source: src/GenPoly/Specialize.cc@ bfd4974

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 bfd4974 was d29fa5f, checked in by Rob Schluntz <rschlunt@…>, 8 years ago

Remove has_result
  • Property mode set to 100644
File size: 15.2 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 "ResolvExpr/FindOpenVars.h" // for findOpenVars
32#include "ResolvExpr/TypeEnvironment.h" // for OpenVarSet, AssertionSet
33#include "Specialize.h"
34#include "SynTree/Attribute.h" // for Attribute
35#include "SynTree/Declaration.h" // for FunctionDecl, DeclarationWit...
36#include "SynTree/Expression.h" // for ApplicationExpr, Expression
37#include "SynTree/Label.h" // for Label, noLabels
38#include "SynTree/Mutator.h" // for mutateAll
39#include "SynTree/Statement.h" // for CompoundStmt, DeclStmt, Expr...
40#include "SynTree/Type.h" // for FunctionType, TupleType, Type
41#include "SynTree/TypeSubstitution.h" // for TypeSubstitution
42#include "SynTree/Visitor.h" // for Visitor
43
44namespace GenPoly {
45 struct Specialize final : public WithTypeSubstitution, public WithStmtsToAdd, public WithVisitorRef<Specialize> {
46 Expression * postmutate( ApplicationExpr *applicationExpr );
47 Expression * postmutate( AddressExpr *castExpr );
48 Expression * postmutate( CastExpr *castExpr );
49
50 void handleExplicitParams( ApplicationExpr *appExpr );
51 Expression * createThunkFunction( FunctionType *funType, Expression *actual, InferredParams *inferParams );
52 Expression * doSpecialization( Type *formalType, Expression *actual, InferredParams *inferParams = nullptr );
53
54 std::string paramPrefix = "_p";
55 };
56
57 /// Looks up open variables in actual type, returning true if any of them are bound in the environment or formal type.
58 bool needsPolySpecialization( Type *formalType, Type *actualType, TypeSubstitution *env ) {
59 if ( env ) {
60 using namespace ResolvExpr;
61 OpenVarSet openVars, closedVars;
62 AssertionSet need, have;
63 findOpenVars( formalType, openVars, closedVars, need, have, false );
64 findOpenVars( actualType, openVars, closedVars, need, have, true );
65 for ( OpenVarSet::const_iterator openVar = openVars.begin(); openVar != openVars.end(); ++openVar ) {
66 Type *boundType = env->lookup( openVar->first );
67 if ( ! boundType ) continue;
68 if ( TypeInstType *typeInst = dynamic_cast< TypeInstType* >( boundType ) ) {
69 if ( closedVars.find( typeInst->get_name() ) == closedVars.end() ) {
70 return true;
71 } // if
72 } else {
73 return true;
74 } // if
75 } // for
76 return false;
77 } else {
78 return false;
79 } // if
80 }
81
82 /// True if both types have the same structure, but not necessarily the same types.
83 /// That is, either both types are tuple types with the same size (recursively), or
84 /// both are not tuple types.
85 bool matchingTupleStructure( Type * t1, Type * t2 ) {
86 TupleType * tuple1 = dynamic_cast< TupleType * >( t1 );
87 TupleType * tuple2 = dynamic_cast< TupleType * >( t2 );
88 if ( tuple1 && tuple2 ) {
89 if ( tuple1->size() != tuple2->size() ) return false;
90 for ( auto types : group_iterate( tuple1->get_types(), tuple2->get_types() ) ) {
91 if ( ! matchingTupleStructure( std::get<0>( types ), std::get<1>( types ) ) ) return false;
92 }
93 return true;
94 } else if ( ! tuple1 && ! tuple2 ) return true;
95 return false;
96 }
97
98 // walk into tuple type and find the number of components
99 size_t singleParameterSize( Type * type ) {
100 if ( TupleType * tt = dynamic_cast< TupleType * >( type ) ) {
101 size_t sz = 0;
102 for ( Type * t : *tt ) {
103 sz += singleParameterSize( t );
104 }
105 return sz;
106 } else {
107 return 1;
108 }
109 }
110
111 // find the total number of components in a parameter list
112 size_t functionParameterSize( FunctionType * ftype ) {
113 size_t sz = 0;
114 for ( DeclarationWithType * p : ftype->get_parameters() ) {
115 sz += singleParameterSize( p->get_type() );
116 }
117 return sz;
118 }
119
120 bool needsTupleSpecialization( Type *formalType, Type *actualType ) {
121 // Needs tuple specialization if the structure of the formal type and actual type do not match.
122 // This is the case if the formal type has ttype polymorphism, or if the structure of tuple types
123 // between the function do not match exactly.
124 if ( FunctionType * fftype = getFunctionType( formalType ) ) {
125 if ( fftype->isTtype() ) return true;
126 // conversion of 0 (null) to function type does not require tuple specialization
127 if ( dynamic_cast< ZeroType * >( actualType ) ) return false;
128 FunctionType * aftype = getFunctionType( actualType->stripReferences() );
129 assertf( aftype, "formal type is a function type, but actual type is not: %s", toString( actualType ).c_str() );
130 // Can't tuple specialize if parameter sizes deeply-differ.
131 if ( functionParameterSize( fftype ) != functionParameterSize( aftype ) ) return false;
132 // tuple-parameter sizes are the same, but actual parameter sizes differ - must tuple specialize
133 if ( fftype->get_parameters().size() != aftype->get_parameters().size() ) return true;
134 // total parameter size can be the same, while individual parameters can have different structure
135 for ( auto params : group_iterate( fftype->get_parameters(), aftype->get_parameters() ) ) {
136 DeclarationWithType * formal = std::get<0>(params);
137 DeclarationWithType * actual = std::get<1>(params);
138 if ( ! matchingTupleStructure( formal->get_type(), actual->get_type() ) ) return true;
139 }
140 }
141 return false;
142 }
143
144 bool needsSpecialization( Type *formalType, Type *actualType, TypeSubstitution *env ) {
145 return needsPolySpecialization( formalType, actualType, env ) || needsTupleSpecialization( formalType, actualType );
146 }
147
148 Expression * Specialize::doSpecialization( Type *formalType, Expression *actual, InferredParams *inferParams ) {
149 assertf( actual->result, "attempting to specialize an untyped expression" );
150 if ( needsSpecialization( formalType, actual->get_result(), env ) ) {
151 if ( FunctionType *funType = getFunctionType( formalType ) ) {
152 ApplicationExpr *appExpr;
153 VariableExpr *varExpr;
154 if ( ( appExpr = dynamic_cast<ApplicationExpr*>( actual ) ) ) {
155 return createThunkFunction( funType, appExpr->get_function(), inferParams );
156 } else if ( ( varExpr = dynamic_cast<VariableExpr*>( actual ) ) ) {
157 return createThunkFunction( funType, varExpr, inferParams );
158 } else {
159 // This likely won't work, as anything that could build an ApplicationExpr probably hit one of the previous two branches
160 return createThunkFunction( funType, actual, inferParams );
161 }
162 } else {
163 return actual;
164 } // if
165 } else {
166 return actual;
167 } // if
168 }
169
170 /// restructures the arguments to match the structure of the formal parameters of the actual function.
171 /// [begin, end) are the exploded arguments.
172 template< typename Iterator, typename OutIterator >
173 void structureArg( Type * type, Iterator & begin, Iterator end, OutIterator out ) {
174 if ( TupleType * tuple = dynamic_cast< TupleType * >( type ) ) {
175 std::list< Expression * > exprs;
176 for ( Type * t : *tuple ) {
177 structureArg( t, begin, end, back_inserter( exprs ) );
178 }
179 *out++ = new TupleExpr( exprs );
180 } else {
181 assertf( begin != end, "reached the end of the arguments while structuring" );
182 *out++ = *begin++;
183 }
184 }
185
186 /// explode assuming simple cases: either type is pure tuple (but not tuple expr) or type is non-tuple.
187 template< typename OutputIterator >
188 void explodeSimple( Expression * expr, OutputIterator out ) {
189 if ( TupleType * tupleType = dynamic_cast< TupleType * > ( expr->get_result() ) ) {
190 // tuple type, recursively index into its components
191 for ( unsigned int i = 0; i < tupleType->size(); i++ ) {
192 explodeSimple( new TupleIndexExpr( expr->clone(), i ), out );
193 }
194 delete expr;
195 } else {
196 // non-tuple type - output a clone of the expression
197 *out++ = expr;
198 }
199 }
200
201 struct EnvTrimmer {
202 TypeSubstitution * env, * newEnv;
203 EnvTrimmer( TypeSubstitution * env, TypeSubstitution * newEnv ) : env( env ), newEnv( newEnv ){}
204 void previsit( TypeDecl * tyDecl ) {
205 // transfer known bindings for seen type variables
206 if ( Type * t = env->lookup( tyDecl->name ) ) {
207 newEnv->add( tyDecl->name, t );
208 }
209 }
210 };
211
212 /// reduce environment to just the parts that are referenced in a given expression
213 TypeSubstitution * trimEnv( ApplicationExpr * expr, TypeSubstitution * env ) {
214 if ( env ) {
215 TypeSubstitution * newEnv = new TypeSubstitution();
216 PassVisitor<EnvTrimmer> trimmer( env, newEnv );
217 expr->accept( trimmer );
218 return newEnv;
219 }
220 return nullptr;
221 }
222
223 /// Generates a thunk that calls `actual` with type `funType` and returns its address
224 Expression * Specialize::createThunkFunction( FunctionType *funType, Expression *actual, InferredParams *inferParams ) {
225 static UniqueName thunkNamer( "_thunk" );
226
227 FunctionType *newType = funType->clone();
228 if ( env ) {
229 // it is important to replace only occurrences of type variables that occur free in the
230 // thunk's type
231 env->applyFree( newType );
232 } // if
233 // create new thunk with same signature as formal type (C linkage, empty body)
234 FunctionDecl *thunkFunc = new FunctionDecl( thunkNamer.newName(), Type::StorageClasses(), LinkageSpec::C, newType, new CompoundStmt( noLabels ) );
235 thunkFunc->fixUniqueId();
236
237 // thunks may be generated and not used - silence warning with attribute
238 thunkFunc->get_attributes().push_back( new Attribute( "unused" ) );
239
240 // thread thunk parameters into call to actual function, naming thunk parameters as we go
241 UniqueName paramNamer( paramPrefix );
242 ApplicationExpr *appExpr = new ApplicationExpr( actual );
243
244 FunctionType * actualType = getFunctionType( actual->get_result() )->clone();
245 if ( env ) {
246 // need to apply the environment to the actual function's type, since it may itself be polymorphic
247 env->apply( actualType );
248 }
249 std::unique_ptr< FunctionType > actualTypeManager( actualType ); // for RAII
250 std::list< DeclarationWithType * >::iterator actualBegin = actualType->get_parameters().begin();
251 std::list< DeclarationWithType * >::iterator actualEnd = actualType->get_parameters().end();
252
253 std::list< Expression * > args;
254 for ( DeclarationWithType* param : thunkFunc->get_functionType()->get_parameters() ) {
255 // name each thunk parameter and explode it - these are then threaded back into the actual function call.
256 param->set_name( paramNamer.newName() );
257 explodeSimple( new VariableExpr( param ), back_inserter( args ) );
258 }
259
260 // walk parameters to the actual function alongside the exploded thunk parameters and restructure the arguments to match the actual parameters.
261 std::list< Expression * >::iterator argBegin = args.begin(), argEnd = args.end();
262 for ( ; actualBegin != actualEnd; ++actualBegin ) {
263 structureArg( (*actualBegin)->get_type(), argBegin, argEnd, back_inserter( appExpr->get_args() ) );
264 }
265
266 appExpr->set_env( trimEnv( appExpr, env ) );
267 if ( inferParams ) {
268 appExpr->get_inferParams() = *inferParams;
269 } // if
270
271 // handle any specializations that may still be present
272 std::string oldParamPrefix = paramPrefix;
273 paramPrefix += "p";
274 // save stmtsToAddBefore in oldStmts
275 std::list< Statement* > oldStmts;
276 oldStmts.splice( oldStmts.end(), stmtsToAddBefore );
277 appExpr->acceptMutator( *visitor );
278 paramPrefix = oldParamPrefix;
279 // write any statements added for recursive specializations into the thunk body
280 thunkFunc->statements->kids.splice( thunkFunc->statements->kids.end(), stmtsToAddBefore );
281 // restore oldStmts into stmtsToAddBefore
282 stmtsToAddBefore.splice( stmtsToAddBefore.end(), oldStmts );
283
284 // add return (or valueless expression) to the thunk
285 Statement *appStmt;
286 if ( funType->returnVals.empty() ) {
287 appStmt = new ExprStmt( noLabels, appExpr );
288 } else {
289 appStmt = new ReturnStmt( noLabels, appExpr );
290 } // if
291 thunkFunc->statements->kids.push_back( appStmt );
292
293 // add thunk definition to queue of statements to add
294 stmtsToAddBefore.push_back( new DeclStmt( noLabels, thunkFunc ) );
295 // return address of thunk function as replacement expression
296 return new AddressExpr( new VariableExpr( thunkFunc ) );
297 }
298
299 void Specialize::handleExplicitParams( ApplicationExpr *appExpr ) {
300 // create thunks for the explicit parameters
301 assert( appExpr->function->result );
302 FunctionType *function = getFunctionType( appExpr->function->result );
303 assert( function );
304 std::list< DeclarationWithType* >::iterator formal;
305 std::list< Expression* >::iterator actual;
306 for ( formal = function->get_parameters().begin(), actual = appExpr->get_args().begin(); formal != function->get_parameters().end() && actual != appExpr->get_args().end(); ++formal, ++actual ) {
307 *actual = doSpecialization( (*formal)->get_type(), *actual, &appExpr->get_inferParams() );
308 }
309 }
310
311 Expression * Specialize::postmutate( ApplicationExpr *appExpr ) {
312 if ( ! InitTweak::isIntrinsicCallExpr( appExpr ) ) {
313 // create thunks for the inferred parameters
314 // don't need to do this for intrinsic calls, because they aren't actually passed
315 // need to handle explicit params before inferred params so that explicit params do not recieve a changed set of inferParams (and change them again)
316 // alternatively, if order starts to matter then copy appExpr's inferParams and pass them to handleExplicitParams.
317 handleExplicitParams( appExpr );
318 for ( InferredParams::iterator inferParam = appExpr->get_inferParams().begin(); inferParam != appExpr->get_inferParams().end(); ++inferParam ) {
319 inferParam->second.expr = doSpecialization( inferParam->second.formalType, inferParam->second.expr, inferParam->second.inferParams.get() );
320 }
321 }
322 return appExpr;
323 }
324
325 Expression * Specialize::postmutate( AddressExpr *addrExpr ) {
326 assert( addrExpr->result );
327 addrExpr->set_arg( doSpecialization( addrExpr->result, addrExpr->arg ) );
328 return addrExpr;
329 }
330
331 Expression * Specialize::postmutate( CastExpr *castExpr ) {
332 if ( castExpr->result->isVoid() ) {
333 // can't specialize if we don't have a return value
334 return castExpr;
335 }
336 Expression *specialized = doSpecialization( castExpr->result, castExpr->arg );
337 if ( specialized != castExpr->arg ) {
338 // assume here that the specialization incorporates the cast
339 return specialized;
340 } else {
341 return castExpr;
342 }
343 }
344
345 void convertSpecializations( std::list< Declaration* >& translationUnit ) {
346 PassVisitor<Specialize> spec;
347 mutateAll( translationUnit, spec );
348 }
349} // namespace GenPoly
350
351// Local Variables: //
352// tab-width: 4 //
353// mode: c++ //
354// compile-command: "make install" //
355// End: //
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