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