/* * Copyright (c) 2017, Oracle and/or its affiliates. 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. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.lang.invoke; import sun.invoke.util.Wrapper; import java.lang.invoke.AbstractConstantGroup.BSCIWithCache; import java.util.Arrays; import static java.lang.invoke.BootstrapCallInfo.makeBootstrapCallInfo; import static java.lang.invoke.ConstantGroup.makeConstantGroup; import static java.lang.invoke.MethodHandleNatives.*; import static java.lang.invoke.MethodHandleStatics.TRACE_METHOD_LINKAGE; import static java.lang.invoke.MethodHandles.Lookup; import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP; final class BootstrapMethodInvoker { /** * Factored code for invoking a bootstrap method for invokedynamic * or a dynamic constant. * @param resultType the expected return type (either CallSite or a constant type) * @param bootstrapMethod the BSM to call * @param name the method name or constant name * @param type the method type or constant type * @param info information passed up from the JVM, to derive static arguments * @param callerClass the class containing the resolved method call or constant load * @param the expected return type * @return the expected value, either a CallSite or a constant value */ static T invoke(Class resultType, MethodHandle bootstrapMethod, // Callee information: String name, Object type, // Extra arguments for BSM, if any: Object info, // Caller information: Class callerClass) { MethodHandles.Lookup caller = IMPL_LOOKUP.in(callerClass); Object result; boolean pullMode = isPullModeBSM(bootstrapMethod); // default value is false boolean vmIsPushing = !staticArgumentsPulled(info); // default value is true MethodHandle pullModeBSM; // match the VM with the BSM if (vmIsPushing) { // VM is pushing arguments at us pullModeBSM = null; if (pullMode) { bootstrapMethod = pushMePullYou(bootstrapMethod, true); } } else { // VM wants us to pull args from it pullModeBSM = pullMode ? bootstrapMethod : pushMePullYou(bootstrapMethod, false); bootstrapMethod = null; } try { // As an optimization we special case various known BSMs, // such as LambdaMetafactory::metafactory and // StringConcatFactory::makeConcatWithConstants. // // By providing static type information or even invoking // exactly, we avoid emitting code to perform runtime // checking. info = maybeReBox(info); if (info == null) { // VM is allowed to pass up a null meaning no BSM args result = invoke(bootstrapMethod, caller, name, type); } else if (!info.getClass().isArray()) { // VM is allowed to pass up a single BSM arg directly // Call to StringConcatFactory::makeConcatWithConstants // with empty constant arguments? if (isStringConcatFactoryBSM(bootstrapMethod.type())) { result = (CallSite)bootstrapMethod .invokeExact(caller, name, (MethodType)type, (String)info, new Object[0]); } else { result = invoke(bootstrapMethod, caller, name, type, info); } } else if (info.getClass() == int[].class) { // VM is allowed to pass up a pair {argc, index} // referring to 'argc' BSM args at some place 'index' // in the guts of the VM (associated with callerClass). // The format of this index pair is private to the // handshake between the VM and this class only. // This supports "pulling" of arguments. // The VM is allowed to do this for any reason. // The code in this method makes up for any mismatches. BootstrapCallInfo bsci = new VM_BSCI<>(bootstrapMethod, name, type, caller, (int[])info); // Pull-mode API is (Lookup, BootstrapCallInfo) -> Object result = pullModeBSM.invoke(caller, bsci); } else { // VM is allowed to pass up a full array of resolved BSM args Object[] argv = (Object[]) info; maybeReBoxElements(argv); MethodType bsmType = bootstrapMethod.type(); if (isLambdaMetafactoryIndyBSM(bsmType) && argv.length == 3) { result = (CallSite)bootstrapMethod .invokeExact(caller, name, (MethodType)type, (MethodType)argv[0], (MethodHandle)argv[1], (MethodType)argv[2]); } else if (isLambdaMetafactoryCondyBSM(bsmType) && argv.length == 3) { result = bootstrapMethod .invokeExact(caller, name, (Class)type, (MethodType)argv[0], (MethodHandle)argv[1], (MethodType)argv[2]); } else if (isStringConcatFactoryBSM(bsmType) && argv.length >= 1) { String recipe = (String)argv[0]; Object[] shiftedArgs = Arrays.copyOfRange(argv, 1, argv.length); result = (CallSite)bootstrapMethod.invokeExact(caller, name, (MethodType)type, recipe, shiftedArgs); } else if (isLambdaMetafactoryAltMetafactoryBSM(bsmType)) { result = (CallSite)bootstrapMethod.invokeExact(caller, name, (MethodType)type, argv); } else { switch (argv.length) { case 0: result = invoke(bootstrapMethod, caller, name, type); break; case 1: result = invoke(bootstrapMethod, caller, name, type, argv[0]); break; case 2: result = invoke(bootstrapMethod, caller, name, type, argv[0], argv[1]); break; case 3: result = invoke(bootstrapMethod, caller, name, type, argv[0], argv[1], argv[2]); break; case 4: result = invoke(bootstrapMethod, caller, name, type, argv[0], argv[1], argv[2], argv[3]); break; case 5: result = invoke(bootstrapMethod, caller, name, type, argv[0], argv[1], argv[2], argv[3], argv[4]); break; case 6: result = invoke(bootstrapMethod, caller, name, type, argv[0], argv[1], argv[2], argv[3], argv[4], argv[5]); break; default: result = invokeWithManyArguments(bootstrapMethod, caller, name, type, argv); } } } if (resultType.isPrimitive()) { // Non-reference conversions are more than just plain casts. // By pushing the value through a funnel of the form (T x)->x, // the boxed result can be widened as needed. See MH::asType. MethodHandle funnel = MethodHandles.identity(resultType); result = funnel.invoke(result); // Now it is the wrapper type for resultType. resultType = Wrapper.asWrapperType(resultType); } return resultType.cast(result); } catch (Error e) { // Pass through an Error, including BootstrapMethodError, any other // form of linkage error, such as IllegalAccessError if the bootstrap // method is inaccessible, or say ThreadDeath/OutOfMemoryError // See the "Linking Exceptions" section for the invokedynamic // instruction in JVMS 6.5. throw e; } catch (Throwable ex) { // Wrap anything else in BootstrapMethodError throw new BootstrapMethodError("bootstrap method initialization exception", ex); } } // If we don't provide static type information for type, we'll generate runtime // checks. Let's try not to... private static Object invoke(MethodHandle bootstrapMethod, Lookup caller, String name, Object type) throws Throwable { if (type instanceof Class) { return bootstrapMethod.invoke(caller, name, (Class)type); } else { return bootstrapMethod.invoke(caller, name, (MethodType)type); } } private static Object invoke(MethodHandle bootstrapMethod, Lookup caller, String name, Object type, Object arg0) throws Throwable { if (type instanceof Class) { return bootstrapMethod.invoke(caller, name, (Class)type, arg0); } else { return bootstrapMethod.invoke(caller, name, (MethodType)type, arg0); } } private static Object invoke(MethodHandle bootstrapMethod, Lookup caller, String name, Object type, Object arg0, Object arg1) throws Throwable { if (type instanceof Class) { return bootstrapMethod.invoke(caller, name, (Class)type, arg0, arg1); } else { return bootstrapMethod.invoke(caller, name, (MethodType)type, arg0, arg1); } } private static Object invoke(MethodHandle bootstrapMethod, Lookup caller, String name, Object type, Object arg0, Object arg1, Object arg2) throws Throwable { if (type instanceof Class) { return bootstrapMethod.invoke(caller, name, (Class)type, arg0, arg1, arg2); } else { return bootstrapMethod.invoke(caller, name, (MethodType)type, arg0, arg1, arg2); } } private static Object invoke(MethodHandle bootstrapMethod, Lookup caller, String name, Object type, Object arg0, Object arg1, Object arg2, Object arg3) throws Throwable { if (type instanceof Class) { return bootstrapMethod.invoke(caller, name, (Class)type, arg0, arg1, arg2, arg3); } else { return bootstrapMethod.invoke(caller, name, (MethodType)type, arg0, arg1, arg2, arg3); } } private static Object invoke(MethodHandle bootstrapMethod, Lookup caller, String name, Object type, Object arg0, Object arg1, Object arg2, Object arg3, Object arg4) throws Throwable { if (type instanceof Class) { return bootstrapMethod.invoke(caller, name, (Class)type, arg0, arg1, arg2, arg3, arg4); } else { return bootstrapMethod.invoke(caller, name, (MethodType)type, arg0, arg1, arg2, arg3, arg4); } } private static Object invoke(MethodHandle bootstrapMethod, Lookup caller, String name, Object type, Object arg0, Object arg1, Object arg2, Object arg3, Object arg4, Object arg5) throws Throwable { if (type instanceof Class) { return bootstrapMethod.invoke(caller, name, (Class)type, arg0, arg1, arg2, arg3, arg4, arg5); } else { return bootstrapMethod.invoke(caller, name, (MethodType)type, arg0, arg1, arg2, arg3, arg4, arg5); } } private static Object invokeWithManyArguments(MethodHandle bootstrapMethod, Lookup caller, String name, Object type, Object[] argv) throws Throwable { final int NON_SPREAD_ARG_COUNT = 3; // (caller, name, type) final int MAX_SAFE_SIZE = MethodType.MAX_MH_ARITY / 2 - NON_SPREAD_ARG_COUNT; if (argv.length >= MAX_SAFE_SIZE) { // to be on the safe side, use invokeWithArguments which handles jumbo lists Object[] newargv = new Object[NON_SPREAD_ARG_COUNT + argv.length]; newargv[0] = caller; newargv[1] = name; newargv[2] = type; System.arraycopy(argv, 0, newargv, NON_SPREAD_ARG_COUNT, argv.length); return bootstrapMethod.invokeWithArguments(newargv); } else { MethodType invocationType = MethodType.genericMethodType(NON_SPREAD_ARG_COUNT + argv.length); MethodHandle typedBSM = bootstrapMethod.asType(invocationType); MethodHandle spreader = invocationType.invokers().spreadInvoker(NON_SPREAD_ARG_COUNT); return spreader.invokeExact(typedBSM, (Object) caller, (Object) name, type, argv); } } private static final MethodType LMF_INDY_MT = MethodType.methodType(CallSite.class, Lookup.class, String.class, MethodType.class, MethodType.class, MethodHandle.class, MethodType.class); private static final MethodType LMF_ALT_MT = MethodType.methodType(CallSite.class, Lookup.class, String.class, MethodType.class, Object[].class); private static final MethodType LMF_CONDY_MT = MethodType.methodType(Object.class, Lookup.class, String.class, Class.class, MethodType.class, MethodHandle.class, MethodType.class); private static final MethodType SCF_MT = MethodType.methodType(CallSite.class, Lookup.class, String.class, MethodType.class, String.class, Object[].class); /** * @return true iff the BSM method type exactly matches * {@see java.lang.invoke.StringConcatFactory#makeConcatWithConstants(MethodHandles.Lookup, * String,MethodType,String,Object...))} */ private static boolean isStringConcatFactoryBSM(MethodType bsmType) { return bsmType == SCF_MT; } /** * @return true iff the BSM method type exactly matches * {@see java.lang.invoke.LambdaMetafactory#metafactory( * MethodHandles.Lookup,String,Class,MethodType,MethodHandle,MethodType)} */ private static boolean isLambdaMetafactoryCondyBSM(MethodType bsmType) { return bsmType == LMF_CONDY_MT; } /** * @return true iff the BSM method type exactly matches * {@see java.lang.invoke.LambdaMetafactory#metafactory( * MethodHandles.Lookup,String,MethodType,MethodType,MethodHandle,MethodType)} */ private static boolean isLambdaMetafactoryIndyBSM(MethodType bsmType) { return bsmType == LMF_INDY_MT; } /** * @return true iff the BSM method type exactly matches * {@see java.lang.invoke.LambdaMetafactory#altMetafactory( * MethodHandles.Lookup,String,MethodType,Object[])} */ private static boolean isLambdaMetafactoryAltMetafactoryBSM(MethodType bsmType) { return bsmType == LMF_ALT_MT; } /** The JVM produces java.lang.Integer values to box * CONSTANT_Integer boxes but does not intern them. * Let's intern them. This is slightly wrong for * a {@code CONSTANT_Dynamic} which produces an * un-interned integer (e.g., {@code new Integer(0)}). */ private static Object maybeReBox(Object x) { if (x instanceof Integer) { int xi = (int) x; if (xi == (byte) xi) x = xi; // must rebox; see JLS 5.1.7 } return x; } private static void maybeReBoxElements(Object[] xa) { for (int i = 0; i < xa.length; i++) { xa[i] = maybeReBox(xa[i]); } } /** Canonical VM-aware implementation of BootstrapCallInfo. * Knows how to dig into the JVM for lazily resolved (pull-mode) constants. */ private static final class VM_BSCI extends BSCIWithCache { private final int[] indexInfo; private final Class caller; // for index resolution only VM_BSCI(MethodHandle bsm, String name, T type, Lookup lookup, int[] indexInfo) { super(bsm, name, type, indexInfo[0]); if (!lookup.hasPrivateAccess()) //D.I.D. throw new AssertionError("bad Lookup object"); this.caller = lookup.lookupClass(); this.indexInfo = indexInfo; // scoop up all the easy stuff right away: prefetchIntoCache(0, size()); } @Override Object fillCache(int i) { Object[] buf = { null }; copyConstants(i, i+1, buf, 0); Object res = wrapNull(buf[0]); cache[i] = res; int next = i + 1; if (next < cache.length && cache[next] == null) maybePrefetchIntoCache(next, false); // try to prefetch return res; } @Override public int copyConstants(int start, int end, Object[] buf, int pos) { int i = start, bufi = pos; while (i < end) { Object x = cache[i]; if (x == null) break; buf[bufi++] = unwrapNull(x); i++; } // give up at first null and grab the rest in one big block if (i >= end) return i; Object[] temp = new Object[end - i]; if (TRACE_METHOD_LINKAGE) { System.out.println("resolving more BSM arguments: " + Arrays.asList(caller.getSimpleName(), Arrays.toString(indexInfo), i, end)); } copyOutBootstrapArguments(caller, indexInfo, i, end, temp, 0, true, null); for (Object x : temp) { x = maybeReBox(x); buf[bufi++] = x; cache[i++] = wrapNull(x); } if (end < cache.length && cache[end] == null) maybePrefetchIntoCache(end, true); // try to prefetch return i; } private static final int MIN_PF = 4; private void maybePrefetchIntoCache(int i, boolean bulk) { int len = cache.length; assert(0 <= i && i <= len); int pfLimit = i; if (bulk) pfLimit += i; // exponential prefetch expansion // try to prefetch at least MIN_PF elements if (pfLimit < i + MIN_PF) pfLimit = i + MIN_PF; if (pfLimit > len || pfLimit < 0) pfLimit = len; // stop prefetching where cache is more full than empty int empty = 0, nonEmpty = 0, lastEmpty = i; for (int j = i; j < pfLimit; j++) { if (cache[j] == null) { empty++; lastEmpty = j; } else { nonEmpty++; if (nonEmpty > empty) { pfLimit = lastEmpty + 1; break; } if (pfLimit < len) pfLimit++; } } if (bulk && empty < MIN_PF && pfLimit < len) return; // not worth the effort prefetchIntoCache(i, pfLimit); } private void prefetchIntoCache(int i, int pfLimit) { if (pfLimit <= i) return; // corner case Object[] temp = new Object[pfLimit - i]; if (TRACE_METHOD_LINKAGE) { System.out.println("prefetching BSM arguments: " + Arrays.asList(caller.getSimpleName(), Arrays.toString(indexInfo), i, pfLimit)); } copyOutBootstrapArguments(caller, indexInfo, i, pfLimit, temp, 0, false, NOT_PRESENT); for (Object x : temp) { if (x != NOT_PRESENT && cache[i] == null) { cache[i] = wrapNull(maybeReBox(x)); } i++; } } } /*non-public*/ static final class PushAdapter { // skeleton for push-mode BSM which wraps a pull-mode BSM: static Object pushToBootstrapMethod(MethodHandle pullModeBSM, MethodHandles.Lookup lookup, String name, Object type, Object... arguments) throws Throwable { ConstantGroup cons = makeConstantGroup(Arrays.asList(arguments)); BootstrapCallInfo bsci = makeBootstrapCallInfo(pullModeBSM, name, type, cons); if (TRACE_METHOD_LINKAGE) System.out.println("pull-mode BSM gets pushed arguments from fake BSCI"); return pullModeBSM.invoke(lookup, bsci); } static final MethodHandle MH_pushToBootstrapMethod; static { final Class THIS_CLASS = PushAdapter.class; try { MH_pushToBootstrapMethod = IMPL_LOOKUP .findStatic(THIS_CLASS, "pushToBootstrapMethod", MethodType.methodType(Object.class, MethodHandle.class, Lookup.class, String.class, Object.class, Object[].class)); } catch (Throwable ex) { throw new InternalError(ex); } } } /*non-public*/ static final class PullAdapter { // skeleton for pull-mode BSM which wraps a push-mode BSM: static Object pullFromBootstrapMethod(MethodHandle pushModeBSM, MethodHandles.Lookup lookup, BootstrapCallInfo bsci) throws Throwable { int argc = bsci.size(); switch (argc) { case 0: return pushModeBSM.invoke(lookup, bsci.invocationName(), bsci.invocationType()); case 1: return pushModeBSM.invoke(lookup, bsci.invocationName(), bsci.invocationType(), bsci.get(0)); case 2: return pushModeBSM.invoke(lookup, bsci.invocationName(), bsci.invocationType(), bsci.get(0), bsci.get(1)); case 3: return pushModeBSM.invoke(lookup, bsci.invocationName(), bsci.invocationType(), bsci.get(0), bsci.get(1), bsci.get(2)); case 4: return pushModeBSM.invoke(lookup, bsci.invocationName(), bsci.invocationType(), bsci.get(0), bsci.get(1), bsci.get(2), bsci.get(3)); case 5: return pushModeBSM.invoke(lookup, bsci.invocationName(), bsci.invocationType(), bsci.get(0), bsci.get(1), bsci.get(2), bsci.get(3), bsci.get(4)); case 6: return pushModeBSM.invoke(lookup, bsci.invocationName(), bsci.invocationType(), bsci.get(0), bsci.get(1), bsci.get(2), bsci.get(3), bsci.get(4), bsci.get(5)); default: final int NON_SPREAD_ARG_COUNT = 3; // (lookup, name, type) final int MAX_SAFE_SIZE = MethodType.MAX_MH_ARITY / 2 - NON_SPREAD_ARG_COUNT; if (argc >= MAX_SAFE_SIZE) { // to be on the safe side, use invokeWithArguments which handles jumbo lists Object[] newargv = new Object[NON_SPREAD_ARG_COUNT + argc]; newargv[0] = lookup; newargv[1] = bsci.invocationName(); newargv[2] = bsci.invocationType(); bsci.copyConstants(0, argc, newargv, NON_SPREAD_ARG_COUNT); return pushModeBSM.invokeWithArguments(newargv); } MethodType invocationType = MethodType.genericMethodType(NON_SPREAD_ARG_COUNT + argc); MethodHandle typedBSM = pushModeBSM.asType(invocationType); MethodHandle spreader = invocationType.invokers().spreadInvoker(NON_SPREAD_ARG_COUNT); Object[] argv = new Object[argc]; bsci.copyConstants(0, argc, argv, 0); return spreader.invokeExact(typedBSM, (Object) lookup, (Object) bsci.invocationName(), bsci.invocationType(), argv); } } static final MethodHandle MH_pullFromBootstrapMethod; static { final Class THIS_CLASS = PullAdapter.class; try { MH_pullFromBootstrapMethod = IMPL_LOOKUP .findStatic(THIS_CLASS, "pullFromBootstrapMethod", MethodType.methodType(Object.class, MethodHandle.class, Lookup.class, BootstrapCallInfo.class)); } catch (Throwable ex) { throw new InternalError(ex); } } } /** Given a push-mode BSM (taking one argument) convert it to a * pull-mode BSM (taking N pre-resolved arguments). * This method is used when, in fact, the JVM is passing up * pre-resolved arguments, but the BSM is expecting lazy stuff. * Or, when goToPushMode is true, do the reverse transform. * (The two transforms are exactly inverse.) */ static MethodHandle pushMePullYou(MethodHandle bsm, boolean goToPushMode) { if (TRACE_METHOD_LINKAGE) { System.out.println("converting BSM of type " + bsm.type() + " to " + (goToPushMode ? "push mode" : "pull mode")); } assert(isPullModeBSM(bsm) == goToPushMode); // there must be a change if (goToPushMode) { return PushAdapter.MH_pushToBootstrapMethod.bindTo(bsm).withVarargs(true); } else { return PullAdapter.MH_pullFromBootstrapMethod.bindTo(bsm).withVarargs(false); } } }