On Wed, Nov 20, 2013 at 7:26 PM, Gopalasubramanian, Ganesh
<[email protected]> wrote:
> Steamroller processors contain a loop predictor and a loop buffer, which may
> make unrolling small loops less important.
> When unrolling small loops for steamroller, making the unrolled loop fit in
> the loop buffer should be a priority.
>
> This patch uses a heuristic approach (number of memory references) to decide
> the unrolling factor for small loops.
> This patch has some noise in SPEC 2006 results.
>
> Bootstrapping passes.
>
> I would like to know your comments before committing.
Please split the patch to target-dependant and target-independant
part, and get target-idependant part reviewed first.
This part:
+ if (ix86_tune != PROCESSOR_BDVER3 && ix86_tune != PROCESSOR_BDVER4)
+ {
+ return nunroll;
+ }
is wrong. You should introduce tune variable (as H.J. suggested) and
check that variable here. Target dependant tuning options should be in
x86-tune.def, so everything regarding tuning can be found in one
place.
+ if (INSN_P (insn) && INSN_CODE (insn) != -1)
+ for_each_rtx (&insn, (rtx_function) ix86_loop_memcount,
&mem_count);
if (NONDEBUG_INSN_P (insn))
for_each_rtx (&PATTERN(insn), ...);
otherwise your heuristics will depend on -g compile option.
+ if ( (mem_count*nunroll) <= 32)
Extra parenthesis.
+static int
+ix86_loop_memcount (rtx *x, unsigned *mem_count)
+{
+ if (*x != NULL_RTX && MEM_P (*x))
*x will never be null for active insns.
Uros.
