## Purpose

This patch is one in a series of code-mods that annotate LLVM’s public
interface for export. This patch annotates the remaining LLVM CodeGen
and CodeGenTypes library interfaces that were missed in, or modified
since, previous patches. The annotations currently have no meaningful
impact on the LLVM build; however, they are a prerequisite to support an
LLVM Windows DLL (shared library) build.

## Background

This effort is tracked in #109483. Additional context is provided in
[this
discourse](https://discourse.llvm.org/t/psa-annotating-llvm-public-interface/85307),
and documentation for `LLVM_ABI` and related annotations is found in the
LLVM repo
[here](https://github.com/llvm/llvm-project/blob/main/llvm/docs/InterfaceExportAnnotations.rst).

## Overview

The bulk of these changes were generated automatically using the
[Interface Definition Scanner (IDS)](https://github.com/compnerd/ids)
tool, followed formatting with `git clang-format`.

The following manual adjustments were also applied after running IDS:
- Explicitly instantiate `CallLowering::setArgFlags` template method
instances in `CodeGen/GlobalISel/CallLowering.h` and annotate them with
`LLVM_ABI`. These methods are already explicitly instantiated in
`lib/CodeGen/GlobalISel/CallLowering.cpp` but were not `extern` declared
in the header.
- Annotate several explicit template instantiations with
`LLVM_EXPORT_TEMPLATE`.
- Include `llvm/CodeGen/Passes.h` from
`llvm/lib/CodeGen/GlobalMergeFunctions.cpp` to pick up the declaration
of `llvm::createGlobalMergeFuncPass` with the `LLVM_ABI` annotation
(instead of adding `LLVM_ABI` to the function definition in this file)

## Validation

Local builds and tests to validate cross-platform compatibility. This
included llvm, clang, and lldb on the following configurations:

- Windows with MSVC
- Windows with Clang
- Linux with GCC
- Linux with Clang
- Darwin with Clang

These are identified by misc-include-cleaner.  I've filtered out those
that break builds.  Also, I'm staying away from llvm-config.h,
config.h, and Compiler.h, which likely cause platform- or
compiler-specific build failures.

This relands commit #115111.
Use traditional way to update post dominator tree, i.e. break critical
edge splitting into insert, insert, delete sequence.
When splitting critical edges, the post dominator tree may change its
root node, and `setNewRoot` only works in normal dominator tree...
See

https://github.com/llvm/llvm-project/blob/6c7e5827eda26990e872eb7c3f0d7866ee3c3171/llvm/include/llvm/Support/GenericDomTree.h#L684-L687

Reverts llvm/llvm-project#115111 Causes #119511

Support critical edge splitting in dominator tree updater. Continue the
work in #100856.

Compile time check:
https://llvm-compile-time-tracker.com/compare.php?from=87c35d782795b54911b3e3a91a5b738d4d870e55&to=42b3e5623a9ab4c3648564dc0926b36f3b438a3a&stat=instructions%3Au

This reverts commit c5e5088033fed170068d818c54af6862e449b545.

Causes large compile-time regressions.

Summary:
- Remove wrappers in `MachineDominatorTree`.
- Remove `MachineDominatorTree` update code in
`MachineBasicBlock::SplitCriticalEdge`.
- Use `MachineDomTreeUpdater` in passes which call
`MachineBasicBlock::SplitCriticalEdge` and preserve
`MachineDominatorTreeWrapperPass` or CFG analyses.

Commit abea99f65a97248974c02a5544eaf25fc4240056 introduced related
methods in 2014. Now we have SemiNCA based dominator tree in 2017 and
dominator tree updater, the solution adopted here seems a bit outdated.

- Add `MachineDominatorTreeAnalysis`
- Add `MachineDominatorTreePrinterPass` There is no test for this
analysis in codebase.

Also, the pass name is renamed to `machine-dom-tree` instead of
`machinedomtree`.

This header is split off from GenericDomTree.h so it can be included
in the source file only. Do this for MachineDominators.h and
MachinePostDominators.h.

Prepare for new pass manager version of `MachineDominatorTreeAnalysis`.
We may need a machine dominator tree version of `DomTreeUpdater` to
handle `SplitCriticalEdge` in some CodeGen passes.