1 /*
   2  * Copyright (c) 2010, 2013, 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.runtime.linker;
  27 
  28 import java.lang.invoke.MethodHandles;
  29 import java.lang.invoke.MethodHandles.Lookup;
  30 import java.lang.invoke.MethodType;
  31 import java.util.concurrent.ConcurrentHashMap;
  32 import java.util.concurrent.ConcurrentMap;
  33 import jdk.internal.dynalink.CallSiteDescriptor;
  34 import jdk.internal.dynalink.support.AbstractCallSiteDescriptor;
  35 import jdk.internal.dynalink.support.CallSiteDescriptorFactory;
  36 import jdk.nashorn.internal.ir.debug.NashornTextifier;
  37 
  38 /**
  39  * Nashorn-specific implementation of Dynalink's {@link CallSiteDescriptor}. The reason we have our own subclass is that
  40  * we can have a more compact representation, as we know that we're always only using {@code "dyn:*"} operations; also
  41  * we're storing flags in an additional primitive field.
  42  */
  43 public final class NashornCallSiteDescriptor extends AbstractCallSiteDescriptor {
  44     /** Flags that the call site references a scope variable (it's an identifier reference or a var declaration, not a
  45      * property access expression. */
  46     public static final int CALLSITE_SCOPE         = 1 << 0;
  47     /** Flags that the call site is in code that uses ECMAScript strict mode. */
  48     public static final int CALLSITE_STRICT        = 1 << 1;
  49     /** Flags that a property getter or setter call site references a scope variable that is located at a known distance
  50      * in the scope chain. Such getters and setters can often be linked more optimally using these assumptions. */
  51     public static final int CALLSITE_FAST_SCOPE    = 1 << 2;
  52     /** Flags that a callsite type is optimistic, i.e. we might get back a wider return value than encoded in the
  53      * descriptor, and in that case we have to throw an UnwarrantedOptimismException */
  54     public static final int CALLSITE_OPTIMISTIC    = 1 << 3;
  55     /** Is this really an apply that we try to call as a call? */
  56     public static final int CALLSITE_APPLY_TO_CALL = 1 << 4;
  57     /** Does this a callsite for a variable declaration? */
  58     public static final int CALLSITE_DECLARE       = 1 << 5;
  59 
  60     /** Flags that the call site is profiled; Contexts that have {@code "profile.callsites"} boolean property set emit
  61      * code where call sites have this flag set. */
  62     public static final int CALLSITE_PROFILE         = 1 << 6;
  63     /** Flags that the call site is traced; Contexts that have {@code "trace.callsites"} property set emit code where
  64      * call sites have this flag set. */
  65     public static final int CALLSITE_TRACE           = 1 << 7;
  66     /** Flags that the call site linkage miss (and thus, relinking) is traced; Contexts that have the keyword
  67      * {@code "miss"} in their {@code "trace.callsites"} property emit code where call sites have this flag set. */
  68     public static final int CALLSITE_TRACE_MISSES    = 1 << 8;
  69     /** Flags that entry/exit to/from the method linked at call site are traced; Contexts that have the keyword
  70      * {@code "enterexit"} in their {@code "trace.callsites"} property emit code where call sites have this flag set. */
  71     public static final int CALLSITE_TRACE_ENTEREXIT = 1 << 9;
  72     /** Flags that values passed as arguments to and returned from the method linked at call site are traced; Contexts
  73      * that have the keyword {@code "values"} in their {@code "trace.callsites"} property emit code where call sites
  74      * have this flag set. */
  75     public static final int CALLSITE_TRACE_VALUES    = 1 << 10;
  76 
  77     //we could have more tracing flags here, for example CALLSITE_TRACE_SCOPE, but bits are a bit precious
  78     //right now given the program points
  79 
  80     /**
  81      * Number of bits the program point is shifted to the left in the flags (lowest bit containing a program point).
  82      * Always one larger than the largest flag shift. Note that introducing a new flag halves the number of program
  83      * points we can have.
  84      * TODO: rethink if we need the various profile/trace flags or the linker can use the Context instead to query its
  85      * trace/profile settings.
  86      */
  87     public static final int CALLSITE_PROGRAM_POINT_SHIFT = 11;
  88 
  89     /**
  90      * Maximum program point value. 21 bits should be enough for anyone
  91      */
  92     public static final int MAX_PROGRAM_POINT_VALUE = (1 << 32 - CALLSITE_PROGRAM_POINT_SHIFT) - 1;
  93 
  94     /**
  95      * Flag mask to get the program point flags
  96      */
  97     public static final int FLAGS_MASK = (1 << CALLSITE_PROGRAM_POINT_SHIFT) - 1;
  98 
  99     private static final ClassValue<ConcurrentMap<NashornCallSiteDescriptor, NashornCallSiteDescriptor>> canonicals =
 100             new ClassValue<ConcurrentMap<NashornCallSiteDescriptor,NashornCallSiteDescriptor>>() {
 101         @Override
 102         protected ConcurrentMap<NashornCallSiteDescriptor, NashornCallSiteDescriptor> computeValue(final Class<?> type) {
 103             return new ConcurrentHashMap<>();
 104         }
 105     };
 106 
 107     private final MethodHandles.Lookup lookup;
 108     private final String operator;
 109     private final String operand;
 110     private final MethodType methodType;
 111     private final int flags;
 112 
 113     /**
 114      * Function used by {@link NashornTextifier} to represent call site flags in
 115      * human readable form
 116      * @param flags call site flags
 117      * @return human readable form of this callsite descriptor
 118      */
 119     public static String toString(final int flags) {
 120         final StringBuilder sb = new StringBuilder();
 121         if ((flags & CALLSITE_SCOPE) != 0) {
 122             if ((flags & CALLSITE_FAST_SCOPE) != 0) {
 123                 sb.append("fastscope ");
 124             } else {
 125                 assert (flags & CALLSITE_FAST_SCOPE) == 0 : "can't be fastscope without scope";
 126                 sb.append("scope ");
 127             }
 128             if ((flags & CALLSITE_DECLARE) != 0) {
 129                 sb.append("declare ");
 130             }
 131         }
 132         if ((flags & CALLSITE_APPLY_TO_CALL) != 0) {
 133             sb.append("apply2call ");
 134         }
 135         if ((flags & CALLSITE_STRICT) != 0) {
 136             sb.append("strict ");
 137         }
 138         return sb.length() == 0 ? "" : " " + sb.toString().trim();
 139     }
 140 
 141     /**
 142      * Retrieves a Nashorn call site descriptor with the specified values. Since call site descriptors are immutable
 143      * this method is at liberty to retrieve canonicalized instances (although it is not guaranteed it will do so).
 144      * @param lookup the lookup describing the script
 145      * @param name the name at the call site, e.g. {@code "dyn:getProp|getElem|getMethod:color"}.
 146      * @param methodType the method type at the call site
 147      * @param flags Nashorn-specific call site flags
 148      * @return a call site descriptor with the specified values.
 149      */
 150     public static NashornCallSiteDescriptor get(final MethodHandles.Lookup lookup, final String name,
 151             final MethodType methodType, final int flags) {
 152         final String[] tokenizedName = CallSiteDescriptorFactory.tokenizeName(name);
 153         assert tokenizedName.length >= 2;
 154         assert "dyn".equals(tokenizedName[0]);
 155         assert tokenizedName[1] != null;
 156         // TODO: see if we can move mangling/unmangling into Dynalink
 157         return get(lookup, tokenizedName[1], tokenizedName.length == 3 ? tokenizedName[2].intern() : null,
 158                 methodType, flags);
 159     }
 160 
 161     private static NashornCallSiteDescriptor get(final MethodHandles.Lookup lookup, final String operator, final String operand, final MethodType methodType, final int flags) {
 162         final NashornCallSiteDescriptor csd = new NashornCallSiteDescriptor(lookup, operator, operand, methodType, flags);
 163         // Many of these call site descriptors are identical (e.g. every getter for a property color will be
 164         // "dyn:getProp:color(Object)Object", so it makes sense canonicalizing them.
 165         final ConcurrentMap<NashornCallSiteDescriptor, NashornCallSiteDescriptor> classCanonicals = canonicals.get(lookup.lookupClass());
 166         final NashornCallSiteDescriptor canonical = classCanonicals.putIfAbsent(csd, csd);
 167         return canonical != null ? canonical : csd;
 168     }
 169 
 170     private NashornCallSiteDescriptor(final MethodHandles.Lookup lookup, final String operator, final String operand,
 171             final MethodType methodType, final int flags) {
 172         this.lookup = lookup;
 173         this.operator = operator;
 174         this.operand = operand;
 175         this.methodType = methodType;
 176         this.flags = flags;
 177     }
 178 
 179     @Override
 180     public int getNameTokenCount() {
 181         return operand == null ? 2 : 3;
 182     }
 183 
 184     @Override
 185     public String getNameToken(final int i) {
 186         switch(i) {
 187         case 0: return "dyn";
 188         case 1: return operator;
 189         case 2:
 190             if(operand != null) {
 191                 return operand;
 192             }
 193             break;
 194         default:
 195             break;
 196         }
 197         throw new IndexOutOfBoundsException(String.valueOf(i));
 198     }
 199 
 200     @Override
 201     public Lookup getLookup() {
 202         return lookup;
 203     }
 204 
 205     @Override
 206     public boolean equals(final CallSiteDescriptor csd) {
 207         return super.equals(csd) && flags == getFlags(csd);
 208     }
 209 
 210     @Override
 211     public MethodType getMethodType() {
 212         return methodType;
 213     }
 214 
 215     /**
 216      * Returns the operator (e.g. {@code "getProp"}) in this call site descriptor's name. Equivalent to
 217      * {@code getNameToken(CallSiteDescriptor.OPERATOR)}. The returned operator can be composite.
 218      * @return the operator in this call site descriptor's name.
 219      */
 220     public String getOperator() {
 221         return operator;
 222     }
 223 
 224     /**
 225      * Returns the first operator in this call site descriptor's name. E.g. if this call site descriptor has a composite
 226      * operation {@code "getProp|getMethod|getElem"}, it will return {@code "getProp"}. Nashorn - being a ECMAScript
 227      * engine - does not distinguish between property, element, and method namespace; ECMAScript objects just have one
 228      * single property namespace for all these, therefore it is largely irrelevant what the composite operation is
 229      * structured like; if the first operation can't be satisfied, neither can the others. The first operation is
 230      * however sometimes used to slightly alter the semantics; for example, a distinction between {@code "getProp"} and
 231      * {@code "getMethod"} being the first operation can translate into whether {@code "__noSuchProperty__"} or
 232      * {@code "__noSuchMethod__"} will be executed in case the property is not found.
 233      * @return the first operator in this call site descriptor's name.
 234      */
 235     public String getFirstOperator() {
 236         final int delim = operator.indexOf(CallSiteDescriptor.OPERATOR_DELIMITER);
 237         return delim == -1 ? operator : operator.substring(0, delim);
 238     }
 239 
 240     /**
 241      * Returns the named operand in this descriptor's name. Equivalent to
 242      * {@code getNameToken(CallSiteDescriptor.NAME_OPERAND)}. E.g. for operation {@code "dyn:getProp:color"}, returns
 243      * {@code "color"}. For call sites without named operands (e.g. {@code "dyn:new"}) returns null.
 244      * @return the named operand in this descriptor's name.
 245      */
 246     public String getOperand() {
 247         return operand;
 248     }
 249 
 250     /**
 251      * Returns the Nashorn-specific flags for this call site descriptor.
 252      * @param desc the descriptor. It can be any kind of a call site descriptor, not necessarily a
 253      * {@code NashornCallSiteDescriptor}. This allows for graceful interoperability when linking Nashorn with code
 254      * generated outside of Nashorn.
 255      * @return the Nashorn-specific flags for the call site, or 0 if the passed descriptor is not a Nashorn call site
 256      * descriptor.
 257      */
 258     public static int getFlags(final CallSiteDescriptor desc) {
 259         return desc instanceof NashornCallSiteDescriptor ? ((NashornCallSiteDescriptor)desc).flags : 0;
 260     }
 261 
 262     /**
 263      * Returns true if this descriptor has the specified flag set, see {@code CALLSITE_*} constants in this class.
 264      * @param flag the tested flag
 265      * @return true if the flag is set, false otherwise
 266      */
 267     private boolean isFlag(final int flag) {
 268         return (flags & flag) != 0;
 269     }
 270 
 271     /**
 272      * Returns true if this descriptor has the specified flag set, see {@code CALLSITE_*} constants in this class.
 273      * @param desc the descriptor. It can be any kind of a call site descriptor, not necessarily a
 274      * {@code NashornCallSiteDescriptor}. This allows for graceful interoperability when linking Nashorn with code
 275      * generated outside of Nashorn.
 276      * @param flag the tested flag
 277      * @return true if the flag is set, false otherwise (it will be false if the descriptor is not a Nashorn call site
 278      * descriptor).
 279      */
 280     private static boolean isFlag(final CallSiteDescriptor desc, final int flag) {
 281         return (getFlags(desc) & flag) != 0;
 282     }
 283 
 284     /**
 285      * Returns true if this descriptor is a Nashorn call site descriptor and has the {@link  #CALLSITE_SCOPE} flag set.
 286      * @param desc the descriptor. It can be any kind of a call site descriptor, not necessarily a
 287      * {@code NashornCallSiteDescriptor}. This allows for graceful interoperability when linking Nashorn with code
 288      * generated outside of Nashorn.
 289      * @return true if the descriptor is a Nashorn call site descriptor, and the flag is set, false otherwise.
 290      */
 291     public static boolean isScope(final CallSiteDescriptor desc) {
 292         return isFlag(desc, CALLSITE_SCOPE);
 293     }
 294 
 295     /**
 296      * Returns true if this descriptor is a Nashorn call site descriptor and has the {@link  #CALLSITE_FAST_SCOPE} flag set.
 297      * @param desc the descriptor. It can be any kind of a call site descriptor, not necessarily a
 298      * {@code NashornCallSiteDescriptor}. This allows for graceful interoperability when linking Nashorn with code
 299      * generated outside of Nashorn.
 300      * @return true if the descriptor is a Nashorn call site descriptor, and the flag is set, false otherwise.
 301      */
 302     public static boolean isFastScope(final CallSiteDescriptor desc) {
 303         return isFlag(desc, CALLSITE_FAST_SCOPE);
 304     }
 305 
 306     /**
 307      * Returns true if this descriptor is a Nashorn call site descriptor and has the {@link  #CALLSITE_STRICT} flag set.
 308      * @param desc the descriptor. It can be any kind of a call site descriptor, not necessarily a
 309      * {@code NashornCallSiteDescriptor}. This allows for graceful interoperability when linking Nashorn with code
 310      * generated outside of Nashorn.
 311      * @return true if the descriptor is a Nashorn call site descriptor, and the flag is set, false otherwise.
 312      */
 313     public static boolean isStrict(final CallSiteDescriptor desc) {
 314         return isFlag(desc, CALLSITE_STRICT);
 315     }
 316 
 317     /**
 318      * Returns true if this is an apply call that we try to call as
 319      * a "call"
 320      * @param desc descriptor
 321      * @return true if apply to call
 322      */
 323     public static boolean isApplyToCall(final CallSiteDescriptor desc) {
 324         return isFlag(desc, CALLSITE_APPLY_TO_CALL);
 325     }
 326 
 327     /**
 328      * Is this an optimistic call site
 329      * @param desc descriptor
 330      * @return true if optimistic
 331      */
 332     public static boolean isOptimistic(final CallSiteDescriptor desc) {
 333         return isFlag(desc, CALLSITE_OPTIMISTIC);
 334     }
 335 
 336     /**
 337      * Does this callsite contain a declaration for its target?
 338      * @param desc descriptor
 339      * @return true if contains declaration
 340      */
 341     public static boolean isDeclaration(final CallSiteDescriptor desc) {
 342         return isFlag(desc, CALLSITE_DECLARE);
 343     }
 344 
 345     /**
 346      * Returns true if {@code flags} has the {@link  #CALLSITE_STRICT} bit set.
 347      * @param flags the flags
 348      * @return true if the flag is set, false otherwise.
 349      */
 350     public static boolean isStrictFlag(final int flags) {
 351         return (flags & CALLSITE_STRICT) != 0;
 352     }
 353 
 354     /**
 355      * Returns true if {@code flags} has the {@link  #CALLSITE_SCOPE} bit set.
 356      * @param flags the flags
 357      * @return true if the flag is set, false otherwise.
 358      */
 359     public static boolean isScopeFlag(final int flags) {
 360         return (flags & CALLSITE_SCOPE) != 0;
 361     }
 362 
 363     /**
 364      * Get a program point from a descriptor (must be optimistic)
 365      * @param desc descriptor
 366      * @return program point
 367      */
 368     public static int getProgramPoint(final CallSiteDescriptor desc) {
 369         assert isOptimistic(desc) : "program point requested from non-optimistic descriptor " + desc;
 370         return getFlags(desc) >> CALLSITE_PROGRAM_POINT_SHIFT;
 371     }
 372 
 373     boolean isProfile() {
 374         return isFlag(CALLSITE_PROFILE);
 375     }
 376 
 377     boolean isTrace() {
 378         return isFlag(CALLSITE_TRACE);
 379     }
 380 
 381     boolean isTraceMisses() {
 382         return isFlag(CALLSITE_TRACE_MISSES);
 383     }
 384 
 385     boolean isTraceEnterExit() {
 386         return isFlag(CALLSITE_TRACE_ENTEREXIT);
 387     }
 388 
 389     boolean isTraceObjects() {
 390         return isFlag(CALLSITE_TRACE_VALUES);
 391     }
 392 
 393     boolean isOptimistic() {
 394         return isFlag(CALLSITE_OPTIMISTIC);
 395     }
 396 
 397     @Override
 398     public CallSiteDescriptor changeMethodType(final MethodType newMethodType) {
 399         return get(getLookup(), operator, operand, newMethodType, flags);
 400     }
 401 
 402 }