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source: src/ResolvExpr/ConversionCost.cc @ 1cc4390

deferred_resn

Last change on this file since 1cc4390 was 4cf2472, checked in by Aaron Moss <a3moss@…>, 5 years ago
Add sign element to cost tuple
Property mode set to `100644`
File size: 23.0 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 "ResolvExpr/Cost.h" // for Cost
23	#include "ResolvExpr/TypeEnvironment.h" // for EqvClass, TypeEnvironment
24	#include "SymTab/Indexer.h" // for Indexer
25	#include "SynTree/Declaration.h" // for TypeDecl, NamedTypeDecl
26	#include "SynTree/Type.h" // for Type, BasicType, TypeInstType
27	#include "typeops.h" // for typesCompatibleIgnoreQualifiers
28
29	namespace ResolvExpr {
30	const Cost Cost::zero = Cost{ 0, 0, 0, 0, 0, 0, 0 };
31	const Cost Cost::infinity = Cost{ -1, -1, -1, -1, -1, 1, -1 };
32	const Cost Cost::unsafe = Cost{ 1, 0, 0, 0, 0, 0, 0 };
33	const Cost Cost::poly = Cost{ 0, 1, 0, 0, 0, 0, 0 };
34	const Cost Cost::safe = Cost{ 0, 0, 1, 0, 0, 0, 0 };
35	const Cost Cost::sign = Cost{ 0, 0, 0, 1, 0, 0, 0 };
36	const Cost Cost::var = Cost{ 0, 0, 0, 0, 1, 0, 0 };
37	const Cost Cost::spec = Cost{ 0, 0, 0, 0, 0, -1, 0 };
38	const Cost Cost::reference = Cost{ 0, 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 ( const EqvClass* eqvClass = env.lookup( destAsTypeInst->name ) ) {
49	if ( eqvClass->type ) {
50	return conversionCost( src, eqvClass->type, 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 ] = {
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, F80, F128 */
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, 14, 15},
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, 13, 14},
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, 13, 14},
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, 12, 13},
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, 11, 12},
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, 10, 11},
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, 9, 10},
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, 8, 9},
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, 8, 9},
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, 7, 8},
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, 6, 7},
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, 5, 6},
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, 2, 3},
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, 1, 2},
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, -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, -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, -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, -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, -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, -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, -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, 4, 4},
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, 3, 3},
260
261	/* F80 */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 1, -1, -1, 1, -1, -1, -1, -1, -1, 0, 1},
262	/* F128 */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 1, -1, -1, -1, -1, -1, -1, 0},
263	};
264	static_assert(
265	sizeof(costMatrix)/sizeof(costMatrix[0][0]) == BasicType::NUMBER_OF_BASIC_TYPES*BasicType::NUMBER_OF_BASIC_TYPES,
266	"Each basic type kind should have a corresponding row in the cost matrix"
267	);
268
269	static const int signMatrix[][ BasicType::NUMBER_OF_BASIC_TYPES ] = {
270	/* 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, F80, F128 */
271	/* Bool */ { 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, -1, -1, -1, 1, 0, 0, 0},
272	/* Char */ { -1, 0, -1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, -1, -1, -1, 0, 1, 0, 0},
273	/* SChar */ { -1, -1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, -1, -1, -1, 0, 1, 0, 0},
274	/* UChar */ { -1, -1, -1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, -1, -1, -1, 1, 0, 0, 0},
275	/* Short */ { -1, -1, -1, -1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, -1, -1, -1, 0, 1, 0, 0},
276	/* UShort */{ -1, -1, -1, -1, -1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, -1, -1, -1, 1, 0, 0, 0},
277	/* Int */ { -1, -1, -1, -1, -1, -1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, -1, -1, -1, 0, 1, 0, 0},
278	/* UInt */ { -1, -1, -1, -1, -1, -1, -1, 0, -1, 0, 1, 0, 0, 0, 0, 0, 0, 0, -1, -1, -1, 1, 0, 0, 0},
279	/* Long */ { -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, -1, -1, -1, 0, 1, 0, 0},
280	/* ULong */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 0, 0, 0, 0, 0, 0, 0, -1, -1, -1, 1, 0, 0, 0},
281	/* LLong */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 0, 0, 0, 0, 0, 0, -1, -1, -1, 0, 1, 0, 0},
282	/* ULLong */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 0, 0, 0, 0, 0, 0, -1, -1, -1, 1, 0, 0, 0},
283
284	/* Float */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 0, 0, 0, 0, 0, -1, -1, -1, -1, -1, 0, 0},
285	/* Double */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 0, -1, 0, 0, -1, -1, -1, -1, -1, 0, 0},
286	/* LDbl */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, -1, -1, 0, -1, -1, -1, -1, -1, -1, 0},
287	/* FCplex */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 0, 0, -1, -1, -1, -1, -1, -1, -1},
288	/* DCplex */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 0, -1, -1, -1, -1, -1, -1, -1},
289	/* LDCplex */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, -1, -1, -1, -1, -1, -1, -1},
290	/* FImag */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 0, 0, 0, 0, 0, -1, -1, -1, -1},
291	/* DImag */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 0, -1, 0, 0, -1, -1, -1, -1},
292	/* LDImag */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, -1, -1, 0, -1, -1, -1, -1},
293
294	/* I128 */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 0, 0, 0, 0, 0, -1, -1, -1, 0, 1, 0, 0},
295	/* U128 */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 0, 0, 0, 0, 0, -1, -1, -1, 1, 0, 0, 0},
296
297	/* F80 */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, -1, -1, 0, -1, -1, -1, -1, -1, 0, 0},
298	/* F128 */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, -1, -1, -1, -1, -1, -1, 0},
299	};
300	static_assert(
301	sizeof(signMatrix)/sizeof(signMatrix[0][0]) == BasicType::NUMBER_OF_BASIC_TYPES*BasicType::NUMBER_OF_BASIC_TYPES,
302	"Each basic type kind should have a corresponding row in the sign matrix"
303	);
304
305
306	void ConversionCost::postvisit( VoidType * ) {
307	cost = Cost::infinity;
308	}
309
310	void ConversionCost::postvisit(BasicType *basicType) {
311	if ( BasicType destAsBasic = dynamic_cast< BasicType >( dest ) ) {
312	int tableResult = costMatrix[ basicType->get_kind() ][ destAsBasic->get_kind() ];
313	if ( tableResult == -1 ) {
314	cost = Cost::unsafe;
315	} else {
316	cost = Cost::zero;
317	cost.incSafe( tableResult );
318	cost.incSign( signMatrix[ basicType->get_kind() ][ destAsBasic->get_kind() ] );
319	} // if
320	} else if ( dynamic_cast< EnumInstType *>( dest ) ) {
321	// xxx - not positive this is correct, but appears to allow casting int => enum
322	cost = Cost::unsafe;
323	} // if
324	// no cases for zero_t/one_t because it should not be possible to convert int, etc. to zero_t/one_t.
325	}
326
327	void ConversionCost::postvisit( PointerType * pointerType ) {
328	if ( PointerType destAsPtr = dynamic_cast< PointerType >( dest ) ) {
329	PRINT( std::cerr << pointerType << " ===> " << destAsPtr << std::endl; )
330	Type::Qualifiers tq1 = pointerType->base->get_qualifiers();
331	Type::Qualifiers tq2 = destAsPtr->base->get_qualifiers();
332	if ( tq1 <= tq2 && typesCompatibleIgnoreQualifiers( pointerType->base, destAsPtr->base, indexer, env ) ) {
333	PRINT( std::cerr << " :: compatible and good qualifiers" << std::endl; )
334	if ( tq1 == tq2 ) {
335	// types are the same
336	cost = Cost::zero;
337	} else {
338	// types are the same, except otherPointer has more qualifiers
339	cost = Cost::safe;
340	}
341	} else {
342	int assignResult = ptrsAssignable( pointerType->base, destAsPtr->base, env );
343	PRINT( std::cerr << " :: " << assignResult << std::endl; )
344	if ( assignResult > 0 && tq1 <= tq2 ) {
345	// 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?
346	if ( tq1 == tq2 ) {
347	cost = Cost::safe;
348	} else if ( tq1 < tq2 ) {
349	cost = Cost::safe+Cost::safe;
350	}
351	} else if ( assignResult < 0 ) {
352	cost = Cost::unsafe;
353	} // if
354	// assignResult == 0 means Cost::Infinity
355	} // if
356	// case case for zero_t because it should not be possible to convert pointers to zero_t.
357	} // if
358	}
359
360	void ConversionCost::postvisit( ArrayType * ) {}
361
362	void ConversionCost::postvisit( ReferenceType * refType ) {
363	// Note: dest can never be a reference, since it would have been caught in an earlier check
364	assert( ! dynamic_cast< ReferenceType * >( dest ) );
365	// convert reference to rvalue: cv T1 & => T2
366	// recursively compute conversion cost from T1 to T2.
367	// cv can be safely dropped because of 'implicit dereference' behavior.
368	cost = costFunc( refType->base, dest, indexer, env );
369	if ( refType->base->get_qualifiers() == dest->get_qualifiers() ) {
370	cost.incReference(); // prefer exact qualifiers
371	} else if ( refType->base->get_qualifiers() < dest->get_qualifiers() ) {
372	cost.incSafe(); // then gaining qualifiers
373	} else {
374	cost.incUnsafe(); // lose qualifiers as last resort
375	}
376	PRINT( std::cerr << refType << " ==> " << dest << " " << cost << std::endl; )
377	}
378
379	void ConversionCost::postvisit( FunctionType * ) {}
380
381	void ConversionCost::postvisit( StructInstType * inst ) {
382	if ( StructInstType destAsInst = dynamic_cast< StructInstType >( dest ) ) {
383	if ( inst->name == destAsInst->name ) {
384	cost = Cost::zero;
385	} // if
386	} // if
387	}
388
389	void ConversionCost::postvisit( UnionInstType * inst ) {
390	if ( UnionInstType destAsInst = dynamic_cast< UnionInstType >( dest ) ) {
391	if ( inst->name == destAsInst->name ) {
392	cost = Cost::zero;
393	} // if
394	} // if
395	}
396
397	void ConversionCost::postvisit( EnumInstType * ) {
398	static Type::Qualifiers q;
399	static BasicType integer( q, BasicType::SignedInt );
400	cost = costFunc( &integer, dest, indexer, env ); // safe if dest >= int
401	if ( cost < Cost::unsafe ) {
402	cost.incSafe();
403	} // if
404	}
405
406	void ConversionCost::postvisit( TraitInstType * ) {}
407
408	void ConversionCost::postvisit( TypeInstType *inst ) {
409	if ( const EqvClass *eqvClass = env.lookup( inst->name ) ) {
410	cost = costFunc( eqvClass->type, dest, indexer, env );
411	} else if ( TypeInstType destAsInst = dynamic_cast< TypeInstType >( dest ) ) {
412	if ( inst->name == destAsInst->name ) {
413	cost = Cost::zero;
414	}
415	} else if ( NamedTypeDecl *namedType = indexer.lookupType( inst->name ) ) {
416	TypeDecl type = dynamic_cast< TypeDecl >( namedType );
417	// all typedefs should be gone by this point
418	assert( type );
419	if ( type->base ) {
420	cost = costFunc( type->base, dest, indexer, env ) + Cost::safe;
421	} // if
422	} // if
423	}
424
425	void ConversionCost::postvisit( TupleType * tupleType ) {
426	Cost c = Cost::zero;
427	if ( TupleType * destAsTuple = dynamic_cast< TupleType * >( dest ) ) {
428	std::list< Type * >::const_iterator srcIt = tupleType->types.begin();
429	std::list< Type * >::const_iterator destIt = destAsTuple->types.begin();
430	while ( srcIt != tupleType->types.end() && destIt != destAsTuple->types.end() ) {
431	Cost newCost = costFunc( srcIt++, destIt++, indexer, env );
432	if ( newCost == Cost::infinity ) {
433	return;
434	} // if
435	c += newCost;
436	} // while
437	if ( destIt != destAsTuple->types.end() ) {
438	cost = Cost::infinity;
439	} else {
440	cost = c;
441	} // if
442	} // if
443	}
444
445	void ConversionCost::postvisit( VarArgsType * ) {
446	if ( dynamic_cast< VarArgsType* >( dest ) ) {
447	cost = Cost::zero;
448	}
449	}
450
451	void ConversionCost::postvisit( ZeroType * ) {
452	if ( dynamic_cast< ZeroType * >( dest ) ) {
453	cost = Cost::zero;
454	} else if ( BasicType destAsBasic = dynamic_cast< BasicType >( dest ) ) {
455	// copied from visit(BasicType*) for signed int, but +1 for safe conversions
456	int tableResult = costMatrix[ BasicType::SignedInt ][ destAsBasic->get_kind() ];
457	if ( tableResult == -1 ) {
458	cost = Cost::unsafe;
459	} else {
460	cost = Cost::zero;
461	cost.incSafe( tableResult + 1 );
462	cost.incSign( signMatrix[ BasicType::SignedInt ][ destAsBasic->get_kind() ] );
463	}
464	} else if ( dynamic_cast< PointerType* >( dest ) ) {
465	cost = Cost::safe;
466	}
467	}
468
469	void ConversionCost::postvisit( OneType * ) {
470	if ( dynamic_cast< OneType * >( dest ) ) {
471	cost = Cost::zero;
472	} else if ( BasicType destAsBasic = dynamic_cast< BasicType >( dest ) ) {
473	// copied from visit(BasicType*) for signed int, but +1 for safe conversions
474	int tableResult = costMatrix[ BasicType::SignedInt ][ destAsBasic->get_kind() ];
475	if ( tableResult == -1 ) {
476	cost = Cost::unsafe;
477	} else {
478	cost = Cost::zero;
479	cost.incSafe( tableResult + 1 );
480	cost.incSign( signMatrix[ BasicType::SignedInt ][ destAsBasic->get_kind() ] );
481	}
482	}
483	}
484	} // namespace ResolvExpr
485
486	// Local Variables: //
487	// tab-width: 4 //
488	// mode: c++ //
489	// compile-command: "make install" //
490	// End: //

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