You are correct. So I should be changing things in the adjust_cost
function instead.
I was also wondering, these instructions modify an internal register
that has been set as a fixed register. However, the compiler optimizes
them out when the accumulator is not retrieved for a calculation. How
can I tell the compiler that it should not remove these instructions.
Here is an example code:
uint64_t foo (uint64_t x, uint64_t y)
{
uint64_t z;
__builtin_newins (x,y); /* Modifies the accumulator */
z = __builtin_retrieve_accum (); /* Retrieve the accumulator */
return z;
}
If I remove the instruction "z = ...;", then the compiler will
optimize out my first builtin call.
Thanks for your help and input,
Jc
On Mon, Dec 14, 2009 at 6:10 PM, Daniel Jacobowitz <d...@false.org> wrote:
> On Mon, Dec 14, 2009 at 05:52:50PM -0500, Jean Christophe Beyler wrote:
>> I thought of that but then how do I add the cost ? I also have another
>> problem: there is a second instruction that would have the exact same
>> signature if I use an unspec.
>>
>> Is there a solution for that and how do I handle the cost then ?
>> - Just say that an unspec has a higher cost?
>
> Are you really talking about rtx_costs? It sounds to me more like you
> want to change your scheduler.
>
> --
> Daniel Jacobowitz
> CodeSourcery
>
