1 /*
2 * Copyright (c) 2008, 2012, 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 sun.invoke.Stable;
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_LIMIT = 14;
79
80 public MethodType erasedType() {
81 return erasedType;
82 }
83
84 public MethodType basicType() {
85 return basicType;
86 }
87
88 public LambdaForm cachedLambdaForm(int which) {
89 return lambdaForms[which];
90 }
91
92 public LambdaForm setCachedLambdaForm(int which, LambdaForm form) {
93 // Should we perform some sort of CAS, to avoid racy duplication?
94 return lambdaForms[which] = form;
95 }
96
97 public MethodHandle basicInvoker() {
98 assert(erasedType == basicType) : "erasedType: " + erasedType + " != basicType: " + basicType; // primitives must be flattened also
99 MethodHandle invoker = basicInvoker;
100 if (invoker != null) return invoker;
101 invoker = basicType.invokers().makeBasicInvoker();
102 basicInvoker = invoker;
103 return invoker;
104 }
105
106 /**
107 * Build an MTF for a given type, which must have all references erased to Object.
108 * This MTF will stand for that type and all un-erased variations.
109 * Eagerly compute some basic properties of the type, common to all variations.
110 */
111 protected MethodTypeForm(MethodType erasedType) {
112 this.erasedType = erasedType;
113
114 Class<?>[] ptypes = erasedType.ptypes();
115 int ptypeCount = ptypes.length;
116 int pslotCount = ptypeCount; // temp. estimate
117 int rtypeCount = 1; // temp. estimate
118 int rslotCount = 1; // temp. estimate
119
120 int[] argToSlotTab = null, slotToArgTab = null;
121
122 // Walk the argument types, looking for primitives.
123 int pac = 0, lac = 0, prc = 0, lrc = 0;
124 Class<?>[] epts = ptypes;
125 Class<?>[] bpts = epts;
126 for (int i = 0; i < epts.length; i++) {
127 Class<?> pt = epts[i];
128 if (pt != Object.class) {
129 ++pac;
130 Wrapper w = Wrapper.forPrimitiveType(pt);
131 if (w.isDoubleWord()) ++lac;
132 if (w.isSubwordOrInt() && pt != int.class) {
133 if (bpts == epts)
134 bpts = bpts.clone();
135 bpts[i] = int.class;
136 }
137 }
138 }
139 pslotCount += lac; // #slots = #args + #longs
140 Class<?> rt = erasedType.returnType();
141 Class<?> bt = rt;
142 if (rt != Object.class) {
143 ++prc; // even void.class counts as a prim here
144 Wrapper w = Wrapper.forPrimitiveType(rt);
145 if (w.isDoubleWord()) ++lrc;
146 if (w.isSubwordOrInt() && rt != int.class)
147 bt = int.class;
148 // adjust #slots, #args
149 if (rt == void.class)
150 rtypeCount = rslotCount = 0;
151 else
152 rslotCount += lrc;
153 }
154 if (epts == bpts && bt == rt) {
155 this.basicType = erasedType;
156 } else {
157 this.basicType = MethodType.makeImpl(bt, bpts, true);
158 }
159 if (lac != 0) {
160 int slot = ptypeCount + lac;
161 slotToArgTab = new int[slot+1];
162 argToSlotTab = new int[1+ptypeCount];
163 argToSlotTab[0] = slot; // argument "-1" is past end of slots
164 for (int i = 0; i < epts.length; i++) {
165 Class<?> pt = epts[i];
166 Wrapper w = Wrapper.forBasicType(pt);
167 if (w.isDoubleWord()) --slot;
168 --slot;
169 slotToArgTab[slot] = i+1; // "+1" see argSlotToParameter note
170 argToSlotTab[1+i] = slot;
171 }
172 assert(slot == 0); // filled the table
173 }
174 this.primCounts = pack(lrc, prc, lac, pac);
175 this.argCounts = pack(rslotCount, rtypeCount, pslotCount, ptypeCount);
176 if (slotToArgTab == null) {
177 int slot = ptypeCount; // first arg is deepest in stack
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 < ptypeCount; i++) {
182 --slot;
183 slotToArgTab[slot] = i+1; // "+1" see argSlotToParameter note
184 argToSlotTab[1+i] = slot;
185 }
186 }
187 this.argToSlotTable = argToSlotTab;
188 this.slotToArgTable = slotToArgTab;
189
190 if (pslotCount >= 256) throw newIllegalArgumentException("too many arguments");
191
192 // send a few bits down to the JVM:
193 this.vmslots = parameterSlotCount();
194
195 if (basicType == erasedType) {
196 lambdaForms = new LambdaForm[LF_LIMIT];
197 } else {
198 lambdaForms = null; // could be basicType.form().lambdaForms;
199 }
200 }
201
202 private static long pack(int a, int b, int c, int d) {
203 assert(((a|b|c|d) & ~0xFFFF) == 0);
204 long hw = ((a << 16) | b), lw = ((c << 16) | d);
205 return (hw << 32) | lw;
206 }
207 private static char unpack(long packed, int word) { // word==0 => return a, ==3 => return d
208 assert(word <= 3);
209 return (char)(packed >> ((3-word) * 16));
210 }
211
212 public int parameterCount() { // # outgoing values
213 return unpack(argCounts, 3);
214 }
215 public int parameterSlotCount() { // # outgoing interpreter slots
216 return unpack(argCounts, 2);
217 }
218 public int returnCount() { // = 0 (V), or 1
219 return unpack(argCounts, 1);
220 }
221 public int returnSlotCount() { // = 0 (V), 2 (J/D), or 1
222 return unpack(argCounts, 0);
223 }
224 public int primitiveParameterCount() {
225 return unpack(primCounts, 3);
226 }
227 public int longPrimitiveParameterCount() {
228 return unpack(primCounts, 2);
229 }
230 public int primitiveReturnCount() { // = 0 (obj), or 1
231 return unpack(primCounts, 1);
232 }
233 public int longPrimitiveReturnCount() { // = 1 (J/D), or 0
234 return unpack(primCounts, 0);
235 }
236 public boolean hasPrimitives() {
237 return primCounts != 0;
238 }
239 public boolean hasNonVoidPrimitives() {
240 if (primCounts == 0) return false;
241 if (primitiveParameterCount() != 0) return true;
242 return (primitiveReturnCount() != 0 && returnCount() != 0);
243 }
244 public boolean hasLongPrimitives() {
245 return (longPrimitiveParameterCount() | longPrimitiveReturnCount()) != 0;
246 }
247 public int parameterToArgSlot(int i) {
248 return argToSlotTable[1+i];
249 }
250 public int argSlotToParameter(int argSlot) {
251 // Note: Empty slots are represented by zero in this table.
252 // Valid arguments slots contain incremented entries, so as to be non-zero.
253 // We return -1 the caller to mean an empty slot.
254 return slotToArgTable[argSlot] - 1;
255 }
256
257 static MethodTypeForm findForm(MethodType mt) {
258 MethodType erased = canonicalize(mt, ERASE, ERASE);
259 if (erased == null) {
260 // It is already erased. Make a new MethodTypeForm.
261 return new MethodTypeForm(mt);
262 } else {
263 // Share the MethodTypeForm with the erased version.
264 return erased.form();
265 }
266 }
267
268 /** Codes for {@link #canonicalize(java.lang.Class, int)}.
269 * ERASE means change every reference to {@code Object}.
270 * WRAP means convert primitives (including {@code void} to their
271 * corresponding wrapper types. UNWRAP means the reverse of WRAP.
272 * INTS means convert all non-void primitive types to int or long,
273 * according to size. LONGS means convert all non-void primitives
274 * to long, regardless of size. RAW_RETURN means convert a type
275 * (assumed to be a return type) to int if it is smaller than an int,
276 * or if it is void.
277 */
278 public static final int NO_CHANGE = 0, ERASE = 1, WRAP = 2, UNWRAP = 3, INTS = 4, LONGS = 5, RAW_RETURN = 6;
279
280 /** Canonicalize the types in the given method type.
281 * If any types change, intern the new type, and return it.
282 * Otherwise return null.
283 */
284 public static MethodType canonicalize(MethodType mt, int howRet, int howArgs) {
285 Class<?>[] ptypes = mt.ptypes();
286 Class<?>[] ptc = MethodTypeForm.canonicalizes(ptypes, howArgs);
287 Class<?> rtype = mt.returnType();
288 Class<?> rtc = MethodTypeForm.canonicalize(rtype, howRet);
289 if (ptc == null && rtc == null) {
290 // It is already canonical.
291 return null;
292 }
293 // Find the erased version of the method type:
294 if (rtc == null) rtc = rtype;
295 if (ptc == null) ptc = ptypes;
296 return MethodType.makeImpl(rtc, ptc, true);
297 }
298
299 /** Canonicalize the given return or param type.
300 * Return null if the type is already canonicalized.
301 */
302 static Class<?> canonicalize(Class<?> t, int how) {
303 Class<?> ct;
304 if (t == Object.class) {
305 // no change, ever
306 } else if (!t.isPrimitive()) {
307 switch (how) {
308 case UNWRAP:
309 ct = Wrapper.asPrimitiveType(t);
310 if (ct != t) return ct;
311 break;
312 case RAW_RETURN:
313 case ERASE:
314 return Object.class;
315 }
316 } else if (t == void.class) {
317 // no change, usually
318 switch (how) {
319 case RAW_RETURN:
320 return int.class;
321 case WRAP:
322 return Void.class;
323 }
324 } else {
325 // non-void primitive
326 switch (how) {
327 case WRAP:
328 return Wrapper.asWrapperType(t);
329 case INTS:
330 if (t == int.class || t == long.class)
331 return null; // no change
332 if (t == double.class)
333 return long.class;
334 return int.class;
335 case LONGS:
336 if (t == long.class)
337 return null; // no change
338 return long.class;
339 case RAW_RETURN:
340 if (t == int.class || t == long.class ||
341 t == float.class || t == double.class)
342 return null; // no change
343 // everything else returns as an int
344 return int.class;
345 }
346 }
347 // no change; return null to signify
348 return null;
349 }
350
351 /** Canonicalize each param type in the given array.
352 * Return null if all types are already canonicalized.
353 */
354 static Class<?>[] canonicalizes(Class<?>[] ts, int how) {
355 Class<?>[] cs = null;
356 for (int imax = ts.length, i = 0; i < imax; i++) {
357 Class<?> c = canonicalize(ts[i], how);
358 if (c == void.class)
359 c = null; // a Void parameter was unwrapped to void; ignore
360 if (c != null) {
361 if (cs == null)
362 cs = ts.clone();
363 cs[i] = c;
364 }
365 }
366 return cs;
367 }
368
369 @Override
370 public String toString() {
371 return "Form"+erasedType;
372 }
373
374 }