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 int vmslots; // total number of parameter slots
51 final MethodType erasedType; // the canonical erasure
52 final MethodType basicType; // the canonical erasure, with primitives simplified
53
54 // Cached adapter information:
55 @Stable String typeString; // argument type signature characters
56 @Stable MethodHandle genericInvoker; // JVM hook for inexact invoke
57 @Stable MethodHandle basicInvoker; // cached instance of MH.invokeBasic
58 @Stable MethodHandle namedFunctionInvoker; // cached helper for LF.NamedFunction
59
60 // Cached lambda form information, for basic types only:
61 final @Stable LambdaForm[] lambdaForms;
62 // Indexes into lambdaForms:
63 static final int
64 LF_INVVIRTUAL = 0, // DMH invokeVirtual
65 LF_INVSTATIC = 1,
66 LF_INVSPECIAL = 2,
67 LF_NEWINVSPECIAL = 3,
68 LF_INVINTERFACE = 4,
69 LF_INVSTATIC_INIT = 5, // DMH invokeStatic with <clinit> barrier
70 LF_INTERPRET = 6, // LF interpreter
71 LF_COUNTER = 7, // CMH wrapper
72 LF_REINVOKE = 8, // other wrapper
73 LF_EX_LINKER = 9, // invokeExact_MT
74 LF_EX_INVOKER = 10, // invokeExact MH
75 LF_GEN_LINKER = 11,
76 LF_GEN_INVOKER = 12,
77 LF_CS_LINKER = 13, // linkToCallSite_CS
78 LF_MH_LINKER = 14, // linkToCallSite_MH
79 LF_GWC = 15,
80 LF_LIMIT = 16;
81
82 public MethodType erasedType() {
83 return erasedType;
84 }
85
86 public MethodType basicType() {
87 return basicType;
88 }
89
90 public LambdaForm cachedLambdaForm(int which) {
91 return lambdaForms[which];
92 }
93
94 synchronized public LambdaForm setCachedLambdaForm(int which, LambdaForm form) {
95 // Simulate a CAS, to avoid racy duplication of results.
96 LambdaForm prev = lambdaForms[which];
97 if (prev != null) return prev;
98 return lambdaForms[which] = form;
99 }
100
101 public MethodHandle basicInvoker() {
102 assert(erasedType == basicType) : "erasedType: " + erasedType + " != basicType: " + basicType; // primitives must be flattened also
103 MethodHandle invoker = basicInvoker;
104 if (invoker != null) return invoker;
105 invoker = DirectMethodHandle.make(invokeBasicMethod(basicType));
106 basicInvoker = invoker;
107 return invoker;
108 }
109
110 // This next one is called from LambdaForm.NamedFunction.<init>.
111 /*non-public*/ static MemberName invokeBasicMethod(MethodType basicType) {
112 assert(basicType == basicType.basicType());
113 try {
114 // Do approximately the same as this public API call:
115 // Lookup.findVirtual(MethodHandle.class, name, type);
116 // But bypass access and corner case checks, since we know exactly what we need.
117 return IMPL_LOOKUP.resolveOrFail(REF_invokeVirtual, MethodHandle.class, "invokeBasic", basicType);
118 } catch (ReflectiveOperationException ex) {
119 throw newInternalError("JVM cannot find invoker for "+basicType, ex);
120 }
121 }
122
123 /**
124 * Build an MTF for a given type, which must have all references erased to Object.
125 * This MTF will stand for that type and all un-erased variations.
126 * Eagerly compute some basic properties of the type, common to all variations.
127 */
128 protected MethodTypeForm(MethodType erasedType) {
129 this.erasedType = erasedType;
130
131 Class<?>[] ptypes = erasedType.ptypes();
132 int ptypeCount = ptypes.length;
133 int pslotCount = ptypeCount; // temp. estimate
134 int rtypeCount = 1; // temp. estimate
135 int rslotCount = 1; // temp. estimate
136
137 int[] argToSlotTab = null, slotToArgTab = null;
138
139 // Walk the argument types, looking for primitives.
140 int pac = 0, lac = 0, prc = 0, lrc = 0;
141 Class<?>[] epts = ptypes;
142 Class<?>[] bpts = epts;
143 for (int i = 0; i < epts.length; i++) {
144 Class<?> pt = epts[i];
145 if (pt != Object.class) {
146 ++pac;
147 Wrapper w = Wrapper.forPrimitiveType(pt);
148 if (w.isDoubleWord()) ++lac;
149 if (w.isSubwordOrInt() && pt != int.class) {
150 if (bpts == epts)
151 bpts = bpts.clone();
152 bpts[i] = int.class;
153 }
154 }
155 }
156 pslotCount += lac; // #slots = #args + #longs
157 Class<?> rt = erasedType.returnType();
158 Class<?> bt = rt;
159 if (rt != Object.class) {
160 ++prc; // even void.class counts as a prim here
161 Wrapper w = Wrapper.forPrimitiveType(rt);
162 if (w.isDoubleWord()) ++lrc;
163 if (w.isSubwordOrInt() && rt != int.class)
164 bt = int.class;
165 // adjust #slots, #args
166 if (rt == void.class)
167 rtypeCount = rslotCount = 0;
168 else
169 rslotCount += lrc;
170 }
171 if (epts == bpts && bt == rt) {
172 this.basicType = erasedType;
173 } else {
174 this.basicType = MethodType.makeImpl(bt, bpts, true);
175 }
176 if (lac != 0) {
177 int slot = ptypeCount + lac;
178 slotToArgTab = new int[slot+1];
179 argToSlotTab = new int[1+ptypeCount];
180 argToSlotTab[0] = slot; // argument "-1" is past end of slots
181 for (int i = 0; i < epts.length; i++) {
182 Class<?> pt = epts[i];
183 Wrapper w = Wrapper.forBasicType(pt);
184 if (w.isDoubleWord()) --slot;
185 --slot;
186 slotToArgTab[slot] = i+1; // "+1" see argSlotToParameter note
187 argToSlotTab[1+i] = slot;
188 }
189 assert(slot == 0); // filled the table
190 }
191 this.primCounts = pack(lrc, prc, lac, pac);
192 this.argCounts = pack(rslotCount, rtypeCount, pslotCount, ptypeCount);
193 if (slotToArgTab == null) {
194 int slot = ptypeCount; // first arg is deepest in stack
195 slotToArgTab = new int[slot+1];
196 argToSlotTab = new int[1+ptypeCount];
197 argToSlotTab[0] = slot; // argument "-1" is past end of slots
198 for (int i = 0; i < ptypeCount; i++) {
199 --slot;
200 slotToArgTab[slot] = i+1; // "+1" see argSlotToParameter note
201 argToSlotTab[1+i] = slot;
202 }
203 }
204 this.argToSlotTable = argToSlotTab;
205 this.slotToArgTable = slotToArgTab;
206
207 if (pslotCount >= 256) throw newIllegalArgumentException("too many arguments");
208
209 // send a few bits down to the JVM:
210 this.vmslots = parameterSlotCount();
211
212 if (basicType == erasedType) {
213 lambdaForms = new LambdaForm[LF_LIMIT];
214 } else {
215 lambdaForms = null; // could be basicType.form().lambdaForms;
216 }
217 }
218
219 private static long pack(int a, int b, int c, int d) {
220 assert(((a|b|c|d) & ~0xFFFF) == 0);
221 long hw = ((a << 16) | b), lw = ((c << 16) | d);
222 return (hw << 32) | lw;
223 }
224 private static char unpack(long packed, int word) { // word==0 => return a, ==3 => return d
225 assert(word <= 3);
226 return (char)(packed >> ((3-word) * 16));
227 }
228
229 public int parameterCount() { // # outgoing values
230 return unpack(argCounts, 3);
231 }
232 public int parameterSlotCount() { // # outgoing interpreter slots
233 return unpack(argCounts, 2);
234 }
235 public int returnCount() { // = 0 (V), or 1
236 return unpack(argCounts, 1);
237 }
238 public int returnSlotCount() { // = 0 (V), 2 (J/D), or 1
239 return unpack(argCounts, 0);
240 }
241 public int primitiveParameterCount() {
242 return unpack(primCounts, 3);
243 }
244 public int longPrimitiveParameterCount() {
245 return unpack(primCounts, 2);
246 }
247 public int primitiveReturnCount() { // = 0 (obj), or 1
248 return unpack(primCounts, 1);
249 }
250 public int longPrimitiveReturnCount() { // = 1 (J/D), or 0
251 return unpack(primCounts, 0);
252 }
253 public boolean hasPrimitives() {
254 return primCounts != 0;
255 }
256 public boolean hasNonVoidPrimitives() {
257 if (primCounts == 0) return false;
258 if (primitiveParameterCount() != 0) return true;
259 return (primitiveReturnCount() != 0 && returnCount() != 0);
260 }
261 public boolean hasLongPrimitives() {
262 return (longPrimitiveParameterCount() | longPrimitiveReturnCount()) != 0;
263 }
264 public int parameterToArgSlot(int i) {
265 return argToSlotTable[1+i];
266 }
267 public int argSlotToParameter(int argSlot) {
268 // Note: Empty slots are represented by zero in this table.
269 // Valid arguments slots contain incremented entries, so as to be non-zero.
270 // We return -1 the caller to mean an empty slot.
271 return slotToArgTable[argSlot] - 1;
272 }
273
274 static MethodTypeForm findForm(MethodType mt) {
275 MethodType erased = canonicalize(mt, ERASE, ERASE);
276 if (erased == null) {
277 // It is already erased. Make a new MethodTypeForm.
278 return new MethodTypeForm(mt);
279 } else {
280 // Share the MethodTypeForm with the erased version.
281 return erased.form();
282 }
283 }
284
285 /** Codes for {@link #canonicalize(java.lang.Class, int)}.
286 * ERASE means change every reference to {@code Object}.
287 * WRAP means convert primitives (including {@code void} to their
288 * corresponding wrapper types. UNWRAP means the reverse of WRAP.
289 * INTS means convert all non-void primitive types to int or long,
290 * according to size. LONGS means convert all non-void primitives
291 * to long, regardless of size. RAW_RETURN means convert a type
292 * (assumed to be a return type) to int if it is smaller than an int,
293 * or if it is void.
294 */
295 public static final int NO_CHANGE = 0, ERASE = 1, WRAP = 2, UNWRAP = 3, INTS = 4, LONGS = 5, RAW_RETURN = 6;
296
297 /** Canonicalize the types in the given method type.
298 * If any types change, intern the new type, and return it.
299 * Otherwise return null.
300 */
301 public static MethodType canonicalize(MethodType mt, int howRet, int howArgs) {
302 Class<?>[] ptypes = mt.ptypes();
303 Class<?>[] ptc = MethodTypeForm.canonicalizes(ptypes, howArgs);
304 Class<?> rtype = mt.returnType();
305 Class<?> rtc = MethodTypeForm.canonicalize(rtype, howRet);
306 if (ptc == null && rtc == null) {
307 // It is already canonical.
308 return null;
309 }
310 // Find the erased version of the method type:
311 if (rtc == null) rtc = rtype;
312 if (ptc == null) ptc = ptypes;
313 return MethodType.makeImpl(rtc, ptc, true);
314 }
315
316 /** Canonicalize the given return or param type.
317 * Return null if the type is already canonicalized.
318 */
319 static Class<?> canonicalize(Class<?> t, int how) {
320 Class<?> ct;
321 if (t == Object.class) {
322 // no change, ever
323 } else if (!t.isPrimitive()) {
324 switch (how) {
325 case UNWRAP:
326 ct = Wrapper.asPrimitiveType(t);
327 if (ct != t) return ct;
328 break;
329 case RAW_RETURN:
330 case ERASE:
331 return Object.class;
332 }
333 } else if (t == void.class) {
334 // no change, usually
335 switch (how) {
336 case RAW_RETURN:
337 return int.class;
338 case WRAP:
339 return Void.class;
340 }
341 } else {
342 // non-void primitive
343 switch (how) {
344 case WRAP:
345 return Wrapper.asWrapperType(t);
346 case INTS:
347 if (t == int.class || t == long.class)
348 return null; // no change
349 if (t == double.class)
350 return long.class;
351 return int.class;
352 case LONGS:
353 if (t == long.class)
354 return null; // no change
355 return long.class;
356 case RAW_RETURN:
357 if (t == int.class || t == long.class ||
358 t == float.class || t == double.class)
359 return null; // no change
360 // everything else returns as an int
361 return int.class;
362 }
363 }
364 // no change; return null to signify
365 return null;
366 }
367
368 /** Canonicalize each param type in the given array.
369 * Return null if all types are already canonicalized.
370 */
371 static Class<?>[] canonicalizes(Class<?>[] ts, int how) {
372 Class<?>[] cs = null;
373 for (int imax = ts.length, i = 0; i < imax; i++) {
374 Class<?> c = canonicalize(ts[i], how);
375 if (c == void.class)
376 c = null; // a Void parameter was unwrapped to void; ignore
377 if (c != null) {
378 if (cs == null)
379 cs = ts.clone();
380 cs[i] = c;
381 }
382 }
383 return cs;
384 }
385
386 @Override
387 public String toString() {
388 return "Form"+erasedType;
389 }
390
391 }