/* * Copyright 2008-2009 Sun Microsystems, Inc. All Rights Reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Sun designates this * particular file as subject to the "Classpath" exception as provided * by Sun in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, * CA 95054 USA or visit www.sun.com if you need additional information or * have any questions. */ package java.dyn; import impl.java.dyn.util.Wrappers; /** * Shared information for a group of method types, which differ * only by reference types, and therefore share a common erasure * and wrapping. *

* For an empirical discussion of the structure of method types, * see * the thread "Avoiding Boxing" on jvm-languages. * There are approximately 2000 distinct erased method types in the JDK. * There are a little over 10 times that number of unerased types. * No more than half of these are likely to be loaded at once. * @author John Rose */ class MethodTypeForm { final int[] argToSlotTable, slotToArgTable; final long argCounts; // packed slot & value counts final long primCounts; // packed prim & double counts final int vmslots; // total number of parameter slots final MethodType erasedType; // the canonical erasure final MethodType wrappedType; // erasure, with primitives wrapped public static MethodTypeForm of(MethodType type) { return type.form; } private MethodTypeForm(MethodType erase) { this.erasedType = erase; MethodType wt = canonType(erase, WRAP); this.wrappedType = (wt == null) ? erase : wt; int ptypeCount = erase.ptypes.length; int pslotCount = ptypeCount; // temp. estimate int rtypeCount = 1; // temp. estimate int rslotCount = 1; // temp. estimate int[] argToSlotTab = null, slotToArgTab = null; // Walk the argument types, looking for primitives. if (wt != null) { int pac = 0, lac = 0, prc = 0, lrc = 0; Class epts[] = erase.ptypes; for (int i = 0; i < epts.length; i++) { Class pt = epts[i]; if (pt != Object.class) { assert(pt.isPrimitive()); ++pac; if (hasTwoArgSlots(pt)) ++lac; } } pslotCount += lac; // #slots = #args + #longs Class rt = erase.rtype; if (rt != Object.class) { ++prc; // even void.class counts as a prim here if (hasTwoArgSlots(rt)) ++lrc; // adjust #slots, #args if (rt == void.class) rtypeCount = rslotCount = 0; else rslotCount += lrc; } if (lac != 0) { int slot = ptypeCount + lac; slotToArgTab = new int[slot+1]; argToSlotTab = new int[1+ptypeCount]; argToSlotTab[0] = slot; // argument "-1" is past end of slots for (int i = 0; i < epts.length; i++) { Class pt = epts[i]; if (hasTwoArgSlots(pt)) --slot; --slot; slotToArgTab[slot] = i+1; // "+1" see argSlotToParameter note argToSlotTab[1+i] = slot; } assert(slot == 0); // filled the table } this.primCounts = pack(lrc, prc, lac, pac); } else { this.primCounts = 0; } this.argCounts = pack(rslotCount, rtypeCount, pslotCount, ptypeCount); if (slotToArgTab == null) { int slot = ptypeCount; // first arg is deepest in stack slotToArgTab = new int[slot+1]; argToSlotTab = new int[1+ptypeCount]; argToSlotTab[0] = slot; // argument "-1" is past end of slots for (int i = 0; i < ptypeCount; i++) { --slot; slotToArgTab[slot] = i+1; // "+1" see argSlotToParameter note argToSlotTab[1+i] = slot; } } this.argToSlotTable = argToSlotTab; this.slotToArgTable = slotToArgTab; if (pslotCount >= 256) throw new IllegalArgumentException("too many arguments"); // send a few bits down to the JVM: this.vmslots = parameterSlotCount(); } private static boolean hasTwoArgSlots(Class type) { return type == long.class || type == double.class; } private static long pack(int a, int b, int c, int d) { assert(((a|b|c|d) & ~0xFFFF) == 0); long hw = ((a << 16) | b), lw = ((c << 16) | d); return (hw << 32) | lw; } private static char unpack(long packed, int word) { // word==0 => return a, ==3 => return d assert(word <= 3); return (char)(packed >> ((3-word) * 16)); } public int parameterCount() { // # outgoing values return unpack(argCounts, 3); } public int parameterSlotCount() { // # outgoing interpreter slots return unpack(argCounts, 2); } public int returnCount() { // = 0 (V), or 1 return unpack(argCounts, 1); } public int returnSlotCount() { // = 0 (V), 2 (J/D), or 1 return unpack(argCounts, 0); } public int primitiveParameterCount() { return unpack(primCounts, 3); } public int longPrimitiveParameterCount() { return unpack(primCounts, 2); } public int primitiveReturnCount() { // = 0 (obj), or 1 return unpack(primCounts, 1); } public int longPrimitiveReturnCount() { // = 1 (J/D), or 0 return unpack(primCounts, 0); } public int parameterToArgSlot(int i) { return argToSlotTable[1+i]; } public int argSlotToParameter(int argSlot) { // Note: Empty slots are represented by zero in this table. // Valid arguments slots contain incremented entries, so as to be non-zero. // We return -1 the caller to mean an empty slot. return slotToArgTable[argSlot] - 1; } static final int ERASE = 1, WRAP = 2, UNWRAP = 4, ARGS_ONLY = 8; static MethodTypeForm findForm(MethodType mt) { MethodType erased = canonType(mt, ERASE); if (erased == null) { // It is already erased. Make a new MethodTypeForm. return new MethodTypeForm(mt); } else { // Share the MethodTypeForm with the erased version. return erased.form; } } /** Canonicalize the types in the given method type. * If any types change, intern the new type, and return it. * Otherwise return null. */ static MethodType canonType(MethodType mt, int how) { Class[] ptc = MethodTypeForm.canonTypes(mt.ptypes, how); Class rtc = null; if ((how & ARGS_ONLY) == 0) rtc = MethodTypeForm.canonType(mt.rtype, how); if (ptc == null && rtc == null) { // It is already canonical. return null; } // Find the erased version of the method type: if (rtc == null) rtc = mt.rtype; if (ptc == null) ptc = mt.ptypes; return MethodType.makeImpl(rtc, ptc, true); } /** Canonicalize the given return or param type. * Return null if the type is already canonicalized. */ static Class canonType(Class t, int how) { if (t == Object.class) { // no change, ever } else if (!t.isPrimitive()) { if ((how & UNWRAP) != 0) { Class pt = Wrappers.asPrimitiveType(t); if (pt != t) return pt; } if ((how & ERASE) != 0) return Object.class; } else { if ((how & WRAP) != 0) { if ((how & ERASE) != 0) return Object.class; return Wrappers.asWrapperType(t); } } // no change; return null to signify return null; } /** Canonicalize each param type in the given array. * Return null if all types are already canonicalized. */ static Class[] canonTypes(Class[] ts, int how) { Class[] cs = null; for (int imax = ts.length, i = 0; i < imax; i++) { Class c = canonType(ts[i], how); if (c != null) { if (cs == null) cs = ts.clone(); cs[i] = c; } } return cs; } }