https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63432
--- Comment #18 from Teresa Johnson <tejohnson at google dot com> ---
On Mon, Oct 6, 2014 at 10:15 PM, Teresa Johnson <tejohn...@google.com> wrote:
> I'm going to finish testing my patch, which passes regular
> x86_64-unknown-linux-gnu bootstrap + regression tests. I am still
> trying to get the lto profiledbootstrap to work. I found some
> workarounds for the undefined reference issue on Honza's blog, and I
Nevermind, that was for something else, the issue was that I needed to
upgrade my binutils from 2.22 to 2.24. Now the LTO profiledbootstrap
is humming along.
Once I get a round of testing in I will send for review.
Thanks,
Teresa
> am trying to get that working. Then I will send to gcc-patches for
> review.
>
> In the meantime, H.J. do you want to try the patch? It is below.
>
> Thanks,
> Teresa
>
> 2014-10-06 Teresa Johnson <tejohn...@google.com>
>
> * tree-ssa-threadupdate.c (estimated_freqs_path): New function.
> (ssa_fix_duplicate_block_edges): Invoke it.
> (mark_threaded_blocks): Make two passes to avoid ordering dependences.
>
> Index: tree-ssa-threadupdate.c
> ===================================================================
> --- tree-ssa-threadupdate.c (revision 215830)
> +++ tree-ssa-threadupdate.c (working copy)
> @@ -959,6 +959,43 @@ update_joiner_offpath_counts (edge epath, basic_bl
> }
>
>
> +/* Check if the paths through RD all have estimated frequencies but zero
> + profile counts. This is more accurate than checking the entry block
> + for a zero profile count, since profile insanities sometimes creep in. */
> +
> +static bool
> +estimated_freqs_path (struct redirection_data *rd)
> +{
> + edge e = rd->incoming_edges->e;
> + vec<jump_thread_edge *> *path = THREAD_PATH (e);
> + edge ein;
> + edge_iterator ei;
> + bool non_zero_freq = false;
> + FOR_EACH_EDGE (ein, ei, e->dest->preds)
> + {
> + if (ein->count)
> + return false;
> + non_zero_freq |= ein->src->frequency != 0;
> + }
> +
> + for (unsigned int i = 1; i < path->length (); i++)
> + {
> + edge epath = (*path)[i]->e;
> + if (epath->src->count)
> + return false;
> + non_zero_freq |= epath->src->frequency != 0;
> + edge esucc;
> + FOR_EACH_EDGE (esucc, ei, epath->src->succs)
> + {
> + if (esucc->count)
> + return false;
> + non_zero_freq |= esucc->src->frequency != 0;
> + }
> + }
> + return non_zero_freq;
> +}
> +
> +
> /* Invoked for routines that have guessed frequencies and no profile
> counts to record the block and edge frequencies for paths through RD
> in the profile count fields of those blocks and edges. This is because
> @@ -1058,9 +1095,11 @@ ssa_fix_duplicate_block_edges (struct redirection_
> data we first take a snapshot of the existing block and edge frequencies
> by copying them into the empty profile count fields. These counts are
> then used to do the incremental updates, and cleared at the end of this
> - routine. */
> + routine. If the function is marked as having a profile, we still check
> + to see if the paths through RD are using estimated frequencies because
> + the routine had zero profile counts. */
> bool do_freqs_to_counts = (profile_status_for_fn (cfun) != PROFILE_READ
> - || !ENTRY_BLOCK_PTR_FOR_FN (cfun)->count);
> + || estimated_freqs_path (rd));
> if (do_freqs_to_counts)
> freqs_to_counts_path (rd);
>
> @@ -2077,35 +2116,48 @@ mark_threaded_blocks (bitmap threaded_blocks)
>
> /* Now iterate again, converting cases where we want to thread
> through a joiner block, but only if no other edge on the path
> - already has a jump thread attached to it. */
> + already has a jump thread attached to it. We do this in two passes,
> + to avoid situations where the order in the paths vec can hide
> overlapping
> + threads (the path is recorded on the incoming edge, so we would miss
> + cases where the second path starts at a downstream edge on the same
> + path). First record all joiner paths, deleting any in the unexpected
> + case where there is already a path for that incoming edge. */
> for (i = 0; i < paths.length (); i++)
> {
> vec<jump_thread_edge *> *path = paths[i];
>
> if ((*path)[1]->type == EDGE_COPY_SRC_JOINER_BLOCK)
> + {
> + /* Attach the path to the starting edge if none is yet recorded. */
> + if ((*path)[0]->e->aux == NULL)
> + (*path)[0]->e->aux = path;
> + else if (dump_file && (dump_flags & TDF_DETAILS))
> + dump_jump_thread_path (dump_file, *path, false);
> + }
> + }
> + /* Second, look for paths that have any other jump thread attached to
> + them, and either finish converting them or cancel them. */
> + for (i = 0; i < paths.length (); i++)
> + {
> + vec<jump_thread_edge *> *path = paths[i];
> + edge e = (*path)[0]->e;
> +
> + if ((*path)[1]->type == EDGE_COPY_SRC_JOINER_BLOCK && e->aux == path)
> {
> unsigned int j;
> -
> - for (j = 0; j < path->length (); j++)
> + for (j = 1; j < path->length (); j++)
> if ((*path)[j]->e->aux != NULL)
> break;
>
> /* If we iterated through the entire path without exiting the loop,
> - then we are good to go, attach the path to the starting edge. */
> + then we are good to go, record it. */
> if (j == path->length ())
> - {
> - edge e = (*path)[0]->e;
> - e->aux = path;
> - bitmap_set_bit (tmp, e->dest->index);
> - }
> + bitmap_set_bit (tmp, e->dest->index);
> else if (dump_file && (dump_flags & TDF_DETAILS))
> - {
> - dump_jump_thread_path (dump_file, *path, false);
> - }
> + dump_jump_thread_path (dump_file, *path, false);
> }
> }
>
> -
> /* If optimizing for size, only thread through block if we don't have
> to duplicate it or it's an otherwise empty redirection block. */
> if (optimize_function_for_size_p (cfun))
>
> --
> Teresa Johnson | Software Engineer | tejohn...@google.com | 408-460-2413
