source: src/GenPoly/Specialize.cc@ 9cb4fc8

ADT arm-eh ast-experimental cleanup-dtors enum forall-pointer-decay jacob/cs343-translation jenkins-sandbox new-ast new-ast-unique-expr pthread-emulation qualifiedEnum
Last change on this file since 9cb4fc8 was 0b00df0, checked in by Aaron Moss <a3moss@…>, 7 years ago

First draft of deferred expression resolution; DOES NOT BUILD
  • Property mode set to 100644
File size: 14.3 KB
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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/UniqueName.h" // for UniqueName
26#include "Common/utility.h" // for group_iterate
27#include "GenPoly.h" // for getFunctionType
28#include "InitTweak/InitTweak.h" // for isIntrinsicCallExpr
29#include "Parser/LinkageSpec.h" // for C
30#include "ResolvExpr/FindOpenVars.h" // for findOpenVars
31#include "ResolvExpr/TypeEnvironment.h" // for OpenVarSet, AssertionSet
32#include "Specialize.h"
33#include "SynTree/Attribute.h" // for Attribute
34#include "SynTree/Declaration.h" // for FunctionDecl, DeclarationWit...
35#include "SynTree/Expression.h" // for ApplicationExpr, Expression
36#include "SynTree/Label.h" // for Label
37#include "SynTree/Mutator.h" // for mutateAll
38#include "SynTree/Statement.h" // for CompoundStmt, DeclStmt, Expr...
39#include "SynTree/Type.h" // for FunctionType, TupleType, Type
40#include "SynTree/TypeSubstitution.h" // for TypeSubstitution
41#include "SynTree/Visitor.h" // for Visitor
42
43namespace GenPoly {
44 struct Specialize final : public WithTypeSubstitution, public WithStmtsToAdd, public WithVisitorRef<Specialize> {
45 Expression * postmutate( ApplicationExpr *applicationExpr );
46 Expression * postmutate( CastExpr *castExpr );
47
48 void handleExplicitParams( ApplicationExpr *appExpr );
49 Expression * createThunkFunction( FunctionType *funType, Expression *actual, InferredParams *inferParams );
50 Expression * doSpecialization( Type *formalType, Expression *actual, InferredParams *inferParams );
51
52 std::string paramPrefix = "_p";
53 };
54
55 /// Looks up open variables in actual type, returning true if any of them are bound in the environment or formal type.
56 bool needsPolySpecialization( Type *formalType, Type *actualType, TypeSubstitution *env ) {
57 if ( env ) {
58 using namespace ResolvExpr;
59 OpenVarSet openVars, closedVars;
60 AssertionSet need, have;
61 findOpenVars( formalType, openVars, closedVars, need, have, false );
62 findOpenVars( actualType, openVars, closedVars, need, have, true );
63 for ( OpenVarSet::const_iterator openVar = openVars.begin(); openVar != openVars.end(); ++openVar ) {
64 Type *boundType = env->lookup( openVar->first );
65 if ( ! boundType ) continue;
66 if ( TypeInstType *typeInst = dynamic_cast< TypeInstType* >( boundType ) ) {
67 // bound to another type variable
68 if ( closedVars.find( typeInst->get_name() ) == closedVars.end() ) {
69 // bound to a closed variable => must specialize
70 return true;
71 } // if
72 } else {
73 // variable is bound to a concrete type => must specialize
74 return true;
75 } // if
76 } // for
77 // none of the type variables are bound
78 return false;
79 } else {
80 // no env
81 return false;
82 } // if
83 }
84
85 /// True if both types have the same structure, but not necessarily the same types.
86 /// That is, either both types are tuple types with the same size (recursively), or
87 /// both are not tuple types.
88 bool matchingTupleStructure( Type * t1, Type * t2 ) {
89 TupleType * tuple1 = dynamic_cast< TupleType * >( t1 );
90 TupleType * tuple2 = dynamic_cast< TupleType * >( t2 );
91 if ( tuple1 && tuple2 ) {
92 if ( tuple1->size() != tuple2->size() ) return false;
93 for ( auto types : group_iterate( tuple1->get_types(), tuple2->get_types() ) ) {
94 if ( ! matchingTupleStructure( std::get<0>( types ), std::get<1>( types ) ) ) return false;
95 }
96 return true;
97 } else if ( ! tuple1 && ! tuple2 ) return true;
98 return false;
99 }
100
101 // walk into tuple type and find the number of components
102 size_t singleParameterSize( Type * type ) {
103 if ( TupleType * tt = dynamic_cast< TupleType * >( type ) ) {
104 size_t sz = 0;
105 for ( Type * t : *tt ) {
106 sz += singleParameterSize( t );
107 }
108 return sz;
109 } else {
110 return 1;
111 }
112 }
113
114 // find the total number of components in a parameter list
115 size_t functionParameterSize( FunctionType * ftype ) {
116 size_t sz = 0;
117 for ( DeclarationWithType * p : ftype->get_parameters() ) {
118 sz += singleParameterSize( p->get_type() );
119 }
120 return sz;
121 }
122
123 bool needsTupleSpecialization( Type *formalType, Type *actualType ) {
124 // Needs tuple specialization if the structure of the formal type and actual type do not match.
125 // This is the case if the formal type has ttype polymorphism, or if the structure of tuple types
126 // between the function do not match exactly.
127 if ( FunctionType * fftype = getFunctionType( formalType ) ) {
128 if ( fftype->isTtype() ) return true;
129 // conversion of 0 (null) to function type does not require tuple specialization
130 if ( dynamic_cast< ZeroType * >( actualType ) ) return false;
131 FunctionType * aftype = getFunctionType( actualType->stripReferences() );
132 assertf( aftype, "formal type is a function type, but actual type is not: %s", toString( actualType ).c_str() );
133 // Can't tuple specialize if parameter sizes deeply-differ.
134 if ( functionParameterSize( fftype ) != functionParameterSize( aftype ) ) return false;
135 // tuple-parameter sizes are the same, but actual parameter sizes differ - must tuple specialize
136 if ( fftype->parameters.size() != aftype->parameters.size() ) return true;
137 // total parameter size can be the same, while individual parameters can have different structure
138 for ( auto params : group_iterate( fftype->parameters, aftype->parameters ) ) {
139 DeclarationWithType * formal = std::get<0>(params);
140 DeclarationWithType * actual = std::get<1>(params);
141 if ( ! matchingTupleStructure( formal->get_type(), actual->get_type() ) ) return true;
142 }
143 }
144 return false;
145 }
146
147 bool needsSpecialization( Type *formalType, Type *actualType, TypeSubstitution *env ) {
148 return needsPolySpecialization( formalType, actualType, env ) || needsTupleSpecialization( formalType, actualType );
149 }
150
151 Expression * Specialize::doSpecialization( Type *formalType, Expression *actual, InferredParams *inferParams ) {
152 assertf( actual->result, "attempting to specialize an untyped expression" );
153 if ( needsSpecialization( formalType, actual->get_result(), env ) ) {
154 if ( FunctionType *funType = getFunctionType( formalType ) ) {
155 if ( ApplicationExpr * appExpr = dynamic_cast<ApplicationExpr*>( actual ) ) {
156 return createThunkFunction( funType, appExpr->get_function(), inferParams );
157 } else if ( VariableExpr * 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 /// Generates a thunk that calls `actual` with type `funType` and returns its address
203 Expression * Specialize::createThunkFunction( FunctionType *funType, Expression *actual, InferredParams *inferParams ) {
204 static UniqueName thunkNamer( "_thunk" );
205
206 FunctionType *newType = funType->clone();
207 if ( env ) {
208 // it is important to replace only occurrences of type variables that occur free in the
209 // thunk's type
210 env->applyFree( newType );
211 } // if
212 // create new thunk with same signature as formal type (C linkage, empty body)
213 FunctionDecl *thunkFunc = new FunctionDecl( thunkNamer.newName(), Type::StorageClasses(), LinkageSpec::C, newType, new CompoundStmt() );
214 thunkFunc->fixUniqueId();
215
216 // thunks may be generated and not used - silence warning with attribute
217 thunkFunc->get_attributes().push_back( new Attribute( "unused" ) );
218
219 // thread thunk parameters into call to actual function, naming thunk parameters as we go
220 UniqueName paramNamer( paramPrefix );
221 ApplicationExpr *appExpr = new ApplicationExpr( actual );
222
223 FunctionType * actualType = getFunctionType( actual->get_result() )->clone();
224 if ( env ) {
225 // need to apply the environment to the actual function's type, since it may itself be polymorphic
226 env->apply( actualType );
227 }
228 std::unique_ptr< FunctionType > actualTypeManager( actualType ); // for RAII
229 std::list< DeclarationWithType * >::iterator actualBegin = actualType->get_parameters().begin();
230 std::list< DeclarationWithType * >::iterator actualEnd = actualType->get_parameters().end();
231
232 std::list< Expression * > args;
233 for ( DeclarationWithType* param : thunkFunc->get_functionType()->get_parameters() ) {
234 // name each thunk parameter and explode it - these are then threaded back into the actual function call.
235 param->set_name( paramNamer.newName() );
236 explodeSimple( new VariableExpr( param ), back_inserter( args ) );
237 }
238
239 // walk parameters to the actual function alongside the exploded thunk parameters and restructure the arguments to match the actual parameters.
240 std::list< Expression * >::iterator argBegin = args.begin(), argEnd = args.end();
241 for ( ; actualBegin != actualEnd; ++actualBegin ) {
242 structureArg( (*actualBegin)->get_type(), argBegin, argEnd, back_inserter( appExpr->get_args() ) );
243 }
244
245 appExpr->env = TypeSubstitution::newFromExpr( appExpr, env );
246 if ( inferParams ) {
247 appExpr->inferParams = *inferParams;
248 } // if
249
250 // handle any specializations that may still be present
251 std::string oldParamPrefix = paramPrefix;
252 paramPrefix += "p";
253 // save stmtsToAddBefore in oldStmts
254 std::list< Statement* > oldStmts;
255 oldStmts.splice( oldStmts.end(), stmtsToAddBefore );
256 appExpr->acceptMutator( *visitor );
257 paramPrefix = oldParamPrefix;
258 // write any statements added for recursive specializations into the thunk body
259 thunkFunc->statements->kids.splice( thunkFunc->statements->kids.end(), stmtsToAddBefore );
260 // restore oldStmts into stmtsToAddBefore
261 stmtsToAddBefore.splice( stmtsToAddBefore.end(), oldStmts );
262
263 // add return (or valueless expression) to the thunk
264 Statement *appStmt;
265 if ( funType->returnVals.empty() ) {
266 appStmt = new ExprStmt( appExpr );
267 } else {
268 appStmt = new ReturnStmt( appExpr );
269 } // if
270 thunkFunc->statements->kids.push_back( appStmt );
271
272 // add thunk definition to queue of statements to add
273 stmtsToAddBefore.push_back( new DeclStmt( thunkFunc ) );
274 // return address of thunk function as replacement expression
275 return new AddressExpr( new VariableExpr( thunkFunc ) );
276 }
277
278 void Specialize::handleExplicitParams( ApplicationExpr *appExpr ) {
279 // create thunks for the explicit parameters
280 assert( appExpr->function->result );
281 FunctionType *function = getFunctionType( appExpr->function->result );
282 assert( function );
283 std::list< DeclarationWithType* >::iterator formal;
284 std::list< Expression* >::iterator actual;
285 for ( formal = function->get_parameters().begin(), actual = appExpr->get_args().begin(); formal != function->get_parameters().end() && actual != appExpr->get_args().end(); ++formal, ++actual ) {
286 *actual = doSpecialization( (*formal)->get_type(), *actual, &appExpr->inferParams );
287 }
288 }
289
290 Expression * Specialize::postmutate( ApplicationExpr *appExpr ) {
291 if ( ! InitTweak::isIntrinsicCallExpr( appExpr ) ) {
292 // create thunks for the inferred parameters
293 // don't need to do this for intrinsic calls, because they aren't actually passed
294 // need to handle explicit params before inferred params so that explicit params do not recieve a changed set of inferParams (and change them again)
295 // alternatively, if order starts to matter then copy appExpr's inferParams and pass them to handleExplicitParams.
296 handleExplicitParams( appExpr );
297 for ( InferredParams::iterator inferParam = appExpr->inferParams.begin(); inferParam != appExpr->inferParams.end(); ++inferParam ) {
298 inferParam->second.expr = doSpecialization( inferParam->second.formalType, inferParam->second.expr, &inferParam->second.expr->inferParams );
299 }
300 }
301 return appExpr;
302 }
303
304 Expression * Specialize::postmutate( CastExpr *castExpr ) {
305 if ( castExpr->result->isVoid() ) {
306 // can't specialize if we don't have a return value
307 return castExpr;
308 }
309 Expression *specialized = doSpecialization( castExpr->result, castExpr->arg, &castExpr->inferParams );
310 if ( specialized != castExpr->arg ) {
311 // assume here that the specialization incorporates the cast
312 return specialized;
313 } else {
314 return castExpr;
315 }
316 }
317
318 void convertSpecializations( std::list< Declaration* >& translationUnit ) {
319 PassVisitor<Specialize> spec;
320 mutateAll( translationUnit, spec );
321 }
322} // namespace GenPoly
323
324// Local Variables: //
325// tab-width: 4 //
326// mode: c++ //
327// compile-command: "make install" //
328// End: //
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