[PATCH] PR string/19907: Incorrect memcpy tests

[H.J. Lu]

On Sun, May 8, 2016 at 10:14 AM, Florian Weimer <fw@deneb.enyo.de> wrote:
> * H. J. Lu:
>
>> +  /* Must clear the destination buffer set by the previous run.  */
>> +  for (i = 0; i < len; i++)
>> +    dst[i] = 0;
>
> Doesn't this need some sort of compiler barrier so that GCC will not
> eliminate the dead stores if it recognizes a memset-style loop?

The code looks like:

 /* Must clear the destination buffer set by the previous run.  */
  for (i = 0; i < len; i++)
    dst[i] = 0;

  if (CALL (impl, dst, src, len) != MEMCPY_RESULT (dst, len))
    {

Compiler doesn't know what CALL (impl, dst, src, len) does
and won't optimize it out.

-- 
H.J.