source: src/Tuples/TupleAssignment.cc@ f1aeede

ADT aaron-thesis arm-eh ast-experimental cleanup-dtors deferred_resn enum forall-pointer-decay jacob/cs343-translation jenkins-sandbox new-ast new-ast-unique-expr no_list persistent-indexer pthread-emulation qualifiedEnum
Last change on this file since f1aeede was 753bf60, checked in by Rob Schluntz <rschlunt@…>, 7 years ago

Resolve RHS tuple assignment alternative with cast to include missing type bindings
  • Property mode set to 100644
File size: 14.8 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// TupleAssignment.cc --
8//
9// Author : Rodolfo G. Esteves
10// Created On : Mon May 18 07:44:20 2015
11// Last Modified By : Peter A. Buhr
12// Last Modified On : Fri Mar 17 09:43:03 2017
13// Update Count : 8
14//
15
16#include <algorithm> // for transform
17#include <cassert> // for assert
18#include <iterator> // for back_insert_iterator, back...
19#include <list> // for _List_const_iterator, _Lis...
20#include <memory> // for unique_ptr, allocator_trai...
21#include <string> // for string
22#include <vector>
23
24#include "CodeGen/OperatorTable.h"
25#include "Common/PassVisitor.h"
26#include "Common/UniqueName.h" // for UniqueName
27#include "Common/utility.h" // for zipWith
28#include "Explode.h" // for explode
29#include "InitTweak/GenInit.h" // for genCtorInit
30#include "InitTweak/InitTweak.h" // for getPointerBase, isAssignment
31#include "Parser/LinkageSpec.h" // for Cforall
32#include "ResolvExpr/Alternative.h" // for AltList, Alternative
33#include "ResolvExpr/AlternativeFinder.h" // for AlternativeFinder, simpleC...
34#include "ResolvExpr/Cost.h" // for Cost
35#include "ResolvExpr/Resolver.h" // for resolveCtorInit
36#include "ResolvExpr/TypeEnvironment.h" // for TypeEnvironment
37#include "ResolvExpr/typeops.h" // for combos
38#include "SynTree/Declaration.h" // for ObjectDecl
39#include "SynTree/Expression.h" // for Expression, CastExpr, Name...
40#include "SynTree/Initializer.h" // for ConstructorInit, SingleInit
41#include "SynTree/Statement.h" // for ExprStmt
42#include "SynTree/Type.h" // for Type, Type::Qualifiers
43#include "SynTree/TypeSubstitution.h" // for TypeSubstitution
44#include "SynTree/Visitor.h" // for Visitor
45
46#if 0
47#define PRINT(x) x
48#else
49#define PRINT(x)
50#endif
51
52namespace Tuples {
53 class TupleAssignSpotter {
54 public:
55 // dispatcher for Tuple (multiple and mass) assignment operations
56 TupleAssignSpotter( ResolvExpr::AlternativeFinder & );
57 void spot( UntypedExpr * expr, std::vector<ResolvExpr::AlternativeFinder> &args );
58
59 private:
60 void match();
61
62 struct Matcher {
63 public:
64 Matcher( TupleAssignSpotter &spotter, const ResolvExpr::AltList& lhs, const
65 ResolvExpr::AltList& rhs );
66 virtual ~Matcher() {}
67 virtual void match( std::list< Expression * > &out ) = 0;
68 ObjectDecl * newObject( UniqueName & namer, Expression * expr );
69 ResolvExpr::AltList lhs, rhs;
70 TupleAssignSpotter &spotter;
71 ResolvExpr::Cost baseCost;
72 std::list< ObjectDecl * > tmpDecls;
73 ResolvExpr::TypeEnvironment compositeEnv;
74 };
75
76 struct MassAssignMatcher : public Matcher {
77 public:
78 MassAssignMatcher( TupleAssignSpotter &spotter, const ResolvExpr::AltList& lhs,
79 const ResolvExpr::AltList& rhs ) : Matcher(spotter, lhs, rhs) {}
80 virtual void match( std::list< Expression * > &out );
81 };
82
83 struct MultipleAssignMatcher : public Matcher {
84 public:
85 MultipleAssignMatcher( TupleAssignSpotter &spotter, const ResolvExpr::AltList& lhs,
86 const ResolvExpr::AltList& rhs ) : Matcher(spotter, lhs, rhs) {}
87 virtual void match( std::list< Expression * > &out );
88 };
89
90 ResolvExpr::AlternativeFinder &currentFinder;
91 std::string fname;
92 std::unique_ptr< Matcher > matcher;
93 };
94
95 /// true if expr is an expression of tuple type
96 bool isTuple( Expression *expr ) {
97 if ( ! expr ) return false;
98 assert( expr->result );
99 return dynamic_cast< TupleType * >( expr->get_result()->stripReferences() );
100 }
101
102 template< typename AltIter >
103 bool isMultAssign( AltIter begin, AltIter end ) {
104 // multiple assignment if more than one alternative in the range or if
105 // the alternative is a tuple
106 if ( begin == end ) return false;
107 if ( isTuple( begin->expr ) ) return true;
108 return ++begin != end;
109 }
110
111 bool refToTuple( Expression *expr ) {
112 assert( expr->get_result() );
113 // also check for function returning tuple of reference types
114 if ( CastExpr * castExpr = dynamic_cast< CastExpr * >( expr ) ) {
115 return refToTuple( castExpr->get_arg() );
116 } else {
117 return isTuple( expr );
118 }
119 return false;
120 }
121
122 void handleTupleAssignment( ResolvExpr::AlternativeFinder & currentFinder, UntypedExpr * expr,
123 std::vector<ResolvExpr::AlternativeFinder> &args ) {
124 TupleAssignSpotter spotter( currentFinder );
125 spotter.spot( expr, args );
126 }
127
128 TupleAssignSpotter::TupleAssignSpotter( ResolvExpr::AlternativeFinder &f )
129 : currentFinder(f) {}
130
131 void TupleAssignSpotter::spot( UntypedExpr * expr,
132 std::vector<ResolvExpr::AlternativeFinder> &args ) {
133 if ( NameExpr *op = dynamic_cast< NameExpr * >(expr->get_function()) ) {
134 if ( CodeGen::isCtorDtorAssign( op->get_name() ) ) {
135 fname = op->get_name();
136
137 // AlternativeFinder will naturally handle this case case, if it's legal
138 if ( args.size() == 0 ) return;
139
140 // if an assignment only takes 1 argument, that's odd, but maybe someone wrote
141 // the function, in which case AlternativeFinder will handle it normally
142 if ( args.size() == 1 && CodeGen::isAssignment( fname ) ) return;
143
144 // look over all possible left-hand-sides
145 for ( ResolvExpr::Alternative& lhsAlt : args[0] ) {
146 // skip non-tuple LHS
147 if ( ! refToTuple(lhsAlt.expr) ) continue;
148
149 // explode is aware of casts - ensure every LHS expression is sent into explode
150 // with a reference cast
151 // xxx - this seems to change the alternatives before the normal
152 // AlternativeFinder flow; maybe this is desired?
153 if ( ! dynamic_cast<CastExpr*>( lhsAlt.expr ) ) {
154 lhsAlt.expr = new CastExpr( lhsAlt.expr,
155 new ReferenceType( Type::Qualifiers(),
156 lhsAlt.expr->result->clone() ) );
157 }
158
159 // explode the LHS so that each field of a tuple-valued-expr is assigned
160 ResolvExpr::AltList lhs;
161 explode( lhsAlt, currentFinder.get_indexer(), back_inserter(lhs), true );
162 for ( ResolvExpr::Alternative& alt : lhs ) {
163 // each LHS value must be a reference - some come in with a cast expression,
164 // if not just cast to reference here
165 if ( ! dynamic_cast<ReferenceType*>( alt.expr->get_result() ) ) {
166 alt.expr = new CastExpr( alt.expr,
167 new ReferenceType( Type::Qualifiers(),
168 alt.expr->get_result()->clone() ) );
169 }
170 }
171
172 if ( args.size() == 1 ) {
173 // mass default-initialization/destruction
174 ResolvExpr::AltList rhs{};
175 matcher.reset( new MassAssignMatcher( *this, lhs, rhs ) );
176 match();
177 } else if ( args.size() > 2 ) {
178 // expand all possible RHS possibilities
179 // TODO build iterative version of this instead of using combos
180 std::vector< ResolvExpr::AltList > rhsAlts;
181 combos( std::next(args.begin(), 1), args.end(),
182 std::back_inserter( rhsAlts ) );
183 for ( const ResolvExpr::AltList& rhsAlt : rhsAlts ) {
184 // multiple assignment
185 ResolvExpr::AltList rhs;
186 explode( rhsAlt, currentFinder.get_indexer(),
187 std::back_inserter(rhs), true );
188 matcher.reset( new MultipleAssignMatcher( *this, lhs, rhs ) );
189 match();
190 }
191 } else {
192 for ( const ResolvExpr::Alternative& rhsAlt : args[1] ) {
193 ResolvExpr::AltList rhs;
194 if ( isTuple(rhsAlt.expr) ) {
195 // multiple assignment
196 explode( rhsAlt, currentFinder.get_indexer(),
197 std::back_inserter(rhs), true );
198 matcher.reset( new MultipleAssignMatcher( *this, lhs, rhs ) );
199 } else {
200 // mass assignment
201 rhs.push_back( rhsAlt );
202 matcher.reset( new MassAssignMatcher( *this, lhs, rhs ) );
203 }
204 match();
205 }
206 }
207 }
208 }
209 }
210 }
211
212 void TupleAssignSpotter::match() {
213 assert ( matcher != 0 );
214
215 std::list< Expression * > new_assigns;
216 matcher->match( new_assigns );
217
218 if ( ! matcher->lhs.empty() || ! matcher->rhs.empty() ) {
219 // if both lhs and rhs are empty then this is the empty tuple case, wherein it's okay for new_assigns to be empty.
220 // if not the empty tuple case, return early so that no new alternatives are generated.
221 if ( new_assigns.empty() ) return;
222 }
223 ResolvExpr::AltList current;
224 // now resolve new assignments
225 for ( std::list< Expression * >::iterator i = new_assigns.begin();
226 i != new_assigns.end(); ++i ) {
227 PRINT(
228 std::cerr << "== resolving tuple assign ==" << std::endl;
229 std::cerr << *i << std::endl;
230 )
231
232 ResolvExpr::AlternativeFinder finder{ currentFinder.get_indexer(),
233 matcher->compositeEnv };
234
235 try {
236 finder.findWithAdjustment(*i);
237 } catch (...) {
238 return; // no match should not mean failure, it just means this particular tuple assignment isn't valid
239 }
240 // prune expressions that don't coincide with
241 ResolvExpr::AltList alts = finder.get_alternatives();
242 assert( alts.size() == 1 );
243 assert( alts.front().expr != 0 );
244 current.push_back( alts.front() );
245 }
246
247 // extract expressions from the assignment alternatives to produce a list of assignments that
248 // together form a single alternative
249 std::list< Expression *> solved_assigns;
250 for ( ResolvExpr::Alternative & alt : current ) {
251 solved_assigns.push_back( alt.expr->clone() );
252 }
253 // combine assignment environments into combined expression environment
254 simpleCombineEnvironments( current.begin(), current.end(), matcher->compositeEnv );
255 // xxx -- was push_front
256 currentFinder.get_alternatives().push_back( ResolvExpr::Alternative(
257 new TupleAssignExpr(solved_assigns, matcher->tmpDecls), matcher->compositeEnv,
258 ResolvExpr::sumCost( current ) + matcher->baseCost ) );
259 }
260
261 TupleAssignSpotter::Matcher::Matcher( TupleAssignSpotter &spotter,
262 const ResolvExpr::AltList &lhs, const ResolvExpr::AltList &rhs )
263 : lhs(lhs), rhs(rhs), spotter(spotter),
264 baseCost( ResolvExpr::sumCost( lhs ) + ResolvExpr::sumCost( rhs ) ) {
265 simpleCombineEnvironments( lhs.begin(), lhs.end(), compositeEnv );
266 simpleCombineEnvironments( rhs.begin(), rhs.end(), compositeEnv );
267 }
268
269 UntypedExpr * createFunc( const std::string &fname, ObjectDecl *left, ObjectDecl *right ) {
270 assert( left );
271 std::list< Expression * > args;
272 args.push_back( new VariableExpr( left ) );
273 // args.push_back( new AddressExpr( new VariableExpr( left ) ) );
274 if ( right ) args.push_back( new VariableExpr( right ) );
275 if ( left->type->referenceDepth() > 1 && CodeGen::isConstructor( fname ) ) {
276 args.front() = new AddressExpr( args.front() );
277 if ( right ) args.back() = new AddressExpr( args.back() );
278 return new UntypedExpr( new NameExpr( "?=?" ), args );
279 } else {
280 return new UntypedExpr( new NameExpr( fname ), args );
281 }
282 }
283
284 // removes environments from subexpressions within statement exprs, which could throw off later passes like those in Box which rely on PolyMutator, and adds the bindings to the compositeEnv
285 // xxx - maybe this should happen in alternative finder for every StmtExpr?
286 struct EnvRemover {
287 void previsit( ExprStmt * stmt ) {
288 assert( compositeEnv );
289 if ( stmt->expr->env ) {
290 compositeEnv->add( *stmt->expr->env );
291 delete stmt->expr->env;
292 stmt->expr->env = nullptr;
293 }
294 }
295
296 ResolvExpr::TypeEnvironment * compositeEnv = nullptr;
297 };
298
299 ObjectDecl * TupleAssignSpotter::Matcher::newObject( UniqueName & namer, Expression * expr ) {
300 assert( expr->result && ! expr->get_result()->isVoid() );
301 ObjectDecl * ret = new ObjectDecl( namer.newName(), Type::StorageClasses(), LinkageSpec::Cforall, nullptr, expr->result->clone(), new SingleInit( expr->clone() ) );
302 // if expression type is a reference, don't need to construct anything, a simple initializer is sufficient.
303 if ( ! dynamic_cast< ReferenceType * >( expr->result ) ) {
304 ConstructorInit * ctorInit = InitTweak::genCtorInit( ret );
305 ret->init = ctorInit;
306 ResolvExpr::resolveCtorInit( ctorInit, spotter.currentFinder.get_indexer() ); // resolve ctor/dtors for the new object
307 PassVisitor<EnvRemover> rm; // remove environments from subexpressions of StmtExprs
308 rm.pass.compositeEnv = &compositeEnv;
309 ctorInit->accept( rm );
310 }
311 PRINT( std::cerr << "new object: " << ret << std::endl; )
312 return ret;
313 }
314
315 void TupleAssignSpotter::MassAssignMatcher::match( std::list< Expression * > &out ) {
316 static UniqueName lhsNamer( "__massassign_L" );
317 static UniqueName rhsNamer( "__massassign_R" );
318 // empty tuple case falls into this matcher, hence the second part of the assert
319 assert( (! lhs.empty() && rhs.size() <= 1) || (lhs.empty() && rhs.empty()) );
320
321 // xxx - may need to split this up into multiple declarations, because potential conversion to references
322 // probably should not reference local variable - see MultipleAssignMatcher::match
323 ObjectDecl * rtmp = rhs.size() == 1 ? newObject( rhsNamer, rhs.front().expr ) : nullptr;
324 for ( ResolvExpr::Alternative & lhsAlt : lhs ) {
325 // create a temporary object for each value in the lhs and create a call involving the rhs
326 ObjectDecl * ltmp = newObject( lhsNamer, lhsAlt.expr );
327 out.push_back( createFunc( spotter.fname, ltmp, rtmp ) );
328 tmpDecls.push_back( ltmp );
329 }
330 if ( rtmp ) tmpDecls.push_back( rtmp );
331 }
332
333 void TupleAssignSpotter::MultipleAssignMatcher::match( std::list< Expression * > &out ) {
334 static UniqueName lhsNamer( "__multassign_L" );
335 static UniqueName rhsNamer( "__multassign_R" );
336
337 if ( lhs.size() == rhs.size() ) {
338 // produce a new temporary object for each value in the lhs and rhs and pairwise create the calls
339 std::list< ObjectDecl * > ltmp;
340 std::list< ObjectDecl * > rtmp;
341 for ( auto p : group_iterate( lhs, rhs ) ) {
342 ResolvExpr::Alternative & lhsAlt = std::get<0>(p);
343 ResolvExpr::Alternative & rhsAlt = std::get<1>(p);
344 // convert RHS to LHS type minus one reference -- important for the case where LHS is && and RHS is lvalue, etc.
345 ReferenceType * lhsType = strict_dynamic_cast<ReferenceType *>( lhsAlt.expr->result );
346 rhsAlt.expr = new CastExpr( rhsAlt.expr, lhsType->base->clone() );
347 ObjectDecl * lobj = newObject( lhsNamer, lhsAlt.expr );
348 ObjectDecl * robj = newObject( rhsNamer, rhsAlt.expr );
349 out.push_back( createFunc(spotter.fname, lobj, robj) );
350 ltmp.push_back( lobj );
351 rtmp.push_back( robj );
352
353 // resolve the cast expression so that rhsAlt return type is bound by the cast type as needed, and transfer the resulting environment
354 ResolvExpr::AlternativeFinder finder{ spotter.currentFinder.get_indexer(), compositeEnv };
355 finder.findWithAdjustment( rhsAlt.expr );
356 assert( finder.get_alternatives().size() == 1 );
357 compositeEnv = std::move( finder.get_alternatives().front().env );
358 }
359 tmpDecls.splice( tmpDecls.end(), ltmp );
360 tmpDecls.splice( tmpDecls.end(), rtmp );
361 }
362 }
363} // namespace Tuples
364
365// Local Variables: //
366// tab-width: 4 //
367// mode: c++ //
368// compile-command: "make install" //
369// End: //
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