From: Will Newton <will.newton@linaro.org>
To: Roland McGrath <roland@hack.frob.com>
Cc: libc-ports@sourceware.org, Patch Tracking <patches@linaro.org>
Subject: Re: [PATCH, v5] ARM: Add Cortex-A15 optimized NEON and VFP memcpy routines, with IFUNC.
Date: Wed, 01 May 2013 18:43:00 -0000 [thread overview]
Message-ID: <CANu=Dmi04i3EeyzirncxsiTqiWV5nRNeg+K63jcU1rs4i50R0w@mail.gmail.com> (raw)
In-Reply-To: <20130501170134.265AC2C096@topped-with-meat.com>
On 1 May 2013 18:01, Roland McGrath <roland@hack.frob.com> wrote:
>> > If __SOFTFP__ is predefined by the compiler, then the compiler is presuming
>> > VFP support anyway. So you can make this:
>> >
>> > #ifdef __SOFTFP__
>> > ldr r1, .Lmemcpy_arm
>> > tst r0, #HWCAP_ARM_VFP
>> > ldrne r1, .Lmemcpy_vfp
>> > #else
>> > ldr r1, .Lmemcpy_vfp
>> > #endif
>> >
>> > (and also conditionalize .Lmemcpy_arm, below).
>>
>> I'm not sure I follow the logic here, could you elaborate?
>
> I dropped a "not" in my first sentence, which might have been confusing.
> The compiler predefines __SOFTFP__ unless it's presuming VFP support. If
> __SOFTFP__ is not defined, then the compiler is already generating code
> that effectively presumes HWCAP_ARM_VFP will be set, so you might as well
> just elide any code testing it at runtime and statically do whatever you
> would do if HWCAP_ARM_VFP were set at runtime.
Ok, that makes sense. I'll make that change.
--
Will Newton
Toolchain Working Group, Linaro
next prev parent reply other threads:[~2013-05-01 18:43 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-30 16:54 Will Newton
2013-04-30 17:08 ` Joseph S. Myers
2013-05-01 9:11 ` Will Newton
2013-04-30 17:18 ` Roland McGrath
2013-05-01 15:26 ` Will Newton
2013-05-01 17:01 ` Roland McGrath
2013-05-01 18:43 ` Will Newton [this message]
2013-05-02 19:54 ` Roland McGrath
2013-05-01 12:53 ` Richard Henderson
2013-05-01 16:50 ` Roland McGrath
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