source: src/Tuples/TupleExpansion.cc@ 490ff5c3

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 490ff5c3 was f240484, checked in by Rob Schluntz <rschlunt@…>, 8 years ago

Convert MemberTupleExpander to PassVisitor
  • Property mode set to 100644
File size: 14.7 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 : Wed Jun 21 17:35:04 2017
13// Update Count : 19
14//
15
16#include <stddef.h> // for size_t
17#include <cassert> // for assert
18#include <list> // for list
19
20#include "Common/PassVisitor.h" // for PassVisitor, WithDeclsToAdd, WithGu...
21#include "Common/ScopedMap.h" // for ScopedMap
22#include "Common/utility.h" // for CodeLocation
23#include "InitTweak/InitTweak.h" // for getFunction
24#include "Parser/LinkageSpec.h" // for Spec, C, Intrinsic
25#include "SynTree/Constant.h" // for Constant
26#include "SynTree/Declaration.h" // for StructDecl, DeclarationWithType
27#include "SynTree/Expression.h" // for UntypedMemberExpr, Expression, Uniq...
28#include "SynTree/Label.h" // for operator==, Label
29#include "SynTree/Mutator.h" // for Mutator
30#include "SynTree/Type.h" // for Type, Type::Qualifiers, TupleType
31#include "SynTree/Visitor.h" // for Visitor
32
33class CompoundStmt;
34class TypeSubstitution;
35
36namespace Tuples {
37 namespace {
38 struct MemberTupleExpander final : public WithShortCircuiting, public WithVisitorRef<MemberTupleExpander> {
39 void premutate( UntypedMemberExpr * ) { visit_children = false; }
40 Expression * postmutate( UntypedMemberExpr * memberExpr );
41 };
42
43 struct UniqueExprExpander final : public WithDeclsToAdd {
44 Expression * postmutate( UniqueExpr * unqExpr );
45
46 std::map< int, Expression * > decls; // not vector, because order added may not be increasing order
47
48 ~UniqueExprExpander() {
49 for ( std::pair<const int, Expression *> & p : decls ) {
50 delete p.second;
51 }
52 }
53 };
54
55 struct TupleAssignExpander {
56 Expression * postmutate( TupleAssignExpr * tupleExpr );
57 };
58
59 struct TupleTypeReplacer : public WithDeclsToAdd, public WithGuards, public WithTypeSubstitution {
60 Type * postmutate( TupleType * tupleType );
61
62 void premutate( CompoundStmt * ) {
63 GuardScope( typeMap );
64 }
65 private:
66 ScopedMap< int, StructDecl * > typeMap;
67 };
68
69 struct TupleIndexExpander {
70 Expression * postmutate( TupleIndexExpr * tupleExpr );
71 };
72
73 struct TupleExprExpander final {
74 Expression * postmutate( TupleExpr * tupleExpr );
75 };
76 }
77
78 void expandMemberTuples( std::list< Declaration * > & translationUnit ) {
79 PassVisitor<MemberTupleExpander> expander;
80 mutateAll( translationUnit, expander );
81 }
82
83 void expandUniqueExpr( std::list< Declaration * > & translationUnit ) {
84 PassVisitor<UniqueExprExpander> unqExpander;
85 mutateAll( translationUnit, unqExpander );
86 }
87
88 void expandTuples( std::list< Declaration * > & translationUnit ) {
89 PassVisitor<TupleAssignExpander> assnExpander;
90 mutateAll( translationUnit, assnExpander );
91
92 PassVisitor<TupleTypeReplacer> replacer;
93 mutateAll( translationUnit, replacer );
94
95 PassVisitor<TupleIndexExpander> idxExpander;
96 mutateAll( translationUnit, idxExpander );
97
98 PassVisitor<TupleExprExpander> exprExpander;
99 mutateAll( translationUnit, exprExpander );
100 }
101
102 namespace {
103 /// given a expression representing the member and an expression representing the aggregate,
104 /// reconstructs a flattened UntypedMemberExpr with the right precedence
105 Expression * reconstructMemberExpr( Expression * member, Expression * aggr, CodeLocation & loc ) {
106 if ( UntypedMemberExpr * memberExpr = dynamic_cast< UntypedMemberExpr * >( member ) ) {
107 // construct a new UntypedMemberExpr with the correct structure , and recursively
108 // expand that member expression.
109 PassVisitor<MemberTupleExpander> expander;
110 UntypedMemberExpr * inner = new UntypedMemberExpr( memberExpr->aggregate, aggr->clone() );
111 UntypedMemberExpr * newMemberExpr = new UntypedMemberExpr( memberExpr->member, inner );
112 inner->location = newMemberExpr->location = loc;
113 memberExpr->member = nullptr;
114 memberExpr->aggregate = nullptr;
115 delete memberExpr;
116 return newMemberExpr->acceptMutator( expander );
117 } else {
118 // not a member expression, so there is nothing to do but attach and return
119 UntypedMemberExpr * newMemberExpr = new UntypedMemberExpr( member, aggr->clone() );
120 newMemberExpr->location = loc;
121 return newMemberExpr;
122 }
123 }
124 }
125
126 Expression * MemberTupleExpander::postmutate( UntypedMemberExpr * memberExpr ) {
127 if ( UntypedTupleExpr * tupleExpr = dynamic_cast< UntypedTupleExpr * > ( memberExpr->member ) ) {
128 Expression * aggr = memberExpr->aggregate->clone()->acceptMutator( *visitor );
129 // aggregate expressions which might be impure must be wrapped in unique expressions
130 // xxx - if there's a member-tuple expression nested in the aggregate, this currently generates the wrong code if a UniqueExpr is not used, and it's purely an optimization to remove the UniqueExpr
131 // if ( Tuples::maybeImpureIgnoreUnique( memberExpr->get_aggregate() ) ) aggr = new UniqueExpr( aggr );
132 aggr = new UniqueExpr( aggr );
133 for ( Expression *& expr : tupleExpr->exprs ) {
134 expr = reconstructMemberExpr( expr, aggr, memberExpr->location );
135 expr->location = memberExpr->location;
136 }
137 delete aggr;
138 tupleExpr->location = memberExpr->location;
139 return tupleExpr;
140 } else {
141 // there may be a tuple expr buried in the aggregate
142 // xxx - this is a memory leak
143 UntypedMemberExpr * newMemberExpr = new UntypedMemberExpr( memberExpr->member->clone(), memberExpr->aggregate->acceptMutator( *visitor ) );
144 newMemberExpr->location = memberExpr->location;
145 return newMemberExpr;
146 }
147 }
148
149 Expression * UniqueExprExpander::postmutate( UniqueExpr * unqExpr ) {
150 const int id = unqExpr->get_id();
151
152 // on first time visiting a unique expr with a particular ID, generate the expression that replaces all UniqueExprs with that ID,
153 // and lookup on subsequent hits. This ensures that all unique exprs with the same ID reference the same variable.
154 if ( ! decls.count( id ) ) {
155 Expression * assignUnq;
156 Expression * var = unqExpr->get_var();
157 if ( unqExpr->get_object() ) {
158 // an object was generated to represent this unique expression -- it should be added to the list of declarations now
159 declsToAddBefore.push_back( unqExpr->get_object() );
160 unqExpr->set_object( nullptr );
161 // steal the expr from the unqExpr
162 assignUnq = UntypedExpr::createAssign( unqExpr->get_var()->clone(), unqExpr->get_expr() );
163 unqExpr->set_expr( nullptr );
164 } else {
165 // steal the already generated assignment to var from the unqExpr - this has been generated by FixInit
166 Expression * expr = unqExpr->get_expr();
167 CommaExpr * commaExpr = strict_dynamic_cast< CommaExpr * >( expr );
168 assignUnq = commaExpr->get_arg1();
169 commaExpr->set_arg1( nullptr );
170 }
171 ObjectDecl * finished = new ObjectDecl( toString( "_unq", id, "_finished_" ), Type::StorageClasses(), LinkageSpec::Cforall, nullptr, new BasicType( Type::Qualifiers(), BasicType::Bool ),
172 new SingleInit( new ConstantExpr( Constant::from_int( 0 ) ) ) );
173 declsToAddBefore.push_back( finished );
174 // (finished ? _unq_expr_N : (_unq_expr_N = <unqExpr->get_expr()>, finished = 1, _unq_expr_N))
175 // This pattern ensures that each unique expression is evaluated once, regardless of evaluation order of the generated C code.
176 Expression * assignFinished = UntypedExpr::createAssign( new VariableExpr(finished), new ConstantExpr( Constant::from_int( 1 ) ) );
177 ConditionalExpr * condExpr = new ConditionalExpr( new VariableExpr( finished ), var->clone(),
178 new CommaExpr( new CommaExpr( assignUnq, assignFinished ), var->clone() ) );
179 condExpr->set_result( var->get_result()->clone() );
180 condExpr->set_env( maybeClone( unqExpr->get_env() ) );
181 decls[id] = condExpr;
182 }
183 delete unqExpr;
184 return decls[id]->clone();
185 }
186
187 Expression * TupleAssignExpander::postmutate( TupleAssignExpr * assnExpr ) {
188 StmtExpr * ret = assnExpr->get_stmtExpr();
189 assnExpr->set_stmtExpr( nullptr );
190 // move env to StmtExpr
191 ret->set_env( assnExpr->get_env() );
192 assnExpr->set_env( nullptr );
193 delete assnExpr;
194 return ret;
195 }
196
197 Type * TupleTypeReplacer::postmutate( TupleType * tupleType ) {
198 unsigned tupleSize = tupleType->size();
199 if ( ! typeMap.count( tupleSize ) ) {
200 // generate struct type to replace tuple type based on the number of components in the tuple
201 StructDecl * decl = new StructDecl( toString( "_tuple", tupleSize, "_" ) );
202 decl->location = tupleType->location;
203 decl->set_body( true );
204 for ( size_t i = 0; i < tupleSize; ++i ) {
205 TypeDecl * tyParam = new TypeDecl( toString( "tuple_param_", tupleSize, "_", i ), Type::StorageClasses(), nullptr, TypeDecl::Dtype, true );
206 decl->get_members().push_back( new ObjectDecl( toString("field_", i ), Type::StorageClasses(), LinkageSpec::C, nullptr, new TypeInstType( Type::Qualifiers(), tyParam->get_name(), tyParam ), nullptr ) );
207 decl->get_parameters().push_back( tyParam );
208 }
209 if ( tupleSize == 0 ) {
210 // empty structs are not standard C. Add a dummy field to empty tuples to silence warnings when a compound literal Tuple0 is created.
211 decl->get_members().push_back( new ObjectDecl( "dummy", Type::StorageClasses(), LinkageSpec::C, nullptr, new BasicType( Type::Qualifiers(), BasicType::SignedInt ), nullptr ) );
212 }
213 typeMap[tupleSize] = decl;
214 declsToAddBefore.push_back( decl );
215 }
216 Type::Qualifiers qualifiers = tupleType->get_qualifiers();
217
218 StructDecl * decl = typeMap[tupleSize];
219 StructInstType * newType = new StructInstType( qualifiers, decl );
220 for ( auto p : group_iterate( tupleType->get_types(), decl->get_parameters() ) ) {
221 Type * t = std::get<0>(p);
222 newType->get_parameters().push_back( new TypeExpr( t->clone() ) );
223 }
224 delete tupleType;
225 return newType;
226 }
227
228 Expression * TupleIndexExpander::postmutate( TupleIndexExpr * tupleExpr ) {
229 Expression * tuple = tupleExpr->get_tuple();
230 assert( tuple );
231 tupleExpr->set_tuple( nullptr );
232 unsigned int idx = tupleExpr->get_index();
233 TypeSubstitution * env = tupleExpr->get_env();
234 tupleExpr->set_env( nullptr );
235 delete tupleExpr;
236
237 StructInstType * type = strict_dynamic_cast< StructInstType * >( tuple->get_result() );
238 StructDecl * structDecl = type->get_baseStruct();
239 assert( structDecl->get_members().size() > idx );
240 Declaration * member = *std::next(structDecl->get_members().begin(), idx);
241 MemberExpr * memExpr = new MemberExpr( strict_dynamic_cast< DeclarationWithType * >( member ), tuple );
242 memExpr->set_env( env );
243 return memExpr;
244 }
245
246 Expression * replaceTupleExpr( Type * result, const std::list< Expression * > & exprs, TypeSubstitution * env ) {
247 if ( result->isVoid() ) {
248 // void result - don't need to produce a value for cascading - just output a chain of comma exprs
249 assert( ! exprs.empty() );
250 std::list< Expression * >::const_iterator iter = exprs.begin();
251 Expression * expr = new CastExpr( *iter++ );
252 for ( ; iter != exprs.end(); ++iter ) {
253 expr = new CommaExpr( expr, new CastExpr( *iter ) );
254 }
255 expr->set_env( env );
256 return expr;
257 } else {
258 // typed tuple expression - produce a compound literal which performs each of the expressions
259 // as a distinct part of its initializer - the produced compound literal may be used as part of
260 // another expression
261 std::list< Initializer * > inits;
262 for ( Expression * expr : exprs ) {
263 inits.push_back( new SingleInit( expr ) );
264 }
265 Expression * expr = new CompoundLiteralExpr( result, new ListInit( inits ) );
266 expr->set_env( env );
267 return expr;
268 }
269 }
270
271 Expression * TupleExprExpander::postmutate( TupleExpr * tupleExpr ) {
272 Type * result = tupleExpr->get_result();
273 std::list< Expression * > exprs = tupleExpr->get_exprs();
274 assert( result );
275 TypeSubstitution * env = tupleExpr->get_env();
276
277 // remove data from shell and delete it
278 tupleExpr->set_result( nullptr );
279 tupleExpr->get_exprs().clear();
280 tupleExpr->set_env( nullptr );
281 delete tupleExpr;
282
283 return replaceTupleExpr( result, exprs, env );
284 }
285
286 Type * makeTupleType( const std::list< Expression * > & exprs ) {
287 // produce the TupleType which aggregates the types of the exprs
288 std::list< Type * > types;
289 Type::Qualifiers qualifiers( Type::Const | Type::Volatile | Type::Restrict | Type::Lvalue | Type::Atomic | Type::Mutex );
290 for ( Expression * expr : exprs ) {
291 assert( expr->get_result() );
292 if ( expr->get_result()->isVoid() ) {
293 // if the type of any expr is void, the type of the entire tuple is void
294 return new VoidType( Type::Qualifiers() );
295 }
296 Type * type = expr->get_result()->clone();
297 types.push_back( type );
298 // the qualifiers on the tuple type are the qualifiers that exist on all component types
299 qualifiers &= type->get_qualifiers();
300 } // for
301 if ( exprs.empty() ) qualifiers = Type::Qualifiers();
302 return new TupleType( qualifiers, types );
303 }
304
305 TypeInstType * isTtype( Type * type ) {
306 if ( TypeInstType * inst = dynamic_cast< TypeInstType * >( type ) ) {
307 if ( inst->get_baseType() && inst->get_baseType()->get_kind() == TypeDecl::Ttype ) {
308 return inst;
309 }
310 }
311 return nullptr;
312 }
313
314 namespace {
315 /// determines if impurity (read: side-effects) may exist in a piece of code. Currently gives a very crude approximation, wherein any function call expression means the code may be impure
316 struct ImpurityDetector : public WithShortCircuiting {
317 ImpurityDetector( bool ignoreUnique ) : ignoreUnique( ignoreUnique ) {}
318
319 void previsit( ApplicationExpr * appExpr ) {
320 visit_children = false;
321 if ( DeclarationWithType * function = InitTweak::getFunction( appExpr ) ) {
322 if ( function->get_linkage() == LinkageSpec::Intrinsic ) {
323 if ( function->get_name() == "*?" || function->get_name() == "?[?]" ) {
324 // intrinsic dereference, subscript are pure, but need to recursively look for impurity
325 visit_children = true;
326 return;
327 }
328 }
329 }
330 maybeImpure = true;
331 }
332 void previsit( UntypedExpr * ) { maybeImpure = true; visit_children = false; }
333 void previsit( UniqueExpr * ) {
334 if ( ignoreUnique ) {
335 // bottom out at unique expression.
336 // The existence of a unique expression doesn't change the purity of an expression.
337 // That is, even if the wrapped expression is impure, the wrapper protects the rest of the expression.
338 visit_children = false;
339 return;
340 }
341 }
342
343 bool maybeImpure = false;
344 bool ignoreUnique;
345 };
346 } // namespace
347
348 bool maybeImpure( Expression * expr ) {
349 PassVisitor<ImpurityDetector> detector( false );
350 expr->accept( detector );
351 return detector.pass.maybeImpure;
352 }
353
354 bool maybeImpureIgnoreUnique( Expression * expr ) {
355 PassVisitor<ImpurityDetector> detector( true );
356 expr->accept( detector );
357 return detector.pass.maybeImpure;
358 }
359} // namespace Tuples
360
361// Local Variables: //
362// tab-width: 4 //
363// mode: c++ //
364// compile-command: "make install" //
365// End: //
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