Re: [PATCH v4 1/3] lib: add bitrev8x4()

From	Anatolij Gustschin <agust@denx.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH v4 1/3] lib: add bitrev8x4()
Date	2016-12-02 09:00 +0100
Message-ID	<sJQVh-HL-9@gated-at.bofh.it> (permalink)
References	<sJD1U-70r-15@gated-at.bofh.it> <sJD1U-70r-13@gated-at.bofh.it> <sJIkW-3mt-3@gated-at.bofh.it> <sJJAl-4m3-5@gated-at.bofh.it>
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Hi Joshua,

On Thu, 1 Dec 2016 16:04:09 -0800
Joshua Clayton stillcompiling@gmail.com wrote:
...
>>> +static __always_inline __attribute_const__ u32 __arch_bitrev8x4(u32 x)
>>> +{
>>> +	__asm__ ("rbit %0, %1; rev %0, %0" : "=r" (x) : "r" (x));  
>> 	return x;  
>Oops thats a little embarrassing;
>I'll add a return.
>>> +}  
>> otherwise you get
>>
>> In function '__arch_bitrev8x4':
>> warning: no return statement in function returning non-void [-Wreturn-type]
>>
>
>I wonder why I do not see this warning when compiling. The inlining, maybe?

do you have CONFIG_HAVE_ARCH_BITREVERSE=y in your .config?
Probably not optimized code is used, otherwise you will send wrong
data to FPGA (due to wrong return values from __arch_bitrev8x4).

Anatolij

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[PATCH v4 1/3] lib: add bitrev8x4() Joshua Clayton <stillcompiling@gmail.com> - 2016-12-01 18:10 +0100
  Re: [PATCH v4 1/3] lib: add bitrev8x4() Anatolij Gustschin <agust@denx.de> - 2016-12-01 23:50 +0100
    Re: [PATCH v4 1/3] lib: add bitrev8x4() Joshua Clayton <stillcompiling@gmail.com> - 2016-12-02 01:10 +0100
      Re: [PATCH v4 1/3] lib: add bitrev8x4() Anatolij Gustschin <agust@denx.de> - 2016-12-02 09:00 +0100

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