/*
* Copyright (c) 2008, 2013, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
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*/
package java.lang.invoke;
import sun.invoke.util.
Wrapper;
import java.lang.ref.
SoftReference;
import static java.lang.invoke.
MethodHandleStatics.*;
/**
* 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 int[]
argToSlotTable,
slotToArgTable;
final long
argCounts; // packed slot & value counts
final long
primCounts; // packed prim & double counts
final
MethodType erasedType; // the canonical erasure
final
MethodType basicType; // the canonical erasure, with primitives simplified
// Cached adapter information:
@
Stable 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 @
Stable 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_LIMIT = 18;
/** 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;
}
private boolean
assertIsBasicType() {
// primitives must be flattened also
assert(
erasedType ==
basicType)
: "erasedType: " +
erasedType + " != basicType: " +
basicType;
return true;
}
public
MethodHandle cachedMethodHandle(int
which) {
assert(
assertIsBasicType());
SoftReference<
MethodHandle>
entry =
methodHandles[
which];
return (
entry != null) ?
entry.
get() : null;
}
synchronized public
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) {
assert(
assertIsBasicType());
SoftReference<
LambdaForm>
entry =
lambdaForms[
which];
return (
entry != null) ?
entry.
get() : null;
}
synchronized public
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
ptypeCount =
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.
int
pac = 0,
lac = 0,
prc = 0,
lrc = 0;
Class<?>[]
epts =
ptypes;
Class<?>[]
bpts =
epts;
for (int
i = 0;
i <
epts.length;
i++) {
Class<?>
pt =
epts[
i];
if (
pt !=
Object.class) {
++
pac;
Wrapper w =
Wrapper.
forPrimitiveType(
pt);
if (
w.
isDoubleWord()) ++
lac;
if (
w.
isSubwordOrInt() &&
pt != int.class) {
if (
bpts ==
epts)
bpts =
bpts.
clone();
bpts[
i] = int.class;
}
}
}
pslotCount +=
lac; // #slots = #args + #longs
Class<?>
rt =
erasedType.
returnType();
Class<?>
bt =
rt;
if (
rt !=
Object.class) {
++
prc; // even void.class counts as a prim here
Wrapper w =
Wrapper.
forPrimitiveType(
rt);
if (
w.
isDoubleWord()) ++
lrc;
if (
w.
isSubwordOrInt() &&
rt != int.class)
bt = int.class;
// adjust #slots, #args
if (
rt == void.class)
rtypeCount =
rslotCount = 0;
else
rslotCount +=
lrc;
}
if (
epts ==
bpts &&
bt ==
rt) {
this.
basicType =
erasedType;
} else {
this.
basicType =
MethodType.
makeImpl(
bt,
bpts, true);
// fill in rest of data from the basic type:
MethodTypeForm that = this.
basicType.
form();
assert(this !=
that);
this.
primCounts =
that.
primCounts;
this.
argCounts =
that.
argCounts;
this.
argToSlotTable =
that.
argToSlotTable;
this.
slotToArgTable =
that.
slotToArgTable;
this.
methodHandles = null;
this.
lambdaForms = null;
return;
}
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];
Wrapper w =
Wrapper.
forBasicType(
pt);
if (
w.
isDoubleWord()) --
slot;
--
slot;
slotToArgTab[
slot] =
i+1; // "+1" see argSlotToParameter note
argToSlotTab[1+
i] =
slot;
}
assert(
slot == 0); // filled the table
} else if (
pac != 0) {
// have primitives but no long primitives; share slot counts with generic
assert(
ptypeCount ==
pslotCount);
MethodTypeForm that =
MethodType.
genericMethodType(
ptypeCount).
form();
assert(this !=
that);
slotToArgTab =
that.
slotToArgTable;
argToSlotTab =
that.
argToSlotTable;
} else {
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.
primCounts =
pack(
lrc,
prc,
lac,
pac);
this.
argCounts =
pack(
rslotCount,
rtypeCount,
pslotCount,
ptypeCount);
this.
argToSlotTable =
argToSlotTab;
this.
slotToArgTable =
slotToArgTab;
if (
pslotCount >= 256) throw
newIllegalArgumentException("too many arguments");
// Initialize caches, but only for basic types
assert(
basicType ==
erasedType);
this.
lambdaForms = new
SoftReference[
LF_LIMIT];
this.
methodHandles = new
SoftReference[
MH_LIMIT];
}
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 boolean
hasPrimitives() {
return
primCounts != 0;
}
public boolean
hasNonVoidPrimitives() {
if (
primCounts == 0) return false;
if (
primitiveParameterCount() != 0) return true;
return (
primitiveReturnCount() != 0 &&
returnCount() != 0);
}
public boolean
hasLongPrimitives() {
return (
longPrimitiveParameterCount() |
longPrimitiveReturnCount()) != 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
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
NO_CHANGE = 0,
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<?>[]
ptc =
MethodTypeForm.
canonicalizeAll(
ptypes,
howArgs);
Class<?>
rtype =
mt.
returnType();
Class<?>
rtc =
MethodTypeForm.
canonicalize(
rtype,
howRet);
if (
ptc == null &&
rtc == null) {
// It is already canonical.
return null;
}
// Find the erased version of the method type:
if (
rtc == null)
rtc =
rtype;
if (
ptc == null)
ptc =
ptypes;
return
MethodType.
makeImpl(
rtc,
ptc, 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);
if (
c == void.class)
c = null; // a Void parameter was unwrapped to void; ignore
if (
c != null) {
if (
cs == null)
cs =
ts.
clone();
cs[
i] =
c;
}
}
return
cs;
}
@
Override
public
String toString() {
return "Form"+
erasedType;
}
}