Ping.
Thanks, Teresa
On Wed, Oct 30, 2013 at 1:15 PM, Teresa Johnson <tejohn...@google.com> wrote:
> On Fri, Oct 18, 2013 at 2:17 PM, Jan Hubicka <hubi...@ucw.cz> wrote:
>>> Here is the patch updated to use the new parameter from r203830.
>>> Passed bootstrap and regression tests.
>>>
>>> 2013-10-18 Jan Hubicka <j...@suse.cz>
>>> Teresa Johnson <tejohn...@google.com>
>>>
>>> * predict.c (handle_missing_profiles): New function.
>>> (counts_to_freqs): Don't overwrite estimated frequencies
>>> when function has no profile counts.
>>> * predict.h (handle_missing_profiles): Declare.
>>> * tree-profile.c (tree_profiling): Invoke handle_missing_profiles.
>>>
>>> Index: predict.c
>>> ===================================================================
>>> --- predict.c (revision 203830)
>>> +++ predict.c (working copy)
>>> @@ -2758,6 +2758,40 @@ estimate_loops (void)
>>> BITMAP_FREE (tovisit);
>>> }
>>>
>>
>> You need block comment. It should explain the problem of COMDATs and how
>> they are handled.
>> It is not an obvious thing.
>
> Done.
>
>>
>>> +void
>>> +handle_missing_profiles (void)
>>> +{
>>> + struct cgraph_node *node;
>>> + int unlikely_count_fraction = PARAM_VALUE (UNLIKELY_BB_COUNT_FRACTION);
>> extra line
>>> + /* See if 0 count function has non-0 count callers. In this case we
>>> + lost some profile. Drop its function profile to PROFILE_GUESSED. */
>>> + FOR_EACH_DEFINED_FUNCTION (node)
>>> + {
>>> + struct cgraph_edge *e;
>>> + gcov_type call_count = 0;
>>> + struct function *fn = DECL_STRUCT_FUNCTION (node->symbol.decl);
>> Extra line
>>> + if (node->count)
>>> + continue;
>>> + for (e = node->callers; e; e = e->next_caller)
>>> + call_count += e->count;
>> What about checking if the sum is way off even for non-0 counts.
>> I.e. for case where function was inlined to some calls but not to others? In
>> that case we may want to scale up the counts (with some resonable care for
>> capping)
>
> In this patch I am not changing any counts, so I am leaving this one
> for follow-on work (even for the routines missing counts completely
> like these, we don't apply any counts, just mark them as guessed. I
> have a follow-on patch to send once this goes in that does apply
> counts to these 0-count routines only when we decide to inline as we
> discussed).
>
>>
>> Also I think the code really should propagate - i.e. have simple worklist and
>> look for functions that are COMDAT and are called by other COMDAT functions
>> where we decided to drop the profile. Having non-trivial chains of comdats
>> is
>> common thing.
>
> Done.
>
>>
>> What about outputting user visible warning/error on the incosnsistency when
>> no COMDAT function is involved same way as we do for BB profile?
>
> Done. This one caught the fact that we have this situation for "extern
> template" functions as well when I tested on cpu2006. I added in a
> check to ignore those when issuing the warning (they are not emitted
> thus don't get any profile counts).
>
> Updated patch below.
>
> Bootstrapped and tested on x86-64-unknown-linux-gnu. Also tested on
> profiledbootstrap and profile-use build of SPEC cpu2006. Ok for trunk?
>
> Thanks,
> Teresa
>
> 2013-10-30 Teresa Johnson <tejohn...@google.com>
>
> * predict.c (drop_profile): New function.
> (handle_missing_profiles): Ditto.
> (counts_to_freqs): Don't overwrite estimated frequencies
> when function has no profile counts.
> * predict.h (handle_missing_profiles): Declare.
> * tree-profile.c (tree_profiling): Invoke handle_missing_profiles.
>
> Index: predict.c
> ===================================================================
> --- predict.c (revision 204213)
> +++ predict.c (working copy)
> @@ -2765,6 +2765,107 @@ estimate_loops (void)
> BITMAP_FREE (tovisit);
> }
>
> +/* Drop the profile for NODE to guessed, and update its frequency based on
> + whether it is expected to be HOT. */
> +
> +static void
> +drop_profile (struct cgraph_node *node, bool hot)
> +{
> + struct function *fn = DECL_STRUCT_FUNCTION (node->decl);
> +
> + if (dump_file)
> + fprintf (dump_file,
> + "Dropping 0 profile for %s/%i. %s based on calls.\n",
> + cgraph_node_name (node), node->order,
> + hot ? "Function is hot" : "Function is normal");
> + /* We only expect to miss profiles for functions that are reached
> + via non-zero call edges in cases where the function may have
> + been linked from another module or library (COMDATs and extern
> + templates). See the comments below for handle_missing_profiles. */
> + if (!DECL_COMDAT (node->decl) && !DECL_EXTERNAL (node->decl))
> + warning (0,
> + "Missing counts for called function %s/%i",
> + cgraph_node_name (node), node->order);
> +
> + profile_status_for_function (fn)
> + = (flag_guess_branch_prob ? PROFILE_GUESSED : PROFILE_ABSENT);
> + node->frequency
> + = hot ? NODE_FREQUENCY_HOT : NODE_FREQUENCY_NORMAL;
> +}
> +
> +/* In the case of COMDAT routines, multiple object files will contain the
> same
> + function and the linker will select one for the binary. In that case
> + all the other copies from the profile instrument binary will be missing
> + profile counts. Look for cases where this happened, due to non-zero
> + call counts going to 0-count functions, and drop the profile to guessed
> + so that we can use the estimated probabilities and avoid optimizing only
> + for size.
> +
> + The other case where the profile may be missing is when the routine
> + is not going to be emitted to the object file, e.g. for "extern template"
> + class methods. Those will be marked DECL_EXTERNAL. Emit a warning in
> + all other cases of non-zero calls to 0-count functions. */
> +
> +void
> +handle_missing_profiles (void)
> +{
> + struct cgraph_node *node;
> + int unlikely_count_fraction = PARAM_VALUE (UNLIKELY_BB_COUNT_FRACTION);
> + vec<struct cgraph_node *> worklist;
> + worklist.create (64);
> +
> + /* See if 0 count function has non-0 count callers. In this case we
> + lost some profile. Drop its function profile to PROFILE_GUESSED. */
> + FOR_EACH_DEFINED_FUNCTION (node)
> + {
> + struct cgraph_edge *e;
> + gcov_type call_count = 0;
> + struct function *fn = DECL_STRUCT_FUNCTION (node->decl);
> +
> + if (node->count)
> + continue;
> + for (e = node->callers; e; e = e->next_caller)
> + call_count += e->count;
> + if (call_count
> + && fn && fn->cfg
> + && (call_count * unlikely_count_fraction >= profile_info->runs))
> + {
> + bool maybe_hot = maybe_hot_count_p (NULL, call_count);
> +
> + drop_profile (node, maybe_hot);
> + worklist.safe_push (node);
> + }
> + }
> +
> + /* Propagate the profile dropping to other 0-count COMDATs that are
> + potentially called by COMDATs we already dropped the profile on. */
> + while (worklist.length () > 0)
> + {
> + struct cgraph_edge *e;
> +
> + node = worklist.pop ();
> + for (e = node->callees; e; e = e->next_caller)
> + {
> + struct cgraph_node *callee = e->callee;
> + struct function *fn = DECL_STRUCT_FUNCTION (callee->decl);
> +
> + if (callee->count > 0)
> + continue;
> + if (DECL_COMDAT (callee->decl) && fn && fn->cfg
> + && profile_status_for_function (fn) == PROFILE_READ)
> + {
> + /* Since there are no non-0 call counts to this function,
> + we don't know for sure whether it is hot. Indicate to
> + the drop_profile routine that function should be marked
> + normal, rather than hot. */
> + drop_profile (node, false);
> + worklist.safe_push (callee);
> + }
> + }
> + }
> + worklist.release ();
> +}
> +
> /* Convert counts measured by profile driven feedback to frequencies.
> Return nonzero iff there was any nonzero execution count. */
>
> @@ -2774,6 +2875,9 @@ counts_to_freqs (void)
> gcov_type count_max, true_count_max = 0;
> basic_block bb;
>
> + if (!ENTRY_BLOCK_PTR->count)
> + return 0;
> +
> FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
> true_count_max = MAX (bb->count, true_count_max);
>
> Index: predict.h
> ===================================================================
> --- predict.h (revision 204213)
> +++ predict.h (working copy)
> @@ -37,6 +37,7 @@ enum prediction
>
> extern void predict_insn_def (rtx, enum br_predictor, enum prediction);
> extern int counts_to_freqs (void);
> +extern void handle_missing_profiles (void);
> extern void estimate_bb_frequencies (bool);
> extern const char *predictor_name (enum br_predictor);
> extern tree build_predict_expr (enum br_predictor, enum prediction);
> Index: tree-profile.c
> ===================================================================
> --- tree-profile.c (revision 204213)
> +++ tree-profile.c (working copy)
> @@ -612,6 +612,8 @@ tree_profiling (void)
> pop_cfun ();
> }
>
> + handle_missing_profiles ();
> +
> del_node_map ();
> return 0;
> }
>
>>
>> Honza
>
>
>
> --
> Teresa Johnson | Software Engineer | tejohn...@google.com | 408-460-2413
--
Teresa Johnson | Software Engineer | tejohn...@google.com | 408-460-2413
