[NFC] [PSI] explain encoding of PercentileCutoff.

[eugenis]

mention that the digits are *decimal* somewhere?

[fmayer]

mention it is decimal

[fmayer]

Ping

[mtrofin]

llvm/include/llvm/Analysis/ProfileSummaryInfo.h

138

I don't think I'd understand what 'whole part' means, but the example is perfectly sufficient. I'd just leave it to the example.

[davidxl]

lgtm

[fmayer]

llvm/include/llvm/Analysis/ProfileSummaryInfo.h

138

I would leave it, it doesn't do harm and is the technical description.

llvm/include/llvm/Analysis/ProfileSummaryInfo.h

bool isFunctionColdInCallGraphNthPercentile(int PercentileCutoff,
                                               const Function *F,
                                               BlockFrequencyInfo &BFI) const;
   /// Returns true if count \p C is considered hot.
   bool isHotCount(uint64_t C) const;
   /// Returns true if count \p C is considered cold.
   bool isColdCount(uint64_t C) const;
   /// Returns true if count \p C is considered hot with regard to a given
   /// hot percentile cutoff value.
+  /// PercentileCutoff is encoded as a 6 digit fixed point number, where the
+  /// first two digits are the whole part. E.g. 995000 is the 99.5 percentile.
   bool isHotCountNthPercentile(int PercentileCutoff, uint64_t C) const;
   /// Returns true if count \p C is considered cold with regard to a given
   /// cold percentile cutoff value.
+  /// PercentileCutoff is encoded as a 6 digit fixed point number, where the
+  /// first two digits are the whole part. E.g. 995000 is the 99.5 percentile.
   bool isColdCountNthPercentile(int PercentileCutoff, uint64_t C) const;
   /// Returns true if BasicBlock \p BB is considered hot.
   bool isHotBlock(const BasicBlock *BB, BlockFrequencyInfo *BFI) const;
   /// Returns true if BasicBlock \p BB is considered cold.
   bool isColdBlock(const BasicBlock *BB, BlockFrequencyInfo *BFI) const;
   /// Returns true if BasicBlock \p BB is considered hot with regard to a given
   /// hot percentile cutoff value.
+  /// PercentileCutoff is encoded as a 6 digit fixed point number, where the
+  /// first two digits are the whole part. E.g. 995000 is the 99.5 percentile.
   bool isHotBlockNthPercentile(int PercentileCutoff, const BasicBlock *BB,
                                BlockFrequencyInfo *BFI) const;
   /// Returns true if BasicBlock \p BB is considered cold with regard to a given
   /// cold percentile cutoff value.
+  /// PercentileCutoff is encoded as a 6 digit fixed point number, where the
+  /// first two digits are the whole part. E.g. 995000 is the 99.5 percentile.
   bool isColdBlockNthPercentile(int PercentileCutoff, const BasicBlock *BB,
                                 BlockFrequencyInfo *BFI) const;
   /// Returns true if the call site \p CB is considered hot.
   bool isHotCallSite(const CallBase &CB, BlockFrequencyInfo *BFI) const;
   /// Returns true if call site \p CB is considered cold.
   bool isColdCallSite(const CallBase &CB, BlockFrequencyInfo *BFI) const;
   /// Returns HotCountThreshold if set. Recompute HotCountThreshold
   /// if not set.