On 03/14/2017 11:13 AM, Richard Biener wrote:
> On Tue, 14 Mar 2017, Martin Liška wrote:
>
>> On 03/14/2017 10:12 AM, Richard Biener wrote:
>>> On Tue, 14 Mar 2017, Martin Liška wrote:
>>>
>>>> On 03/14/2017 09:13 AM, Richard Biener wrote:
>>>>> On Tue, 14 Mar 2017, Martin Liška wrote:
>>>>>
>>>>>> On 03/13/2017 04:16 PM, Richard Biener wrote:
>>>>>>> On Mon, 13 Mar 2017, Martin Liška wrote:
>>>>>>>
>>>>>>>> On 03/13/2017 02:53 PM, Richard Biener wrote:
>>>>>>>>> On Mon, 13 Mar 2017, Martin Liška wrote:
>>>>>>>>>
>>>>>>>>>> On 03/13/2017 02:01 PM, Richard Biener wrote:
>>>>>>>>>>> On Mon, 13 Mar 2017, Richard Biener wrote:
>>>>>>>>>>>
>>>>>>>>>>>> On Fri, 10 Mar 2017, Martin Liška wrote:
>>>>>>>>>>>>
>>>>>>>>>>>>> Hello.
>>>>>>>>>>>>>
>>>>>>>>>>>>> As briefly discussed in the PR, there are BB that do not
>>>>>>>>>>>>> correspond to a real
>>>>>>>>>>>>> line in source
>>>>>>>>>>>>> code. profile.c emits locations for all BBs that have a gimple
>>>>>>>>>>>>> statement
>>>>>>>>>>>>> belonging to a line.
>>>>>>>>>>>>> I hope these should be marked in gcov utility and not added in
>>>>>>>>>>>>> --all-block
>>>>>>>>>>>>> mode to counts of lines.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Patch survives make check RUNTESTFLAGS="gcov.exp".
>>>>>>>>>>>>>
>>>>>>>>>>>>> Thanks for review and feedback.
>>>>>>>>>>>>
>>>>>>>>>>>> Humm, the patch doesn't seem to change the BBs associated with a
>>>>>>>>>>>> line
>>>>>>>>>>>> but rather somehow changes how we compute counts (the patch lacks a
>>>>>>>>>>>> description of how you arrived at it). I expected the line-to-BB
>>>>>>>>>>>> assignment process to be changed (whereever that is...).
>>>>>>>>>>
>>>>>>>>>> Currently, each basic block must belong to a source line. It's how
>>>>>>>>>> gcov
>>>>>>>>>> iterates all blocks (via lines).
>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> Ah, ok, looking at where output_location is called on I see we do
>>>>>>>>>>> not
>>>>>>>>>>> assign any line to that block. But still why does
>>>>>>>>>>> line->has_block (arc->src) return true?
>>>>>>>>>>
>>>>>>>>>> Good objection! Problematic that 4->5 edge really comes from the
>>>>>>>>>> same line.
>>>>>>>>>>
>>>>>>>>>> <bb 4> [0.00%]:
>>>>>>>>>> ret_7 = 111;
>>>>>>>>>> PROF_edge_counter_10 = __gcov0.UuT[0];
>>>>>>>>>> PROF_edge_counter_11 = PROF_edge_counter_10 + 1;
>>>>>>>>>> __gcov0.UuT[0] = PROF_edge_counter_11;
>>>>>>>>>>
>>>>>>>>>> <bb 5> [0.00%]:
>>>>>>>>>> # ret_1 = PHI <ret_5(3), ret_7(4)>
>>>>>>>>>> goto <bb 7>; [0.00%]
>>>>>>>>>
>>>>>>>>> Yes, but that's basically meaningless, unless not all edges come from
>>>>>>>>> the
>>>>>>>>> same line? I see nowhere where we'd explicitely assign lines to
>>>>>>>>> edges so it must be gcov "reconstructing" this somewhere.
>>>>>>>>
>>>>>>>> That's why I added the another flag. We stream locations for basic
>>>>>>>> blocks via
>>>>>>>> 'output_location' function. And assignment blocks to lines happens
>>>>>>>> here:
>>>>>>>>
>>>>>>>> static void
>>>>>>>> add_line_counts (coverage_t *coverage, function_t *fn)
>>>>>>>> {
>>>>>>>> ...
>>>>>>>> if (!ix || ix + 1 == fn->num_blocks)
>>>>>>>> /* Entry or exit block */;
>>>>>>>> else if (flag_all_blocks)
>>>>>>>> {
>>>>>>>> line_t *block_line = line;
>>>>>>>>
>>>>>>>> if (!block_line)
>>>>>>>> block_line = &sources[fn->src].lines[fn->line];
>>>>>>>>
>>>>>>>> block->chain = block_line->u.blocks;
>>>>>>>> block_line->u.blocks = block;
>>>>>>>> }
>>>>>>>>
>>>>>>>> where line is always changes when we reach a BB that has a source line
>>>>>>>> assigned. Thus it's changed
>>>>>>>> for BB 4 and that's why BB 5 is added to same line.
>>>>>>>
>>>>>>> Ah, so this means we should "clear" the current line for BB 5 in
>>>>>>> output_location? At least I don't see how your patch may not regress
>>>>>>> some cases where the line wasn't output as an optimization?
>>>>>>
>>>>>> The new flag on block is kind of clearing that the BB is artificial and
>>>>>> in fact does not
>>>>>> belong to the line. I didn't want to do a bigger refactoring how blocks
>>>>>> are iterated via lines.
>>>>>>
>>>>>> Can you be please more specific about such a case?
>>>>>
>>>>> in profile.c I see
>>>>>
>>>>> if (name_differs || line_differs)
>>>>> {
>>>>> if (!*offset)
>>>>> {
>>>>> *offset = gcov_write_tag (GCOV_TAG_LINES);
>>>>> gcov_write_unsigned (bb->index);
>>>>> name_differs = line_differs=true;
>>>>> }
>>>>>
>>>>> ...
>>>>>
>>>>> so if line_differs is false we might not output GCOV_TAG_LINES either
>>>>> because 1) optimization, less stuff output, 2) the block has no line.
>>>>> Looks like we can't really distinguish those.
>>>>
>>>> Agree with that.
>>>>
>>>>>
>>>>> Not sure how on the input side we end up associating a BB with
>>>>> a line if nothing was output for it though.
>>>>>
>>>>> That is, with your change don't we need
>>>>>
>>>>> Index: gcc/profile.c
>>>>> ===================================================================
>>>>> --- gcc/profile.c (revision 246082)
>>>>> +++ gcc/profile.c (working copy)
>>>>> @@ -941,8 +941,6 @@ output_location (char const *file_name,
>>>>> name_differs = !prev_file_name || filename_cmp (file_name,
>>>>> prev_file_name);
>>>>> line_differs = prev_line != line;
>>>>>
>>>>> - if (name_differs || line_differs)
>>>>> - {
>>>>> if (!*offset)
>>>>> {
>>>>> *offset = gcov_write_tag (GCOV_TAG_LINES);
>>>>> @@ -950,6 +948,9 @@ output_location (char const *file_name,
>>>>> name_differs = line_differs=true;
>>>>> }
>>>>>
>>>>> + if (name_differs || line_differs)
>>>>> + {
>>>>> +
>>>>> /* If this is a new source file, then output the
>>>>> file's name to the .bb file. */
>>>>> if (name_differs)
>>>>>
>>>>> to resolve this ambiguity? That is, _always_ emit GCOV_TAG_LINES
>>>>> for a BB? So then a BB w/o GCOV_TAG_LINES does _not_ have any
>>>>> lines associated.
>>>>
>>>> That should revolve it. Let me find and example where we do not emit
>>>> GCOV_TAG_LINES jsut because there's not difference in lines.
>>>
>>> sth like
>>>
>>> a = b < 1 ? (c < 3 ? d : c);
>>>
>>> or even
>>>
>>> if (..) { ... } else { ... }
>>
>> These samples work, however your patch would break situations like:
>>
>> 1: 10:int main ()
>> -: 11:{
>> -: 12: int i;
>> -: 13:
>> 22: 14: for (i = 0; i < 10; i++) /* count(11) */
>> 10: 15: noop (); /* count(10) */
>>
>> where 22 is summed as (1+10+11), which kind of makes sense as it contains
>> of 3 statements.
>
> 22 is with my patch or without? I think 22 makes no sense.
>
> Richard.
With your patch.
Martin
>
>> Martin
>>
>>>
>>>
>>>> Martin
>>>>
>>>>>
>>>>> Richard.
>>>>>
>>>>>
>>>>>> Hope Nathan will find time to provide review as he's familiar with
>>>>>> content of gcov.c.
>>>>>>
>>>>>> Martin
>>>>>>
>>>>>>>
>>>>>>> OTOH I don't know much about gcov format.
>>>>>>>
>>>>>>> Richard.
>>>>>>>
>>>>>>>> Martin
>>>>>>>>
>>>>>>>>>
>>>>>>>>> Richard.
>>>>>>>>>
>>>>>>>>>> Martin
>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> Richard.
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>
>>>>
>>>
>>
>>
>
