On Oct 26, 2010, at 1:27 PM, Dave Korn wrote:
> On 26/10/2010 17:16, Paul Koning wrote:
>> On Oct 25, 2010, at 9:28 PM, Dave Korn wrote:
>>> ...
>>>
>>> What happens if you dereference i and j before the memcpy in foo? Do you
>>> then get int-sized shared alignment in movmemM?
>>>
>>> extern int *i, *j; void foo (void) { *i; *j; memcpy (i, j, 10); }
>>
>> That doesn't make any difference; I still get alignment 1.
>>
>
> That sounds like a missed optimisation opportunity to me, but maybe there's
> some reason the compiler can't infer a larger alignment. (Or maybe the reads
> got discarded, you might need volatile to avoid that?)
No, they weren't discarded, I can see them in the output assembler code.
Actually, I wrote *i = 20; *j = 10;
paul
