[16] RFR (S) 8249749: modify a primitive array through a stream and a for cycle causes jre crash

[Doerr, Martin]

Hi Vladimir,

we are hitting the following assertion after this change was pushed:
assert(my_pack(s) == __null) failed: only in one pack

Stack:
V  [jvm.dll+0xbbac55]  SuperWord::construct_my_pack_map+0x135  (superword.cpp:1723)
V  [jvm.dll+0xbb57f7]  SuperWord::SLP_extract+0x427  (superword.cpp:520)
V  [jvm.dll+0xbcba0b]  SuperWord::transform_loop+0x48b  (superword.cpp:170)
V  [jvm.dll+0x895a09]  PhaseIdealLoop::build_and_optimize+0xef9  (loopnode.cpp:3270)
V  [jvm.dll+0x3df4b6]  Compile::Optimize+0xf76  (compile.cpp:2187)
...

Seems to be reproducible by JTREG test compiler/vectorization/TestComplexAddrExpr.java on some x64 and aarch64 machines.
(May depend on CPU model.)

Is this a known issue?
Or should I open a bug?

Best regards,
Martin


> -----Original Message-----
> From: hotspot-compiler-dev <hotspot-compiler-dev-
> retn at openjdk.java.net> On Behalf Of Vladimir Kozlov
> Sent: Montag, 10. August 2020 19:03
> To: hotspot compiler <hotspot-compiler-dev at openjdk.java.net>
> Subject: Re: [16] RFR (S) 8249749: modify a primitive array through a stream
> and a for cycle causes jre crash
> 
> Thank you, Vladimir
> 
> Vladimir K
> 
> On 8/10/20 2:04 AM, Vladimir Ivanov wrote:
> >
> >> http://cr.openjdk.java.net/~kvn/8249749/webrev.00/
> >
> > Looks good.
> >
> > Best regards,
> > Vladimir Ivanov
> >
> >> https://bugs.openjdk.java.net/browse/JDK-8249749
> >>
> >> SuperWord does not recognize array indexing pattern used in the test
> due to additional AddI node:
> >>
> >> AddI(AddI(Invariant(j*n), Loop_phi(i)), Loop_inc(1))
> >>
> >> As result it can't find memory reference to align vectors. But code ignores
> that and continue execution.
> >> Later when align_to_ref is referenced we hit SEGV because it is NULL.
> >>
> >> The fix is to check align_to_ref for NULL early and bailout.
> >>
> >> I also adjusted code in SWPointer::scaled_iv_plus_offset() to recognize
> this address pattern to vectorize test's code.
> >> And added missing _invar setting.
> >>
> >> And I slightly modified tracking code to investigate this issue.
> >>
> >> Added new test to check some complex address expressions similar to
> bug's test case. Not all cases in test are
> >> vectorized - there are other conditions which prevent that.
> >>
> >> Tested tier1,tier2,hs-tier3,precheckin-comp
> >>
> >> Thanks,
> >> Vladimir K