NashornCallSiteDescriptor.java revision 1483:7cb19fa78763
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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 26package jdk.nashorn.internal.runtime.linker; 27 28import java.lang.invoke.MethodHandles; 29import java.lang.invoke.MethodHandles.Lookup; 30import java.lang.invoke.MethodType; 31import java.security.AccessControlContext; 32import java.security.AccessController; 33import java.security.PrivilegedAction; 34import java.util.concurrent.ConcurrentHashMap; 35import java.util.concurrent.ConcurrentMap; 36import jdk.internal.dynalink.CallSiteDescriptor; 37import jdk.internal.dynalink.CompositeOperation; 38import jdk.internal.dynalink.NamedOperation; 39import jdk.internal.dynalink.Operation; 40import jdk.internal.dynalink.StandardOperation; 41import jdk.internal.dynalink.support.NameCodec; 42import jdk.nashorn.internal.ir.debug.NashornTextifier; 43import jdk.nashorn.internal.runtime.AccessControlContextFactory; 44import jdk.nashorn.internal.runtime.ScriptRuntime; 45 46/** 47 * Nashorn-specific implementation of Dynalink's {@link CallSiteDescriptor}. 48 * The reason we have our own subclass is that we're storing flags in an 49 * additional primitive field. The class also exposes some useful utilities in 50 * form of static methods. 51 */ 52public final class NashornCallSiteDescriptor extends CallSiteDescriptor { 53 // Lowest three bits describe the operation 54 /** Property getter operation {@code obj.prop} */ 55 public static final int GET_PROPERTY = 0; 56 /** Element getter operation {@code obj[index]} */ 57 public static final int GET_ELEMENT = 1; 58 /** Property getter operation, subsequently invoked {@code obj.prop()} */ 59 public static final int GET_METHOD_PROPERTY = 2; 60 /** Element getter operation, subsequently invoked {@code obj[index]()} */ 61 public static final int GET_METHOD_ELEMENT = 3; 62 /** Property setter operation {@code obj.prop = value} */ 63 public static final int SET_PROPERTY = 4; 64 /** Element setter operation {@code obj[index] = value} */ 65 public static final int SET_ELEMENT = 5; 66 /** Call operation {@code fn(args...)} */ 67 public static final int CALL = 6; 68 /** New operation {@code new Constructor(args...)} */ 69 public static final int NEW = 7; 70 71 private static final int OPERATION_MASK = 7; 72 73 // Correspond to the operation indices above. 74 private static final Operation[] OPERATIONS = new Operation[] { 75 new CompositeOperation(StandardOperation.GET_PROPERTY, StandardOperation.GET_ELEMENT, StandardOperation.GET_METHOD), 76 new CompositeOperation(StandardOperation.GET_ELEMENT, StandardOperation.GET_PROPERTY, StandardOperation.GET_METHOD), 77 new CompositeOperation(StandardOperation.GET_METHOD, StandardOperation.GET_PROPERTY, StandardOperation.GET_ELEMENT), 78 new CompositeOperation(StandardOperation.GET_METHOD, StandardOperation.GET_ELEMENT, StandardOperation.GET_PROPERTY), 79 new CompositeOperation(StandardOperation.SET_PROPERTY, StandardOperation.SET_ELEMENT), 80 new CompositeOperation(StandardOperation.SET_ELEMENT, StandardOperation.SET_PROPERTY), 81 StandardOperation.CALL, 82 StandardOperation.NEW 83 }; 84 85 /** Flags that the call site references a scope variable (it's an identifier reference or a var declaration, not a 86 * property access expression. */ 87 public static final int CALLSITE_SCOPE = 1 << 3; 88 /** Flags that the call site is in code that uses ECMAScript strict mode. */ 89 public static final int CALLSITE_STRICT = 1 << 4; 90 /** Flags that a property getter or setter call site references a scope variable that is located at a known distance 91 * in the scope chain. Such getters and setters can often be linked more optimally using these assumptions. */ 92 public static final int CALLSITE_FAST_SCOPE = 1 << 5; 93 /** Flags that a callsite type is optimistic, i.e. we might get back a wider return value than encoded in the 94 * descriptor, and in that case we have to throw an UnwarrantedOptimismException */ 95 public static final int CALLSITE_OPTIMISTIC = 1 << 6; 96 /** Is this really an apply that we try to call as a call? */ 97 public static final int CALLSITE_APPLY_TO_CALL = 1 << 7; 98 /** Does this a callsite for a variable declaration? */ 99 public static final int CALLSITE_DECLARE = 1 << 8; 100 101 /** Flags that the call site is profiled; Contexts that have {@code "profile.callsites"} boolean property set emit 102 * code where call sites have this flag set. */ 103 public static final int CALLSITE_PROFILE = 1 << 9; 104 /** Flags that the call site is traced; Contexts that have {@code "trace.callsites"} property set emit code where 105 * call sites have this flag set. */ 106 public static final int CALLSITE_TRACE = 1 << 10; 107 /** Flags that the call site linkage miss (and thus, relinking) is traced; Contexts that have the keyword 108 * {@code "miss"} in their {@code "trace.callsites"} property emit code where call sites have this flag set. */ 109 public static final int CALLSITE_TRACE_MISSES = 1 << 11; 110 /** Flags that entry/exit to/from the method linked at call site are traced; Contexts that have the keyword 111 * {@code "enterexit"} in their {@code "trace.callsites"} property emit code where call sites have this flag set. */ 112 public static final int CALLSITE_TRACE_ENTEREXIT = 1 << 12; 113 /** Flags that values passed as arguments to and returned from the method linked at call site are traced; Contexts 114 * that have the keyword {@code "values"} in their {@code "trace.callsites"} property emit code where call sites 115 * have this flag set. */ 116 public static final int CALLSITE_TRACE_VALUES = 1 << 13; 117 118 //we could have more tracing flags here, for example CALLSITE_TRACE_SCOPE, but bits are a bit precious 119 //right now given the program points 120 121 /** 122 * Number of bits the program point is shifted to the left in the flags (lowest bit containing a program point). 123 * Always one larger than the largest flag shift. Note that introducing a new flag halves the number of program 124 * points we can have. 125 * TODO: rethink if we need the various profile/trace flags or the linker can use the Context instead to query its 126 * trace/profile settings. 127 */ 128 public static final int CALLSITE_PROGRAM_POINT_SHIFT = 14; 129 130 /** 131 * Maximum program point value. We have 18 bits left over after flags, and 132 * it should be plenty. Program points are local to a single function. Every 133 * function maps to a single JVM bytecode method that can have at most 65535 134 * bytes. (Large functions are synthetically split into smaller functions.) 135 * A single invokedynamic is 5 bytes; even if a method consists of only 136 * invokedynamic instructions that leaves us with at most 65535/5 = 13107 137 * program points for the largest single method; those can be expressed on 138 * 14 bits. It is true that numbering of program points is independent of 139 * bytecode representation, but if a function would need more than ~14 bits 140 * for the program points, then it is reasonable to presume splitter 141 * would've split it into several smaller functions already. 142 */ 143 public static final int MAX_PROGRAM_POINT_VALUE = (1 << 32 - CALLSITE_PROGRAM_POINT_SHIFT) - 1; 144 145 /** 146 * Flag mask to get the program point flags 147 */ 148 public static final int FLAGS_MASK = (1 << CALLSITE_PROGRAM_POINT_SHIFT) - 1; 149 150 private static final ClassValue<ConcurrentMap<NashornCallSiteDescriptor, NashornCallSiteDescriptor>> canonicals = 151 new ClassValue<ConcurrentMap<NashornCallSiteDescriptor,NashornCallSiteDescriptor>>() { 152 @Override 153 protected ConcurrentMap<NashornCallSiteDescriptor, NashornCallSiteDescriptor> computeValue(final Class<?> type) { 154 return new ConcurrentHashMap<>(); 155 } 156 }; 157 158 private static final AccessControlContext GET_LOOKUP_PERMISSION_CONTEXT = 159 AccessControlContextFactory.createAccessControlContext(CallSiteDescriptor.GET_LOOKUP_PERMISSION_NAME); 160 161 private final int flags; 162 163 /** 164 * Function used by {@link NashornTextifier} to represent call site flags in 165 * human readable form 166 * @param flags call site flags 167 * @return human readable form of this callsite descriptor 168 */ 169 public static String toString(final int flags) { 170 final StringBuilder sb = new StringBuilder(); 171 if ((flags & CALLSITE_SCOPE) != 0) { 172 if ((flags & CALLSITE_FAST_SCOPE) != 0) { 173 sb.append("fastscope "); 174 } else { 175 assert (flags & CALLSITE_FAST_SCOPE) == 0 : "can't be fastscope without scope"; 176 sb.append("scope "); 177 } 178 if ((flags & CALLSITE_DECLARE) != 0) { 179 sb.append("declare "); 180 } 181 } 182 if ((flags & CALLSITE_APPLY_TO_CALL) != 0) { 183 sb.append("apply2call "); 184 } 185 if ((flags & CALLSITE_STRICT) != 0) { 186 sb.append("strict "); 187 } 188 return sb.length() == 0 ? "" : " " + sb.toString().trim(); 189 } 190 191 /** 192 * Given call site flags, returns the operation name encoded in them. 193 * @param flags flags 194 * @return the operation name 195 */ 196 public static String getOperationName(final int flags) { 197 switch(flags & OPERATION_MASK) { 198 case 0: return "GET_PROPERTY"; 199 case 1: return "GET_ELEMENT"; 200 case 2: return "GET_METHOD_PROPERTY"; 201 case 3: return "GET_METHOD_ELEMENT"; 202 case 4: return "SET_PROPERTY"; 203 case 5: return "SET_ELEMENT"; 204 case 6: return "CALL"; 205 case 7: return "NEW"; 206 default: throw new AssertionError(); 207 } 208 } 209 210 /** 211 * Retrieves a Nashorn call site descriptor with the specified values. Since call site descriptors are immutable 212 * this method is at liberty to retrieve canonicalized instances (although it is not guaranteed it will do so). 213 * @param lookup the lookup describing the script 214 * @param name the name at the call site. Can not be null, but it can be empty. 215 * @param methodType the method type at the call site 216 * @param flags Nashorn-specific call site flags 217 * @return a call site descriptor with the specified values. 218 */ 219 public static NashornCallSiteDescriptor get(final MethodHandles.Lookup lookup, final String name, 220 final MethodType methodType, final int flags) { 221 final Operation baseOp = OPERATIONS[flags & OPERATION_MASK]; 222 final String decodedName = NameCodec.decode(name); 223 // TODO: introduce caching of NamedOperation 224 final Operation op = decodedName.isEmpty() ? baseOp : new NamedOperation(baseOp, decodedName); 225 return get(lookup, op, methodType, flags); 226 } 227 228 private static NashornCallSiteDescriptor get(final MethodHandles.Lookup lookup, final Operation operation, final MethodType methodType, final int flags) { 229 final NashornCallSiteDescriptor csd = new NashornCallSiteDescriptor(lookup, operation, methodType, flags); 230 // Many of these call site descriptors are identical (e.g. every getter for a property color will be 231 // "GET_PROPERTY:color(Object)Object", so it makes sense canonicalizing them. 232 final ConcurrentMap<NashornCallSiteDescriptor, NashornCallSiteDescriptor> classCanonicals = canonicals.get(lookup.lookupClass()); 233 final NashornCallSiteDescriptor canonical = classCanonicals.putIfAbsent(csd, csd); 234 return canonical != null ? canonical : csd; 235 } 236 237 private NashornCallSiteDescriptor(final MethodHandles.Lookup lookup, final Operation operation, final MethodType methodType, final int flags) { 238 super(lookup, operation, methodType); 239 this.flags = flags; 240 } 241 242 static Lookup getLookupInternal(final CallSiteDescriptor csd) { 243 if (csd instanceof NashornCallSiteDescriptor) { 244 return ((NashornCallSiteDescriptor)csd).getLookupPrivileged(); 245 } 246 return AccessController.doPrivileged((PrivilegedAction<Lookup>)()->csd.getLookup(), GET_LOOKUP_PERMISSION_CONTEXT); 247 } 248 249 @Override 250 public boolean equals(final Object obj) { 251 return super.equals(obj) && flags == ((NashornCallSiteDescriptor)obj).flags; 252 } 253 254 @Override 255 public int hashCode() { 256 return super.hashCode() ^ flags; 257 } 258 259 /** 260 * Returns the named operand in this descriptor's operation. Equivalent to 261 * {@code ((NamedOperation)getOperation()).getName().toString()} for call 262 * sites with a named operand. For call sites without named operands returns null. 263 * @return the named operand in this descriptor's operation. 264 */ 265 public String getOperand() { 266 return getOperand(this); 267 } 268 269 /** 270 * Returns the named operand in the passed descriptor's operation. 271 * Equivalent to 272 * {@code ((NamedOperation)desc.getOperation()).getName().toString()} for 273 * descriptors with a named operand. For descriptors without named operands 274 * returns null. 275 * @param desc the call site descriptors 276 * @return the named operand in this descriptor's operation. 277 */ 278 public static String getOperand(final CallSiteDescriptor desc) { 279 final Operation operation = desc.getOperation(); 280 return operation instanceof NamedOperation ? ((NamedOperation)operation).getName().toString() : null; 281 } 282 283 /** 284 * Returns the first operation in this call site descriptor's potentially 285 * composite operation. E.g. if this call site descriptor has a composite 286 * operation {@code GET_PROPERTY|GET_METHOD|GET_ELEM}, it will return 287 * {@code GET_PROPERTY}. Nashorn - being a ECMAScript engine - does not 288 * distinguish between property, element, and method namespace; ECMAScript 289 * objects just have one single property namespace for all these, therefore 290 * it is largely irrelevant what the composite operation is structured like; 291 * if the first operation can't be satisfied, neither can the others. The 292 * first operation is however sometimes used to slightly alter the 293 * semantics; for example, a distinction between {@code GET_PROPERTY} and 294 * {@code GET_METHOD} being the first operation can translate into whether 295 * {@code "__noSuchProperty__"} or {@code "__noSuchMethod__"} will be 296 * executed in case the property is not found. Note that if a call site 297 * descriptor comes from outside of Nashorn, its class will be different, 298 * and there is no guarantee about the way it composes its operations. For 299 * that reason, for potentially foreign call site descriptors you should use 300 * {@link #getFirstStandardOperation(CallSiteDescriptor)} instead. 301 * @return the first operation in this call site descriptor. Note this will 302 * always be a {@code StandardOperation} as Nashorn internally only uses 303 * standard operations. 304 */ 305 public StandardOperation getFirstOperation() { 306 final Operation base = NamedOperation.getBaseOperation(getOperation()); 307 if (base instanceof CompositeOperation) { 308 return (StandardOperation)((CompositeOperation)base).getOperation(0); 309 } 310 return (StandardOperation)base; 311 } 312 313 /** 314 * Returns the first standard operation in the (potentially composite) 315 * operation of the passed call site descriptor. 316 * @param desc the call site descriptor. 317 * @return Returns the first standard operation in the (potentially 318 * composite) operation of the passed call site descriptor. Can return null 319 * if the call site contains no standard operations. 320 */ 321 public static StandardOperation getFirstStandardOperation(final CallSiteDescriptor desc) { 322 final Operation base = NamedOperation.getBaseOperation(desc.getOperation()); 323 if (base instanceof StandardOperation) { 324 return (StandardOperation)base; 325 } else if (base instanceof CompositeOperation) { 326 final CompositeOperation cop = (CompositeOperation)base; 327 for(int i = 0; i < cop.getOperationCount(); ++i) { 328 final Operation op = cop.getOperation(i); 329 if (op instanceof StandardOperation) { 330 return (StandardOperation)op; 331 } 332 } 333 } 334 return null; 335 } 336 337 /** 338 * Returns the error message to be used when CALL or NEW is used on a non-function. 339 * 340 * @param obj object on which CALL or NEW is used 341 * @return error message 342 */ 343 public String getFunctionErrorMessage(final Object obj) { 344 final String funcDesc = getOperand(); 345 return funcDesc != null? funcDesc : ScriptRuntime.safeToString(obj); 346 } 347 348 /** 349 * Returns the error message to be used when CALL or NEW is used on a non-function. 350 * 351 * @param desc call site descriptor 352 * @param obj object on which CALL or NEW is used 353 * @return error message 354 */ 355 public static String getFunctionErrorMessage(final CallSiteDescriptor desc, final Object obj) { 356 return desc instanceof NashornCallSiteDescriptor ? 357 ((NashornCallSiteDescriptor)desc).getFunctionErrorMessage(obj) : 358 ScriptRuntime.safeToString(obj); 359 } 360 361 /** 362 * Returns the Nashorn-specific flags for this call site descriptor. 363 * @param desc the descriptor. It can be any kind of a call site descriptor, not necessarily a 364 * {@code NashornCallSiteDescriptor}. This allows for graceful interoperability when linking Nashorn with code 365 * generated outside of Nashorn. 366 * @return the Nashorn-specific flags for the call site, or 0 if the passed descriptor is not a Nashorn call site 367 * descriptor. 368 */ 369 public static int getFlags(final CallSiteDescriptor desc) { 370 return desc instanceof NashornCallSiteDescriptor ? ((NashornCallSiteDescriptor)desc).flags : 0; 371 } 372 373 /** 374 * Returns true if this descriptor has the specified flag set, see {@code CALLSITE_*} constants in this class. 375 * @param flag the tested flag 376 * @return true if the flag is set, false otherwise 377 */ 378 private boolean isFlag(final int flag) { 379 return (flags & flag) != 0; 380 } 381 382 /** 383 * Returns true if this descriptor has the specified flag set, see {@code CALLSITE_*} constants in this class. 384 * @param desc the descriptor. It can be any kind of a call site descriptor, not necessarily a 385 * {@code NashornCallSiteDescriptor}. This allows for graceful interoperability when linking Nashorn with code 386 * generated outside of Nashorn. 387 * @param flag the tested flag 388 * @return true if the flag is set, false otherwise (it will be false if the descriptor is not a Nashorn call site 389 * descriptor). 390 */ 391 private static boolean isFlag(final CallSiteDescriptor desc, final int flag) { 392 return (getFlags(desc) & flag) != 0; 393 } 394 395 /** 396 * Returns true if this descriptor is a Nashorn call site descriptor and has the {@link #CALLSITE_SCOPE} flag set. 397 * @param desc the descriptor. It can be any kind of a call site descriptor, not necessarily a 398 * {@code NashornCallSiteDescriptor}. This allows for graceful interoperability when linking Nashorn with code 399 * generated outside of Nashorn. 400 * @return true if the descriptor is a Nashorn call site descriptor, and the flag is set, false otherwise. 401 */ 402 public static boolean isScope(final CallSiteDescriptor desc) { 403 return isFlag(desc, CALLSITE_SCOPE); 404 } 405 406 /** 407 * Returns true if this descriptor is a Nashorn call site descriptor and has the {@link #CALLSITE_FAST_SCOPE} flag set. 408 * @param desc the descriptor. It can be any kind of a call site descriptor, not necessarily a 409 * {@code NashornCallSiteDescriptor}. This allows for graceful interoperability when linking Nashorn with code 410 * generated outside of Nashorn. 411 * @return true if the descriptor is a Nashorn call site descriptor, and the flag is set, false otherwise. 412 */ 413 public static boolean isFastScope(final CallSiteDescriptor desc) { 414 return isFlag(desc, CALLSITE_FAST_SCOPE); 415 } 416 417 /** 418 * Returns true if this descriptor is a Nashorn call site descriptor and has the {@link #CALLSITE_STRICT} flag set. 419 * @param desc the descriptor. It can be any kind of a call site descriptor, not necessarily a 420 * {@code NashornCallSiteDescriptor}. This allows for graceful interoperability when linking Nashorn with code 421 * generated outside of Nashorn. 422 * @return true if the descriptor is a Nashorn call site descriptor, and the flag is set, false otherwise. 423 */ 424 public static boolean isStrict(final CallSiteDescriptor desc) { 425 return isFlag(desc, CALLSITE_STRICT); 426 } 427 428 /** 429 * Returns true if this is an apply call that we try to call as 430 * a "call" 431 * @param desc descriptor 432 * @return true if apply to call 433 */ 434 public static boolean isApplyToCall(final CallSiteDescriptor desc) { 435 return isFlag(desc, CALLSITE_APPLY_TO_CALL); 436 } 437 438 /** 439 * Is this an optimistic call site 440 * @param desc descriptor 441 * @return true if optimistic 442 */ 443 public static boolean isOptimistic(final CallSiteDescriptor desc) { 444 return isFlag(desc, CALLSITE_OPTIMISTIC); 445 } 446 447 /** 448 * Does this callsite contain a declaration for its target? 449 * @param desc descriptor 450 * @return true if contains declaration 451 */ 452 public static boolean isDeclaration(final CallSiteDescriptor desc) { 453 return isFlag(desc, CALLSITE_DECLARE); 454 } 455 456 /** 457 * Returns true if {@code flags} has the {@link #CALLSITE_STRICT} bit set. 458 * @param flags the flags 459 * @return true if the flag is set, false otherwise. 460 */ 461 public static boolean isStrictFlag(final int flags) { 462 return (flags & CALLSITE_STRICT) != 0; 463 } 464 465 /** 466 * Returns true if {@code flags} has the {@link #CALLSITE_SCOPE} bit set. 467 * @param flags the flags 468 * @return true if the flag is set, false otherwise. 469 */ 470 public static boolean isScopeFlag(final int flags) { 471 return (flags & CALLSITE_SCOPE) != 0; 472 } 473 474 /** 475 * Get a program point from a descriptor (must be optimistic) 476 * @param desc descriptor 477 * @return program point 478 */ 479 public static int getProgramPoint(final CallSiteDescriptor desc) { 480 assert isOptimistic(desc) : "program point requested from non-optimistic descriptor " + desc; 481 return getFlags(desc) >> CALLSITE_PROGRAM_POINT_SHIFT; 482 } 483 484 boolean isProfile() { 485 return isFlag(CALLSITE_PROFILE); 486 } 487 488 boolean isTrace() { 489 return isFlag(CALLSITE_TRACE); 490 } 491 492 boolean isTraceMisses() { 493 return isFlag(CALLSITE_TRACE_MISSES); 494 } 495 496 boolean isTraceEnterExit() { 497 return isFlag(CALLSITE_TRACE_ENTEREXIT); 498 } 499 500 boolean isTraceObjects() { 501 return isFlag(CALLSITE_TRACE_VALUES); 502 } 503 504 boolean isOptimistic() { 505 return isFlag(CALLSITE_OPTIMISTIC); 506 } 507 508 @Override 509 public CallSiteDescriptor changeMethodTypeInternal(final MethodType newMethodType) { 510 return get(getLookupPrivileged(), getOperation(), newMethodType, flags); 511 } 512} 513