source: src/GenPoly/Specialize.cc@ cf90b88

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 cf90b88 was cf90b88, checked in by Rob Schluntz <rschlunt@…>, 8 years ago

Convert Specialize to PassVisitor
  • Property mode set to 100644
File size: 15.3 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> // for assert, assertf
17#include <iterator> // for back_insert_iterator, back_i...
18#include <map> // for _Rb_tree_iterator, _Rb_tree_...
19#include <memory> // for unique_ptr
20#include <string> // for string
21#include <tuple> // for get
22#include <utility> // for pair
23
24#include "Common/PassVisitor.h"
25#include "Common/SemanticError.h" // for SemanticError
26#include "Common/UniqueName.h" // for UniqueName
27#include "Common/utility.h" // for group_iterate
28#include "GenPoly.h" // for getFunctionType
29#include "InitTweak/InitTweak.h" // for isIntrinsicCallExpr
30#include "Parser/LinkageSpec.h" // for C
31#include "PolyMutator.h" // for PolyMutator
32#include "ResolvExpr/FindOpenVars.h" // for findOpenVars
33#include "ResolvExpr/TypeEnvironment.h" // for OpenVarSet, AssertionSet
34#include "Specialize.h"
35#include "SynTree/Attribute.h" // for Attribute
36#include "SynTree/Declaration.h" // for FunctionDecl, DeclarationWit...
37#include "SynTree/Expression.h" // for ApplicationExpr, Expression
38#include "SynTree/Label.h" // for Label, noLabels
39#include "SynTree/Mutator.h" // for mutateAll
40#include "SynTree/Statement.h" // for CompoundStmt, DeclStmt, Expr...
41#include "SynTree/Type.h" // for FunctionType, TupleType, Type
42#include "SynTree/TypeSubstitution.h" // for TypeSubstitution
43#include "SynTree/Visitor.h" // for Visitor
44
45namespace GenPoly {
46 struct Specialize final : public WithTypeSubstitution, public WithStmtsToAdd, public WithVisitorRef<Specialize> {
47 Expression * postmutate( ApplicationExpr *applicationExpr );
48 Expression * postmutate( AddressExpr *castExpr );
49 Expression * postmutate( CastExpr *castExpr );
50
51 void handleExplicitParams( ApplicationExpr *appExpr );
52 Expression * createThunkFunction( FunctionType *funType, Expression *actual, InferredParams *inferParams );
53 Expression * doSpecialization( Type *formalType, Expression *actual, InferredParams *inferParams = nullptr );
54
55 std::string paramPrefix = "_p";
56 };
57
58 /// Looks up open variables in actual type, returning true if any of them are bound in the environment or formal type.
59 bool needsPolySpecialization( Type *formalType, Type *actualType, TypeSubstitution *env ) {
60 if ( env ) {
61 using namespace ResolvExpr;
62 OpenVarSet openVars, closedVars;
63 AssertionSet need, have;
64 findOpenVars( formalType, openVars, closedVars, need, have, false );
65 findOpenVars( actualType, openVars, closedVars, need, have, true );
66 for ( OpenVarSet::const_iterator openVar = openVars.begin(); openVar != openVars.end(); ++openVar ) {
67 Type *boundType = env->lookup( openVar->first );
68 if ( ! boundType ) continue;
69 if ( TypeInstType *typeInst = dynamic_cast< TypeInstType* >( boundType ) ) {
70 if ( closedVars.find( typeInst->get_name() ) == closedVars.end() ) {
71 return true;
72 } // if
73 } else {
74 return true;
75 } // if
76 } // for
77 return false;
78 } else {
79 return false;
80 } // if
81 }
82
83 /// True if both types have the same structure, but not necessarily the same types.
84 /// That is, either both types are tuple types with the same size (recursively), or
85 /// both are not tuple types.
86 bool matchingTupleStructure( Type * t1, Type * t2 ) {
87 TupleType * tuple1 = dynamic_cast< TupleType * >( t1 );
88 TupleType * tuple2 = dynamic_cast< TupleType * >( t2 );
89 if ( tuple1 && tuple2 ) {
90 if ( tuple1->size() != tuple2->size() ) return false;
91 for ( auto types : group_iterate( tuple1->get_types(), tuple2->get_types() ) ) {
92 if ( ! matchingTupleStructure( std::get<0>( types ), std::get<1>( types ) ) ) return false;
93 }
94 return true;
95 } else if ( ! tuple1 && ! tuple2 ) return true;
96 return false;
97 }
98
99 // walk into tuple type and find the number of components
100 size_t singleParameterSize( Type * type ) {
101 if ( TupleType * tt = dynamic_cast< TupleType * >( type ) ) {
102 size_t sz = 0;
103 for ( Type * t : *tt ) {
104 sz += singleParameterSize( t );
105 }
106 return sz;
107 } else {
108 return 1;
109 }
110 }
111
112 // find the total number of components in a parameter list
113 size_t functionParameterSize( FunctionType * ftype ) {
114 size_t sz = 0;
115 for ( DeclarationWithType * p : ftype->get_parameters() ) {
116 sz += singleParameterSize( p->get_type() );
117 }
118 return sz;
119 }
120
121 bool needsTupleSpecialization( Type *formalType, Type *actualType ) {
122 // Needs tuple specialization if the structure of the formal type and actual type do not match.
123 // This is the case if the formal type has ttype polymorphism, or if the structure of tuple types
124 // between the function do not match exactly.
125 if ( FunctionType * fftype = getFunctionType( formalType ) ) {
126 if ( fftype->isTtype() ) return true;
127 // conversion of 0 (null) to function type does not require tuple specialization
128 if ( dynamic_cast< ZeroType * >( actualType ) ) return false;
129 FunctionType * aftype = getFunctionType( actualType->stripReferences() );
130 assertf( aftype, "formal type is a function type, but actual type is not: %s", toString( actualType ).c_str() );
131 // Can't tuple specialize if parameter sizes deeply-differ.
132 if ( functionParameterSize( fftype ) != functionParameterSize( aftype ) ) return false;
133 // tuple-parameter sizes are the same, but actual parameter sizes differ - must tuple specialize
134 if ( fftype->get_parameters().size() != aftype->get_parameters().size() ) return true;
135 // total parameter size can be the same, while individual parameters can have different structure
136 for ( auto params : group_iterate( fftype->get_parameters(), aftype->get_parameters() ) ) {
137 DeclarationWithType * formal = std::get<0>(params);
138 DeclarationWithType * actual = std::get<1>(params);
139 if ( ! matchingTupleStructure( formal->get_type(), actual->get_type() ) ) return true;
140 }
141 }
142 return false;
143 }
144
145 bool needsSpecialization( Type *formalType, Type *actualType, TypeSubstitution *env ) {
146 return needsPolySpecialization( formalType, actualType, env ) || needsTupleSpecialization( formalType, actualType );
147 }
148
149 Expression * Specialize::doSpecialization( Type *formalType, Expression *actual, InferredParams *inferParams ) {
150 assertf( actual->has_result(), "attempting to specialize an untyped expression" );
151 if ( needsSpecialization( formalType, actual->get_result(), env ) ) {
152 if ( FunctionType *funType = getFunctionType( formalType ) ) {
153 ApplicationExpr *appExpr;
154 VariableExpr *varExpr;
155 if ( ( appExpr = dynamic_cast<ApplicationExpr*>( actual ) ) ) {
156 return createThunkFunction( funType, appExpr->get_function(), inferParams );
157 } else if ( ( varExpr = dynamic_cast<VariableExpr*>( actual ) ) ) {
158 return createThunkFunction( funType, varExpr, inferParams );
159 } else {
160 // This likely won't work, as anything that could build an ApplicationExpr probably hit one of the previous two branches
161 return createThunkFunction( funType, actual, inferParams );
162 }
163 } else {
164 return actual;
165 } // if
166 } else {
167 return actual;
168 } // if
169 }
170
171 /// restructures the arguments to match the structure of the formal parameters of the actual function.
172 /// [begin, end) are the exploded arguments.
173 template< typename Iterator, typename OutIterator >
174 void structureArg( Type * type, Iterator & begin, Iterator end, OutIterator out ) {
175 if ( TupleType * tuple = dynamic_cast< TupleType * >( type ) ) {
176 std::list< Expression * > exprs;
177 for ( Type * t : *tuple ) {
178 structureArg( t, begin, end, back_inserter( exprs ) );
179 }
180 *out++ = new TupleExpr( exprs );
181 } else {
182 assertf( begin != end, "reached the end of the arguments while structuring" );
183 *out++ = *begin++;
184 }
185 }
186
187 /// explode assuming simple cases: either type is pure tuple (but not tuple expr) or type is non-tuple.
188 template< typename OutputIterator >
189 void explodeSimple( Expression * expr, OutputIterator out ) {
190 if ( TupleType * tupleType = dynamic_cast< TupleType * > ( expr->get_result() ) ) {
191 // tuple type, recursively index into its components
192 for ( unsigned int i = 0; i < tupleType->size(); i++ ) {
193 explodeSimple( new TupleIndexExpr( expr->clone(), i ), out );
194 }
195 delete expr;
196 } else {
197 // non-tuple type - output a clone of the expression
198 *out++ = expr;
199 }
200 }
201
202 struct EnvTrimmer {
203 TypeSubstitution * env, * newEnv;
204 EnvTrimmer( TypeSubstitution * env, TypeSubstitution * newEnv ) : env( env ), newEnv( newEnv ){}
205 void previsit( TypeDecl * tyDecl ) {
206 // transfer known bindings for seen type variables
207 if ( Type * t = env->lookup( tyDecl->name ) ) {
208 newEnv->add( tyDecl->name, t );
209 }
210 }
211 };
212
213 /// reduce environment to just the parts that are referenced in a given expression
214 TypeSubstitution * trimEnv( ApplicationExpr * expr, TypeSubstitution * env ) {
215 if ( env ) {
216 TypeSubstitution * newEnv = new TypeSubstitution();
217 PassVisitor<EnvTrimmer> trimmer( env, newEnv );
218 expr->accept( trimmer );
219 return newEnv;
220 }
221 return nullptr;
222 }
223
224 /// Generates a thunk that calls `actual` with type `funType` and returns its address
225 Expression * Specialize::createThunkFunction( FunctionType *funType, Expression *actual, InferredParams *inferParams ) {
226 static UniqueName thunkNamer( "_thunk" );
227
228 FunctionType *newType = funType->clone();
229 if ( env ) {
230 // it is important to replace only occurrences of type variables that occur free in the
231 // thunk's type
232 env->applyFree( newType );
233 } // if
234 // create new thunk with same signature as formal type (C linkage, empty body)
235 FunctionDecl *thunkFunc = new FunctionDecl( thunkNamer.newName(), Type::StorageClasses(), LinkageSpec::C, newType, new CompoundStmt( noLabels ) );
236 thunkFunc->fixUniqueId();
237
238 // thunks may be generated and not used - silence warning with attribute
239 thunkFunc->get_attributes().push_back( new Attribute( "unused" ) );
240
241 // thread thunk parameters into call to actual function, naming thunk parameters as we go
242 UniqueName paramNamer( paramPrefix );
243 ApplicationExpr *appExpr = new ApplicationExpr( actual );
244
245 FunctionType * actualType = getFunctionType( actual->get_result() )->clone();
246 if ( env ) {
247 // need to apply the environment to the actual function's type, since it may itself be polymorphic
248 env->apply( actualType );
249 }
250 std::unique_ptr< FunctionType > actualTypeManager( actualType ); // for RAII
251 std::list< DeclarationWithType * >::iterator actualBegin = actualType->get_parameters().begin();
252 std::list< DeclarationWithType * >::iterator actualEnd = actualType->get_parameters().end();
253
254 std::list< Expression * > args;
255 for ( DeclarationWithType* param : thunkFunc->get_functionType()->get_parameters() ) {
256 // name each thunk parameter and explode it - these are then threaded back into the actual function call.
257 param->set_name( paramNamer.newName() );
258 explodeSimple( new VariableExpr( param ), back_inserter( args ) );
259 }
260
261 // walk parameters to the actual function alongside the exploded thunk parameters and restructure the arguments to match the actual parameters.
262 std::list< Expression * >::iterator argBegin = args.begin(), argEnd = args.end();
263 for ( ; actualBegin != actualEnd; ++actualBegin ) {
264 structureArg( (*actualBegin)->get_type(), argBegin, argEnd, back_inserter( appExpr->get_args() ) );
265 }
266
267 appExpr->set_env( trimEnv( appExpr, env ) );
268 if ( inferParams ) {
269 appExpr->get_inferParams() = *inferParams;
270 } // if
271
272 // handle any specializations that may still be present
273 std::string oldParamPrefix = paramPrefix;
274 paramPrefix += "p";
275 // save stmtsToAddBefore in oldStmts
276 std::list< Statement* > oldStmts;
277 oldStmts.splice( oldStmts.end(), stmtsToAddBefore );
278 appExpr->acceptMutator( *visitor );
279 paramPrefix = oldParamPrefix;
280 // write any statements added for recursive specializations into the thunk body
281 thunkFunc->statements->kids.splice( thunkFunc->statements->kids.end(), stmtsToAddBefore );
282 // restore oldStmts into stmtsToAddBefore
283 stmtsToAddBefore.splice( stmtsToAddBefore.end(), oldStmts );
284
285 // add return (or valueless expression) to the thunk
286 Statement *appStmt;
287 if ( funType->returnVals.empty() ) {
288 appStmt = new ExprStmt( noLabels, appExpr );
289 } else {
290 appStmt = new ReturnStmt( noLabels, appExpr );
291 } // if
292 thunkFunc->statements->kids.push_back( appStmt );
293
294 // add thunk definition to queue of statements to add
295 stmtsToAddBefore.push_back( new DeclStmt( noLabels, thunkFunc ) );
296 // return address of thunk function as replacement expression
297 return new AddressExpr( new VariableExpr( thunkFunc ) );
298 }
299
300 void Specialize::handleExplicitParams( ApplicationExpr *appExpr ) {
301 // create thunks for the explicit parameters
302 assert( appExpr->function->result );
303 FunctionType *function = getFunctionType( appExpr->function->result );
304 assert( function );
305 std::list< DeclarationWithType* >::iterator formal;
306 std::list< Expression* >::iterator actual;
307 for ( formal = function->get_parameters().begin(), actual = appExpr->get_args().begin(); formal != function->get_parameters().end() && actual != appExpr->get_args().end(); ++formal, ++actual ) {
308 *actual = doSpecialization( (*formal)->get_type(), *actual, &appExpr->get_inferParams() );
309 }
310 }
311
312 Expression * Specialize::postmutate( ApplicationExpr *appExpr ) {
313 if ( ! InitTweak::isIntrinsicCallExpr( appExpr ) ) {
314 // create thunks for the inferred parameters
315 // don't need to do this for intrinsic calls, because they aren't actually passed
316 // need to handle explicit params before inferred params so that explicit params do not recieve a changed set of inferParams (and change them again)
317 // alternatively, if order starts to matter then copy appExpr's inferParams and pass them to handleExplicitParams.
318 handleExplicitParams( appExpr );
319 for ( InferredParams::iterator inferParam = appExpr->get_inferParams().begin(); inferParam != appExpr->get_inferParams().end(); ++inferParam ) {
320 inferParam->second.expr = doSpecialization( inferParam->second.formalType, inferParam->second.expr, inferParam->second.inferParams.get() );
321 }
322 }
323 return appExpr;
324 }
325
326 Expression * Specialize::postmutate( AddressExpr *addrExpr ) {
327 assert( addrExpr->result );
328 addrExpr->set_arg( doSpecialization( addrExpr->result, addrExpr->arg ) );
329 return addrExpr;
330 }
331
332 Expression * Specialize::postmutate( CastExpr *castExpr ) {
333 if ( castExpr->result->isVoid() ) {
334 // can't specialize if we don't have a return value
335 return castExpr;
336 }
337 Expression *specialized = doSpecialization( castExpr->result, castExpr->arg );
338 if ( specialized != castExpr->arg ) {
339 // assume here that the specialization incorporates the cast
340 return specialized;
341 } else {
342 return castExpr;
343 }
344 }
345
346 void convertSpecializations( std::list< Declaration* >& translationUnit ) {
347 PassVisitor<Specialize> spec;
348 mutateAll( translationUnit, spec );
349 }
350} // namespace GenPoly
351
352// Local Variables: //
353// tab-width: 4 //
354// mode: c++ //
355// compile-command: "make install" //
356// End: //
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