[llvm] [IPO] Prevent removal of some convergent attr (PR #134863)

[Matt Arsenault via llvm-commits]

Nathan =?utf-8?q?Gauër?= <brioche at google.com>,
Nathan =?utf-8?q?Gauër?= <brioche at google.com>,
Nathan =?utf-8?q?Gauër?= <brioche at google.com>
Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/134863 at github.com>


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@@ -2902,6 +2902,22 @@ struct AANonConvergentImpl : public AANonConvergent {
   }
 };
 
+static bool FunctionCalledWithConvergenceToken(const Function *F) {
+  for (auto &Use : F->uses()) {
+    CallBase *CB = dyn_cast<CallBase>(Use.getUser());
+    if (!CB)
+      continue;
+
+    // We are not called, just used as an argument.
+    if (CB->getCalledFunction() != F)
+      continue;
+
+    if (CB->getConvergenceControlToken())
+      return true;
+  }
+  return false;
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arsenm wrote:

This needs to be a conservatively correct true. If the address is captured you do not know the users. If the function is externally visible, you also do not know the users. 

https://github.com/llvm/llvm-project/pull/134863