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Re: [PATCH] gcov: Mark BBs that do not correspond to a line in source code (PR gcov-profile/79891).


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%]

Martin

> 
> Richard.
> 


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