[lld] [lld][MachO]Multi-threaded i/o. Twice as fast linking a large project. (PR #147134)

[Ellis Hoag via llvm-commits]

================
@@ -1687,6 +1811,14 @@ bool link(ArrayRef<const char *> argsArr, llvm::raw_ostream &stdoutOS,
     }
   }
 
+  if (auto *arg = args.getLastArg(OPT_read_threads)) {
+    StringRef v(arg->getValue());
+    unsigned threads = 0;
+    if (!llvm::to_integer(v, threads, 0) || threads < 0)
----------------
ellishg wrote:

Is there any reason to allow `--read-threads=0`? If this case is used to disable paging in files, can you explain that in the help message?

```suggestion
    if (!llvm::to_integer(v, threads, 0) || threads <= 0)
```

https://github.com/llvm/llvm-project/pull/147134