source: src/Tuples/TupleExpansion.cc@ f229fc2

new-env with_gc
Last change on this file since f229fc2 was 68f9c43, checked in by Aaron Moss <a3moss@…>, 8 years ago

First pass at delete removal
  • Property mode set to 100644
File size: 14.3 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// 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
49 struct TupleAssignExpander {
50 Expression * postmutate( TupleAssignExpr * tupleExpr );
51 };
52
53 struct TupleTypeReplacer : public WithDeclsToAdd, public WithGuards, public WithTypeSubstitution {
54 Type * postmutate( TupleType * tupleType );
55
56 void premutate( CompoundStmt * ) {
57 GuardScope( typeMap );
58 }
59 private:
60 ScopedMap< int, StructDecl * > typeMap;
61 };
62
63 struct TupleIndexExpander {
64 Expression * postmutate( TupleIndexExpr * tupleExpr );
65 };
66
67 struct TupleExprExpander final {
68 Expression * postmutate( TupleExpr * tupleExpr );
69 };
70 }
71
72 void expandMemberTuples( std::list< Declaration * > & translationUnit ) {
73 PassVisitor<MemberTupleExpander> expander;
74 mutateAll( translationUnit, expander );
75 }
76
77 void expandUniqueExpr( std::list< Declaration * > & translationUnit ) {
78 PassVisitor<UniqueExprExpander> unqExpander;
79 mutateAll( translationUnit, unqExpander );
80 }
81
82 void expandTuples( std::list< Declaration * > & translationUnit ) {
83 PassVisitor<TupleAssignExpander> assnExpander;
84 mutateAll( translationUnit, assnExpander );
85
86 PassVisitor<TupleTypeReplacer> replacer;
87 mutateAll( translationUnit, replacer );
88
89 PassVisitor<TupleIndexExpander> idxExpander;
90 mutateAll( translationUnit, idxExpander );
91
92 PassVisitor<TupleExprExpander> exprExpander;
93 mutateAll( translationUnit, exprExpander );
94 }
95
96 namespace {
97 /// given a expression representing the member and an expression representing the aggregate,
98 /// reconstructs a flattened UntypedMemberExpr with the right precedence
99 Expression * reconstructMemberExpr( Expression * member, Expression * aggr, CodeLocation & loc ) {
100 if ( UntypedMemberExpr * memberExpr = dynamic_cast< UntypedMemberExpr * >( member ) ) {
101 // construct a new UntypedMemberExpr with the correct structure , and recursively
102 // expand that member expression.
103 PassVisitor<MemberTupleExpander> expander;
104 UntypedMemberExpr * inner = new UntypedMemberExpr( memberExpr->aggregate, aggr->clone() );
105 UntypedMemberExpr * newMemberExpr = new UntypedMemberExpr( memberExpr->member, inner );
106 inner->location = newMemberExpr->location = loc;
107 return newMemberExpr->acceptMutator( expander );
108 } else {
109 // not a member expression, so there is nothing to do but attach and return
110 UntypedMemberExpr * newMemberExpr = new UntypedMemberExpr( member, aggr->clone() );
111 newMemberExpr->location = loc;
112 return newMemberExpr;
113 }
114 }
115 }
116
117 Expression * MemberTupleExpander::postmutate( UntypedMemberExpr * memberExpr ) {
118 if ( UntypedTupleExpr * tupleExpr = dynamic_cast< UntypedTupleExpr * > ( memberExpr->member ) ) {
119 Expression * aggr = memberExpr->aggregate->clone()->acceptMutator( *visitor );
120 // aggregate expressions which might be impure must be wrapped in unique expressions
121 // 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
122 // if ( Tuples::maybeImpureIgnoreUnique( memberExpr->get_aggregate() ) ) aggr = new UniqueExpr( aggr );
123 aggr = new UniqueExpr( aggr );
124 for ( Expression *& expr : tupleExpr->exprs ) {
125 expr = reconstructMemberExpr( expr, aggr, memberExpr->location );
126 expr->location = memberExpr->location;
127 }
128 tupleExpr->location = memberExpr->location;
129 return tupleExpr;
130 } else {
131 // there may be a tuple expr buried in the aggregate
132 // xxx - this is a memory leak
133 UntypedMemberExpr * newMemberExpr = new UntypedMemberExpr( memberExpr->member->clone(), memberExpr->aggregate->acceptMutator( *visitor ) );
134 newMemberExpr->location = memberExpr->location;
135 return newMemberExpr;
136 }
137 }
138
139 Expression * UniqueExprExpander::postmutate( UniqueExpr * unqExpr ) {
140 const int id = unqExpr->get_id();
141
142 // on first time visiting a unique expr with a particular ID, generate the expression that replaces all UniqueExprs with that ID,
143 // and lookup on subsequent hits. This ensures that all unique exprs with the same ID reference the same variable.
144 if ( ! decls.count( id ) ) {
145 Expression * assignUnq;
146 Expression * var = unqExpr->get_var();
147 if ( unqExpr->get_object() ) {
148 // an object was generated to represent this unique expression -- it should be added to the list of declarations now
149 declsToAddBefore.push_back( unqExpr->get_object() );
150 unqExpr->set_object( nullptr );
151 // steal the expr from the unqExpr
152 assignUnq = UntypedExpr::createAssign( unqExpr->get_var()->clone(), unqExpr->get_expr() );
153 unqExpr->set_expr( nullptr );
154 } else {
155 // steal the already generated assignment to var from the unqExpr - this has been generated by FixInit
156 Expression * expr = unqExpr->get_expr();
157 CommaExpr * commaExpr = strict_dynamic_cast< CommaExpr * >( expr );
158 assignUnq = commaExpr->get_arg1();
159 commaExpr->set_arg1( nullptr );
160 }
161 ObjectDecl * finished = new ObjectDecl( toString( "_unq", id, "_finished_" ), Type::StorageClasses(), LinkageSpec::Cforall, nullptr, new BasicType( Type::Qualifiers(), BasicType::Bool ),
162 new SingleInit( new ConstantExpr( Constant::from_int( 0 ) ) ) );
163 declsToAddBefore.push_back( finished );
164 // (finished ? _unq_expr_N : (_unq_expr_N = <unqExpr->get_expr()>, finished = 1, _unq_expr_N))
165 // This pattern ensures that each unique expression is evaluated once, regardless of evaluation order of the generated C code.
166 Expression * assignFinished = UntypedExpr::createAssign( new VariableExpr(finished), new ConstantExpr( Constant::from_int( 1 ) ) );
167 ConditionalExpr * condExpr = new ConditionalExpr( new VariableExpr( finished ), var->clone(),
168 new CommaExpr( new CommaExpr( assignUnq, assignFinished ), var->clone() ) );
169 condExpr->set_result( var->get_result()->clone() );
170 condExpr->set_env( maybeClone( unqExpr->get_env() ) );
171 decls[id] = condExpr;
172 }
173 return decls[id]->clone();
174 }
175
176 Expression * TupleAssignExpander::postmutate( TupleAssignExpr * assnExpr ) {
177 StmtExpr * ret = assnExpr->get_stmtExpr();
178 assnExpr->set_stmtExpr( nullptr );
179 // move env to StmtExpr
180 ret->set_env( assnExpr->get_env() );
181 assnExpr->set_env( nullptr );
182 return ret;
183 }
184
185 Type * TupleTypeReplacer::postmutate( TupleType * tupleType ) {
186 unsigned tupleSize = tupleType->size();
187 if ( ! typeMap.count( tupleSize ) ) {
188 // generate struct type to replace tuple type based on the number of components in the tuple
189 StructDecl * decl = new StructDecl( toString( "_tuple", tupleSize, "_" ) );
190 decl->location = tupleType->location;
191 decl->set_body( true );
192 for ( size_t i = 0; i < tupleSize; ++i ) {
193 TypeDecl * tyParam = new TypeDecl( toString( "tuple_param_", tupleSize, "_", i ), Type::StorageClasses(), nullptr, TypeDecl::Dtype, true );
194 decl->get_members().push_back( new ObjectDecl( toString("field_", i ), Type::StorageClasses(), LinkageSpec::C, nullptr, new TypeInstType( Type::Qualifiers(), tyParam->get_name(), tyParam ), nullptr ) );
195 decl->get_parameters().push_back( tyParam );
196 }
197 if ( tupleSize == 0 ) {
198 // empty structs are not standard C. Add a dummy field to empty tuples to silence warnings when a compound literal Tuple0 is created.
199 decl->get_members().push_back( new ObjectDecl( "dummy", Type::StorageClasses(), LinkageSpec::C, nullptr, new BasicType( Type::Qualifiers(), BasicType::SignedInt ), nullptr ) );
200 }
201 typeMap[tupleSize] = decl;
202 declsToAddBefore.push_back( decl );
203 }
204 Type::Qualifiers qualifiers = tupleType->get_qualifiers();
205
206 StructDecl * decl = typeMap[tupleSize];
207 StructInstType * newType = new StructInstType( qualifiers, decl );
208 for ( auto p : group_iterate( tupleType->get_types(), decl->get_parameters() ) ) {
209 Type * t = std::get<0>(p);
210 newType->get_parameters().push_back( new TypeExpr( t->clone() ) );
211 }
212 return newType;
213 }
214
215 Expression * TupleIndexExpander::postmutate( TupleIndexExpr * tupleExpr ) {
216 Expression * tuple = tupleExpr->get_tuple();
217 assert( tuple );
218 tupleExpr->set_tuple( nullptr );
219 unsigned int idx = tupleExpr->get_index();
220 TypeSubstitution * env = tupleExpr->get_env();
221 tupleExpr->set_env( nullptr );
222
223 StructInstType * type = strict_dynamic_cast< StructInstType * >( tuple->get_result() );
224 StructDecl * structDecl = type->get_baseStruct();
225 assert( structDecl->get_members().size() > idx );
226 Declaration * member = *std::next(structDecl->get_members().begin(), idx);
227 MemberExpr * memExpr = new MemberExpr( strict_dynamic_cast< DeclarationWithType * >( member ), tuple );
228 memExpr->set_env( env );
229 return memExpr;
230 }
231
232 Expression * replaceTupleExpr( Type * result, const std::list< Expression * > & exprs, TypeSubstitution * env ) {
233 if ( result->isVoid() ) {
234 // void result - don't need to produce a value for cascading - just output a chain of comma exprs
235 assert( ! exprs.empty() );
236 std::list< Expression * >::const_iterator iter = exprs.begin();
237 Expression * expr = new CastExpr( *iter++ );
238 for ( ; iter != exprs.end(); ++iter ) {
239 expr = new CommaExpr( expr, new CastExpr( *iter ) );
240 }
241 expr->set_env( env );
242 return expr;
243 } else {
244 // typed tuple expression - produce a compound literal which performs each of the expressions
245 // as a distinct part of its initializer - the produced compound literal may be used as part of
246 // another expression
247 std::list< Initializer * > inits;
248 for ( Expression * expr : exprs ) {
249 inits.push_back( new SingleInit( expr ) );
250 }
251 Expression * expr = new CompoundLiteralExpr( result, new ListInit( inits ) );
252 expr->set_env( env );
253 return expr;
254 }
255 }
256
257 Expression * TupleExprExpander::postmutate( TupleExpr * tupleExpr ) {
258 Type * result = tupleExpr->get_result();
259 std::list< Expression * > exprs = tupleExpr->get_exprs();
260 assert( result );
261 TypeSubstitution * env = tupleExpr->get_env();
262
263 // remove data from shell
264 tupleExpr->set_env( nullptr );
265
266 return replaceTupleExpr( result, exprs, env );
267 }
268
269 Type * makeTupleType( const std::list< Expression * > & exprs ) {
270 // produce the TupleType which aggregates the types of the exprs
271 std::list< Type * > types;
272 Type::Qualifiers qualifiers( Type::Const | Type::Volatile | Type::Restrict | Type::Lvalue | Type::Atomic | Type::Mutex );
273 for ( Expression * expr : exprs ) {
274 assert( expr->get_result() );
275 if ( expr->get_result()->isVoid() ) {
276 // if the type of any expr is void, the type of the entire tuple is void
277 return new VoidType( Type::Qualifiers() );
278 }
279 Type * type = expr->get_result()->clone();
280 types.push_back( type );
281 // the qualifiers on the tuple type are the qualifiers that exist on all component types
282 qualifiers &= type->get_qualifiers();
283 } // for
284 if ( exprs.empty() ) qualifiers = Type::Qualifiers();
285 return new TupleType( qualifiers, types );
286 }
287
288 TypeInstType * isTtype( Type * type ) {
289 if ( TypeInstType * inst = dynamic_cast< TypeInstType * >( type ) ) {
290 if ( inst->get_baseType() && inst->get_baseType()->get_kind() == TypeDecl::Ttype ) {
291 return inst;
292 }
293 }
294 return nullptr;
295 }
296
297 namespace {
298 /// 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
299 struct ImpurityDetector : public WithShortCircuiting {
300 ImpurityDetector( bool ignoreUnique ) : ignoreUnique( ignoreUnique ) {}
301
302 void previsit( ApplicationExpr * appExpr ) {
303 visit_children = false;
304 if ( DeclarationWithType * function = InitTweak::getFunction( appExpr ) ) {
305 if ( function->get_linkage() == LinkageSpec::Intrinsic ) {
306 if ( function->get_name() == "*?" || function->get_name() == "?[?]" ) {
307 // intrinsic dereference, subscript are pure, but need to recursively look for impurity
308 visit_children = true;
309 return;
310 }
311 }
312 }
313 maybeImpure = true;
314 }
315 void previsit( UntypedExpr * ) { maybeImpure = true; visit_children = false; }
316 void previsit( UniqueExpr * ) {
317 if ( ignoreUnique ) {
318 // bottom out at unique expression.
319 // The existence of a unique expression doesn't change the purity of an expression.
320 // That is, even if the wrapped expression is impure, the wrapper protects the rest of the expression.
321 visit_children = false;
322 return;
323 }
324 }
325
326 bool maybeImpure = false;
327 bool ignoreUnique;
328 };
329 } // namespace
330
331 bool maybeImpure( Expression * expr ) {
332 PassVisitor<ImpurityDetector> detector( false );
333 expr->accept( detector );
334 return detector.pass.maybeImpure;
335 }
336
337 bool maybeImpureIgnoreUnique( Expression * expr ) {
338 PassVisitor<ImpurityDetector> detector( true );
339 expr->accept( detector );
340 return detector.pass.maybeImpure;
341 }
342} // namespace Tuples
343
344// Local Variables: //
345// tab-width: 4 //
346// mode: c++ //
347// compile-command: "make install" //
348// End: //
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