[llvm] annotate interfaces in llvm/IR for DLL export (#141650)

## Purpose

This patch is one in a series of code-mods that annotate LLVM’s public
interface for export. This patch annotates the `llvm/IR`,
`llvm/IRPrinter`, and `llvm/IRReader` libraries. These 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).

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 on
Linux:
- Add `#include "llvm/Support/Compiler.h"` to files where it was not
auto-added by IDS due to no pre-existing block of include statements.
- Add `LLVM_ABI_FRIEND` to friend member functions declared with
`LLVM_ABI`
- Add `LLVM_TEMPLATE_ABI` and `LLVM_EXPORT_TEMPLATE` to exported
instantiated templates
- Add `LLVM_ABI` to a subset of private class methods and fields that
require export
- Add `LLVM_ABI` to a small number of symbols that require export but
are not declared in headers
- Reorder `LLVM_ABI` with `[[deprecated]]` and `[[nodiscard]]`
attributes.

## 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

1 files changed, 2 insertions, 1 deletions

diff --git a/llvm/lib/IR/DebugInfoMetadata.cpp b/llvm/lib/IR/DebugInfoMetadata.cpp
index 6735bf7..473114b 100644
--- a/llvm/lib/IR/DebugInfoMetadata.cpp
+++ b/llvm/lib/IR/DebugInfoMetadata.cpp
@@ -22,6 +22,7 @@
 #include "llvm/IR/Type.h"
 #include "llvm/IR/Value.h"
 #include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Compiler.h"
 
 #include <numeric>
 #include <optional>
@@ -36,7 +37,7 @@ cl::opt<bool> EnableFSDiscriminator(
 
 // When true, preserves line and column number by picking one of the merged
 // location info in a deterministic manner to assist sample based PGO.
-cl::opt<bool> PickMergedSourceLocations(
+LLVM_ABI cl::opt<bool> PickMergedSourceLocations(
     "pick-merged-source-locations", cl::init(false), cl::Hidden,
     cl::desc("Preserve line and column number when merging locations."));
 } // namespace llvm