[PATCH] D130569: [Driver] Use libatomic for 32-bit SPARC atomics support on Linux [clang-linux-sparc-libatomic.patch, submitted 2022-07-26]

[Rainer Orth via Phabricator via cfe-commits]

ro created this revision.
ro added reviewers: glaubitz, jrtc27, MaskRay, efriedma.
ro added a project: clang.
Herald added subscribers: StephenFan, fedor.sergeev, jyknight.
Herald added a project: All.
ro requested review of this revision.

This is the Linux/sparc64 equivalent to D118021 
<https://reviews.llvm.org/D118021>, necessary to provide an external 
implementation of atomics on 32-bit SPARC which LLVM cannot inline even with 
`-mcpu=v9` or an equivalent default.

Tested on `sparc64-unknown-linux-gnu`.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D130569

Files:
  clang/lib/Driver/ToolChains/Gnu.cpp


Index: clang/lib/Driver/ToolChains/Gnu.cpp
===================================================================
--- clang/lib/Driver/ToolChains/Gnu.cpp
+++ clang/lib/Driver/ToolChains/Gnu.cpp
@@ -631,6 +631,14 @@
 
       AddRunTimeLibs(ToolChain, D, CmdArgs, Args);
 
+      // LLVM support for atomics on 32-bit SPARC V8+ is incomplete, so
+      // forcibly link with libatomic as a workaround.
+      if (getToolChain().getTriple().getArch() == llvm::Triple::sparc) {
+        CmdArgs.push_back("--as-needed");
+        CmdArgs.push_back("-latomic");
+        CmdArgs.push_back("--no-as-needed");
+      }
+
       if (WantPthread && !isAndroid)
         CmdArgs.push_back("-lpthread");
 



Index: clang/lib/Driver/ToolChains/Gnu.cpp
===================================================================
--- clang/lib/Driver/ToolChains/Gnu.cpp
+++ clang/lib/Driver/ToolChains/Gnu.cpp
@@ -631,6 +631,14 @@
 
       AddRunTimeLibs(ToolChain, D, CmdArgs, Args);
 
+      // LLVM support for atomics on 32-bit SPARC V8+ is incomplete, so
+      // forcibly link with libatomic as a workaround.
+      if (getToolChain().getTriple().getArch() == llvm::Triple::sparc) {
+        CmdArgs.push_back("--as-needed");
+        CmdArgs.push_back("-latomic");
+        CmdArgs.push_back("--no-as-needed");
+      }
+
       if (WantPthread && !isAndroid)
         CmdArgs.push_back("-lpthread");
 

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