MethodTypeForm.java revision 12745:f068a4ffddd2
1/* 2 * Copyright (c) 2008, 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 26package java.lang.invoke; 27 28import sun.invoke.util.Wrapper; 29import java.lang.ref.SoftReference; 30import static java.lang.invoke.MethodHandleStatics.*; 31 32/** 33 * Shared information for a group of method types, which differ 34 * only by reference types, and therefore share a common erasure 35 * and wrapping. 36 * <p> 37 * For an empirical discussion of the structure of method types, 38 * see <a href="http://groups.google.com/group/jvm-languages/browse_thread/thread/ac9308ae74da9b7e/"> 39 * the thread "Avoiding Boxing" on jvm-languages</a>. 40 * There are approximately 2000 distinct erased method types in the JDK. 41 * There are a little over 10 times that number of unerased types. 42 * No more than half of these are likely to be loaded at once. 43 * @author John Rose 44 */ 45final class MethodTypeForm { 46 final int[] argToSlotTable, slotToArgTable; 47 final long argCounts; // packed slot & value counts 48 final long primCounts; // packed prim & double counts 49 final MethodType erasedType; // the canonical erasure 50 final MethodType basicType; // the canonical erasure, with primitives simplified 51 52 // Cached adapter information: 53 @Stable final SoftReference<MethodHandle>[] methodHandles; 54 // Indexes into methodHandles: 55 static final int 56 MH_BASIC_INV = 0, // cached instance of MH.invokeBasic 57 MH_NF_INV = 1, // cached helper for LF.NamedFunction 58 MH_UNINIT_CS = 2, // uninitialized call site 59 MH_LIMIT = 3; 60 61 // Cached lambda form information, for basic types only: 62 final @Stable SoftReference<LambdaForm>[] lambdaForms; 63 // Indexes into lambdaForms: 64 static final int 65 LF_INVVIRTUAL = 0, // DMH invokeVirtual 66 LF_INVSTATIC = 1, 67 LF_INVSPECIAL = 2, 68 LF_NEWINVSPECIAL = 3, 69 LF_INVINTERFACE = 4, 70 LF_INVSTATIC_INIT = 5, // DMH invokeStatic with <clinit> barrier 71 LF_INTERPRET = 6, // LF interpreter 72 LF_REBIND = 7, // BoundMethodHandle 73 LF_DELEGATE = 8, // DelegatingMethodHandle 74 LF_DELEGATE_BLOCK_INLINING = 9, // Counting DelegatingMethodHandle w/ @DontInline 75 LF_EX_LINKER = 10, // invokeExact_MT (for invokehandle) 76 LF_EX_INVOKER = 11, // MHs.invokeExact 77 LF_GEN_LINKER = 12, // generic invoke_MT (for invokehandle) 78 LF_GEN_INVOKER = 13, // generic MHs.invoke 79 LF_CS_LINKER = 14, // linkToCallSite_CS 80 LF_MH_LINKER = 15, // linkToCallSite_MH 81 LF_GWC = 16, // guardWithCatch (catchException) 82 LF_GWT = 17, // guardWithTest 83 LF_LIMIT = 18; 84 85 /** Return the type corresponding uniquely (1-1) to this MT-form. 86 * It might have any primitive returns or arguments, but will have no references except Object. 87 */ 88 public MethodType erasedType() { 89 return erasedType; 90 } 91 92 /** Return the basic type derived from the erased type of this MT-form. 93 * A basic type is erased (all references Object) and also has all primitive 94 * types (except int, long, float, double, void) normalized to int. 95 * Such basic types correspond to low-level JVM calling sequences. 96 */ 97 public MethodType basicType() { 98 return basicType; 99 } 100 101 private boolean assertIsBasicType() { 102 // primitives must be flattened also 103 assert(erasedType == basicType) 104 : "erasedType: " + erasedType + " != basicType: " + basicType; 105 return true; 106 } 107 108 public MethodHandle cachedMethodHandle(int which) { 109 assert(assertIsBasicType()); 110 SoftReference<MethodHandle> entry = methodHandles[which]; 111 return (entry != null) ? entry.get() : null; 112 } 113 114 public synchronized MethodHandle setCachedMethodHandle(int which, MethodHandle mh) { 115 // Simulate a CAS, to avoid racy duplication of results. 116 SoftReference<MethodHandle> entry = methodHandles[which]; 117 if (entry != null) { 118 MethodHandle prev = entry.get(); 119 if (prev != null) { 120 return prev; 121 } 122 } 123 methodHandles[which] = new SoftReference<>(mh); 124 return mh; 125 } 126 127 public LambdaForm cachedLambdaForm(int which) { 128 assert(assertIsBasicType()); 129 SoftReference<LambdaForm> entry = lambdaForms[which]; 130 return (entry != null) ? entry.get() : null; 131 } 132 133 public synchronized LambdaForm setCachedLambdaForm(int which, LambdaForm form) { 134 // Simulate a CAS, to avoid racy duplication of results. 135 SoftReference<LambdaForm> entry = lambdaForms[which]; 136 if (entry != null) { 137 LambdaForm prev = entry.get(); 138 if (prev != null) { 139 return prev; 140 } 141 } 142 lambdaForms[which] = new SoftReference<>(form); 143 return form; 144 } 145 146 /** 147 * Build an MTF for a given type, which must have all references erased to Object. 148 * This MTF will stand for that type and all un-erased variations. 149 * Eagerly compute some basic properties of the type, common to all variations. 150 */ 151 @SuppressWarnings({"rawtypes", "unchecked"}) 152 protected MethodTypeForm(MethodType erasedType) { 153 this.erasedType = erasedType; 154 155 Class<?>[] ptypes = erasedType.ptypes(); 156 int ptypeCount = ptypes.length; 157 int pslotCount = ptypeCount; // temp. estimate 158 int rtypeCount = 1; // temp. estimate 159 int rslotCount = 1; // temp. estimate 160 161 int[] argToSlotTab = null, slotToArgTab = null; 162 163 // Walk the argument types, looking for primitives. 164 int pac = 0, lac = 0, prc = 0, lrc = 0; 165 Class<?>[] epts = ptypes; 166 Class<?>[] bpts = epts; 167 for (int i = 0; i < epts.length; i++) { 168 Class<?> pt = epts[i]; 169 if (pt != Object.class) { 170 ++pac; 171 Wrapper w = Wrapper.forPrimitiveType(pt); 172 if (w.isDoubleWord()) ++lac; 173 if (w.isSubwordOrInt() && pt != int.class) { 174 if (bpts == epts) 175 bpts = bpts.clone(); 176 bpts[i] = int.class; 177 } 178 } 179 } 180 pslotCount += lac; // #slots = #args + #longs 181 Class<?> rt = erasedType.returnType(); 182 Class<?> bt = rt; 183 if (rt != Object.class) { 184 ++prc; // even void.class counts as a prim here 185 Wrapper w = Wrapper.forPrimitiveType(rt); 186 if (w.isDoubleWord()) ++lrc; 187 if (w.isSubwordOrInt() && rt != int.class) 188 bt = int.class; 189 // adjust #slots, #args 190 if (rt == void.class) 191 rtypeCount = rslotCount = 0; 192 else 193 rslotCount += lrc; 194 } 195 if (epts == bpts && bt == rt) { 196 this.basicType = erasedType; 197 } else { 198 this.basicType = MethodType.makeImpl(bt, bpts, true); 199 // fill in rest of data from the basic type: 200 MethodTypeForm that = this.basicType.form(); 201 assert(this != that); 202 this.primCounts = that.primCounts; 203 this.argCounts = that.argCounts; 204 this.argToSlotTable = that.argToSlotTable; 205 this.slotToArgTable = that.slotToArgTable; 206 this.methodHandles = null; 207 this.lambdaForms = null; 208 return; 209 } 210 if (lac != 0) { 211 int slot = ptypeCount + lac; 212 slotToArgTab = new int[slot+1]; 213 argToSlotTab = new int[1+ptypeCount]; 214 argToSlotTab[0] = slot; // argument "-1" is past end of slots 215 for (int i = 0; i < epts.length; i++) { 216 Class<?> pt = epts[i]; 217 Wrapper w = Wrapper.forBasicType(pt); 218 if (w.isDoubleWord()) --slot; 219 --slot; 220 slotToArgTab[slot] = i+1; // "+1" see argSlotToParameter note 221 argToSlotTab[1+i] = slot; 222 } 223 assert(slot == 0); // filled the table 224 } else if (pac != 0) { 225 // have primitives but no long primitives; share slot counts with generic 226 assert(ptypeCount == pslotCount); 227 MethodTypeForm that = MethodType.genericMethodType(ptypeCount).form(); 228 assert(this != that); 229 slotToArgTab = that.slotToArgTable; 230 argToSlotTab = that.argToSlotTable; 231 } else { 232 int slot = ptypeCount; // first arg is deepest in stack 233 slotToArgTab = new int[slot+1]; 234 argToSlotTab = new int[1+ptypeCount]; 235 argToSlotTab[0] = slot; // argument "-1" is past end of slots 236 for (int i = 0; i < ptypeCount; i++) { 237 --slot; 238 slotToArgTab[slot] = i+1; // "+1" see argSlotToParameter note 239 argToSlotTab[1+i] = slot; 240 } 241 } 242 this.primCounts = pack(lrc, prc, lac, pac); 243 this.argCounts = pack(rslotCount, rtypeCount, pslotCount, ptypeCount); 244 this.argToSlotTable = argToSlotTab; 245 this.slotToArgTable = slotToArgTab; 246 247 if (pslotCount >= 256) throw newIllegalArgumentException("too many arguments"); 248 249 // Initialize caches, but only for basic types 250 assert(basicType == erasedType); 251 this.lambdaForms = new SoftReference[LF_LIMIT]; 252 this.methodHandles = new SoftReference[MH_LIMIT]; 253 } 254 255 private static long pack(int a, int b, int c, int d) { 256 assert(((a|b|c|d) & ~0xFFFF) == 0); 257 long hw = ((a << 16) | b), lw = ((c << 16) | d); 258 return (hw << 32) | lw; 259 } 260 private static char unpack(long packed, int word) { // word==0 => return a, ==3 => return d 261 assert(word <= 3); 262 return (char)(packed >> ((3-word) * 16)); 263 } 264 265 public int parameterCount() { // # outgoing values 266 return unpack(argCounts, 3); 267 } 268 public int parameterSlotCount() { // # outgoing interpreter slots 269 return unpack(argCounts, 2); 270 } 271 public int returnCount() { // = 0 (V), or 1 272 return unpack(argCounts, 1); 273 } 274 public int returnSlotCount() { // = 0 (V), 2 (J/D), or 1 275 return unpack(argCounts, 0); 276 } 277 public int primitiveParameterCount() { 278 return unpack(primCounts, 3); 279 } 280 public int longPrimitiveParameterCount() { 281 return unpack(primCounts, 2); 282 } 283 public int primitiveReturnCount() { // = 0 (obj), or 1 284 return unpack(primCounts, 1); 285 } 286 public int longPrimitiveReturnCount() { // = 1 (J/D), or 0 287 return unpack(primCounts, 0); 288 } 289 public boolean hasPrimitives() { 290 return primCounts != 0; 291 } 292 public boolean hasNonVoidPrimitives() { 293 if (primCounts == 0) return false; 294 if (primitiveParameterCount() != 0) return true; 295 return (primitiveReturnCount() != 0 && returnCount() != 0); 296 } 297 public boolean hasLongPrimitives() { 298 return (longPrimitiveParameterCount() | longPrimitiveReturnCount()) != 0; 299 } 300 public int parameterToArgSlot(int i) { 301 return argToSlotTable[1+i]; 302 } 303 public int argSlotToParameter(int argSlot) { 304 // Note: Empty slots are represented by zero in this table. 305 // Valid arguments slots contain incremented entries, so as to be non-zero. 306 // We return -1 the caller to mean an empty slot. 307 return slotToArgTable[argSlot] - 1; 308 } 309 310 static MethodTypeForm findForm(MethodType mt) { 311 MethodType erased = canonicalize(mt, ERASE, ERASE); 312 if (erased == null) { 313 // It is already erased. Make a new MethodTypeForm. 314 return new MethodTypeForm(mt); 315 } else { 316 // Share the MethodTypeForm with the erased version. 317 return erased.form(); 318 } 319 } 320 321 /** Codes for {@link #canonicalize(java.lang.Class, int)}. 322 * ERASE means change every reference to {@code Object}. 323 * WRAP means convert primitives (including {@code void} to their 324 * corresponding wrapper types. UNWRAP means the reverse of WRAP. 325 * INTS means convert all non-void primitive types to int or long, 326 * according to size. LONGS means convert all non-void primitives 327 * to long, regardless of size. RAW_RETURN means convert a type 328 * (assumed to be a return type) to int if it is smaller than an int, 329 * or if it is void. 330 */ 331 public static final int NO_CHANGE = 0, ERASE = 1, WRAP = 2, UNWRAP = 3, INTS = 4, LONGS = 5, RAW_RETURN = 6; 332 333 /** Canonicalize the types in the given method type. 334 * If any types change, intern the new type, and return it. 335 * Otherwise return null. 336 */ 337 public static MethodType canonicalize(MethodType mt, int howRet, int howArgs) { 338 Class<?>[] ptypes = mt.ptypes(); 339 Class<?>[] ptc = MethodTypeForm.canonicalizeAll(ptypes, howArgs); 340 Class<?> rtype = mt.returnType(); 341 Class<?> rtc = MethodTypeForm.canonicalize(rtype, howRet); 342 if (ptc == null && rtc == null) { 343 // It is already canonical. 344 return null; 345 } 346 // Find the erased version of the method type: 347 if (rtc == null) rtc = rtype; 348 if (ptc == null) ptc = ptypes; 349 return MethodType.makeImpl(rtc, ptc, true); 350 } 351 352 /** Canonicalize the given return or param type. 353 * Return null if the type is already canonicalized. 354 */ 355 static Class<?> canonicalize(Class<?> t, int how) { 356 Class<?> ct; 357 if (t == Object.class) { 358 // no change, ever 359 } else if (!t.isPrimitive()) { 360 switch (how) { 361 case UNWRAP: 362 ct = Wrapper.asPrimitiveType(t); 363 if (ct != t) return ct; 364 break; 365 case RAW_RETURN: 366 case ERASE: 367 return Object.class; 368 } 369 } else if (t == void.class) { 370 // no change, usually 371 switch (how) { 372 case RAW_RETURN: 373 return int.class; 374 case WRAP: 375 return Void.class; 376 } 377 } else { 378 // non-void primitive 379 switch (how) { 380 case WRAP: 381 return Wrapper.asWrapperType(t); 382 case INTS: 383 if (t == int.class || t == long.class) 384 return null; // no change 385 if (t == double.class) 386 return long.class; 387 return int.class; 388 case LONGS: 389 if (t == long.class) 390 return null; // no change 391 return long.class; 392 case RAW_RETURN: 393 if (t == int.class || t == long.class || 394 t == float.class || t == double.class) 395 return null; // no change 396 // everything else returns as an int 397 return int.class; 398 } 399 } 400 // no change; return null to signify 401 return null; 402 } 403 404 /** Canonicalize each param type in the given array. 405 * Return null if all types are already canonicalized. 406 */ 407 static Class<?>[] canonicalizeAll(Class<?>[] ts, int how) { 408 Class<?>[] cs = null; 409 for (int imax = ts.length, i = 0; i < imax; i++) { 410 Class<?> c = canonicalize(ts[i], how); 411 if (c == void.class) 412 c = null; // a Void parameter was unwrapped to void; ignore 413 if (c != null) { 414 if (cs == null) 415 cs = ts.clone(); 416 cs[i] = c; 417 } 418 } 419 return cs; 420 } 421 422 @Override 423 public String toString() { 424 return "Form"+erasedType; 425 } 426} 427