[clang] [llvm] [SystemZ] Add support for __builtin_setjmp and __builtin_longjmp (PR #116642)

[Ulrich Weigand via cfe-commits]

================
@@ -4619,6 +4619,12 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
     // Buffer is a void**.
     Address Buf = EmitPointerWithAlignment(E->getArg(0));
 
+    if (getTarget().getTriple().getArch() == llvm::Triple::systemz) {
+      // Call LLVM's EH setjmp, which is lightweight.
----------------
uweigand wrote:

I think the comment here should explain that we're not filling any fields of the jmp_buf here and leave it all to the back-end.

https://github.com/llvm/llvm-project/pull/116642