Zero JVM segfaulting on linux-sparc

[Severin Gehwolf]

Hi Adrian,

On Fri, 2018-12-21 at 13:27 +0100, John Paul Adrian Glaubitz wrote:
> Hi Severin!
> 
> On 12/21/18 10:12 AM, Severin Gehwolf wrote:
> > It could be that you are hitting a GCC bug specific to linux sparc.
> > Then again, why wouldn't you hit it for a server JVM. As a temporary
> > work-around you could try this (compile without opt as prior JDK-
> > 8210425, not tested):
> > 
> > diff --git a/make/hotspot/lib/JvmOverrideFiles.gmk b/make/hotspot/lib/JvmOverrideFiles.gmk
> > --- a/make/hotspot/lib/JvmOverrideFiles.gmk
> > +++ b/make/hotspot/lib/JvmOverrideFiles.gmk
> > @@ -49,6 +49,15 @@
> >  # by using -ffp-contract=off on GCC/Clang platforms.
> >  ifneq ($(FDLIBM_CFLAGS), )
> >    LIBJVM_FDLIBM_COPY_OPT_FLAG := $(CXX_O_FLAG_NORM)
> > +  # Don't optimize fdlibm-fork for Zero on Linux spark
> > +  # See JDK-XXXX
> > +  ifeq ($(call check-jvm-feature, zero), true)
> > +    ifeq ($(OPENJDK_TARGET_OS), linux)
> > +      ifeq ($(OPENJDK_TARGET_CPU_ARCH), spark)
> > +        LIBJVM_FDLIBM_COPY_OPT_FLAG := $(CXX_O_FLAG_NONE)
> > +      endif
> > +    endif
> > +  endif
> >  endif
> 
> This indeed fixes the problem for me, with the spelling fix for "sparc" ;-).

OK. It's rather curious. What are the different flags being used?
Pre/post patch? It looks as if this happens (on Linux sparc):

Zero and '-ffp-contract=off -O2' => bad build
Zero and '-ffp-contract=off -O0' => good build
Server and '-ffp-contract=off -O2' => good build

Thanks,
Severin