What is the usual number of iterations?
David
On Fri, Oct 25, 2013 at 4:10 PM, Dehao Chen <de...@google.com> wrote:
> If the propagation finds an infinite look, if the in-edge count is
> non-zero, then it will cause compiler go into infinite loop when
> building with AutoFDO.
>
> Bootstrapped and regression test on-going.
>
> OK for google-4_8 branch?
>
> Thanks,
> Dehao
>
> Index: gcc/auto-profile.c
> ===================================================================
> --- gcc/auto-profile.c (revision 204027)
> +++ gcc/auto-profile.c (working copy)
> @@ -1287,6 +1287,7 @@ afdo_propagate (void)
> {
> basic_block bb;
> bool changed = true;
> + int i = 0;
>
> FOR_ALL_BB (bb)
> {
> @@ -1295,7 +1296,7 @@ afdo_propagate (void)
> bb->flags |= BB_ANNOTATED;
> }
>
> - while (changed)
> + while (changed && i++ < PARAM_VALUE
> (PARAM_AUTOFDO_MAX_PROPAGATE_ITERATIONS))
> {
> changed = false;
>
> Index: gcc/params.def
> ===================================================================
> --- gcc/params.def (revision 204027)
> +++ gcc/params.def (working copy)
> @@ -460,6 +460,14 @@ DEFPARAM(PARAM_MAX_PREDICTED_ITERATIONS,
> "The maximum number of loop iterations we predict statically",
> 100, 0, 0)
>
> +/* This parameter controls the maximum iterations that AutoFDO profile
> + prpagation algorithm will run for a specific CFG. */
> +
> +DEFPARAM(PARAM_AUTOFDO_MAX_PROPAGATE_ITERATIONS,
> + "max-autofdo-max-propagate-iterations",
> + "The maximum number of AutoFDO profile propagation iterations",
> + 1000, 0, 0)
> +
> /* This parameter controls the probability of builtin_expect. The default
> value is 90%. This empirical value is obtained through the weighted
> probability of FDO counters (with the FDO count value as the weight)
