[clang] [llvm] [LLVM] Add GNU make jobserver support (PR #145131)

[Artem Belevich via llvm-commits]

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@@ -1420,12 +1420,18 @@ int main(int Argc, char **Argv) {
 
   parallel::strategy = hardware_concurrency(1);
   if (auto *Arg = Args.getLastArg(OPT_wrapper_jobs)) {
-    unsigned Threads = 0;
-    if (!llvm::to_integer(Arg->getValue(), Threads) || Threads == 0)
-      reportError(createStringError("%s: expected a positive integer, got '%s'",
-                                    Arg->getSpelling().data(),
-                                    Arg->getValue()));
-    parallel::strategy = hardware_concurrency(Threads);
+    StringRef Val = Arg->getValue();
+    if (Val.equals_insensitive("jobserver"))
+      parallel::strategy = jobserver_concurrency();
+    else {
+      unsigned Threads = 0;
+      if (!llvm::to_integer(Val, Threads) || Threads == 0) {
+        reportError(createStringError(
+            "%s: expected a positive integer or 'jobserver', got '%s'",
+            Arg->getSpelling().data(), Val.data()));
+      } else
+        parallel::strategy = hardware_concurrency(Threads);
+    }
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Artem-B wrote:

Nit: `{}` are not needed.

https://github.com/llvm/llvm-project/pull/145131