[aarch64-port-dev ] RFR: 8193266: AArch64: TestOptionsWithRanges.java SIGSEGV

[Andrew Haley]

On 09/12/17 11:37, Andrew Haley wrote:
> Hmm.  This sort-of papers over the problem, in that it disables XOR-
> encoding of class metadata.  I would have thought it makes more sense
> to set narrow_klass_base high enough so that this does not happen.  We
> really want narrow_klass_shift to be zero if we can, which should be
> OK if the shared klasses are in a 4G range.

And I now see that in the very odd code in question the shift is set
to 3, regardless of the fact that it's not necessary.  Something to
do with AOT, which I guess always does the shift.  I'd prefer
AArch64 always to set the shift to zero, and we could then search
for a suitable base.  We never need a shift for compressed classes,
given that 4G seems to be hard-wired as a maximum size.

We could establish the convention that the shift is always zero
on AArch64, and then this problem would go away completely.

-- 
Andrew Haley
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
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