1.9.0-ea-b64 regression (AIOOB thrown where it shouldn't be thrown)

[Dawid Weiss]

Good news. I have a repro that crashes for me every time and it only
contains open-source code (and some data). Bad news: it's probably a
compiler bug because everything works just fine with -Xint.

I'll put it together into a repro tomorrow, hopefully, and will ask
somebody with the right permission to file an issue in Jira. Should be
relatively easy to narrow it down by bisecting hs repo commits.

Dawid

On Sat, May 23, 2015 at 2:19 PM, Dawid Weiss
<dawid.weiss at carrotsearch.com> wrote:
> Hi Rory, everyone,
>
> I've ran into an issue with a suspicious ArrayIndexOutOfBounds on ea
> builds of JDK 1.9.0. Here's some context:
>
> - we run separate builds for 1.7, 1.8 and 1.9ea VMs and only the 1.9
> build currently fails (Windows, Linux environments, 64-bit),
>
> - the bug/ issue is a suspicious AIOOB on:
>
> org.apache.commons.compress.compressors.bzip2.BZip2CompressorInputStream.setupBlock(BZip2CompressorInputStream.java:820)
>
> which happens to be the line of code inside this for loop:
>
>         for (int i = 0, lastShadow = this.last; i <= lastShadow; i++) {
>             tt[cftab[ll8[i] & 0xff]++] = i;
>         }
>
> Which array access this is exactly is hard to tell, but the *same*
> bzip input file does not produce the error on any other JVM (or an
> earlier releases of 1.9ea). This code is deterministic in the test
> that uses the above routine.
>
> - the problem *only* appears from 1.9ea_b64; on earlier releases the
> same code passes just fine (bisected it back from b45),
>
> - I also checked 1.9ea_b65 (which happens to be on the download server
> but wasn't properly announced yet?). The problem persists.
>
> - the problem does reproduce on the build server (Windows and Linux).
> Interestingly, I couldn't reproduce it locally. The code is
> proprietary, I couldn't narrow it down yet to something that would
> reproduce (sigh).
>
> I realize this is insufficient information to get started, but perhaps
> this issue is already known or somebody may have a clue at what is
> going on (CCing hotspot-compiler-dev)?
>
> Dawid