1/* 2 * Copyright (c) 2008, 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 26package java.lang.invoke; 27 28import jdk.internal.vm.annotation.Stable; 29import sun.invoke.util.Wrapper; 30 31import java.lang.ref.SoftReference; 32 33import 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 */ 48final 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_LIMIT = 20; 89 90 /** Return the type corresponding uniquely (1-1) to this MT-form. 91 * It might have any primitive returns or arguments, but will have no references except Object. 92 */ 93 public MethodType erasedType() { 94 return erasedType; 95 } 96 97 /** Return the basic type derived from the erased type of this MT-form. 98 * A basic type is erased (all references Object) and also has all primitive 99 * types (except int, long, float, double, void) normalized to int. 100 * Such basic types correspond to low-level JVM calling sequences. 101 */ 102 public MethodType basicType() { 103 return basicType; 104 } 105 106 private boolean assertIsBasicType() { 107 // primitives must be flattened also 108 assert(erasedType == basicType) 109 : "erasedType: " + erasedType + " != basicType: " + basicType; 110 return true; 111 } 112 113 public MethodHandle cachedMethodHandle(int which) { 114 assert(assertIsBasicType()); 115 SoftReference<MethodHandle> entry = methodHandles[which]; 116 return (entry != null) ? entry.get() : null; 117 } 118 119 public synchronized MethodHandle setCachedMethodHandle(int which, MethodHandle mh) { 120 // Simulate a CAS, to avoid racy duplication of results. 121 SoftReference<MethodHandle> entry = methodHandles[which]; 122 if (entry != null) { 123 MethodHandle prev = entry.get(); 124 if (prev != null) { 125 return prev; 126 } 127 } 128 methodHandles[which] = new SoftReference<>(mh); 129 return mh; 130 } 131 132 public LambdaForm cachedLambdaForm(int which) { 133 assert(assertIsBasicType()); 134 SoftReference<LambdaForm> entry = lambdaForms[which]; 135 return (entry != null) ? entry.get() : null; 136 } 137 138 public synchronized LambdaForm setCachedLambdaForm(int which, LambdaForm form) { 139 // Simulate a CAS, to avoid racy duplication of results. 140 SoftReference<LambdaForm> entry = lambdaForms[which]; 141 if (entry != null) { 142 LambdaForm prev = entry.get(); 143 if (prev != null) { 144 return prev; 145 } 146 } 147 lambdaForms[which] = new SoftReference<>(form); 148 return form; 149 } 150 151 /** 152 * Build an MTF for a given type, which must have all references erased to Object. 153 * This MTF will stand for that type and all un-erased variations. 154 * Eagerly compute some basic properties of the type, common to all variations. 155 */ 156 @SuppressWarnings({"rawtypes", "unchecked"}) 157 protected MethodTypeForm(MethodType erasedType) { 158 this.erasedType = erasedType; 159 160 Class<?>[] ptypes = erasedType.ptypes(); 161 int ptypeCount = ptypes.length; 162 int pslotCount = ptypeCount; // temp. estimate 163 int rtypeCount = 1; // temp. estimate 164 int rslotCount = 1; // temp. estimate 165 166 int[] argToSlotTab = null, slotToArgTab = null; 167 168 // Walk the argument types, looking for primitives. 169 int pac = 0, lac = 0, prc = 0, lrc = 0; 170 Class<?>[] epts = ptypes; 171 Class<?>[] bpts = epts; 172 for (int i = 0; i < epts.length; i++) { 173 Class<?> pt = epts[i]; 174 if (pt != Object.class) { 175 ++pac; 176 Wrapper w = Wrapper.forPrimitiveType(pt); 177 if (w.isDoubleWord()) ++lac; 178 if (w.isSubwordOrInt() && pt != int.class) { 179 if (bpts == epts) 180 bpts = bpts.clone(); 181 bpts[i] = int.class; 182 } 183 } 184 } 185 pslotCount += lac; // #slots = #args + #longs 186 Class<?> rt = erasedType.returnType(); 187 Class<?> bt = rt; 188 if (rt != Object.class) { 189 ++prc; // even void.class counts as a prim here 190 Wrapper w = Wrapper.forPrimitiveType(rt); 191 if (w.isDoubleWord()) ++lrc; 192 if (w.isSubwordOrInt() && rt != int.class) 193 bt = int.class; 194 // adjust #slots, #args 195 if (rt == void.class) 196 rtypeCount = rslotCount = 0; 197 else 198 rslotCount += lrc; 199 } 200 if (epts == bpts && bt == rt) { 201 this.basicType = erasedType; 202 } else { 203 this.basicType = MethodType.makeImpl(bt, bpts, true); 204 // fill in rest of data from the basic type: 205 MethodTypeForm that = this.basicType.form(); 206 assert(this != that); 207 this.primCounts = that.primCounts; 208 this.argCounts = that.argCounts; 209 this.argToSlotTable = that.argToSlotTable; 210 this.slotToArgTable = that.slotToArgTable; 211 this.methodHandles = null; 212 this.lambdaForms = null; 213 return; 214 } 215 if (lac != 0) { 216 int slot = ptypeCount + lac; 217 slotToArgTab = new int[slot+1]; 218 argToSlotTab = new int[1+ptypeCount]; 219 argToSlotTab[0] = slot; // argument "-1" is past end of slots 220 for (int i = 0; i < epts.length; i++) { 221 Class<?> pt = epts[i]; 222 Wrapper w = Wrapper.forBasicType(pt); 223 if (w.isDoubleWord()) --slot; 224 --slot; 225 slotToArgTab[slot] = i+1; // "+1" see argSlotToParameter note 226 argToSlotTab[1+i] = slot; 227 } 228 assert(slot == 0); // filled the table 229 } else if (pac != 0) { 230 // have primitives but no long primitives; share slot counts with generic 231 assert(ptypeCount == pslotCount); 232 MethodTypeForm that = MethodType.genericMethodType(ptypeCount).form(); 233 assert(this != that); 234 slotToArgTab = that.slotToArgTable; 235 argToSlotTab = that.argToSlotTable; 236 } else { 237 int slot = ptypeCount; // first arg is deepest in stack 238 slotToArgTab = new int[slot+1]; 239 argToSlotTab = new int[1+ptypeCount]; 240 argToSlotTab[0] = slot; // argument "-1" is past end of slots 241 for (int i = 0; i < ptypeCount; i++) { 242 --slot; 243 slotToArgTab[slot] = i+1; // "+1" see argSlotToParameter note 244 argToSlotTab[1+i] = slot; 245 } 246 } 247 this.primCounts = pack(lrc, prc, lac, pac); 248 this.argCounts = pack(rslotCount, rtypeCount, pslotCount, ptypeCount); 249 this.argToSlotTable = argToSlotTab; 250 this.slotToArgTable = slotToArgTab; 251 252 if (pslotCount >= 256) throw newIllegalArgumentException("too many arguments"); 253 254 // Initialize caches, but only for basic types 255 assert(basicType == erasedType); 256 this.lambdaForms = new SoftReference[LF_LIMIT]; 257 this.methodHandles = new SoftReference[MH_LIMIT]; 258 } 259 260 private static long pack(int a, int b, int c, int d) { 261 assert(((a|b|c|d) & ~0xFFFF) == 0); 262 long hw = ((a << 16) | b), lw = ((c << 16) | d); 263 return (hw << 32) | lw; 264 } 265 private static char unpack(long packed, int word) { // word==0 => return a, ==3 => return d 266 assert(word <= 3); 267 return (char)(packed >> ((3-word) * 16)); 268 } 269 270 public int parameterCount() { // # outgoing values 271 return unpack(argCounts, 3); 272 } 273 public int parameterSlotCount() { // # outgoing interpreter slots 274 return unpack(argCounts, 2); 275 } 276 public int returnCount() { // = 0 (V), or 1 277 return unpack(argCounts, 1); 278 } 279 public int returnSlotCount() { // = 0 (V), 2 (J/D), or 1 280 return unpack(argCounts, 0); 281 } 282 public int primitiveParameterCount() { 283 return unpack(primCounts, 3); 284 } 285 public int longPrimitiveParameterCount() { 286 return unpack(primCounts, 2); 287 } 288 public int primitiveReturnCount() { // = 0 (obj), or 1 289 return unpack(primCounts, 1); 290 } 291 public int longPrimitiveReturnCount() { // = 1 (J/D), or 0 292 return unpack(primCounts, 0); 293 } 294 public boolean hasPrimitives() { 295 return primCounts != 0; 296 } 297 public boolean hasNonVoidPrimitives() { 298 if (primCounts == 0) return false; 299 if (primitiveParameterCount() != 0) return true; 300 return (primitiveReturnCount() != 0 && returnCount() != 0); 301 } 302 public boolean hasLongPrimitives() { 303 return (longPrimitiveParameterCount() | longPrimitiveReturnCount()) != 0; 304 } 305 public int parameterToArgSlot(int i) { 306 return argToSlotTable[1+i]; 307 } 308 public int argSlotToParameter(int argSlot) { 309 // Note: Empty slots are represented by zero in this table. 310 // Valid arguments slots contain incremented entries, so as to be non-zero. 311 // We return -1 the caller to mean an empty slot. 312 return slotToArgTable[argSlot] - 1; 313 } 314 315 static MethodTypeForm findForm(MethodType mt) { 316 MethodType erased = canonicalize(mt, ERASE, ERASE); 317 if (erased == null) { 318 // It is already erased. Make a new MethodTypeForm. 319 return new MethodTypeForm(mt); 320 } else { 321 // Share the MethodTypeForm with the erased version. 322 return erased.form(); 323 } 324 } 325 326 /** Codes for {@link #canonicalize(java.lang.Class, int)}. 327 * ERASE means change every reference to {@code Object}. 328 * WRAP means convert primitives (including {@code void} to their 329 * corresponding wrapper types. UNWRAP means the reverse of WRAP. 330 * INTS means convert all non-void primitive types to int or long, 331 * according to size. LONGS means convert all non-void primitives 332 * to long, regardless of size. RAW_RETURN means convert a type 333 * (assumed to be a return type) to int if it is smaller than an int, 334 * or if it is void. 335 */ 336 public static final int NO_CHANGE = 0, ERASE = 1, WRAP = 2, UNWRAP = 3, INTS = 4, LONGS = 5, RAW_RETURN = 6; 337 338 /** Canonicalize the types in the given method type. 339 * If any types change, intern the new type, and return it. 340 * Otherwise return null. 341 */ 342 public static MethodType canonicalize(MethodType mt, int howRet, int howArgs) { 343 Class<?>[] ptypes = mt.ptypes(); 344 Class<?>[] ptc = MethodTypeForm.canonicalizeAll(ptypes, howArgs); 345 Class<?> rtype = mt.returnType(); 346 Class<?> rtc = MethodTypeForm.canonicalize(rtype, howRet); 347 if (ptc == null && rtc == null) { 348 // It is already canonical. 349 return null; 350 } 351 // Find the erased version of the method type: 352 if (rtc == null) rtc = rtype; 353 if (ptc == null) ptc = ptypes; 354 return MethodType.makeImpl(rtc, ptc, true); 355 } 356 357 /** Canonicalize the given return or param type. 358 * Return null if the type is already canonicalized. 359 */ 360 static Class<?> canonicalize(Class<?> t, int how) { 361 Class<?> ct; 362 if (t == Object.class) { 363 // no change, ever 364 } else if (!t.isPrimitive()) { 365 switch (how) { 366 case UNWRAP: 367 ct = Wrapper.asPrimitiveType(t); 368 if (ct != t) return ct; 369 break; 370 case RAW_RETURN: 371 case ERASE: 372 return Object.class; 373 } 374 } else if (t == void.class) { 375 // no change, usually 376 switch (how) { 377 case RAW_RETURN: 378 return int.class; 379 case WRAP: 380 return Void.class; 381 } 382 } else { 383 // non-void primitive 384 switch (how) { 385 case WRAP: 386 return Wrapper.asWrapperType(t); 387 case INTS: 388 if (t == int.class || t == long.class) 389 return null; // no change 390 if (t == double.class) 391 return long.class; 392 return int.class; 393 case LONGS: 394 if (t == long.class) 395 return null; // no change 396 return long.class; 397 case RAW_RETURN: 398 if (t == int.class || t == long.class || 399 t == float.class || t == double.class) 400 return null; // no change 401 // everything else returns as an int 402 return int.class; 403 } 404 } 405 // no change; return null to signify 406 return null; 407 } 408 409 /** Canonicalize each param type in the given array. 410 * Return null if all types are already canonicalized. 411 */ 412 static Class<?>[] canonicalizeAll(Class<?>[] ts, int how) { 413 Class<?>[] cs = null; 414 for (int imax = ts.length, i = 0; i < imax; i++) { 415 Class<?> c = canonicalize(ts[i], how); 416 if (c == void.class) 417 c = null; // a Void parameter was unwrapped to void; ignore 418 if (c != null) { 419 if (cs == null) 420 cs = ts.clone(); 421 cs[i] = c; 422 } 423 } 424 return cs; 425 } 426 427 @Override 428 public String toString() { 429 return "Form"+erasedType; 430 } 431} 432