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

[Hongtao Yu via Phabricator via llvm-commits]

hoy added inline comments.


================
Comment at: llvm/tools/llvm-profgen/ProfileGenerator.cpp:444
+  ProbeCounterMap ProbeCounter;
+  extractProbesFromRange(preprocessRangeCounter(RangeCounter), ProbeCounter);
+
----------------
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.




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Comment at: llvm/tools/llvm-profgen/ProfileGenerator.cpp:497
   FunctionProfile->addTotalSamples(Count);
+  if (WithProbe) {
+    const auto *FuncDesc = Binary->getFuncDescForGUID(Function::getGUID(FunctionProfile->getName()));
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wenlei wrote:
> Perhaps we don't need a parameter for this, just use `Binary->usePseudoProbes()` instead.
Sounds good.


================
Comment at: llvm/tools/llvm-profgen/ProfileGenerator.cpp:901
 
-void CSProfileGenerator::extractProbesFromRange(const RangeSample &RangeCounter,
+void ProfileGeneratorBase::extractProbesFromRange(const RangeSample &RangeCounter,
                                                 ProbeCounterMap &ProbeCounter) {
----------------
wenlei wrote:
> nit: move this closer to the functions definitions for ProfileGeneratorBase.
done.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D120335/new/

https://reviews.llvm.org/D120335