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* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package java.lang.invoke;
import sun.invoke.util.Wrapper;
import static java.lang.invoke.MethodHandleStatics.*;
import static java.lang.invoke.MethodHandleNatives.Constants.*;
import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;
/**
* 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 int vmslots; // total number of parameter slots
final MethodType erasedType; // the canonical erasure
final MethodType basicType; // the canonical erasure, with primitives simplified
// Cached adapter information:
@Stable String typeString; // argument type signature characters
@Stable MethodHandle genericInvoker; // JVM hook for inexact invoke
@Stable MethodHandle basicInvoker; // cached instance of MH.invokeBasic
@Stable MethodHandle namedFunctionInvoker; // cached helper for LF.NamedFunction
// Cached lambda form information, for basic types only:
final @Stable 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_COUNTER = 7, // CMH wrapper
LF_REINVOKE = 8, // other wrapper
LF_EX_LINKER = 9, // invokeExact_MT
LF_EX_INVOKER = 10, // invokeExact MH
LF_GEN_LINKER = 11,
LF_GEN_INVOKER = 12,
LF_CS_LINKER = 13, // linkToCallSite_CS
LF_MH_LINKER = 14, // linkToCallSite_MH
LF_GWC = 15,
LF_LIMIT = 16;
public MethodType erasedType() {
return erasedType;
}
public MethodType basicType() {
return basicType;
}
public LambdaForm cachedLambdaForm(int which) {
return lambdaForms[which];
}
synchronized public LambdaForm setCachedLambdaForm(int which, LambdaForm form) {
// Simulate a CAS, to avoid racy duplication of results.
LambdaForm prev = lambdaForms[which];
if (prev != null) return prev;
return lambdaForms[which] = form;
}
public MethodHandle basicInvoker() {
assert(erasedType == basicType) : "erasedType: " + erasedType + " != basicType: " + basicType; // primitives must be flattened also
MethodHandle invoker = basicInvoker;
if (invoker != null) return invoker;
invoker = DirectMethodHandle.make(invokeBasicMethod(basicType));
basicInvoker = invoker;
return invoker;
}
// This next one is called from LambdaForm.NamedFunction.<init>.
/*non-public*/ static MemberName invokeBasicMethod(MethodType basicType) {
assert(basicType == basicType.basicType());
try {
// Do approximately the same as this public API call:
// Lookup.findVirtual(MethodHandle.class, name, type);
// But bypass access and corner case checks, since we know exactly what we need.
return IMPL_LOOKUP.resolveOrFail(REF_invokeVirtual, MethodHandle.class, "invokeBasic", basicType);
} catch (ReflectiveOperationException ex) {
throw newInternalError("JVM cannot find invoker for "+basicType, ex);
}
}
/**
* 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.
*/
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);
}
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
}
this.primCounts = pack(lrc, prc, lac, pac);
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 newIllegalArgumentException("too many arguments");
// send a few bits down to the JVM:
this.vmslots = parameterSlotCount();
if (basicType == erasedType) {
lambdaForms = new LambdaForm[LF_LIMIT];
} else {
lambdaForms = null; // could be basicType.form().lambdaForms;
}
}
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.canonicalizes(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<?>[] canonicalizes(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;
}
}