The ifdef tree uses __powerpc__ so 32-bit PPC is supported as well.

--- llvm-14.0.6.src/unittests/Support/Host.cpp.old	2022-06-22 16:46:24.000000000 +0000
+++ llvm-14.0.6.src/unittests/Support/Host.cpp	2022-11-28 02:15:41.512865406 +0000
@@ -40,7 +40,7 @@
     // some systems.
     return (Host.isOSWindows() && llvm_is_multithreaded()) ||
            Host.isOSDarwin() || (Host.isX86() && Host.isOSLinux()) ||
-           (Host.isPPC64() && Host.isOSLinux()) ||
+           (Host.isPPC() && Host.isOSLinux()) ||
            (Host.isSystemZ() && (Host.isOSLinux() || Host.isOSzOS()));
   }