source: src/GenPoly/Specialize.cc@ f196351

ADT aaron-thesis arm-eh ast-experimental cleanup-dtors deferred_resn demangler enum forall-pointer-decay jacob/cs343-translation jenkins-sandbox new-ast new-ast-unique-expr new-env no_list persistent-indexer pthread-emulation qualifiedEnum resolv-new with_gc
Last change on this file since f196351 was 969ee0df, checked in by Rob Schluntz <rschlunt@…>, 8 years ago

conversion of zero_t to function type does not require tuple specialization [fixes #17]
  • Property mode set to 100644
File size: 14.1 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// Specialize.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 : Thu Mar 16 07:53:59 2017
13// Update Count : 31
14//
15
16#include <cassert>
17
18#include "Specialize.h"
19#include "GenPoly.h"
20#include "PolyMutator.h"
21
22#include "Parser/ParseNode.h"
23
24#include "SynTree/Expression.h"
25#include "SynTree/Statement.h"
26#include "SynTree/Type.h"
27#include "SynTree/Attribute.h"
28#include "SynTree/TypeSubstitution.h"
29#include "SynTree/Mutator.h"
30#include "ResolvExpr/FindOpenVars.h"
31#include "Common/UniqueName.h"
32#include "Common/utility.h"
33#include "InitTweak/InitTweak.h"
34#include "Tuples/Tuples.h"
35
36namespace GenPoly {
37 class Specialize final : public PolyMutator {
38 public:
39 using PolyMutator::mutate;
40 virtual Expression * mutate( ApplicationExpr *applicationExpr ) override;
41 virtual Expression * mutate( AddressExpr *castExpr ) override;
42 virtual Expression * mutate( CastExpr *castExpr ) override;
43 // virtual Expression * mutate( LogicalExpr *logicalExpr );
44 // virtual Expression * mutate( ConditionalExpr *conditionalExpr );
45 // virtual Expression * mutate( CommaExpr *commaExpr );
46
47 void handleExplicitParams( ApplicationExpr *appExpr );
48 Expression * createThunkFunction( FunctionType *funType, Expression *actual, InferredParams *inferParams );
49 Expression * doSpecialization( Type *formalType, Expression *actual, InferredParams *inferParams = nullptr );
50
51 std::string paramPrefix = "_p";
52 };
53
54 /// Looks up open variables in actual type, returning true if any of them are bound in the environment or formal type.
55 bool needsPolySpecialization( Type *formalType, Type *actualType, TypeSubstitution *env ) {
56 if ( env ) {
57 using namespace ResolvExpr;
58 OpenVarSet openVars, closedVars;
59 AssertionSet need, have;
60 findOpenVars( formalType, openVars, closedVars, need, have, false );
61 findOpenVars( actualType, openVars, closedVars, need, have, true );
62 for ( OpenVarSet::const_iterator openVar = openVars.begin(); openVar != openVars.end(); ++openVar ) {
63 Type *boundType = env->lookup( openVar->first );
64 if ( ! boundType ) continue;
65 if ( TypeInstType *typeInst = dynamic_cast< TypeInstType* >( boundType ) ) {
66 if ( closedVars.find( typeInst->get_name() ) == closedVars.end() ) {
67 return true;
68 } // if
69 } else {
70 return true;
71 } // if
72 } // for
73 return false;
74 } else {
75 return false;
76 } // if
77 }
78
79 /// True if both types have the same structure, but not necessarily the same types.
80 /// That is, either both types are tuple types with the same size (recursively), or
81 /// both are not tuple types.
82 bool matchingTupleStructure( Type * t1, Type * t2 ) {
83 TupleType * tuple1 = dynamic_cast< TupleType * >( t1 );
84 TupleType * tuple2 = dynamic_cast< TupleType * >( t2 );
85 if ( tuple1 && tuple2 ) {
86 if ( tuple1->size() != tuple2->size() ) return false;
87 for ( auto types : group_iterate( tuple1->get_types(), tuple2->get_types() ) ) {
88 if ( ! matchingTupleStructure( std::get<0>( types ), std::get<1>( types ) ) ) return false;
89 }
90 return true;
91 } else if ( ! tuple1 && ! tuple2 ) return true;
92 return false;
93 }
94
95 bool needsTupleSpecialization( Type *formalType, Type *actualType ) {
96 // Needs tuple specialization if the structure of the formal type and actual type do not match.
97 // This is the case if the formal type has ttype polymorphism, or if the structure of tuple types
98 // between the function do not match exactly.
99 if ( FunctionType * fftype = getFunctionType( formalType ) ) {
100 if ( fftype->isTtype() ) return true;
101 // conversion of 0 (null) to function type does not require tuple specialization
102 if ( dynamic_cast< ZeroType * >( actualType ) ) return false;
103 FunctionType * aftype = getFunctionType( actualType );
104 assertf( aftype, "formal type is a function type, but actual type is not." );
105 if ( fftype->get_parameters().size() != aftype->get_parameters().size() ) return true;
106 for ( auto params : group_iterate( fftype->get_parameters(), aftype->get_parameters() ) ) {
107 DeclarationWithType * formal = std::get<0>(params);
108 DeclarationWithType * actual = std::get<1>(params);
109 if ( ! matchingTupleStructure( formal->get_type(), actual->get_type() ) ) return true;
110 }
111 }
112 return false;
113 }
114
115 bool needsSpecialization( Type *formalType, Type *actualType, TypeSubstitution *env ) {
116 return needsPolySpecialization( formalType, actualType, env ) || needsTupleSpecialization( formalType, actualType );
117 }
118
119 Expression * Specialize::doSpecialization( Type *formalType, Expression *actual, InferredParams *inferParams ) {
120 assertf( actual->has_result(), "attempting to specialize an untyped expression" );
121 if ( needsSpecialization( formalType, actual->get_result(), env ) ) {
122 if ( FunctionType *funType = getFunctionType( formalType ) ) {
123 ApplicationExpr *appExpr;
124 VariableExpr *varExpr;
125 if ( ( appExpr = dynamic_cast<ApplicationExpr*>( actual ) ) ) {
126 return createThunkFunction( funType, appExpr->get_function(), inferParams );
127 } else if ( ( varExpr = dynamic_cast<VariableExpr*>( actual ) ) ) {
128 return createThunkFunction( funType, varExpr, inferParams );
129 } else {
130 // This likely won't work, as anything that could build an ApplicationExpr probably hit one of the previous two branches
131 return createThunkFunction( funType, actual, inferParams );
132 }
133 } else {
134 return actual;
135 } // if
136 } else {
137 return actual;
138 } // if
139 }
140
141 /// restructures the arguments to match the structure of the formal parameters of the actual function.
142 /// [begin, end) are the exploded arguments.
143 template< typename Iterator, typename OutIterator >
144 void structureArg( Type * type, Iterator & begin, Iterator end, OutIterator out ) {
145 if ( TupleType * tuple = dynamic_cast< TupleType * >( type ) ) {
146 std::list< Expression * > exprs;
147 for ( Type * t : *tuple ) {
148 structureArg( t, begin, end, back_inserter( exprs ) );
149 }
150 *out++ = new TupleExpr( exprs );
151 } else {
152 assertf( begin != end, "reached the end of the arguments while structuring" );
153 *out++ = *begin++;
154 }
155 }
156
157 /// explode assuming simple cases: either type is pure tuple (but not tuple expr) or type is non-tuple.
158 template< typename OutputIterator >
159 void explodeSimple( Expression * expr, OutputIterator out ) {
160 if ( TupleType * tupleType = dynamic_cast< TupleType * > ( expr->get_result() ) ) {
161 // tuple type, recursively index into its components
162 for ( unsigned int i = 0; i < tupleType->size(); i++ ) {
163 explodeSimple( new TupleIndexExpr( expr->clone(), i ), out );
164 }
165 delete expr;
166 } else {
167 // non-tuple type - output a clone of the expression
168 *out++ = expr;
169 }
170 }
171
172 struct EnvTrimmer : public Visitor {
173 TypeSubstitution * env, * newEnv;
174 EnvTrimmer( TypeSubstitution * env, TypeSubstitution * newEnv ) : env( env ), newEnv( newEnv ){}
175 virtual void visit( TypeDecl * tyDecl ) {
176 // transfer known bindings for seen type variables
177 if ( Type * t = env->lookup( tyDecl->get_name() ) ) {
178 newEnv->add( tyDecl->get_name(), t );
179 }
180 }
181 };
182
183 /// reduce environment to just the parts that are referenced in a given expression
184 TypeSubstitution * trimEnv( ApplicationExpr * expr, TypeSubstitution * env ) {
185 if ( env ) {
186 TypeSubstitution * newEnv = new TypeSubstitution();
187 EnvTrimmer trimmer( env, newEnv );
188 expr->accept( trimmer );
189 return newEnv;
190 }
191 return nullptr;
192 }
193
194 /// Generates a thunk that calls `actual` with type `funType` and returns its address
195 Expression * Specialize::createThunkFunction( FunctionType *funType, Expression *actual, InferredParams *inferParams ) {
196 static UniqueName thunkNamer( "_thunk" );
197
198 FunctionType *newType = funType->clone();
199 if ( env ) {
200 // it is important to replace only occurrences of type variables that occur free in the
201 // thunk's type
202 env->applyFree( newType );
203 } // if
204 // create new thunk with same signature as formal type (C linkage, empty body)
205 FunctionDecl *thunkFunc = new FunctionDecl( thunkNamer.newName(), Type::StorageClasses(), LinkageSpec::C, newType, new CompoundStmt( noLabels ) );
206 thunkFunc->fixUniqueId();
207
208 // thunks may be generated and not used - silence warning with attribute
209 thunkFunc->get_attributes().push_back( new Attribute( "unused" ) );
210
211 // thread thunk parameters into call to actual function, naming thunk parameters as we go
212 UniqueName paramNamer( paramPrefix );
213 ApplicationExpr *appExpr = new ApplicationExpr( actual );
214
215 FunctionType * actualType = getFunctionType( actual->get_result() )->clone();
216 if ( env ) {
217 // need to apply the environment to the actual function's type, since it may itself be polymorphic
218 env->apply( actualType );
219 }
220 std::unique_ptr< FunctionType > actualTypeManager( actualType ); // for RAII
221 std::list< DeclarationWithType * >::iterator actualBegin = actualType->get_parameters().begin();
222 std::list< DeclarationWithType * >::iterator actualEnd = actualType->get_parameters().end();
223
224 std::list< Expression * > args;
225 for ( DeclarationWithType* param : thunkFunc->get_functionType()->get_parameters() ) {
226 // name each thunk parameter and explode it - these are then threaded back into the actual function call.
227 param->set_name( paramNamer.newName() );
228 explodeSimple( new VariableExpr( param ), back_inserter( args ) );
229 }
230
231 // walk parameters to the actual function alongside the exploded thunk parameters and restructure the arguments to match the actual parameters.
232 std::list< Expression * >::iterator argBegin = args.begin(), argEnd = args.end();
233 for ( ; actualBegin != actualEnd; ++actualBegin ) {
234 structureArg( (*actualBegin)->get_type(), argBegin, argEnd, back_inserter( appExpr->get_args() ) );
235 }
236
237 appExpr->set_env( trimEnv( appExpr, env ) );
238 if ( inferParams ) {
239 appExpr->get_inferParams() = *inferParams;
240 } // if
241
242 // handle any specializations that may still be present
243 std::string oldParamPrefix = paramPrefix;
244 paramPrefix += "p";
245 // save stmtsToAdd in oldStmts
246 std::list< Statement* > oldStmts;
247 oldStmts.splice( oldStmts.end(), stmtsToAdd );
248 mutate( appExpr );
249 paramPrefix = oldParamPrefix;
250 // write any statements added for recursive specializations into the thunk body
251 thunkFunc->get_statements()->get_kids().splice( thunkFunc->get_statements()->get_kids().end(), stmtsToAdd );
252 // restore oldStmts into stmtsToAdd
253 stmtsToAdd.splice( stmtsToAdd.end(), oldStmts );
254
255 // add return (or valueless expression) to the thunk
256 Statement *appStmt;
257 if ( funType->get_returnVals().empty() ) {
258 appStmt = new ExprStmt( noLabels, appExpr );
259 } else {
260 appStmt = new ReturnStmt( noLabels, appExpr );
261 } // if
262 thunkFunc->get_statements()->get_kids().push_back( appStmt );
263
264 // add thunk definition to queue of statements to add
265 stmtsToAdd.push_back( new DeclStmt( noLabels, thunkFunc ) );
266 // return address of thunk function as replacement expression
267 return new AddressExpr( new VariableExpr( thunkFunc ) );
268 }
269
270 void Specialize::handleExplicitParams( ApplicationExpr *appExpr ) {
271 // create thunks for the explicit parameters
272 assert( appExpr->get_function()->has_result() );
273 FunctionType *function = getFunctionType( appExpr->get_function()->get_result() );
274 assert( function );
275 std::list< DeclarationWithType* >::iterator formal;
276 std::list< Expression* >::iterator actual;
277 for ( formal = function->get_parameters().begin(), actual = appExpr->get_args().begin(); formal != function->get_parameters().end() && actual != appExpr->get_args().end(); ++formal, ++actual ) {
278 *actual = doSpecialization( (*formal )->get_type(), *actual, &appExpr->get_inferParams() );
279 }
280 }
281
282 Expression * Specialize::mutate( ApplicationExpr *appExpr ) {
283 appExpr->get_function()->acceptMutator( *this );
284 mutateAll( appExpr->get_args(), *this );
285
286 if ( ! InitTweak::isIntrinsicCallExpr( appExpr ) ) {
287 // create thunks for the inferred parameters
288 // don't need to do this for intrinsic calls, because they aren't actually passed
289 // need to handle explicit params before inferred params so that explicit params do not recieve a changed set of inferParams (and change them again)
290 // alternatively, if order starts to matter then copy appExpr's inferParams and pass them to handleExplicitParams.
291 handleExplicitParams( appExpr );
292 for ( InferredParams::iterator inferParam = appExpr->get_inferParams().begin(); inferParam != appExpr->get_inferParams().end(); ++inferParam ) {
293 inferParam->second.expr = doSpecialization( inferParam->second.formalType, inferParam->second.expr, inferParam->second.inferParams.get() );
294 }
295 }
296 return appExpr;
297 }
298
299 Expression * Specialize::mutate( AddressExpr *addrExpr ) {
300 addrExpr->get_arg()->acceptMutator( *this );
301 assert( addrExpr->has_result() );
302 addrExpr->set_arg( doSpecialization( addrExpr->get_result(), addrExpr->get_arg() ) );
303 return addrExpr;
304 }
305
306 Expression * Specialize::mutate( CastExpr *castExpr ) {
307 castExpr->get_arg()->acceptMutator( *this );
308 if ( castExpr->get_result()->isVoid() ) {
309 // can't specialize if we don't have a return value
310 return castExpr;
311 }
312 Expression *specialized = doSpecialization( castExpr->get_result(), castExpr->get_arg() );
313 if ( specialized != castExpr->get_arg() ) {
314 // assume here that the specialization incorporates the cast
315 return specialized;
316 } else {
317 return castExpr;
318 }
319 }
320
321 // Removing these for now. Richard put these in for some reason, but it's not clear why.
322 // In particular, copy constructors produce a comma expression, and with this code the parts
323 // of that comma expression are not specialized, which causes problems.
324
325 // Expression * Specialize::mutate( LogicalExpr *logicalExpr ) {
326 // return logicalExpr;
327 // }
328
329 // Expression * Specialize::mutate( ConditionalExpr *condExpr ) {
330 // return condExpr;
331 // }
332
333 // Expression * Specialize::mutate( CommaExpr *commaExpr ) {
334 // return commaExpr;
335 // }
336
337 void convertSpecializations( std::list< Declaration* >& translationUnit ) {
338 Specialize spec;
339 mutateAll( translationUnit, spec );
340 }
341} // namespace GenPoly
342
343// Local Variables: //
344// tab-width: 4 //
345// mode: c++ //
346// compile-command: "make install" //
347// End: //
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