[Bug 3533] HotSpot generates code with unaligned stack, crashes on SSE operations

[bugzilla-daemon at icedtea.classpath.org]

https://icedtea.classpath.org/bugzilla/show_bug.cgi?id=3533

--- Comment #16 from Andrew John Hughes <gnu.andrew at redhat.com> ---
(In reply to Maciej S. Szmigiero from comment #13)
> (In reply to Andrew John Hughes from comment #11)
> > Thanks for filing the bug.
> 
> You are welcome.
> 
> > I still don't see what has changed here to cause this bug. You've noted
> > yourself that the code in the VM hasn't changed recently, so something else
> > in your stack (gcc, linker, kernel, glibc) must have changed in order for
> > this bug to surface.
> 
> Well, it looks like the bug was always there, but it just didn't cause any
> negative effects (like crashes) until recently.
> 
> I think this change in observable behavior was caused by recent GCC versions
> (like 7.3.0) getting smarter in generating SSE-aware code.
> 

Possibly, though I believe we've even done Fedora builds with GCC 8.

On the other hand, distros tend to build binaries for the lowest common
denominator. These are the Fedora GCC 8 build flags:

-g -pipe -Wformat -Wno-cpp -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2
-Wp,-D_GLIBCXX_ASSERTIONS  -fstack-p\
rotector-strong -grecord-gcc-switches
-specs=/usr/lib/rpm/redhat/redhat-hardened-cc1
-specs=/usr/lib/rpm/redhat/redhat-annobin-\
cc1 -m32 -march=i686 -mtune=generic -fasynchronous-unwind-tables
-fstack-clash-protection -mcet -fcf-protection -std=gnu++98 -W\
no-error -fno-delete-null-pointer-checks -fno-lifetime-dse

https://koji.fedoraproject.org/koji/buildinfo?buildID=1055554
https://kojipkgs.fedoraproject.org//packages/java-1.8.0-openjdk/1.8.0.161/9.b14.fc29/data/logs/i686/build.log

Oracle's binaries will be built in a similar way, so I suggest the problem
there is a collision with optimisations in glibc.

> > It's also still not clear to me how to reproduce this.
> 
> I guess you want to reproduce the actual crash, not just a misaligned stack
> .
> You can try to rebuild icedtea with GCC 7.3.0 using
> {C,XX}FLAGS="-O2 -march=pentium-m".
> 
> As far as I can remember, this on its own generated only occasional JVM
> crashes,
> for example when compiling a large number of java files.

I'll look at adding that to a Fedora x86 build. Locally, I've used -march=core2
(Intel Core 2 CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3 and SSSE3
instruction set support) since I installed Gentoo a decade ago and not seen
problems.

> 
> The situation that JVM crashes 100% of time happens when glibc-2.26 is also
> recompiled with such compiler and settings.

Locally, I still need to upgrade from 2.24 so there may be something in that.

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