The frontend currently opens the path provided via
`-fprofile-instrument-use-path=` to learn the kind of the
instrumentation data and set the `CodeGenOptions::ProfileUse` value.
This happens during command-line parsing, where we don't have a
correctly configured VFS yet, so the behavior is quite different from
all other frontend inputs. We need to move this logic out of the
frontend command line parsing logic somewhere where we do have the
configured VFS.

The complication is that the `ProfileUse` flag is being used to set
preprocessor macros, and there isn't a great place between command line
parsing and preprocessor initialization to perform this logic.

This PR solves the issue by deducing the kind of instrumentation data
right in the driver and then passing it via a new flag to the frontend.
This shouldn't change observable behavior of Clang on the driver level,
and only affects the frontend command line interface, which is an
implementation detail anyway.

Fix a `CHECK-NOT` line in a cspgo clang test

Either remove legacy PM run lines or change them to use new PM.

As per the discussion on D58375, we disable test that have optimizations under
the new PM. This patch adds -fno-experimental-new-pass-manager to RUNS that:

- Already run with optimizations (-O1 or higher) that were missed in D58375.
- Explicitly test new PM behavior along side some new PM RUNS, but are missing
  this flag if new PM is enabled by default.
- Specify -O without the number. Based on getOptimizationLevel(), it seems the
  default is 2, and the IR appears to be the same when changed to -O2, so
  update the test to explicitly say -O2 and provide -fno-experimental-new-pass-manager`.

Differential Revision: https://reviews.llvm.org/D63156

llvm-svn: 364066

Part 2 of CSPGO change in Clang: Add test cases.

Differential Revision: https://reviews.llvm.org/D54176

llvm-svn: 355563

llvm-svn: 355454

Part 2 of CSPGO change in Clang: Add test cases.

Differential Revision: https://reviews.llvm.org/D54176

llvm-svn: 355432