@Uninterruptible
private static void copyAndReplaceGlobalRefs(AddressArray newGlobalRefs) {
for (int i = 0; i < JNIGlobalRefs.length(); i++) {
newGlobalRefs.set(i, JNIGlobalRefs.get(i));
}
JNIGlobalRefs = newGlobalRefs;
}
static int newGlobalRef(Object referent) {
if (VM.VerifyAssertions)
VM._assert(MemoryManager.validRef(ObjectReference.fromObject(referent)));
if (free >= JNIGlobalRefs.length()) {
AddressArray newGlobalRefs = AddressArray.create(JNIGlobalRefs.length() * 2);
copyAndReplaceGlobalRefs(newGlobalRefs);
}
JNIGlobalRefs.set(free, Magic.objectAsAddress(referent));
return -free++;
}
// return (address of) next ref in the current "frame" on the
// threads JNIEnvironment stack of refs
// When at the end of the current frame, update register locations to point
// to the non-volatile registers saved in the JNI transition frame.
//
public Address getNextReferenceAddress() {
// first report jni refs in the current frame in the jniRef side stack
// until all in the frame are reported
//
if (jniNextRef > jniFramePtr) {
Address ref_address = Magic.objectAsAddress(jniRefs).plus(jniNextRef);
jniNextRef -= BYTES_IN_ADDRESS;
return ref_address;
}
// no more refs to report, before returning 0, setup for processing
// the next jni frame, if any
// jniNextRef -> savedFramePtr for another "frame" of refs for another
// sequence of Native C frames lower in the stack, or to 0 if this is the
// last jni frame in the JNIRefs stack. If more frames, initialize for a
// later scan of those refs.
//
if (jniFramePtr > 0) {
jniFramePtr = jniRefs.get(jniFramePtr >> LOG_BYTES_IN_ADDRESS).toInt();
jniNextRef = jniNextRef - BYTES_IN_ADDRESS;
}
// set register locations for non-volatiles to point to registers saved in
// the JNI transition frame at a fixed negative offset from the callers FP.
// the save non-volatiles are EBX EBP and EDI.
//
registerLocations.set(EDI.value(), framePtr.plus(JNICompiler.EDI_SAVE_OFFSET));
registerLocations.set(EBX.value(), framePtr.plus(JNICompiler.EBX_SAVE_OFFSET));
registerLocations.set(EBP.value(), framePtr.plus(JNICompiler.EBP_SAVE_OFFSET));
return Address.zero(); // no more refs to report
}
@Uninterruptible
static Object globalRef(int index) {
if (VM.VerifyAssertions) VM._assert(!isWeakRef(index));
return Magic.addressAsObject(JNIGlobalRefs.get(-index));
}
static void deleteGlobalRef(int index) {
if (VM.VerifyAssertions) VM._assert(!isWeakRef(index));
JNIGlobalRefs.set(-index, Address.zero());
}
/**
* Weak Global References are global references (negative numbers), with the 2^30 bit UNset. Mask in
* the 2^30 bit to get the real index into the table.
*/
public class JNIGlobalRefTable {
@Entrypoint public static AddressArray JNIGlobalRefs = AddressArray.create(100);
private static int free = 1;
static int newGlobalRef(Object referent) {
if (VM.VerifyAssertions)
VM._assert(MemoryManager.validRef(ObjectReference.fromObject(referent)));
if (free >= JNIGlobalRefs.length()) {
AddressArray newGlobalRefs = AddressArray.create(JNIGlobalRefs.length() * 2);
copyAndReplaceGlobalRefs(newGlobalRefs);
}
JNIGlobalRefs.set(free, Magic.objectAsAddress(referent));
return -free++;
}
@Uninterruptible
private static void copyAndReplaceGlobalRefs(AddressArray newGlobalRefs) {
for (int i = 0; i < JNIGlobalRefs.length(); i++) {
newGlobalRefs.set(i, JNIGlobalRefs.get(i));
}
JNIGlobalRefs = newGlobalRefs;
}
/* Weak references are returned with the STRONG_REF_BIT bit UNset. */
public static final int STRONG_REF_BIT = 1 << 30;
static int newWeakRef(Object referent) {
int gref = newGlobalRef(new WeakReference<Object>(referent));
return gref & ~STRONG_REF_BIT;
}
static void deleteGlobalRef(int index) {
if (VM.VerifyAssertions) VM._assert(!isWeakRef(index));
JNIGlobalRefs.set(-index, Address.zero());
}
static void deleteWeakRef(int index) {
if (VM.VerifyAssertions) VM._assert(isWeakRef(index));
int gref = index | STRONG_REF_BIT;
deleteGlobalRef(gref);
}
@Uninterruptible
static Object globalRef(int index) {
if (VM.VerifyAssertions) VM._assert(!isWeakRef(index));
return Magic.addressAsObject(JNIGlobalRefs.get(-index));
}
@Uninterruptible
static Object weakRef(int index) {
if (VM.VerifyAssertions) VM._assert(isWeakRef(index));
@SuppressWarnings("unchecked") // yes, we're being bad.
WeakReference<Object> ref = (WeakReference<Object>) globalRef(index | STRONG_REF_BIT);
return java.lang.ref.JikesRVMSupport.uninterruptibleReferenceGet(ref);
}
@Uninterruptible
static Object ref(int index) {
if (isWeakRef(index)) {
return weakRef(index);
} else {
return globalRef(index);
}
}
@Uninterruptible
static boolean isWeakRef(int index) {
return (index & STRONG_REF_BIT) == 0;
}
}