This patch replaces (llvm::|)Optional< with std::optional<.  I'll post
a separate patch to clean up the "using" declarations, #include
"llvm/ADT/Optional.h", etc.

This is part of an effort to migrate from llvm::Optional to
std::optional:

https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716

This patch adds #include <optional> to those files containing
llvm::Optional<...> or Optional<...>.

I'll post a separate patch to actually replace llvm::Optional with
std::optional.

This is part of an effort to migrate from llvm::Optional to
std::optional:

https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716

This patch mechanically replaces None with std::nullopt where the
compiler would warn if None were deprecated.  The intent is to reduce
the amount of manual work required in migrating from Optional to
std::optional.

This is part of an effort to migrate from llvm::Optional to
std::optional:

https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716

Resubmission of https://reviews.llvm.org/D130309 with the 2 patches that fixed the linux buildbot, and new windows fixes.

The FileSpec APIs allow users to modify instance variables directly by getting a non const reference to the directory and filename instance variables. This makes it impossible to control all of the times the FileSpec object is modified so we can clear cached member variables like m_resolved and with an upcoming patch caching if the file is relative or absolute. This patch modifies the APIs of FileSpec so no one can modify the directory or filename instance variables directly by adding set accessors and by removing the get accessors that are non const.

Many clients were using FileSpec::GetCString(...) which returned a unique C string from a ConstString'ified version of the result of GetPath() which returned a std::string. This caused many locations to use this convenient function incorrectly and could cause many strings to be added to the constant string pool that didn't need to. Most clients were converted to using FileSpec::GetPath().c_str() when possible. Other clients were modified to use the newly renamed version of this function which returns an actualy ConstString:

ConstString FileSpec::GetPathAsConstString(bool denormalize = true) const;

This avoids the issue where people were getting an already uniqued "const char *" that came from a ConstString only to put the "const char *" back into a "ConstString" object. By returning the ConstString instead of a "const char *" clients can be more efficient with the result.

The patch:
- Removes the non const GetDirectory() and GetFilename() get accessors
- Adds set accessors to replace the above functions: SetDirectory() and SetFilename().
- Adds ClearDirectory() and ClearFilename() to replace usage of the FileSpec::GetDirectory().Clear()/FileSpec::GetFilename().Clear() call sites
- Fixed all incorrect usage of FileSpec::GetCString() to use FileSpec::GetPath().c_str() where appropriate, and updated other call sites that wanted a ConstString to use the newly returned ConstString appropriately and efficiently.

Differential Revision: https://reviews.llvm.org/D130549

This reverts commit 9429b67b8e300e638d7828bbcb95585f85c4df4d.

It broke the build on Windows, see comments on https://reviews.llvm.org/D130309

It also reverts these follow-ups:

Revert "Fix buildbot breakage after https://reviews.llvm.org/D130309."
This reverts commit f959d815f4637890ebbacca379f1c38ab47e4e14.

Revert "Fix buildbot breakage after https://reviews.llvm.org/D130309."
This reverts commit 0bbce7a4c2d2bff622bdadd4323f93f5d90e6d24.

Revert "Cache the value for absolute path in FileSpec."
This reverts commit dabe877248b85b34878e75d5510339325ee087d0.

The FileSpect APIs allow users to modify instance variables directly by getting a non const reference to the directory and filename instance variables. This makes it impossibly to control all of the times the FileSpec object is modified so we can clear the cache. This patch modifies the APIs of FileSpec so no one can modify the directory or filename directly by adding set accessors and by removing the get accessors that are non const.

Many clients were using FileSpec::GetCString(...) which returned a unique C string from a ConstString'ified version of the result of GetPath() which returned a std::string. This caused many locations to use this convenient function incorrectly and could cause many strings to be added to the constant string pool that didn't need to. Most clients were converted to using FileSpec::GetPath().c_str() when possible. Other clients were modified to use the newly renamed version of this function which returns an actualy ConstString:
    ConstString FileSpec::GetPathAsConstString(bool denormalize = true) const;

This avoids the issue where people were getting an already uniqued "const char *" that came from a ConstString only to put the "const char *" back into a "ConstString" object. By returning the ConstString instead of a "const char *" clients can be more efficient with the result.

The patch:
- Removes the non const GetDirectory() and GetFilename() get accessors
- Adds set accessors to replace the above functions: SetDirectory() and SetFilename().
- Adds ClearDirectory() and ClearFilename() to replace usage of the FileSpec::GetDirectory().Clear()/FileSpec::GetFilename().Clear() call sites
- Fixed all incorrect usage of FileSpec::GetCString() to use FileSpec::GetPath().c_str() where appropriate, and updated other call sites that wanted a ConstString to use the newly returned ConstString appropriately and efficiently.

Differential Revision: https://reviews.llvm.org/D130309

As previously discussed with @jj10306, we didn't really have a name for
the post-mortem (or offline) trace session representation, which is in
fact a folder with a bunch of files. We decided to call this folder
"trace bundle", and the main JSON file in it "trace bundle description
file". This naming is pretty decent, so I'm refactoring all the existing
code to account for that.

Differential Revision: https://reviews.llvm.org/D128484

Add trace load functionality to SBDebugger via the `LoadTraceFromFile` method.
Update intelpt test case class to have `testTraceLoad` method so we can take advantage of
the testApiAndSB decorator to test both the CLI and SB without duplicating code.

Differential Revision: https://reviews.llvm.org/D128107

Having a member variable TraceIntelPT * makes it look as if it was
optional. I'm using instead a weak_ptr to indicate that it's not
optional and the object is under the ownership of TraceIntelPT.

Besides that, I've simplified the Perf aux and data buffers copying by
using vector.insert.

I'm also renaming Lookup2 to Lookup. The 2 in the name is confusing.

Differential Revision: https://reviews.llvm.org/D127881

As discusses offline with @jj10305, we are updating some naming used throughout the code, specially in the json schema

- traceBuffer -> iptTrace
- core -> cpu

Differential Revision: https://reviews.llvm.org/D127817