I'm planning to remove StringRef::equals in favor of
StringRef::operator==.

- StringRef::operator==/!= outnumber StringRef::equals by a factor of
  70 under llvm/ in terms of their usage.

- The elimination of StringRef::equals brings StringRef closer to
  std::string_view, which has operator== but not equals.

- S == "foo" is more readable than S.equals("foo"), especially for
  !Long.Expression.equals("str") vs Long.Expression != "str".

The goal is to enable analysis of these passes by way of OSS-Fuzz, where
they currently lack code coverage

(https://storage.googleapis.com/oss-fuzz-coverage/llvm/reports/20231225/linux/src/llvm-project/llvm/lib/Transforms/Scalar/report.html)

---------

Signed-off-by: David Korczynski <david@adalogics.com>

This patch replaces uses of StringRef::{starts,ends}with with
StringRef::{starts,ends}_with for consistency with
std::{string,string_view}::{starts,ends}_with in C++20.

I'm planning to deprecate and eventually remove
StringRef::{starts,ends}with.

I also ran `git clang-format` to get the headers in the right order for
the new location, which has changed the order of other headers in two
files.

These are not directly related to the CLI, and are mostly (always?) used when
mutating the modules as part of fuzzing.

Motivation: split FuzzerCLI into its own library that does not depend on IR.
Subprojects that don't use IR should be be fuzzed without the dependency.

Differential Revision: https://reviews.llvm.org/D125080

Discourse thread: https://discourse.llvm.org/t/include-what-you-use-include-cleanup
Differential Revision: https://reviews.llvm.org/D121332

This is a follow up to D105628 (commit 1db2551cc1a356a67c096). I had
missed to replace 'unswitch' by 'simple-loop-unswitch' in one place.

There was an alias between 'simplifycfg' and 'simplify-cfg' in the
PassRegistry. That was the original reason for this patch, which
effectively removes the alias.

This patch also replaces all occurrances of 'simplify-cfg'
by 'simplifycfg'. Reason for choosing that form for the name is
that it matches the DEBUG_TYPE for the pass, and the legacy PM name
and also how it is spelled out in other passes such as
'loop-simplifycfg', and in other options such as
'simplifycfg-merge-cond-stores'.

I for some reason the name should be changed to 'simplify-cfg' in
the future, then I think such a renaming should be more widely done
and not only impacting the PassRegistry.

Reviewed By: aeubanks

Differential Revision: https://reviews.llvm.org/D105627

In future patches I will be setting the IsText parameter frequently so I will refactor the args to be in the following order. I have removed the FileSize parameter because it is never used.

```
  static ErrorOr<std::unique_ptr<MemoryBuffer>>
  getFile(const Twine &Filename, bool IsText = false,
          bool RequiresNullTerminator = true, bool IsVolatile = false);

  static ErrorOr<std::unique_ptr<MemoryBuffer>>
  getFileOrSTDIN(const Twine &Filename, bool IsText = false,
                 bool RequiresNullTerminator = true);

 static ErrorOr<std::unique_ptr<MB>>
 getFileAux(const Twine &Filename, uint64_t MapSize, uint64_t Offset,
            bool IsText, bool RequiresNullTerminator, bool IsVolatile);

  static ErrorOr<std::unique_ptr<WritableMemoryBuffer>>
  getFile(const Twine &Filename, bool IsVolatile = false);
```

Reviewed By: jhenderson

Differential Revision: https://reviews.llvm.org/D99182

The legacy pass was called "loop-reduce".

This lowers the number of check-llvm failures under NPM by 83.

Reviewed By: ychen

Differential Revision: https://reviews.llvm.org/D82925