[PATCH] ia64: Fix memchr for large input sizes (BZ #22603)

[Adhemerval Zanella]

On 14/12/2017 09:13, Adhemerval Zanella wrote:
> Current optimized ia64 memchr uses a strategy to check for last address
> by adding the input one with expected size.  However it does not take
> care for possible overflow.
> 
> It was triggered by 3038145ca23 where default rawmemchr now uses memchr
> (p, c, (size_t)-1).
> 
> This patch fixes it by implement a satured addition where overflows
> sets the maximum pointer size to UINTPTR_MAX.
> 
> Checked on ia64-linux-gnu where it fixes both stratcliff and
> test-rawmemchr failures.
> 
> 	Adhemerval Zanella  <adhemerval.zanella@linaro.org>
> 	James Clarke <jrtc27@jrtc27.com>
> 
> 	[BZ #22603]
> 	* sysdeps/ia64/memchr.S (__memchr): Avoid overflow in pointer
> 	addition.
> ---
>  ChangeLog             | 7 +++++++
>  sysdeps/ia64/memchr.S | 4 ++++
>  2 files changed, 11 insertions(+)
> 
> diff --git a/sysdeps/ia64/memchr.S b/sysdeps/ia64/memchr.S
> index d60cf7b..9a0abc6 100644
> --- a/sysdeps/ia64/memchr.S
> +++ b/sysdeps/ia64/memchr.S
> @@ -67,6 +67,10 @@ ENTRY(__memchr)
>  	.body
>  	mov	ret0 = str
>  	add	last = str, in2		// last byte
> +	;;
> +	cmp.ltu	p6, p0 = last, str
> +	;;
> +(p6)	mov	last = -1
>  	and	tmp = 7, str		// tmp = str % 8
>  	cmp.ne	p7, p0 = r0, r0		// clear p7
>  	extr.u	chr = in1, 0, 8		// chr = (unsigned char) in1
> 

I will commit this shortly if no one opposes it.