[all-commits] [llvm/llvm-project] 26a866: [MemProf] Handle missing tail call frames (#75823)

[Teresa Johnson via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 26a8664ed4573ef1559c4edc7b254a10d186d428
      https://github.com/llvm/llvm-project/commit/26a8664ed4573ef1559c4edc7b254a10d186d428
  Author: Teresa Johnson <tejohnson at google.com>
  Date:   2024-01-11 (Thu, 11 Jan 2024)

  Changed paths:
    M llvm/include/llvm/IR/ModuleSummaryIndex.h
    M llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
    M llvm/lib/Transforms/IPO/MemProfContextDisambiguation.cpp
    A llvm/test/ThinLTO/X86/memprof-tailcall-nonunique.ll
    A llvm/test/ThinLTO/X86/memprof-tailcall.ll
    A llvm/test/Transforms/MemProfContextDisambiguation/tailcall-nonunique.ll
    A llvm/test/Transforms/MemProfContextDisambiguation/tailcall.ll

  Log Message:
  -----------
  [MemProf] Handle missing tail call frames (#75823)

If tail call optimization was not disabled for the profiled binary, the
call contexts will be missing frames for tail calls. Handle this by
performing a limited search through tail call edges for the profiled
callee when a discontinuity is detected. The search depth is adjustable
but defaults to 5.

If we are able to identify a short sequence of tail calls, update the
graph for those calls. In the case of ThinLTO, synthesize the necessary
CallsiteInfos for carrying the cloning information to the backends.