[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");
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hubert-reinterpretcast wrote:

> This minimizes the risk of inadvertently impacting sanitizer handling on non-AIX targets.

Generally, placing the code in a more widely used path will lead to more likely detection of problems. In other words, minimizing the risk of inadvertently impacting sanitizer handling on AIX targets _increases the risk_ of having broken sanitizer handling on AIX. Considering that the risk of breaking non-AIX should be low (especially in an undetected manner) and that the risk of incorrect sanitizer handling on AIX is high during active development, I think deliberate attempts to isolate the AIX code (as opposed to using common code paths) is a mistake.

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