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Re: [PATCH 4/4] arm: Enable ARM mode for armv6 strlen
- From: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>
- To: Phil Blundell <pb at pbcl dot net>, libc-alpha at sourceware dot org
- Date: Thu, 12 Apr 2018 09:41:27 -0300
- Subject: Re: [PATCH 4/4] arm: Enable ARM mode for armv6 strlen
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- References: <1523481378-16290-1-git-send-email-adhemerval.zanella@linaro.org> <1523481378-16290-4-git-send-email-adhemerval.zanella@linaro.org> <1523484770.1959.2.camel@pbcl.net>
On 11/04/2018 19:12, Phil Blundell wrote:
> On Wed, 2018-04-11 at 18:16 -0300, Adhemerval Zanella wrote:
>> Current optimized armv6t2 strlen uses the NO_THUMB wrongly to
>> conditionalize thumb instruction usage. The flags is meant to be
>> defined before sysdep.h inclusion and to indicate the assembly
>> requires to build in ARM mode, not to check whether thumb is
>> enable or not. This patch fixes it by using the GCC provided
>> '__thumb__' instead.
>
> Is it ever useful to build for ARM-state when on armv6t2 (i.e. Thumb2
> is guaranteed to be available)? It's not totally obvious from reading
> the source that the ARM version is going to be better in any way than
> the Thumb one.
I guess not, but even though the implementation allows it and the flag
usage is wrong. Another option would just remove ARM code, but I think
for this we will need to also add configure check to require thumb as
well.
>
> Assuming that this is indeed something worth supporting, I think the
> short log for the patch ought to say "armv6t2" not "armv6".
Right, I changed it locally.