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Re: [RFC] interpreter use of closures and return types
- From: Aurelien Jarno <aurelien at aurel32 dot net>
- To: Matthew Fortune <Matthew dot Fortune at imgtec dot com>
- Cc: "java-patches at gcc dot gnu dot org" <java-patches at gcc dot gnu dot org>, Yunqiang Su <Yunqiang dot Su at imgtec dot com>
- Date: Wed, 22 Jun 2016 18:48:51 +0200
- Subject: Re: [RFC] interpreter use of closures and return types
- Authentication-results: sourceware.org; auth=none
- References: <6D39441BF12EF246A7ABCE6654B023537E45723C at HHMAIL01 dot hh dot imgtec dot org>
Hi,
On 2016-06-22 11:54, Matthew Fortune wrote:
> Hi,
>
> While working on getting mips64el support in place for Debian we found a
> bug relating to libgcj/libffi and closures for MIPS n32 and n64. The bug
> is essentially that return types <= 32bit do not end up correctly sign
> extended in registers when a function is called via a closure. A test case
> showing what I think the problem boils down to is at the end of this email.
> Switch between the two lines in foo_binding to see the difference. Note
> that this will not fail on x86 but I believe it will fail on any big endian
> architecture.
>
> The root of the problem seems to be in a oddity of FFI that integer return
> values less than word (or rather register) size are returned as an ffi_arg.
> The java interpreter does not appear to adhere to this and the patch below
> seems to fix the issue. Can anyone comment if this looks like the right
> approach?
>
> I think there may be a similar issue in the lang/reflect/natVMProxy.cc
> code (unbox function) by code inspection alone but haven't investigated
> further.
>
> If this looks OK I'll do some full testsuite runs.
I have been testing Matthew's patch in the last days. I confirm this
patch correctly fixes the original issue I reported him, the fact that
the Arrays.sort() method sort arrays incorrectly. This in turns cause
ecj to fail finding most of the identifiers. With this patch I can use
ecj and rebuild it with itself without any problem.
Aurelien
--
Aurelien Jarno GPG: 4096R/1DDD8C9B
aurelien@aurel32.net http://www.aurel32.net