1 /* 2 * Copyright (c) 2008, 2018, 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 java.lang.invoke; 27 28 import jdk.internal.vm.annotation.Stable; 29 import sun.invoke.util.Wrapper; 30 31 import java.lang.ref.SoftReference; 32 33 import static java.lang.invoke.MethodHandleStatics.newIllegalArgumentException; 34 35 /** 36 * Shared information for a group of method types, which differ 37 * only by reference types, and therefore share a common erasure 38 * and wrapping. 39 * <p> 40 * For an empirical discussion of the structure of method types, 41 * see <a href="http://groups.google.com/group/jvm-languages/browse_thread/thread/ac9308ae74da9b7e/"> 42 * the thread "Avoiding Boxing" on jvm-languages</a>. 43 * There are approximately 2000 distinct erased method types in the JDK. 44 * There are a little over 10 times that number of unerased types. 45 * No more than half of these are likely to be loaded at once. 46 * @author John Rose 47 */ 48 final class MethodTypeForm { 49 final int[] argToSlotTable, slotToArgTable; 50 final long argCounts; // packed slot & value counts 51 final long primCounts; // packed prim & double counts 52 final MethodType erasedType; // the canonical erasure 53 final MethodType basicType; // the canonical erasure, with primitives simplified 54 55 // Cached adapter information: 56 @Stable final SoftReference<MethodHandle>[] methodHandles; 57 // Indexes into methodHandles: 58 static final int 59 MH_BASIC_INV = 0, // cached instance of MH.invokeBasic 60 MH_NF_INV = 1, // cached helper for LF.NamedFunction 61 MH_UNINIT_CS = 2, // uninitialized call site 62 MH_LIMIT = 3; 63 64 // Cached lambda form information, for basic types only: 65 final @Stable SoftReference<LambdaForm>[] lambdaForms; 66 // Indexes into lambdaForms: 67 static final int 68 LF_INVVIRTUAL = 0, // DMH invokeVirtual 69 LF_INVSTATIC = 1, 70 LF_INVSPECIAL = 2, 71 LF_NEWINVSPECIAL = 3, 72 LF_INVINTERFACE = 4, 73 LF_INVSTATIC_INIT = 5, // DMH invokeStatic with <clinit> barrier 74 LF_INTERPRET = 6, // LF interpreter 75 LF_REBIND = 7, // BoundMethodHandle 76 LF_DELEGATE = 8, // DelegatingMethodHandle 77 LF_DELEGATE_BLOCK_INLINING = 9, // Counting DelegatingMethodHandle w/ @DontInline 78 LF_EX_LINKER = 10, // invokeExact_MT (for invokehandle) 79 LF_EX_INVOKER = 11, // MHs.invokeExact 80 LF_GEN_LINKER = 12, // generic invoke_MT (for invokehandle) 81 LF_GEN_INVOKER = 13, // generic MHs.invoke 82 LF_CS_LINKER = 14, // linkToCallSite_CS 83 LF_MH_LINKER = 15, // linkToCallSite_MH 84 LF_GWC = 16, // guardWithCatch (catchException) 85 LF_GWT = 17, // guardWithTest 86 LF_TF = 18, // tryFinally 87 LF_LOOP = 19, // loop 88 LF_INVSPECIAL_IFC = 20, // DMH invokeSpecial of (private) interface method 89 LF_LIMIT = 21; 90 91 /** Return the type corresponding uniquely (1-1) to this MT-form. 92 * It might have any primitive returns or arguments, but will have no references except Object. 93 */ erasedType()94 public MethodType erasedType() { 95 return erasedType; 96 } 97 98 /** Return the basic type derived from the erased type of this MT-form. 99 * A basic type is erased (all references Object) and also has all primitive 100 * types (except int, long, float, double, void) normalized to int. 101 * Such basic types correspond to low-level JVM calling sequences. 102 */ basicType()103 public MethodType basicType() { 104 return basicType; 105 } 106 assertIsBasicType()107 private boolean assertIsBasicType() { 108 // primitives must be flattened also 109 assert(erasedType == basicType) 110 : "erasedType: " + erasedType + " != basicType: " + basicType; 111 return true; 112 } 113 cachedMethodHandle(int which)114 public MethodHandle cachedMethodHandle(int which) { 115 assert(assertIsBasicType()); 116 SoftReference<MethodHandle> entry = methodHandles[which]; 117 return (entry != null) ? entry.get() : null; 118 } 119 setCachedMethodHandle(int which, MethodHandle mh)120 public synchronized MethodHandle setCachedMethodHandle(int which, MethodHandle mh) { 121 // Simulate a CAS, to avoid racy duplication of results. 122 SoftReference<MethodHandle> entry = methodHandles[which]; 123 if (entry != null) { 124 MethodHandle prev = entry.get(); 125 if (prev != null) { 126 return prev; 127 } 128 } 129 methodHandles[which] = new SoftReference<>(mh); 130 return mh; 131 } 132 cachedLambdaForm(int which)133 public LambdaForm cachedLambdaForm(int which) { 134 assert(assertIsBasicType()); 135 SoftReference<LambdaForm> entry = lambdaForms[which]; 136 return (entry != null) ? entry.get() : null; 137 } 138 setCachedLambdaForm(int which, LambdaForm form)139 public synchronized LambdaForm setCachedLambdaForm(int which, LambdaForm form) { 140 // Simulate a CAS, to avoid racy duplication of results. 141 SoftReference<LambdaForm> entry = lambdaForms[which]; 142 if (entry != null) { 143 LambdaForm prev = entry.get(); 144 if (prev != null) { 145 return prev; 146 } 147 } 148 lambdaForms[which] = new SoftReference<>(form); 149 return form; 150 } 151 152 /** 153 * Build an MTF for a given type, which must have all references erased to Object. 154 * This MTF will stand for that type and all un-erased variations. 155 * Eagerly compute some basic properties of the type, common to all variations. 156 */ 157 @SuppressWarnings({"rawtypes", "unchecked"}) MethodTypeForm(MethodType erasedType)158 protected MethodTypeForm(MethodType erasedType) { 159 this.erasedType = erasedType; 160 161 Class<?>[] ptypes = erasedType.ptypes(); 162 int ptypeCount = ptypes.length; 163 int pslotCount = ptypeCount; // temp. estimate 164 int rtypeCount = 1; // temp. estimate 165 int rslotCount = 1; // temp. estimate 166 167 int[] argToSlotTab = null, slotToArgTab = null; 168 169 // Walk the argument types, looking for primitives. 170 int pac = 0, lac = 0, prc = 0, lrc = 0; 171 Class<?>[] epts = ptypes; 172 Class<?>[] bpts = epts; 173 for (int i = 0; i < epts.length; i++) { 174 Class<?> pt = epts[i]; 175 if (pt != Object.class) { 176 ++pac; 177 Wrapper w = Wrapper.forPrimitiveType(pt); 178 if (w.isDoubleWord()) ++lac; 179 if (w.isSubwordOrInt() && pt != int.class) { 180 if (bpts == epts) 181 bpts = bpts.clone(); 182 bpts[i] = int.class; 183 } 184 } 185 } 186 pslotCount += lac; // #slots = #args + #longs 187 Class<?> rt = erasedType.returnType(); 188 Class<?> bt = rt; 189 if (rt != Object.class) { 190 ++prc; // even void.class counts as a prim here 191 Wrapper w = Wrapper.forPrimitiveType(rt); 192 if (w.isDoubleWord()) ++lrc; 193 if (w.isSubwordOrInt() && rt != int.class) 194 bt = int.class; 195 // adjust #slots, #args 196 if (rt == void.class) 197 rtypeCount = rslotCount = 0; 198 else 199 rslotCount += lrc; 200 } 201 if (epts == bpts && bt == rt) { 202 this.basicType = erasedType; 203 } else { 204 this.basicType = MethodType.makeImpl(bt, bpts, true); 205 // fill in rest of data from the basic type: 206 MethodTypeForm that = this.basicType.form(); 207 assert(this != that); 208 this.primCounts = that.primCounts; 209 this.argCounts = that.argCounts; 210 this.argToSlotTable = that.argToSlotTable; 211 this.slotToArgTable = that.slotToArgTable; 212 this.methodHandles = null; 213 this.lambdaForms = null; 214 return; 215 } 216 if (lac != 0) { 217 int slot = ptypeCount + lac; 218 slotToArgTab = new int[slot+1]; 219 argToSlotTab = new int[1+ptypeCount]; 220 argToSlotTab[0] = slot; // argument "-1" is past end of slots 221 for (int i = 0; i < epts.length; i++) { 222 Class<?> pt = epts[i]; 223 Wrapper w = Wrapper.forBasicType(pt); 224 if (w.isDoubleWord()) --slot; 225 --slot; 226 slotToArgTab[slot] = i+1; // "+1" see argSlotToParameter note 227 argToSlotTab[1+i] = slot; 228 } 229 assert(slot == 0); // filled the table 230 } else if (pac != 0) { 231 // have primitives but no long primitives; share slot counts with generic 232 assert(ptypeCount == pslotCount); 233 MethodTypeForm that = MethodType.genericMethodType(ptypeCount).form(); 234 assert(this != that); 235 slotToArgTab = that.slotToArgTable; 236 argToSlotTab = that.argToSlotTable; 237 } else { 238 int slot = ptypeCount; // first arg is deepest in stack 239 slotToArgTab = new int[slot+1]; 240 argToSlotTab = new int[1+ptypeCount]; 241 argToSlotTab[0] = slot; // argument "-1" is past end of slots 242 for (int i = 0; i < ptypeCount; i++) { 243 --slot; 244 slotToArgTab[slot] = i+1; // "+1" see argSlotToParameter note 245 argToSlotTab[1+i] = slot; 246 } 247 } 248 this.primCounts = pack(lrc, prc, lac, pac); 249 this.argCounts = pack(rslotCount, rtypeCount, pslotCount, ptypeCount); 250 this.argToSlotTable = argToSlotTab; 251 this.slotToArgTable = slotToArgTab; 252 253 if (pslotCount >= 256) throw newIllegalArgumentException("too many arguments"); 254 255 // Initialize caches, but only for basic types 256 assert(basicType == erasedType); 257 this.lambdaForms = new SoftReference[LF_LIMIT]; 258 this.methodHandles = new SoftReference[MH_LIMIT]; 259 } 260 pack(int a, int b, int c, int d)261 private static long pack(int a, int b, int c, int d) { 262 assert(((a|b|c|d) & ~0xFFFF) == 0); 263 long hw = ((a << 16) | b), lw = ((c << 16) | d); 264 return (hw << 32) | lw; 265 } unpack(long packed, int word)266 private static char unpack(long packed, int word) { // word==0 => return a, ==3 => return d 267 assert(word <= 3); 268 return (char)(packed >> ((3-word) * 16)); 269 } 270 parameterCount()271 public int parameterCount() { // # outgoing values 272 return unpack(argCounts, 3); 273 } parameterSlotCount()274 public int parameterSlotCount() { // # outgoing interpreter slots 275 return unpack(argCounts, 2); 276 } returnCount()277 public int returnCount() { // = 0 (V), or 1 278 return unpack(argCounts, 1); 279 } returnSlotCount()280 public int returnSlotCount() { // = 0 (V), 2 (J/D), or 1 281 return unpack(argCounts, 0); 282 } primitiveParameterCount()283 public int primitiveParameterCount() { 284 return unpack(primCounts, 3); 285 } longPrimitiveParameterCount()286 public int longPrimitiveParameterCount() { 287 return unpack(primCounts, 2); 288 } primitiveReturnCount()289 public int primitiveReturnCount() { // = 0 (obj), or 1 290 return unpack(primCounts, 1); 291 } longPrimitiveReturnCount()292 public int longPrimitiveReturnCount() { // = 1 (J/D), or 0 293 return unpack(primCounts, 0); 294 } hasPrimitives()295 public boolean hasPrimitives() { 296 return primCounts != 0; 297 } hasNonVoidPrimitives()298 public boolean hasNonVoidPrimitives() { 299 if (primCounts == 0) return false; 300 if (primitiveParameterCount() != 0) return true; 301 return (primitiveReturnCount() != 0 && returnCount() != 0); 302 } hasLongPrimitives()303 public boolean hasLongPrimitives() { 304 return (longPrimitiveParameterCount() | longPrimitiveReturnCount()) != 0; 305 } parameterToArgSlot(int i)306 public int parameterToArgSlot(int i) { 307 return argToSlotTable[1+i]; 308 } argSlotToParameter(int argSlot)309 public int argSlotToParameter(int argSlot) { 310 // Note: Empty slots are represented by zero in this table. 311 // Valid arguments slots contain incremented entries, so as to be non-zero. 312 // We return -1 the caller to mean an empty slot. 313 return slotToArgTable[argSlot] - 1; 314 } 315 findForm(MethodType mt)316 static MethodTypeForm findForm(MethodType mt) { 317 MethodType erased = canonicalize(mt, ERASE, ERASE); 318 if (erased == null) { 319 // It is already erased. Make a new MethodTypeForm. 320 return new MethodTypeForm(mt); 321 } else { 322 // Share the MethodTypeForm with the erased version. 323 return erased.form(); 324 } 325 } 326 327 /** Codes for {@link #canonicalize(java.lang.Class, int)}. 328 * ERASE means change every reference to {@code Object}. 329 * WRAP means convert primitives (including {@code void} to their 330 * corresponding wrapper types. UNWRAP means the reverse of WRAP. 331 * INTS means convert all non-void primitive types to int or long, 332 * according to size. LONGS means convert all non-void primitives 333 * to long, regardless of size. RAW_RETURN means convert a type 334 * (assumed to be a return type) to int if it is smaller than an int, 335 * or if it is void. 336 */ 337 public static final int NO_CHANGE = 0, ERASE = 1, WRAP = 2, UNWRAP = 3, INTS = 4, LONGS = 5, RAW_RETURN = 6; 338 339 /** Canonicalize the types in the given method type. 340 * If any types change, intern the new type, and return it. 341 * Otherwise return null. 342 */ canonicalize(MethodType mt, int howRet, int howArgs)343 public static MethodType canonicalize(MethodType mt, int howRet, int howArgs) { 344 Class<?>[] ptypes = mt.ptypes(); 345 Class<?>[] ptc = MethodTypeForm.canonicalizeAll(ptypes, howArgs); 346 Class<?> rtype = mt.returnType(); 347 Class<?> rtc = MethodTypeForm.canonicalize(rtype, howRet); 348 if (ptc == null && rtc == null) { 349 // It is already canonical. 350 return null; 351 } 352 // Find the erased version of the method type: 353 if (rtc == null) rtc = rtype; 354 if (ptc == null) ptc = ptypes; 355 return MethodType.makeImpl(rtc, ptc, true); 356 } 357 358 /** Canonicalize the given return or param type. 359 * Return null if the type is already canonicalized. 360 */ canonicalize(Class<?> t, int how)361 static Class<?> canonicalize(Class<?> t, int how) { 362 Class<?> ct; 363 if (t == Object.class) { 364 // no change, ever 365 } else if (!t.isPrimitive()) { 366 switch (how) { 367 case UNWRAP: 368 ct = Wrapper.asPrimitiveType(t); 369 if (ct != t) return ct; 370 break; 371 case RAW_RETURN: 372 case ERASE: 373 return Object.class; 374 } 375 } else if (t == void.class) { 376 // no change, usually 377 switch (how) { 378 case RAW_RETURN: 379 return int.class; 380 case WRAP: 381 return Void.class; 382 } 383 } else { 384 // non-void primitive 385 switch (how) { 386 case WRAP: 387 return Wrapper.asWrapperType(t); 388 case INTS: 389 if (t == int.class || t == long.class) 390 return null; // no change 391 if (t == double.class) 392 return long.class; 393 return int.class; 394 case LONGS: 395 if (t == long.class) 396 return null; // no change 397 return long.class; 398 case RAW_RETURN: 399 if (t == int.class || t == long.class || 400 t == float.class || t == double.class) 401 return null; // no change 402 // everything else returns as an int 403 return int.class; 404 } 405 } 406 // no change; return null to signify 407 return null; 408 } 409 410 /** Canonicalize each param type in the given array. 411 * Return null if all types are already canonicalized. 412 */ canonicalizeAll(Class<?>[] ts, int how)413 static Class<?>[] canonicalizeAll(Class<?>[] ts, int how) { 414 Class<?>[] cs = null; 415 for (int imax = ts.length, i = 0; i < imax; i++) { 416 Class<?> c = canonicalize(ts[i], how); 417 if (c == void.class) 418 c = null; // a Void parameter was unwrapped to void; ignore 419 if (c != null) { 420 if (cs == null) 421 cs = ts.clone(); 422 cs[i] = c; 423 } 424 } 425 return cs; 426 } 427 428 @Override toString()429 public String toString() { 430 return "Form"+erasedType; 431 } 432 } 433