[llvm] [OFFLOAD] Stricter enforcement of user offload disable (PR #133470)

[Joseph Huber via llvm-commits]

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@@ -31,6 +32,12 @@ void initRuntime() {
   if (PM == nullptr)
     PM = new PluginManager();
 
+  if (OffloadPolicy::isOffloadDisabled()) {
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jhuber6 wrote:

I'm not sure if that's really correct. Offloading being disabled just means that we don't need the plugins. Theoretically OMPT could still do something AFAIK. Seems more straightforward to just say that none of the plugins work and call it a day. Have you noticed a lot of overhead from initializing OMPT? It's `dlopen` and a few `dlsym` calls.

https://github.com/llvm/llvm-project/pull/133470