## 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

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

Identified with misc-include-cleaner.

Move implementations of `GenericDomTreeUpdater` to
GenericDomTreeUpdaterImpl.h

This reverts commit 0f8849349ae3d3f2f537ad6ab233a586fb39d375.
Resolve conflict in `MachinePostDominators.h` There is a conflict after
merging #96378, resolved in #96852. Both PRs modified
`MachinePostDominators.h` and triggered build failure.

Reverts llvm/llvm-project#95369
Many build bots failed

This commit converts most of `DomTreeUpdater` into
`GenericDomTreeUpdater` class template, so IR and MIR can reuse some
codes.
There are some differences between interfaces of `BasicBlock` and
`MachineBasicBlock`, so subclasses still need to implement some
functions, like `forceFlushDeletedBB`.