[PATCH] D120335: [llvm-profgen] Generating probe-based non-CS profile.
Hongtao Yu via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Tue Mar 1 12:18:06 PST 2022
hoy added inline comments.
Herald added a project: All.
================
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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