Good catch! I agree that it should not be final and the constant field
should be static. I will take JDK-8193325 and follow up this issue.
-1 is ambiguous but should be initialized to a valid index when filled
by the VM. We tried to keep it compact for footprint concern. Anyway I
will propose a patch.
Mandy
On 12/12/17 11:08 AM, Martin Buchholz wrote:
Out of curiosity, I looked more at StackFrameInfo, and saw:
short bci is final and is only ever assigned to -1 in java code. What's up
with that? Ohh, it seems to be magically frobbed in hotspot:
void java_lang_StackFrameInfo::set_bci(oop element, int value) {
element->int_field_put(_bci_offset, value);
}
BUT: bci should not be final if hotspot magic is frobbing it. Can we add a
comment explaining the magic? Also set_bci seems to disagree about the
type of bci - it's trying to set an int field, but bci is a short!
Also, I expected "int value" above to be "jint value" - it's a java type!
I would prefer bci to be a java int, not short, so that it can hold all
possible bytecode index values in a natural way, together with -1 for
"invalid". Right now, -1 is ambiguous - it might mean bci == 65535.
Also, I see
private final byte RETAIN_CLASS_REF = 0x01;
Shouldn't that be static?
