Identified with misc-include-cleaner.

This is a helper to avoid writing `getModule()->getDataLayout()`. I
regularly try to use this method only to remember it doesn't exist...

`getModule()->getDataLayout()` is also a common (the most common?)
reason why code has to include the Module.h header.

This pass isn't used anywhere and thus has no test coverage. Remove it
for these reasons.

For whatever reason, there was no entry in
`llvm/include/llvm/LinkAllPasses.h` to remove.

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

Since std::optional does not offer getPointer(), this patch replaces
X.getPointer() with &*X to make the migration from llvm::Optional to
std::optional easier.

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

Differential Revision: https://reviews.llvm.org/D138466

Clang-format InstructionSimplify and convert all "FunctionName"s to
"functionName".  This patch does touch a lot of files but gets done with
the cleanup of InstructionSimplify in one commit.

This is the alternative to the less invasive clang-format only patch: D126783

Reviewed By: spatel, rengolin

Differential Revision: https://reviews.llvm.org/D126889

Logic in this pass assumes that all users of loop instructions are
either in the same loop or are LCSSA Phis. In fact, there can also
be users in unreachable blocks that currently break assertions.
Such users don't need to go to the next round of simplifications.

Reviewed By: fhahn
Differential Revision: https://reviews.llvm.org/D124368

Estimated impact on preprocessor output line:
before: 1062981579
after:  1062494547

Discourse thread: https://discourse.llvm.org/t/include-what-you-use-include-cleanup
Differential Revision: https://reviews.llvm.org/D120817