[PATCH] D92998: [CSSPGO][llvm-profgen] Pseudo probe based CS profile generation

[Lei Wang via Phabricator via llvm-commits]

wlei added inline comments.


================
Comment at: llvm/tools/llvm-profgen/ProfileGenerator.cpp:42
   if (SampleType == PERF_LBR_STACK) {
+    // Enable context-sensitive functionalities in SampleProf
+    FunctionSamples::ProfileIsCS = true;
----------------
hoy wrote:
> wlei wrote:
> > hoy wrote:
> > > The setting of the two flags should not be necessary on the profile generation side. They are used on the loader side. Do you see any issue without setting them?
> > Yeah, if not explicitly setting here, the value will be false.
> > 
> > you see in llvm/lib/Transforms/IPO/SampleProfile.cpp:
> > 
> > ```
> >   // Apply tweaks if context-sensitive profile is available.
> >   if (Reader->profileIsCS()) {
> >     ProfileIsCS = true;
> >     FunctionSamples::ProfileIsCS = true;
> > 
> >     // Tracker for profiles under different context
> >     ContextTracker =
> >         std::make_unique<SampleContextTracker>(Reader->getProfiles());
> >   }
> > ```
> > It's set when the reader know it's a CS profile. But for llvm-profgen side, it doesn't set this.
> > 
> I see. So `ContextTracker` used in profile generation?
Not `ContextTracker`, it's the SampleProfileWriter to write the text format of profile, like:

```
  if (FunctionSamples::ProfileIsCS)
    OS << "[" << S.getNameWithContext() << "]:" << S.getTotalSamples();
  else
    OS << S.getName() << ":" << S.getTotalSamples();
```

```
    if (FunctionSamples::ProfileIsProbeBased) {
      OS.indent(Indent + 1);
      OS << "!CFGChecksum: " << S.getFunctionHash() << "\n";
    }
```







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https://reviews.llvm.org/D92998