RFR (S, URGENT) 8149038: SIGSEGV at frame::is_interpreted_frame_valid -> StubRoutines::SafeFetchN

[Coleen Phillimore]

Hi Markus,  Thank you for reviewing.  I want to keep the backout as 
simple as possible so don't want to give myself the chance to mess up 
with a cleanup.

On 2/4/16 6:08 PM, Markus Gronlund wrote:
> Hi Coleen,
>
> Thanks for reverting, looks good.
>
> /Markus
>
> PS I don’t know if you want to go straight back to the previous version, but I still think this piece could be tightened a bit:
>
> bool Method::has_method_vptr(const void* ptr) {
>    assert(ptr != NULL, "invariant");
>
>    // This assumes that the vtbl pointer is the first word of a C++ object.
>    // This assumption is also in universe.cpp patch_klass_vtble
>    const Method m;
>    return dereference_vptr(&m) == dereference_vptr(ptr);

Yes, this is nicer.
> }
>
> // Check that this pointer is valid by checking that the vtbl pointer matches
> bool Method::is_valid_method() const {
>    if (this == NULL) {
>      return false;
>    }
>    if ((intptr_t(this) & (wordSize - 1)) != 0) {
>      return false;
>    }
>    if (!is_metaspace_object()) {
>      return false;
>    }
>    return has_method_vptr(this);
> }
>

I like 'else's.  Are they less efficient?


Thanks,
Coleen

>
> -----Original Message-----
> From: Coleen Phillimore
> Sent: den 4 februari 2016 23:44
> To: hotspot-dev at openjdk.java.net
> Subject: Re: RFR (S, URGENT) 8149038: SIGSEGV at frame::is_interpreted_frame_valid -> StubRoutines::SafeFetchN
>
>
>
> On 2/4/16 5:40 PM, Coleen Phillimore wrote:
>> Summary: Backout change for 8146984 but add an alignment check which
>> may have caught original bug.
>>
>> Will retest with new check once this isn't an integration blocker. Ran
>> original tests that failed.
>>
>> open webrev at http://cr.openjdk.java.net/~coleenp/8149038.01/
>> bug link https://bugs.openjdk.java.net/browse/JDK-8149038
> The original bug is:
>
> https://bugs.openjdk.java.net/browse/JDK-8146984
>
> Coleen
>> Thanks,
>> Coleen