From: Jeff Law <jeffreyalaw@gmail.com>
To: Martin Simmons <qqxnjvamvxwx@dyxyl.com>
Cc: gdb@sourceware.org
Subject: Re: Fwd: [RFA] Fix for mcore simulator
Date: Wed, 11 Oct 2023 10:49:11 -0600 [thread overview]
Message-ID: <5894d55f-d930-43c7-8811-d1e9bcda688b@gmail.com> (raw)
In-Reply-To: <je8r8acg9f.fsf@debian-BULLSEYE-live-builder-AMD64>
On 10/10/23 15:35, Martin Simmons wrote:
>>>>>> On Thu, 5 Oct 2023 10:09:44 -0600, Jeff Law via Gdb said:
>>
>> Of course if the code is supposed to behave the same, then that points
>> to problems elsewhere (assembler, linker, simulator). Sure enough the
>> mcore simulator was mis-handling the sign extension instructions. The
>> simulator implementation of sextb is via paired shift-by-24 operations.
>> Similarly the simulator implements sexth via paired shift-by-16 operations.
>>
>> The temporary holding the value was declared as a "long" thus this
>> approach worked fine for hosts with a 32 bit wide long and failed
>> miserably for hosts with a 64 bit wide long.
>>
>> This patch makes the shift count automatically adjust based on the size
>> of the temporary. It includes a simple test for sextb and sexth. I
>> have _not_ done a full audit of the mcore simulator for more 32->64 bit
>> issues.
>
> The use of long seems bogus to me. Why not just declare tmp as int32_t?
That code likely predates any modernization efforts in gdbsim and
binutils-gdb as a whole -- it's the old interp style simulator that was
common in the 90s.
I wouldn't lose any sleep if someone took up that task (modernizing that
codebase) but my interest in mcore is essentially zero, so it won't be me.
Jeff
prev parent reply other threads:[~2023-10-11 16:49 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1d854df9-b28c-41eb-af7c-e3a423885558@gmail.com>
2023-10-05 16:09 ` Jeff Law
2023-10-10 17:21 ` Tom Tromey
2023-10-10 21:35 ` Martin Simmons
2023-10-11 16:49 ` Jeff Law [this message]
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