[PATCH] D125023: [CSSPGO][Preinliner] Use linear threshold to drive inline decision.

[Wenlei He via Phabricator via llvm-commits]

wenlei added inline comments.


================
Comment at: llvm/tools/llvm-profgen/CSPreInliner.cpp:164
+    // 10% cutff to cap the threshold.
+    uint64_t CapCount = ProfileSummaryBuilder::getEntryForPercentile(
+                            Summary->getDetailedSummary(), 100000 /* 10% */)
----------------
> Use the count at 10% cutff to cap the threshold. 

nit: people should be able to figure out what this is all about, but this comment can be confusing. maybe let's just make it more clear that "we normalize hotness to be [0,1], then linearly adjust threshold based on normalized hotness. "

That comment couples with more explicit code for readability.

```
NormalizationUpperBound = ProfileSummaryBuilder::getEntryForPercentile(...)
NormalizationLowerBound = ColdCountThreshold (or ProfileSummaryBuilder::getEntryForPercentile(...) )

NormalizedHotness = ...
SampleThreshold = ...
```



================
Comment at: llvm/tools/llvm-profgen/CSPreInliner.cpp:172
+    SampleThreshold = SampleHotCallSiteThreshold * NormalizedHotness * 100 +
+                      SampleColdCallSiteThreshold + 1;
+  }
----------------
Perhaps worth a comment for this `+1` (so later on others don't think it's non-critical and attempt to clean it up) 


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D125023/new/

https://reviews.llvm.org/D125023