[clang] d5ba663 - [AIX][clang][compiler_rt] rename libatomic archive to libclang_rt (#197485)

[via cfe-commits]

Author: Alison Zhang
Date: 2026-05-21T14:58:44-04:00
New Revision: d5ba663c28ec6374f02e630f79459d4ef639f51c

URL: https://github.com/llvm/llvm-project/commit/d5ba663c28ec6374f02e630f79459d4ef639f51c
DIFF: https://github.com/llvm/llvm-project/commit/d5ba663c28ec6374f02e630f79459d4ef639f51c.diff

LOG: [AIX][clang][compiler_rt] rename libatomic archive to libclang_rt (#197485)

This PR implements the following on AIX to avoid conflicts between LLVM
libatomic and the GNU libatomic in the AIX toolbox as they share the
same library name:

- Updates the clang driver to use `-lcompiler_rt` instead of `-latomic`
- Renames the compiler-rt archive from `libatomic.a` to
`libcompiler_rt.a`

Only the archive and not the shared object (`libatomic.so.1`) is renamed
because renaming one component is enough to distinguish between the LLVM
and GNU libatomic libraries. This also allows us to add additional
shared objects to the `libcompiler_rt.a` archive in the future if
needed.

Added: 
    

Modified: 
    clang/docs/ReleaseNotes.rst
    clang/lib/Driver/ToolChain.cpp
    clang/lib/Driver/ToolChains/AIX.cpp
    clang/test/Driver/fprofile-update.c
    compiler-rt/lib/builtins/CMakeLists.txt

Removed: 
    


################################################################################
diff  --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index a9017f44058be..a490dc5469a27 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -771,6 +771,10 @@ AIX Support
   (instead of `all`) which only extracts static init from archive members which
   would otherwise be referenced.
   (See https://www.ibm.com/docs/en/aix/7.2.0?topic=l-ld-command for details).
+- The driver now uses ``-lcompiler_rt`` instead of ``-latomic``, and the compiler-rt
+  archive has been renamed from ``libatomic.a`` to ``libcompiler_rt.a`` to avoid conflicts
+  between the LLVM libatomic and the GNU libatomic from the AIX toolbox as they share
+  the same library name.
 
 NetBSD Support
 ^^^^^^^^^^^^^^

diff  --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp
index 21d61a60224cb..511eb3757456b 100644
--- a/clang/lib/Driver/ToolChain.cpp
+++ b/clang/lib/Driver/ToolChain.cpp
@@ -978,7 +978,10 @@ void ToolChain::addFortranRuntimeLibs(const ArgList &Args,
     if ((OMPRuntime == Driver::OMPRT_OMP &&
          RuntimeLib == ToolChain::RLT_Libgcc) &&
         !getTriple().isKnownWindowsMSVCEnvironment()) {
-      CmdArgs.push_back("-latomic");
+      if (getTriple().isOSAIX())
+        CmdArgs.push_back("-lcompiler_rt");
+      else
+        CmdArgs.push_back("-latomic");
     }
   }
 }

diff  --git a/clang/lib/Driver/ToolChains/AIX.cpp b/clang/lib/Driver/ToolChains/AIX.cpp
index e36910f9aaf46..01b2c8ec18a35 100644
--- a/clang/lib/Driver/ToolChains/AIX.cpp
+++ b/clang/lib/Driver/ToolChains/AIX.cpp
@@ -594,7 +594,7 @@ void AIX::addProfileRTLibs(const llvm::opt::ArgList &Args,
             Args.getLastArgNoClaim(options::OPT_fprofile_update_EQ)) {
       StringRef Val = A->getValue();
       if (Val == "atomic" || Val == "prefer-atomic")
-        CmdArgs.push_back("-latomic");
+        CmdArgs.push_back("-lcompiler_rt");
     }
   }
 

diff  --git a/clang/test/Driver/fprofile-update.c b/clang/test/Driver/fprofile-update.c
index 3313a2c1cb9af..c297b2b4931f8 100644
--- a/clang/test/Driver/fprofile-update.c
+++ b/clang/test/Driver/fprofile-update.c
@@ -18,5 +18,5 @@
 // RUN: %clang -### %s --target=powerpc-unknown-aix -fprofile-generate -fprofile-update=prefer-atomic 2>&1 | FileCheck %s --check-prefix=AIX
 // RUN: %clang -### %s --target=powerpc-unknown-aix -fprofile-generate 2>&1 | FileCheck %s --check-prefix=AIX-NOATOMIC
 // RUN: %clang -### %s --target=powerpc-unknown-aix -fprofile-generate -fprofile-update=single 2>&1 | FileCheck %s --check-prefix=AIX-NOATOMIC
-// AIX: "-latomic"
-// AIX-NOATOMIC-NOT: "-latomic"
+// AIX: "-lcompiler_rt"
+// AIX-NOATOMIC-NOT: "-lcompiler_rt"

diff  --git a/compiler-rt/lib/builtins/CMakeLists.txt b/compiler-rt/lib/builtins/CMakeLists.txt
index 3fa21578c86ad..3d18bdd8a80af 100644
--- a/compiler-rt/lib/builtins/CMakeLists.txt
+++ b/compiler-rt/lib/builtins/CMakeLists.txt
@@ -1137,10 +1137,10 @@ if(COMPILER_RT_BUILD_STANDALONE_LIBATOMIC)
     endif()
   endforeach()
   # FIXME: On AIX, we have to archive built shared libraries into a static
-  # archive, i.e., libatomic.a. Once cmake adds support of such usage for AIX,
+  # archive, i.e., libcompiler_rt.a. Once cmake adds support of such usage for AIX,
   # this ad-hoc part can be removed.
   if(OS_NAME MATCHES "AIX")
-    archive_aix_libatomic(clang_rt.atomic libatomic
+    archive_aix_libatomic(clang_rt.atomic libcompiler_rt
                           ARCHS ${BUILTIN_SUPPORTED_ARCH}
                           PARENT_TARGET builtins-standalone-atomic)
   endif()