[PATCH] D40702: [PGO] More fix to infinite loop profiling

[David Li via Phabricator via llvm-commits]

davidxl created this revision.
Herald added a subscriber: sanjoy.

The IR instrumentation uses MST to decide instrumentation points. It relies adding a fake edge from the function exit block (with no successors) to the fake node. Otherwise edges needed to be instrumented may end up in MST (and therefore not instrumented).

With infinite loop, the exit block may not exist thus the instrumentation will be wrong.  Without the fix, the runtime test case added in r319463 will have zero entry count for main (or any parent function of an infinite loop).

After this is fix, there will be more fixes needed in BFI to avoid the body count from being dropped.


https://reviews.llvm.org/D40702

Files:
  lib/Transforms/Instrumentation/CFGMST.h
  lib/Transforms/Instrumentation/PGOInstrumentation.cpp
  test/Transforms/PGOProfile/infinite_loop_gen.ll

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