[PATCH] D120335: [llvm-profgen] Generating probe-based non-CS profile.

[Hongtao Yu via Phabricator via llvm-commits]

hoy added inline comments.
Herald added a project: All.


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Comment at: llvm/tools/llvm-profgen/ProfileGenerator.cpp:444
+  ProbeCounterMap ProbeCounter;
+  extractProbesFromRange(preprocessRangeCounter(RangeCounter), ProbeCounter);
+
----------------
wenlei wrote:
> hoy wrote:
> > wenlei wrote:
> > > hoy wrote:
> > > > wlei wrote:
> > > > > So here we don't use the way like CS-profile to generate the zero-count(in ProfileGenerator.cpp: 981), instead we reuse the `preprocessRangeCounter` to initialize all function range with zero, the probe inside the function will naturally be added with zero count. I guess this is the same to the way of CS-profile, right?
> > > > Yes, we are using the non-CS way of reporting zero counted probes. There is a difference between CS and non-CS in that for CS, the non-executed probes are reported for its owner frame only, while for non-CS, such probes are reported for the whole inline nest. 
> > > Both preprocessRangeCounter and extractProbesFromRange calls findDisjointRanges, which is duplicated. 
> > > 
> > > > for CS, the non-executed probes are reported for its owner frame only, while for non-CS, such probes are reported for the whole inline nest. 
> > > 
> > > what does the term "owner frame" refer to? can you elaborate the above? 
> > By owner frame I mean the inlinee frame that originally directly contains the probe. Eg., given function A, A inlines B and one original probe of B is sampled, for CS, all of other original probes of B will be reported. None of the original probes of A will be reported if none of A's probe is sampled. But for non-CS, all of A's and B's probes will be reported even if only one B's probe is sampled. 
> > 
> > A real example is in the attached inline-pseudoprobe.test where we have
> > 
> >    ; CHECK:     main:88:0
> >    ; CHECK-NEXT: 1: 0
> >    ; CHECK-NEXT: 2: foo:88
> >    ; CHECK-NEXT:  1: 0
> >    ; CHECK-NEXT:  2: 15
> > 
> > 
> > the corresponding CS profile is in inline-cs-pseudoprobe.test where there is no profile generated for the main function.
> > 
> > 
> Ok, thanks for clarification - that makes sense. Suggestion: use canonical terms like "inlinee frame" or "leaf inlinee frame" instead of nebulous terms like "owner frame" to avoid confusion. 
> 
> > Both preprocessRangeCounter and extractProbesFromRange calls findDisjointRanges, which is duplicated. 
> 
> Something we can do to avoid redundant findDisjointRanges? 
> Something we can do to avoid redundant findDisjointRanges?

Good point. Sorry for missing this earliser. I made it conditional.


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