[clang] [compiler-rt] [Sanitizers] the access size (8 bytes) exceeds the max lock-free size (4 bytes) for 32-bit (PR #125388)

[Hubert Tong via llvm-commits]

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@@ -338,6 +338,13 @@ void aix::Linker::ConstructJob(Compilation &C, const JobAction &JA,
     CmdArgs.push_back("-lpthread");
   }
   const char *Exec = Args.MakeArgString(ToolChain.GetLinkerPath());
+    
+// Required for 64-bit atomic operations used in sanitizer runtimes 
+// (e.g., sanitizer_common's atomic utilities). On 32-bit AIX, these 
+// are not natively supported, necessitating linkage with -latomic.
+  if (Sanitize.hasAnySanitizer() && IsArch32Bit) {
+    CmdArgs.push_back("-latomic");
----------------
hubert-reinterpretcast wrote:

> Please let me know if there are additional points to consider.

The addition of `-latomic` is not actually required _even on AIX_ if the only sanitizer runtimes that are linked in are purely shared libraries.

The addition of `-latomic` for 32-bit AIX belongs in `clang::tools::driver::linkSanitizerRuntimeDeps` because the wider logic is already present to call that function only when sanitizer runtimes that contain static components are linked in.

See
https://github.com/llvm/llvm-project/blob/f7294776570e125b94bb5625905cbc57a4956760/clang/lib/Driver/ToolChains/Gnu.cpp#L541
https://github.com/llvm/llvm-project/blob/f7294776570e125b94bb5625905cbc57a4956760/clang/lib/Driver/ToolChains/Gnu.cpp#L585-L586
https://github.com/llvm/llvm-project/blob/f7294776570e125b94bb5625905cbc57a4956760/clang/lib/Driver/ToolChains/CommonArgs.cpp#L1607-L1608
https://github.com/llvm/llvm-project/blob/f7294776570e125b94bb5625905cbc57a4956760/clang/lib/Driver/ToolChains/CommonArgs.cpp#L1678

https://github.com/llvm/llvm-project/pull/125388