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Date: Fri, 20 Oct 2017 21:36:45 +0200
From: Szabolcs Nagy <nsz@...t70.net>
To: musl@...ts.openwall.com
Subject: Re: Build failure on ARM <5

* Reiner Herrmann <reiner@...ner-h.de> [2017-10-20 21:04:00 +0200]:
> Hi,
> 
> musl 1.1.17 fails to build [1] on arm versions <5 because
> of an unsupported clz instruction.
> The attached patch by Adrian Bunk [2] fixes this issue.
> 

this is my bug sorry,

> diff --git a/arch/arm/atomic_arch.h b/arch/arm/atomic_arch.h
> index a121010f..c5c56f81 100644
> --- a/arch/arm/atomic_arch.h
> +++ b/arch/arm/atomic_arch.h
> @@ -82,9 +82,13 @@ static inline void a_crash()
>  		: : : "memory");
>  }
>  
> +#if __ARM_ARCH >= 5
> +

this is not enough: v5t and v6 only supports clz in arm mode
v6t2 and v7 supports it in thumb mode too.

i think we should either check for >= 7 conservatively or check
__ARM_FEATURE_CLZ which is defined in
https://developer.arm.com/docs/ihi0053/b/arm-c-language-extensions-release-11

>  #define a_clz_32 a_clz_32
>  static inline int a_clz_32(uint32_t x)
>  {
>  	__asm__ ("clz %0, %1" : "=r"(x) : "r"(x));
>  	return x;
>  }
> +
> +#endif
> -- 
> 2.15.0.rc1
> 



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