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