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* 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.
*
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package java.lang.invoke;
import sun.invoke.util.Wrapper;
import java.lang.ref.SoftReference;
import static java.lang.invoke.MethodHandleStatics.newIllegalArgumentException;
/**
* Shared information for a group of method types, which differ
* only by reference types, and therefore share a common erasure
* and wrapping.
* <p>
* For an empirical discussion of the structure of method types,
* see <a href="http://groups.google.com/group/jvm-languages/browse_thread/thread/ac9308ae74da9b7e/">
* the thread "Avoiding Boxing" on jvm-languages</a>.
* 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
*/
final class MethodTypeForm {
final short parameterSlotCount;
final short primitiveCount;
final MethodType erasedType; // the canonical erasure
final MethodType basicType; // the canonical erasure, with primitives simplified
// Cached adapter information:
final SoftReference<MethodHandle>[] methodHandles;
// Indexes into methodHandles:
static final int
MH_BASIC_INV = 0, // cached instance of MH.invokeBasic
MH_NF_INV = 1, // cached helper for LF.NamedFunction
MH_UNINIT_CS = 2, // uninitialized call site
MH_LIMIT = 3;
// Cached lambda form information, for basic types only:
final SoftReference<LambdaForm>[] lambdaForms;
// Indexes into lambdaForms:
static final int
LF_INVVIRTUAL = 0, // DMH invokeVirtual
LF_INVSTATIC = 1,
LF_INVSPECIAL = 2,
LF_NEWINVSPECIAL = 3,
LF_INVINTERFACE = 4,
LF_INVSTATIC_INIT = 5, // DMH invokeStatic with <clinit> barrier
LF_INTERPRET = 6, // LF interpreter
LF_REBIND = 7, // BoundMethodHandle
LF_DELEGATE = 8, // DelegatingMethodHandle
LF_DELEGATE_BLOCK_INLINING = 9, // Counting DelegatingMethodHandle w/ @DontInline
LF_EX_LINKER = 10, // invokeExact_MT (for invokehandle)
LF_EX_INVOKER = 11, // MHs.invokeExact
LF_GEN_LINKER = 12, // generic invoke_MT (for invokehandle)
LF_GEN_INVOKER = 13, // generic MHs.invoke
LF_CS_LINKER = 14, // linkToCallSite_CS
LF_MH_LINKER = 15, // linkToCallSite_MH
LF_GWC = 16, // guardWithCatch (catchException)
LF_GWT = 17, // guardWithTest
LF_TF = 18, // tryFinally
LF_LOOP = 19, // loop
LF_INVSPECIAL_IFC = 20, // DMH invokeSpecial of (private) interface method
LF_LIMIT = 21;
/** Return the type corresponding uniquely (1-1) to this MT-form.
* It might have any primitive returns or arguments, but will have no references except Object.
*/
public MethodType erasedType() {
return erasedType;
}
/** Return the basic type derived from the erased type of this MT-form.
* A basic type is erased (all references Object) and also has all primitive
* types (except int, long, float, double, void) normalized to int.
* Such basic types correspond to low-level JVM calling sequences.
*/
public MethodType basicType() {
return basicType;
}
public MethodHandle cachedMethodHandle(int which) {
SoftReference<MethodHandle> entry = methodHandles[which];
return (entry != null) ? entry.get() : null;
}
public synchronized MethodHandle setCachedMethodHandle(int which, MethodHandle mh) {
// Simulate a CAS, to avoid racy duplication of results.
SoftReference<MethodHandle> entry = methodHandles[which];
if (entry != null) {
MethodHandle prev = entry.get();
if (prev != null) {
return prev;
}
}
methodHandles[which] = new SoftReference<>(mh);
return mh;
}
public LambdaForm cachedLambdaForm(int which) {
SoftReference<LambdaForm> entry = lambdaForms[which];
return (entry != null) ? entry.get() : null;
}
public synchronized LambdaForm setCachedLambdaForm(int which, LambdaForm form) {
// Simulate a CAS, to avoid racy duplication of results.
SoftReference<LambdaForm> entry = lambdaForms[which];
if (entry != null) {
LambdaForm prev = entry.get();
if (prev != null) {
return prev;
}
}
lambdaForms[which] = new SoftReference<>(form);
return form;
}
/**
* Build an MTF for a given type, which must have all references erased to Object.
* This MTF will stand for that type and all un-erased variations.
* Eagerly compute some basic properties of the type, common to all variations.
*/
@SuppressWarnings({"rawtypes", "unchecked"})
protected MethodTypeForm(MethodType erasedType) {
this.erasedType = erasedType;
Class<?>[] ptypes = erasedType.ptypes();
int pslotCount = ptypes.length;
// Walk the argument types, looking for primitives.
short primitiveCount = 0, longArgCount = 0;
Class<?>[] erasedPtypes = ptypes;
Class<?>[] basicPtypes = erasedPtypes;
for (int i = 0; i < erasedPtypes.length; i++) {
Class<?> ptype = erasedPtypes[i];
if (ptype != Object.class) {
++primitiveCount;
Wrapper w = Wrapper.forPrimitiveType(ptype);
if (w.isDoubleWord()) ++longArgCount;
if (w.isSubwordOrInt() && ptype != int.class) {
if (basicPtypes == erasedPtypes)
basicPtypes = basicPtypes.clone();
basicPtypes[i] = int.class;
}
}
}
pslotCount += longArgCount; // #slots = #args + #longs
Class<?> returnType = erasedType.returnType();
Class<?> basicReturnType = returnType;
if (returnType != Object.class) {
++primitiveCount; // even void.class counts as a prim here
Wrapper w = Wrapper.forPrimitiveType(returnType);
if (w.isSubwordOrInt() && returnType != int.class)
basicReturnType = int.class;
}
if (erasedPtypes == basicPtypes && basicReturnType == returnType) {
// Basic type
this.basicType = erasedType;
if (pslotCount >= 256) throw newIllegalArgumentException("too many arguments");
this.primitiveCount = primitiveCount;
this.parameterSlotCount = (short)pslotCount;
this.lambdaForms = new SoftReference[LF_LIMIT];
this.methodHandles = new SoftReference[MH_LIMIT];
} else {
this.basicType = MethodType.makeImpl(basicReturnType, basicPtypes, true);
// fill in rest of data from the basic type:
MethodTypeForm that = this.basicType.form();
assert(this != that);
this.parameterSlotCount = that.parameterSlotCount;
this.primitiveCount = that.primitiveCount;
this.methodHandles = null;
this.lambdaForms = null;
}
}
public int parameterCount() {
return erasedType.parameterCount();
}
public int parameterSlotCount() {
return parameterSlotCount;
}
public boolean hasPrimitives() {
return primitiveCount != 0;
}
static MethodTypeForm findForm(MethodType mt) {
MethodType erased = canonicalize(mt, ERASE, 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();
}
}
/** Codes for {@link #canonicalize(java.lang.Class, int)}.
* ERASE means change every reference to {@code Object}.
* WRAP means convert primitives (including {@code void} to their
* corresponding wrapper types. UNWRAP means the reverse of WRAP.
* INTS means convert all non-void primitive types to int or long,
* according to size. LONGS means convert all non-void primitives
* to long, regardless of size. RAW_RETURN means convert a type
* (assumed to be a return type) to int if it is smaller than an int,
* or if it is void.
*/
public static final int ERASE = 1, WRAP = 2, UNWRAP = 3, INTS = 4, LONGS = 5, RAW_RETURN = 6;
/** Canonicalize the types in the given method type.
* If any types change, intern the new type, and return it.
* Otherwise return null.
*/
public static MethodType canonicalize(MethodType mt, int howRet, int howArgs) {
Class<?>[] ptypes = mt.ptypes();
Class<?>[] ptypesCanonical = canonicalizeAll(ptypes, howArgs);
Class<?> rtype = mt.returnType();
Class<?> rtypeCanonical = canonicalize(rtype, howRet);
if (ptypesCanonical == null && rtypeCanonical == null) {
// It is already canonical.
return null;
}
// Find the erased version of the method type:
if (rtypeCanonical == null) rtypeCanonical = rtype;
if (ptypesCanonical == null) ptypesCanonical = ptypes;
return MethodType.makeImpl(rtypeCanonical, ptypesCanonical, true);
}
/** Canonicalize the given return or param type.
* Return null if the type is already canonicalized.
*/
static Class<?> canonicalize(Class<?> t, int how) {
Class<?> ct;
if (t == Object.class) {
// no change, ever
} else if (!t.isPrimitive()) {
switch (how) {
case UNWRAP:
ct = Wrapper.asPrimitiveType(t);
if (ct != t) return ct;
break;
case RAW_RETURN:
case ERASE:
return Object.class;
}
} else if (t == void.class) {
// no change, usually
switch (how) {
case RAW_RETURN:
return int.class;
case WRAP:
return Void.class;
}
} else {
// non-void primitive
switch (how) {
case WRAP:
return Wrapper.asWrapperType(t);
case INTS:
if (t == int.class || t == long.class)
return null; // no change
if (t == double.class)
return long.class;
return int.class;
case LONGS:
if (t == long.class)
return null; // no change
return long.class;
case RAW_RETURN:
if (t == int.class || t == long.class ||
t == float.class || t == double.class)
return null; // no change
// everything else returns as an int
return int.class;
}
}
// 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<?>[] canonicalizeAll(Class<?>[] ts, int how) {
Class<?>[] cs = null;
for (int imax = ts.length, i = 0; i < imax; i++) {
Class<?> c = canonicalize(ts[i], how);
// Void parameters may be unwrapped to void; ignore those
if (c != null && c != void.class) {
if (cs == null)
cs = ts.clone();
cs[i] = c;
}
}
return cs;
}
@Override
public String toString() {
return "Form"+erasedType;
}
}