[llvm] [cmake] Add minor version to library SONAME (PR #79376)

[Tom Stellard via llvm-commits]

https://github.com/tstellar created https://github.com/llvm/llvm-project/pull/79376

We need to do this now that we are bumping the minor release number when we create the release branch.

This also results in a slight change to the library names for LLVM.  The main library now has a more convential library name: 'libLLVM.so.$major.$minor'.  The old library name: libLLVM-$major.so is now a symlink that points to the new library.  However, the symlink is not present in the build directory.  It is only present in the install directory.

The library name was changed because it helped to keep the CMake changes more simple.

Fixes #76273

>From d07c8b82b0964fda3ff736d8e8345dd73229d361 Mon Sep 17 00:00:00 2001
From: Tom Stellard <tstellar at redhat.com>
Date: Wed, 24 Jan 2024 21:38:23 +0000
Subject: [PATCH] [cmake] Add minor version to library SONAME

We need to do this now that we are bumping the minor release number
when we create the release branch.

This also results in a slight change to the library names for LLVM.  The
main library now has a more convential library name:
'libLLVM.so.$major.$minor'.  The old library name: libLLVM-$major.so
is now a symlink that points to the new library.  However, the
symlink is not present in the build directory.  It is only present
in the install directory.

The library name was changed because it helped to keep the CMake changes
more simple.

Fixes #76273
---
 llvm/CMakeLists.txt                  | 2 +-
 llvm/cmake/modules/AddLLVM.cmake     | 6 +++---
 llvm/tools/llvm-shlib/CMakeLists.txt | 5 ++++-
 3 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/llvm/CMakeLists.txt b/llvm/CMakeLists.txt
index 485c76b8bb936da..419c64d295ee3a0 100644
--- a/llvm/CMakeLists.txt
+++ b/llvm/CMakeLists.txt
@@ -35,7 +35,7 @@ endif()
 
 if(NOT DEFINED LLVM_SHLIB_SYMBOL_VERSION)
   # "Symbol version prefix for libLLVM.so"
-  set(LLVM_SHLIB_SYMBOL_VERSION "LLVM_${LLVM_VERSION_MAJOR}")
+  set(LLVM_SHLIB_SYMBOL_VERSION "LLVM_${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}")
 endif()
 
 if ((CMAKE_GENERATOR MATCHES "Visual Studio") AND (MSVC_TOOLSET_VERSION LESS 142) AND (CMAKE_GENERATOR_TOOLSET STREQUAL ""))
diff --git a/llvm/cmake/modules/AddLLVM.cmake b/llvm/cmake/modules/AddLLVM.cmake
index 5e9896185528246..80774b6dd43673d 100644
--- a/llvm/cmake/modules/AddLLVM.cmake
+++ b/llvm/cmake/modules/AddLLVM.cmake
@@ -108,7 +108,7 @@ function(add_llvm_symbol_exports target_name export_file)
       COMMAND "${Python3_EXECUTABLE}" "-c"
       "import sys; \
        lines = ['    ' + l.rstrip() for l in sys.stdin] + ['  local: *;']; \
-       print('LLVM_${LLVM_VERSION_MAJOR} {'); \
+       print('LLVM_${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR} {'); \
        print('  global:') if len(lines) > 1 else None; \
        print(';\\n'.join(lines) + '\\n};')"
       < ${export_file} > ${native_export_file}
@@ -647,8 +647,8 @@ function(llvm_add_library name)
       set_target_properties(${name}
         PROPERTIES
         # Since 4.0.0, the ABI version is indicated by the major version
-        SOVERSION ${LLVM_VERSION_MAJOR}${LLVM_VERSION_SUFFIX}
-        VERSION ${LLVM_VERSION_MAJOR}${LLVM_VERSION_SUFFIX})
+        SOVERSION ${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}${LLVM_VERSION_SUFFIX}
+        VERSION ${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}${LLVM_VERSION_SUFFIX})
     endif()
   endif()
 
diff --git a/llvm/tools/llvm-shlib/CMakeLists.txt b/llvm/tools/llvm-shlib/CMakeLists.txt
index a47a0ec84c625c6..09c15e304614c4a 100644
--- a/llvm/tools/llvm-shlib/CMakeLists.txt
+++ b/llvm/tools/llvm-shlib/CMakeLists.txt
@@ -33,7 +33,10 @@ if(LLVM_BUILD_LLVM_DYLIB)
   if (LLVM_LINK_LLVM_DYLIB)
     set(INSTALL_WITH_TOOLCHAIN INSTALL_WITH_TOOLCHAIN)
   endif()
-  add_llvm_library(LLVM SHARED DISABLE_LLVM_LINK_LLVM_DYLIB SONAME ${INSTALL_WITH_TOOLCHAIN} ${SOURCES})
+  add_llvm_library(LLVM SHARED DISABLE_LLVM_LINK_LLVM_DYLIB OUTPUT_NAME LLVM ${INSTALL_WITH_TOOLCHAIN} ${SOURCES})
+  # Add symlink for backwards compatibility with old library name
+  get_target_property(LLVM_DYLIB_FILENAME LLVM OUTPUT_NAME)
+  llvm_install_library_symlink(LLVM-${LLVM_VERSION_MAJOR}${LLVM_VERSION_SUFFIX} ${LLVM_DYLIB_FILENAME} SHARED COMPONENT LLVM)
 
   list(REMOVE_DUPLICATES LIB_NAMES)
   if("${CMAKE_SYSTEM_NAME}" STREQUAL "Darwin")