[llvm] [ProfCheck][NFC] Make Function argument from branch weight setter optional (PR #166032)

[Aiden Grossman via llvm-commits]

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@@ -274,9 +274,10 @@ void llvm::setExplicitlyUnknownBranchWeights(Instruction &I,
 }
 
 void llvm::setExplicitlyUnknownBranchWeightsIfProfiled(Instruction &I,
-                                                       Function &F,
-                                                       StringRef PassName) {
-  if (std::optional<Function::ProfileCount> EC = F.getEntryCount();
+                                                       StringRef PassName,
+                                                       const Function *F) {
+  F = F ? F : I.getFunction();
+  if (std::optional<Function::ProfileCount> EC = F->getEntryCount();
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boomanaiden154 wrote:

Do we want to add an assert here that `F` is not `nullptr`?

This refactoring does add a footgun in that if you have an Instruction that is not attached to a function, but forget to pass in the function explicitly, we then try to call `getEntryCount` on `nullptr`. I guess there ends up being a tradeoff on callsite complexity in the normal place (where I is attached to a function) versus ensuring we correctly handle the edge case in all circumstances. No real opinion on my end on what is better.

https://github.com/llvm/llvm-project/pull/166032