1 /*
2 * Copyright (c) 2010, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package jdk.nashorn.internal.ir;
27
28 import java.io.PrintWriter;
29 import java.util.ArrayList;
30 import java.util.Arrays;
31 import java.util.Collections;
32 import java.util.Comparator;
33 import java.util.LinkedHashMap;
34 import java.util.List;
35 import java.util.Map;
36 import jdk.nashorn.internal.codegen.Label;
37 import jdk.nashorn.internal.ir.annotations.Immutable;
38 import jdk.nashorn.internal.ir.visitor.NodeVisitor;
39
40 /**
41 * IR representation for a list of statements.
42 */
43 @Immutable
44 public class Block extends Node implements BreakableNode, Terminal, Flags<Block> {
45 private static final long serialVersionUID = 1L;
46
47 /** List of statements */
48 protected final List<Statement> statements;
49
50 /** Symbol table - keys must be returned in the order they were put in. */
51 protected final Map<String, Symbol> symbols;
52
53 /** Entry label. */
54 private final Label entryLabel;
55
56 /** Break label. */
57 private final Label breakLabel;
58
59 /** Does the block/function need a new scope? Is this synthetic? */
60 protected final int flags;
61
62 /**
63 * @see JoinPredecessor
64 */
65 private final LocalVariableConversion conversion;
66
67 /** Flag indicating that this block needs scope */
68 public static final int NEEDS_SCOPE = 1 << 0;
69
70 /**
71 * Is this block tagged as terminal based on its contents
72 * (usually the last statement)
73 */
74 public static final int IS_TERMINAL = 1 << 2;
75
76 /**
77 * Is this block the eager global scope - i.e. the original program. This isn't true for the
78 * outermost level of recompiles
79 */
80 public static final int IS_GLOBAL_SCOPE = 1 << 3;
81
82 /**
83 * Is this block a synthetic one introduced by Parser?
84 */
85 public static final int IS_SYNTHETIC = 1 << 4;
86
87 /**
88 * Constructor
89 *
90 * @param token The first token of the block
91 * @param finish The index of the last character
92 * @param flags The flags of the block
93 * @param statements All statements in the block
94 */
95 public Block(final long token, final int finish, final int flags, final Statement... statements) {
96 super(token, finish);
97
98 this.statements = Arrays.asList(statements);
99 this.symbols = new LinkedHashMap<>();
100 this.entryLabel = new Label("block_entry");
101 this.breakLabel = new Label("block_break");
102 final int len = statements.length;
103 final int terminalFlags = len > 0 && statements[len - 1].hasTerminalFlags() ? IS_TERMINAL : 0;
104 this.flags = terminalFlags | flags;
105 this.conversion = null;
106 }
107
108 /**
109 * Constructs a new block
110 *
111 * @param token The first token of the block
112 * @param finish The index of the last character
113 * @param statements All statements in the block
114 */
115 public Block(final long token, final int finish, final Statement...statements){
116 this(token, finish, IS_SYNTHETIC, statements);
117 }
118
119 /**
120 * Constructs a new block
121 *
122 * @param token The first token of the block
123 * @param finish The index of the last character
124 * @param statements All statements in the block
125 */
126 public Block(final long token, final int finish, final List<Statement> statements){
127 this(token, finish, IS_SYNTHETIC, statements);
128 }
129
130 /**
131 * Constructor
132 *
133 * @param token The first token of the block
134 * @param finish The index of the last character
135 * @param flags The flags of the block
136 * @param statements All statements in the block
137 */
138 public Block(final long token, final int finish, final int flags, final List<Statement> statements) {
139 this(token, finish, flags, statements.toArray(new Statement[0]));
140 }
141
142 private Block(final Block block, final int finish, final List<Statement> statements, final int flags, final Map<String, Symbol> symbols, final LocalVariableConversion conversion) {
143 super(block, finish);
144 this.statements = statements;
145 this.flags = flags;
146 this.symbols = new LinkedHashMap<>(symbols); //todo - symbols have no dependencies on any IR node and can as far as we understand it be shallow copied now
147 this.entryLabel = new Label(block.entryLabel);
148 this.breakLabel = new Label(block.breakLabel);
149 this.conversion = conversion;
150 }
151
152 /**
153 * Is this block the outermost eager global scope - i.e. the primordial program?
154 * Used for global anchor point for scope depth computation for recompilation code
155 * @return true if outermost eager global scope
156 */
157 public boolean isGlobalScope() {
158 return getFlag(IS_GLOBAL_SCOPE);
159 }
160
161 /**
162 * Returns true if this block defines any symbols.
163 * @return true if this block defines any symbols.
164 */
165 public boolean hasSymbols() {
166 return !symbols.isEmpty();
167 }
168
169 /**
170 * Replaces symbols defined in this block with different symbols. Used to ensure symbol tables are
171 * immutable upon construction and have copy-on-write semantics. Note that this method only replaces the
172 * symbols in the symbol table, it does not act on any contained AST nodes that might reference the symbols.
173 * Those should be updated separately as this method is meant to be used as part of such an update pass.
174 * @param lc the current lexical context
175 * @param replacements the map of symbol replacements
176 * @return a new block with replaced symbols, or this block if none of the replacements modified the symbol
177 * table.
178 */
179 public Block replaceSymbols(final LexicalContext lc, final Map<Symbol, Symbol> replacements) {
180 if (symbols.isEmpty()) {
181 return this;
182 }
183 final LinkedHashMap<String, Symbol> newSymbols = new LinkedHashMap<>(symbols);
184 for (final Map.Entry<String, Symbol> entry: newSymbols.entrySet()) {
185 final Symbol newSymbol = replacements.get(entry.getValue());
186 assert newSymbol != null : "Missing replacement for " + entry.getKey();
187 entry.setValue(newSymbol);
188 }
189 return Node.replaceInLexicalContext(lc, this, new Block(this, finish, statements, flags, newSymbols, conversion));
190 }
191
192 /**
193 * Returns a copy of this block with a shallow copy of the symbol table.
194 * @return a copy of this block with a shallow copy of the symbol table.
195 */
196 public Block copyWithNewSymbols() {
197 return new Block(this, finish, statements, flags, new LinkedHashMap<>(symbols), conversion);
198 }
199
200 @Override
201 public Node ensureUniqueLabels(final LexicalContext lc) {
202 return Node.replaceInLexicalContext(lc, this, new Block(this, finish, statements, flags, symbols, conversion));
203 }
204
205 /**
206 * Assist in IR navigation.
207 *
208 * @param visitor IR navigating visitor.
209 * @return new or same node
210 */
211 @Override
212 public Node accept(final LexicalContext lc, final NodeVisitor<? extends LexicalContext> visitor) {
213 if (visitor.enterBlock(this)) {
214 return visitor.leaveBlock(setStatements(lc, Node.accept(visitor, statements)));
215 }
216
217 return this;
218 }
219
220 /**
221 * Get a copy of the list for all the symbols defined in this block
222 * @return symbol iterator
223 */
224 public List<Symbol> getSymbols() {
225 return symbols.isEmpty() ? Collections.emptyList() : Collections.unmodifiableList(new ArrayList<>(symbols.values()));
226 }
227
228 /**
229 * Retrieves an existing symbol defined in the current block.
230 * @param name the name of the symbol
231 * @return an existing symbol with the specified name defined in the current block, or null if this block doesn't
232 * define a symbol with this name.T
233 */
234 public Symbol getExistingSymbol(final String name) {
235 return symbols.get(name);
236 }
237
238 /**
239 * Test if this block represents a <tt>catch</tt> block in a <tt>try</tt> statement.
240 * This is used by the Splitter as catch blocks are not be subject to splitting.
241 *
242 * @return true if this block represents a catch block in a try statement.
243 */
244 public boolean isCatchBlock() {
245 return statements.size() == 1 && statements.get(0) instanceof CatchNode;
246 }
247
248 @Override
249 public void toString(final StringBuilder sb, final boolean printType) {
250 for (final Node statement : statements) {
251 statement.toString(sb, printType);
252 sb.append(';');
253 }
254 }
255
256 /**
257 * Print symbols in block in alphabetical order, sorted on name
258 * Used for debugging, see the --print-symbols flag
259 *
260 * @param stream print writer to output symbols to
261 *
262 * @return true if symbols were found
263 */
264 public boolean printSymbols(final PrintWriter stream) {
265 final List<Symbol> values = new ArrayList<>(symbols.values());
266
267 Collections.sort(values, new Comparator<Symbol>() {
268 @Override
269 public int compare(final Symbol s0, final Symbol s1) {
270 return s0.getName().compareTo(s1.getName());
271 }
272 });
273
274 for (final Symbol symbol : values) {
275 symbol.print(stream);
276 }
277
278 return !values.isEmpty();
279 }
280
281 /**
282 * Tag block as terminal or non terminal
283 * @param lc lexical context
284 * @param isTerminal is block terminal
285 * @return same block, or new if flag changed
286 */
287 public Block setIsTerminal(final LexicalContext lc, final boolean isTerminal) {
288 return isTerminal ? setFlag(lc, IS_TERMINAL) : clearFlag(lc, IS_TERMINAL);
289 }
290
291 @Override
292 public int getFlags() {
293 return flags;
294 }
295
296 /**
297 * Is this a terminal block, i.e. does it end control flow like ending with a throw or return?
298 *
299 * @return true if this node statement is terminal
300 */
301 @Override
302 public boolean isTerminal() {
303 return getFlag(IS_TERMINAL);
304 }
305
306 /**
307 * Get the entry label for this block
308 * @return the entry label
309 */
310 public Label getEntryLabel() {
311 return entryLabel;
312 }
313
314 @Override
315 public Label getBreakLabel() {
316 return breakLabel;
317 }
318
319 @Override
320 public Block setLocalVariableConversion(final LexicalContext lc, final LocalVariableConversion conversion) {
321 if(this.conversion == conversion) {
322 return this;
323 }
324 return Node.replaceInLexicalContext(lc, this, new Block(this, finish, statements, flags, symbols, conversion));
325 }
326
327 @Override
328 public LocalVariableConversion getLocalVariableConversion() {
329 return conversion;
330 }
331
332 /**
333 * Get the list of statements in this block
334 *
335 * @return a list of statements
336 */
337 public List<Statement> getStatements() {
338 return Collections.unmodifiableList(statements);
339 }
340
341 /**
342 * Returns the number of statements in the block.
343 * @return the number of statements in the block.
344 */
345 public int getStatementCount() {
346 return statements.size();
347 }
348
349 /**
350 * Returns the line number of the first statement in the block.
351 * @return the line number of the first statement in the block, or -1 if the block has no statements.
352 */
353 public int getFirstStatementLineNumber() {
354 if(statements == null || statements.isEmpty()) {
355 return -1;
356 }
357 return statements.get(0).getLineNumber();
358 }
359
360 /**
361 * Returns the last statement in the block.
362 * @return the last statement in the block, or null if the block has no statements.
363 */
364 public Statement getLastStatement() {
365 return statements.isEmpty() ? null : statements.get(statements.size() - 1);
366 }
367
368 /**
369 * Reset the statement list for this block
370 *
371 * @param lc lexical context
372 * @param statements new statement list
373 * @return new block if statements changed, identity of statements == block.statements
374 */
375 public Block setStatements(final LexicalContext lc, final List<Statement> statements) {
376 if (this.statements == statements) {
377 return this;
378 }
379 int lastFinish = 0;
380 if (!statements.isEmpty()) {
381 lastFinish = statements.get(statements.size() - 1).getFinish();
382 }
383 return Node.replaceInLexicalContext(lc, this, new Block(this, Math.max(finish, lastFinish), statements, flags, symbols, conversion));
384 }
385
386 /**
387 * Add or overwrite an existing symbol in the block
388 *
389 * @param symbol symbol
390 */
391 public void putSymbol(final Symbol symbol) {
392 symbols.put(symbol.getName(), symbol);
393 }
394
395 /**
396 * Check whether scope is necessary for this Block
397 *
398 * @return true if this function needs a scope
399 */
400 public boolean needsScope() {
401 return (flags & NEEDS_SCOPE) == NEEDS_SCOPE;
402 }
403
404 /**
405 * Check whether this block is synthetic or not.
406 *
407 * @return true if this is a synthetic block
408 */
409 public boolean isSynthetic() {
410 return (flags & IS_SYNTHETIC) == IS_SYNTHETIC;
411 }
412
413 @Override
414 public Block setFlags(final LexicalContext lc, final int flags) {
415 if (this.flags == flags) {
416 return this;
417 }
418 return Node.replaceInLexicalContext(lc, this, new Block(this, finish, statements, flags, symbols, conversion));
419 }
420
421 @Override
422 public Block clearFlag(final LexicalContext lc, final int flag) {
423 return setFlags(lc, flags & ~flag);
424 }
425
426 @Override
427 public Block setFlag(final LexicalContext lc, final int flag) {
428 return setFlags(lc, flags | flag);
429 }
430
431 @Override
432 public boolean getFlag(final int flag) {
433 return (flags & flag) == flag;
434 }
435
436 /**
437 * Set the needs scope flag.
438 * @param lc lexicalContext
439 * @return new block if state changed, otherwise this
440 */
441 public Block setNeedsScope(final LexicalContext lc) {
442 if (needsScope()) {
443 return this;
444 }
445
446 return Node.replaceInLexicalContext(lc, this, new Block(this, finish, statements, flags | NEEDS_SCOPE, symbols, conversion));
447 }
448
449 /**
450 * Computationally determine the next slot for this block,
451 * indexed from 0. Use this as a relative base when computing
452 * frames
453 * @return next slot
454 */
455 public int nextSlot() {
456 int next = 0;
457 for (final Symbol symbol : getSymbols()) {
458 if (symbol.hasSlot()) {
459 next += symbol.slotCount();
460 }
461 }
462 return next;
463 }
464
465 /**
466 * Determine whether this block needs to provide its scope object creator for use by its child nodes.
467 * This is only necessary for synthetic parent blocks of for-in loops with lexical declarations.
468 *
469 * @see ForNode#needsScopeCreator()
470 * @return true if child nodes need access to this block's scope creator
471 */
472 public boolean providesScopeCreator() {
473 return needsScope() && isSynthetic()
474 && (getLastStatement() instanceof ForNode)
475 && ((ForNode) getLastStatement()).needsScopeCreator();
476 }
477
478 @Override
479 public boolean isBreakableWithoutLabel() {
480 return false;
481 }
482
483 @Override
484 public List<Label> getLabels() {
485 return Collections.unmodifiableList(Arrays.asList(entryLabel, breakLabel));
486 }
487
488 @Override
489 public Node accept(final NodeVisitor<? extends LexicalContext> visitor) {
490 return Acceptor.accept(this, visitor);
491 }
492 }