[PATCH] D138893: [llvm-profdata] Use flattening sample profile in profile supplementation

[Rong Xu via Phabricator via llvm-commits]

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We need to flatten the SampleFDO profile in profile supplementation
because the InstrFDO profile does not have inlined callsite counters.
Without flattening profile, FDO optimizations are not stable:
we will not supplement the second generation profile when the modified
functions are all inlined.

This patch fixes this issue: we will flatten the profile for functions
that appears in FDO profile.

Note that we only need to find the hot/warm functions in SampleFDO
profile, so we will not perform a full flatten. We will use
a DFS traversal to compute the accumulated entry count and max bodycount.
This is much cheaper than full flattening.


https://reviews.llvm.org/D138893

Files:
  llvm/test/tools/llvm-profdata/Inputs/flatten_instr.proftext
  llvm/test/tools/llvm-profdata/Inputs/flatten_sample.proftext
  llvm/test/tools/llvm-profdata/suppl-instr-with-sample-flatten.test
  llvm/tools/llvm-profdata/llvm-profdata.cpp

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