ 0, 0, 1, 0, 0, 0 };
36	const Cost Cost::spec = Cost{ 0, 0, 0, -1, 0, 0 };
37	const Cost Cost::safe = Cost{ 0, 0, 0, 0, 1, 0 };
38	const Cost Cost::reference = Cost{ 0, 0, 0, 0, 0, 1 };
39
40	#if 0
41	#define PRINT(x) x
42	#else
43	#define PRINT(x)
44	#endif
45	Cost conversionCost( Type src, Type dest, const SymTab::Indexer &indexer, const TypeEnvironment &env ) {
46	if ( TypeInstType destAsTypeInst = dynamic_cast< TypeInstType >( dest ) ) {
47	PRINT( std::cerr << "type inst " << destAsTypeInst->name; )
48	if ( ClassRef eqvClass = env.lookup( destAsTypeInst->name ) ) {
49	if ( Type* boundTy = eqvClass.get_bound().type ) {
50	return conversionCost( src, boundTy, indexer, env );
51	} else {
52	return Cost::infinity;
53	}
54	} else if ( NamedTypeDecl *namedType = indexer.lookupType( destAsTypeInst->name ) ) {
55	PRINT( std::cerr << " found" << std::endl; )
56	TypeDecl type = dynamic_cast< TypeDecl >( namedType );
57	// all typedefs should be gone by this point
58	assert( type );
59	if ( type->base ) {
60	return conversionCost( src, type->base, indexer, env ) + Cost::safe;
61	} // if
62	} // if
63	PRINT( std::cerr << " not found" << std::endl; )
64	} // if
65	PRINT(
66	std::cerr << "src is ";
67	src->print( std::cerr );
68	std::cerr << std::endl << "dest is ";
69	dest->print( std::cerr );
70	std::cerr << std::endl << "env is" << std::endl;
71	env.print( std::cerr, 8 );
72	)
73	if ( typesCompatibleIgnoreQualifiers( src, dest, indexer, env ) ) {
74	PRINT( std::cerr << "compatible!" << std::endl; )
75	return Cost::zero;
76	} else if ( dynamic_cast< VoidType* >( dest ) ) {
77	return Cost::safe;
78	} else if ( ReferenceType * refType = dynamic_cast< ReferenceType * > ( dest ) ) {
79	PRINT( std::cerr << "conversionCost: dest is reference" << std::endl; )
80	return convertToReferenceCost( src, refType, indexer, env, [](Type * t1, Type * t2, const SymTab::Indexer &, const TypeEnvironment & env ){
81	return ptrsAssignable( t1, t2, env );
82	});
83	} else {
84	PassVisitor<ConversionCost> converter( dest, indexer, env, conversionCost );
85	src->accept( converter );
86	if ( converter.pass.get_cost() == Cost::infinity ) {
87	return Cost::infinity;
88	} else {
89	return converter.pass.get_cost() + Cost::zero;
90	} // if
91	} // if
92	}
93
94	Cost convertToReferenceCost( Type * src, Type * dest, int diff, const SymTab::Indexer & indexer, const TypeEnvironment & env, PtrsFunction func ) {
95	PRINT( std::cerr << "convert to reference cost... diff " << diff << " " << src << " / " << dest << std::endl; )
96	if ( diff > 0 ) {
97	// TODO: document this
98	Cost cost = convertToReferenceCost( strict_dynamic_cast< ReferenceType * >( src )->base, dest, diff-1, indexer, env, func );
99	cost.incReference();
100	return cost;
101	} else if ( diff < -1 ) {
102	// TODO: document this
103	Cost cost = convertToReferenceCost( src, strict_dynamic_cast< ReferenceType * >( dest )->base, diff+1, indexer, env, func );
104	cost.incReference();
105	return cost;
106	} else if ( diff == 0 ) {
107	ReferenceType * srcAsRef = dynamic_cast< ReferenceType * >( src );
108	ReferenceType * destAsRef = dynamic_cast< ReferenceType * >( dest );
109	if ( srcAsRef && destAsRef ) { // pointer-like conversions between references
110	PRINT( std::cerr << "converting between references" << std::endl; )
111	Type::Qualifiers tq1 = srcAsRef->base->get_qualifiers();
112	Type::Qualifiers tq2 = destAsRef->base->get_qualifiers();
113	if ( tq1 <= tq2 && typesCompatibleIgnoreQualifiers( srcAsRef->base, destAsRef->base, indexer, env ) ) {
114	PRINT( std::cerr << " :: compatible and good qualifiers" << std::endl; )
115	if ( tq1 == tq2 ) {
116	// types are the same
117	return Cost::zero;
118	} else {
119	// types are the same, except otherPointer has more qualifiers
120	return Cost::safe;
121	}
122	} else { // xxx - this discards reference qualifiers from consideration -- reducing qualifiers is a safe conversion; is this right?
123	int assignResult = func( srcAsRef->base, destAsRef->base, indexer, env );
124	PRINT( std::cerr << "comparing references: " << assignResult << " " << srcAsRef << " " << destAsRef << std::endl; )
125	if ( assignResult > 0 ) {
126	return Cost::safe;
127	} else if ( assignResult < 0 ) {
128	return Cost::unsafe;
129	} // if
130	} // if
131	} else {
132	PRINT( std::cerr << "reference to rvalue conversion" << std::endl; )
133	PassVisitor<ConversionCost> converter( dest, indexer, env, conversionCost );
134	src->accept( converter );
135	return converter.pass.get_cost();
136	} // if
137	} else {
138	ReferenceType * destAsRef = dynamic_cast< ReferenceType * >( dest );
139	assert( diff == -1 && destAsRef );
140	PRINT( std::cerr << "dest is: " << dest << " / src is: " << src << std::endl; )
141	if ( typesCompatibleIgnoreQualifiers( src, destAsRef->base, indexer, env ) ) {
142	PRINT( std::cerr << "converting compatible base type" << std::endl; )
143	if ( src->get_lvalue() ) {
144	PRINT(
145	std::cerr << "lvalue to reference conversion" << std::endl;
146	std::cerr << src << " => " << destAsRef << std::endl;
147	)
148	// lvalue-to-reference conversion: cv lvalue T => cv T &
149	if ( src->get_qualifiers() == destAsRef->base->get_qualifiers() ) {
150	return Cost::reference; // cost needs to be non-zero to add cast
151	} if ( src->get_qualifiers() < destAsRef->base->get_qualifiers() ) {
152	return Cost::safe; // cost needs to be higher than previous cast to differentiate adding qualifiers vs. keeping same
153	} else {
154	return Cost::unsafe;
155	} // if
156	} else if ( destAsRef->base->get_const() ) {
157	PRINT( std::cerr << "rvalue to const ref conversion" << std::endl; )
158	// rvalue-to-const-reference conversion: T => const T &
159	return Cost::safe;
160	} else {
161	PRINT( std::cerr << "rvalue to non-const reference conversion" << std::endl; )
162	// rvalue-to-reference conversion: T => T &
163	return Cost::unsafe;
164	} // if
165	} // if
166	PRINT( std::cerr << "attempting to convert from incompatible base type -- fail" << std::endl; )
167	}
168	return Cost::infinity;
169	}
170
171	Cost convertToReferenceCost( Type * src, ReferenceType * dest, const SymTab::Indexer & indexer, const TypeEnvironment & env, PtrsFunction func ) {
172	int sdepth = src->referenceDepth(), ddepth = dest->referenceDepth();
173	Cost cost = convertToReferenceCost( src, dest, sdepth-ddepth, indexer, env, func );
174	PRINT( std::cerr << "convertToReferenceCost result: " << cost << std::endl; )
175	return cost;
176	}
177
178	ConversionCost::ConversionCost( Type *dest, const SymTab::Indexer &indexer, const TypeEnvironment &env, CostFunction costFunc )
179	: dest( dest ), indexer( indexer ), cost( Cost::infinity ), env( env ), costFunc( costFunc ) {
180	}
181
182	/*
183	Old
184	===
185	Double
186	\|
187	Float
188	\|
189	ULong
190	/ \
191	UInt Long
192	\ /
193	Int
194	\|
195	Ushort
196	\|
197	Short
198	\|
199	Uchar
200	/ \
201	Schar Char
202
203	New
204	===
205	+-----LongDoubleComplex--+
206	LongDouble--+ \| +-LongDoubleImag
207	\| +---DoubleComplex---+ \|
208	Double------+ \| +----DoubleImag
209	\| +-FloatComplex-+ \|
210	Float---------+ +-------FloatImag
211	\|
212	ULongLong
213	\|
214	LongLong
215	\|
216	ULong
217	/ \
218	UInt Long
219	\ /
220	Int
221	\|
222	Ushort
223	\|
224	Short
225	\|
226	Uchar
227	/ \
228	Schar Char
229	\ /
230	Bool
231	*/
232
233	static const int costMatrix[ BasicType::NUMBER_OF_BASIC_TYPES ][ BasicType::NUMBER_OF_BASIC_TYPES ] = {
234	/* Src \ Dest: Bool Char SChar UChar Short UShort Int UInt Long ULong LLong ULLong Float Double LDbl FCplex DCplex LDCplex FImag DImag LDImag I128, U128 */
235	/* Bool */ { 0, 1, 1, 2, 3, 4, 5, 6, 6, 7, 8, 9, 12, 13, 14, 12, 13, 14, -1, -1, -1, 10, 11, },
236	/* Char */ { -1, 0, -1, 1, 2, 3, 4, 5, 5, 6, 7, 8, 11, 12, 13, 11, 12, 13, -1, -1, -1, 9, 10, },
237	/* SChar */ { -1, -1, 0, 1, 2, 3, 4, 5, 5, 6, 7, 8, 11, 12, 13, 11, 12, 13, -1, -1, -1, 9, 10, },
238	/* UChar */ { -1, -1, -1, 0, 1, 2, 3, 4, 4, 5, 6, 7, 10, 11, 12, 10, 11, 12, -1, -1, -1, 8, 9, },
239	/* Short */ { -1, -1, -1, -1, 0, 1, 2, 3, 3, 4, 5, 6, 9, 10, 11, 9, 10, 11, -1, -1, -1, 7, 8, },
240	/* UShort */{ -1, -1, -1, -1, -1, 0, 1, 2, 2, 3, 4, 5, 8, 9, 10, 8, 9, 10, -1, -1, -1, 6, 7, },
241	/* Int */ { -1, -1, -1, -1, -1, -1, 0, 1, 1, 2, 3, 4, 7, 8, 9, 7, 8, 9, -1, -1, -1, 5, 6, },
242	/* UInt */ { -1, -1, -1, -1, -1, -1, -1, 0, -1, 1, 2, 3, 6, 7, 8, 6, 7, 8, -1, -1, -1, 4, 5, },
243	/* Long */ { -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 6, 7, 8, 6, 7, 8, -1, -1, -1, 4, 5, },
244	/* ULong */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 5, 6, 7, 5, 6, 7, -1, -1, -1, 3, 4, },
245	/* LLong */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 4, 5, 6, 4, 5, 6, -1, -1, -1, 2, 3, },
246	/* ULLong */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 3, 4, 5, 3, 4, 5, -1, -1, -1, 1, 2, },
247
248	/* Float */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 1, 2, 3, -1, -1, -1, -1, -1, },
249	/* Double */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, -1, 1, 2, -1, -1, -1, -1, -1, },
250	/* LDbl */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, -1, -1, 1, -1, -1, -1, -1, -1, },
251	/* FCplex */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, -1, -1, -1, -1, -1, },
252	/* DCplex */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, -1, -1, -1, -1, -1, },
253	/* LDCplex */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, -1, -1, -1, -1, -1, },
254	/* FImag */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 1, 2, 3, 0, 1, 2, -1, -1, },
255	/* DImag */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 1, 2, -1, 0, 1, -1, -1, },
256	/* LDImag */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 1, -1, -1, 0, -1, -1, },
257
258	/* I128 */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 2, 3, 4, 3, 4, 5, -1, -1, -1, 0, 1, },
259	/* U128 */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 1, 2, 3, 2, 3, 4, -1, -1, -1, -1, 0, },
260	};
261
262	void ConversionCost::postvisit( VoidType * ) {
263	cost = Cost::infinity;
264	}
265
266	void ConversionCost::postvisit(BasicType *basicType) {
267	if ( BasicType destAsBasic = dynamic_cast< BasicType >( dest ) ) {
268	int tableResult = costMatrix[ basicType->get_kind() ][ destAsBasic->get_kind() ];
269	if ( tableResult == -1 ) {
270	cost = Cost::unsafe;
271	} else {
272	cost = Cost::zero;
273	cost.incSafe( tableResult );
274	} // if
275	} else if ( dynamic_cast< EnumInstType *>( dest ) ) {
276	// xxx - not positive this is correct, but appears to allow casting int => enum
277	cost = Cost::unsafe;
278	} // if
279	// no cases for zero_t/one_t because it should not be possible to convert int, etc. to zero_t/one_t.
280	}
281
282	void ConversionCost::postvisit( PointerType * pointerType ) {
283	if ( PointerType destAsPtr = dynamic_cast< PointerType >( dest ) ) {
284	PRINT( std::cerr << pointerType << " ===> " << destAsPtr << std::endl; )
285	Type::Qualifiers tq1 = pointerType->base->get_qualifiers();
286	Type::Qualifiers tq2 = destAsPtr->base->get_qualifiers();
287	if ( tq1 <= tq2 && typesCompatibleIgnoreQualifiers( pointerType->base, destAsPtr->base, indexer, env ) ) {
288	PRINT( std::cerr << " :: compatible and good qualifiers" << std::endl; )
289	if ( tq1 == tq2 ) {
290	// types are the same
291	cost = Cost::zero;
292	} else {
293	// types are the same, except otherPointer has more qualifiers
294	cost = Cost::safe;
295	}
296	} else {
297	int assignResult = ptrsAssignable( pointerType->base, destAsPtr->base, env );
298	PRINT( std::cerr << " :: " << assignResult << std::endl; )
299	if ( assignResult > 0 && tq1 <= tq2 ) {
300	// xxx - want the case where qualifiers are added to be more expensive than the case where qualifiers are the same. Is 1 safe vs. 2 safe correct?
301	if ( tq1 == tq2 ) {
302	cost = Cost::safe;
303	} else if ( tq1 < tq2 ) {
304	cost = Cost::safe+Cost::safe;
305	}
306	} else if ( assignResult < 0 ) {
307	cost = Cost::unsafe;
308	} // if
309	// assignResult == 0 means Cost::Infinity
310	} // if
311	// case case for zero_t because it should not be possible to convert pointers to zero_t.
312	} // if
313	}
314
315	void ConversionCost::postvisit( ArrayType * ) {}
316
317	void ConversionCost::postvisit( ReferenceType * refType ) {
318	// Note: dest can never be a reference, since it would have been caught in an earlier check
319	assert( ! dynamic_cast< ReferenceType * >( dest ) );
320	// convert reference to rvalue: cv T1 & => T2
321	// recursively compute conversion cost from T1 to T2.
322	// cv can be safely dropped because of 'implicit dereference' behavior.
323	cost = costFunc( refType->base, dest, indexer, env );
324	if ( refType->base->get_qualifiers() == dest->get_qualifiers() ) {
325	cost.incReference(); // prefer exact qualifiers
326	} else if ( refType->base->get_qualifiers() < dest->get_qualifiers() ) {
327	cost.incSafe(); // then gaining qualifiers
328	} else {
329	cost.incUnsafe(); // lose qualifiers as last resort
330	}
331	PRINT( std::cerr << refType << " ==> " << dest << " " << cost << std::endl; )
332	}
333
334	void ConversionCost::postvisit( FunctionType * ) {}
335
336	void ConversionCost::postvisit( StructInstType * inst ) {
337	if ( StructInstType destAsInst = dynamic_cast< StructInstType >( dest ) ) {
338	if ( inst->name == destAsInst->name ) {
339	cost = Cost::zero;
340	} // if
341	} // if
342	}
343
344	void ConversionCost::postvisit( UnionInstType * inst ) {
345	if ( UnionInstType destAsInst = dynamic_cast< UnionInstType >( dest ) ) {
346	if ( inst->name == destAsInst->name ) {
347	cost = Cost::zero;
348	} // if
349	} // if
350	}
351
352	void ConversionCost::postvisit( EnumInstType * ) {
353	static Type::Qualifiers q;
354	static BasicType* integer = new_static_root<BasicType>( q, BasicType::SignedInt );
355	cost = costFunc( integer, dest, indexer, env ); // safe if dest >= int
356	if ( cost < Cost::unsafe ) {
357	cost.incSafe();
358	} // if
359	}
360
361	void ConversionCost::postvisit( TraitInstType * ) {}
362
363	void ConversionCost::postvisit( TypeInstType *inst ) {
364	if ( ClassRef eqvClass = env.lookup( inst->name ) ) {
365	cost = costFunc( eqvClass.get_bound().type, dest, indexer, env );
366	} else if ( TypeInstType destAsInst = dynamic_cast< TypeInstType >( dest ) ) {
367	if ( inst->name == destAsInst->name ) {
368	cost = Cost::zero;
369	}
370	} else if ( NamedTypeDecl *namedType = indexer.lookupType( inst->name ) ) {
371	TypeDecl type = dynamic_cast< TypeDecl >( namedType );
372	// all typedefs should be gone by this point
373	assert( type );
374	if ( type->base ) {
375	cost = costFunc( type->base, dest, indexer, env ) + Cost::safe;
376	} // if
377	} // if
378	}
379
380	void ConversionCost::postvisit( TupleType * tupleType ) {
381	Cost c = Cost::zero;
382	if ( TupleType * destAsTuple = dynamic_cast< TupleType * >( dest ) ) {
383	std::list< Type * >::const_iterator srcIt = tupleType->types.begin();
384	std::list< Type * >::const_iterator destIt = destAsTuple->types.begin();
385	while ( srcIt != tupleType->types.end() && destIt != destAsTuple->types.end() ) {
386	Cost newCost = costFunc( srcIt++, destIt++, indexer, env );
387	if ( newCost == Cost::infinity ) {
388	return;
389	} // if
390	c += newCost;
391	} // while
392	if ( destIt != destAsTuple->types.end() ) {
393	cost = Cost::infinity;
394	} else {
395	cost = c;
396	} // if
397	} // if
398	}
399
400	void ConversionCost::postvisit( VarArgsType * ) {
401	if ( dynamic_cast< VarArgsType* >( dest ) ) {
402	cost = Cost::zero;
403	}
404	}
405
406	void ConversionCost::postvisit( ZeroType * ) {
407	if ( dynamic_cast< ZeroType * >( dest ) ) {
408	cost = Cost::zero;
409	} else if ( BasicType destAsBasic = dynamic_cast< BasicType >( dest ) ) {
410	// copied from visit(BasicType*) for signed int, but +1 for safe conversions
411	int tableResult = costMatrix[ BasicType::SignedInt ][ destAsBasic->get_kind() ];
412	if ( tableResult == -1 ) {
413	cost = Cost::unsafe;
414	} else {
415	cost = Cost::zero;
416	cost.incSafe( tableResult + 1 );
417	}
418	} else if ( dynamic_cast< PointerType* >( dest ) ) {
419	cost = Cost::safe;
420	}
421	}
422
423	void ConversionCost::postvisit( OneType * ) {
424	if ( dynamic_cast< OneType * >( dest ) ) {
425	cost = Cost::zero;
426	} else if ( BasicType destAsBasic = dynamic_cast< BasicType >( dest ) ) {
427	// copied from visit(BasicType*) for signed int, but +1 for safe conversions
428	int tableResult = costMatrix[ BasicType::SignedInt ][ destAsBasic->get_kind() ];
429	if ( tableResult == -1 ) {
430	cost = Cost::unsafe;
431	} else {
432	cost = Cost::zero;
433	cost.incSafe( tableResult + 1 );
434	}
435	}
436	}
437	} // namespace ResolvExpr
438
439	// Local Variables: //
440	// tab-width: 4 //
441	// mode: c++ //
442	// compile-command: "make install" //
443	// End: //

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