#125983

Identified with misc-include-cleaner.

Reverts the above commit, as it updates a common header function and
did not update all callsites:

  https://lab.llvm.org/buildbot/#/builders/29/builds/382

This reverts commit 6481dc57612671ebe77fe9c34214fba94e1b3b27.

Uses the new InsertPosition class (added in #94226) to simplify some of
the IRBuilder interface, and removes the need to pass a BasicBlock
alongside a BasicBlock::iterator, using the fact that we can now get the
parent basic block from the iterator even if it points to the sentinel.
This patch removes the BasicBlock argument from each constructor or call
to setInsertPoint.

This has no functional effect, but later on as we look to remove the
`Instruction *InsertBefore` argument from instruction-creation
(discussed
[here](https://discourse.llvm.org/t/psa-instruction-constructors-changing-to-iterator-only-insertion/77845)),
this will simplify the process by allowing us to deprecate the
InsertPosition constructor directly and catch all the cases where we use
instructions rather than iterators.

We have a pass for MVE to perform lane interleaving to make use of top/bottom
instructions, that adds shuffles before extends and after truncates. This
extends it to also start from add reductions, where the order of lanes does not
matter so the shuffle is not needed. We need to be careful about not breaking
the form of existing reductions, but otherwise can save some instructions and
awkward extends.

Differential Revision: https://reviews.llvm.org/D143396

With C++17 there is no Clang pedantic warning or MSVC C5051.

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

Add a number of intrinsics which natively lower to MVE operations to the
lane interleaving pass, allowing it to efficiently interleave the lanes
of chucks of operations containing these intrinsics.

Differential Revision: https://reviews.llvm.org/D97293

FP16 to FP32 converts can be handled in MVE lane interleaving, much like
the sext/zext lowering we do. This expands the pass with fpext and
fptrunc handling, and basic fp operations allowing more efficient
lowering of fp vectors.

Differential Revision: https://reviews.llvm.org/D97292