Anton Bikineev 7b85e76500 [PGO] Consider parent context when weighing branches with likelyhood.
Generally, with PGO enabled the C++20 likelyhood attributes shall be
dropped assuming the profile has a good coverage. However, currently
this is not the case for the following code:

 if (always_false()) [[likely]] {
   ...
 }

The patch fixes this and drops the attribute, if the parent context was
executed in the profile. The patch still preserves the attribute, if the
parent context was not executed, e.g. to support the cases when the
profile has insufficient coverage.

Differential Revision: https://reviews.llvm.org/D134456
2022-10-08 23:49:27 +02:00
..

These are tests for instrumentation based profiling.  This specifically means
the -fprofile-instr-generate and -fprofile-instr-use driver flags.

Tests in this directory should usually test both:

  - the generation of instrumentation (-fprofile-instr-generate), and
  - the use of profile data from instrumented runs (-fprofile-instr-use).

In order to test -fprofile-instr-use without actually running an instrumented
program, .profdata files are checked into Inputs/.

The input source files must include a main function such that building with
-fprofile-instr-generate and running the resulting program generates the same
.profdata file that is consumed by the tests for -fprofile-instr-use.  Even
tests that only check -fprofile-instr-use should include such a main function,
so that profile data can be regenerated as the .profdata file format evolves.