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From: Blue Swirl <blauwirbel@gmail.com>
Date: Mon, 14 Mar 2011 21:14:55 +0200
Message-ID: <AANLkTikjaYi1LemEB9-HJidGuHa0FBAiR04rBADuRfqK@mail.gmail.com>
Subject: Re: [Qemu-devel] Re: qemu-0.14.0 doesn't compile on ppc32
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To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: Peter Maydell <peter.maydell@linaro.org>, Alexander Graf <agraf@suse.de>, qemu-devel@nongnu.org, Paolo Bonzini <pbonzini@redhat.com>, nello martuscielli <ppc.addon@gmail.com>, Aurelien Jarno <aurelien@aurel32.net>

On Mon, Mar 14, 2011 at 12:33 PM, Stefan Hajnoczi <stefanha@gmail.com> wrot=
e:
> On Mon, Mar 14, 2011 at 10:23 AM, Peter Maydell
> <peter.maydell@linaro.org> wrote:
>> On 21 February 2011 08:10, Paolo Bonzini <pbonzini@redhat.com> wrote:
>>> On 02/20/2011 06:32 PM, Peter Maydell wrote:
>>>> Some of qemu's code does seem to trigger rather excessive memory
>>>> use by gcc; for instance we've had problems with memory usage
>>>> building for ARM with gcc of target-sparc/translate.c wanting
>>>> gigabytes of RAM with some compiler flags:
>>>> https://bugs.launchpad.net/gcc-linaro/+bug/714921
>>>>
>>>> I suspect it's all those large switch statements...
>>>
>>> It's on my todo list to report it to GCC, since this memory-hog behavio=
r is
>>> a GCC regression.
>>
>> We've been working on this in Linaro, and the following two patches
>> have been posted upstream:
>>
>> =C2=A0 =C2=A0http://gcc.gnu.org/ml/gcc-patches/2011-03/msg00193.html
>> =C2=A0 =C2=A0http://gcc.gnu.org/ml/gcc-patches/2011-03/msg00255.html
>>
>> so you can probably cross that item off your todo list :-)
>
> Interesting. =C2=A0Alexander Graf and I recently hit an out of memory whe=
n
> building translate.o on ppc64 host. =C2=A0It was solved by adding more RA=
M
> to the box but this patch looks nice too ;).

Maybe the switch blocks should be rearranged, or inline attribute
removed from the functions. Are the nested switch and if statements
optimal from performance point of view or could there be a faster and
less memory hungry version?