[llvm] [profcheck] Add unknown branch weight for inlined memchr calls. (PR #160964)

[Mircea Trofin via llvm-commits]

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@@ -1350,6 +1350,11 @@ static bool foldMemChr(CallInst *Call, DomTreeUpdater *DTU,
   BB->getTerminator()->eraseFromParent();
   SwitchInst *SI = IRB.CreateSwitch(
       IRB.CreateTrunc(Call->getArgOperand(1), ByteTy), BBNext, N);
+  Function *F = Call->getFunction();
+  assert(F && "Instruction does not belong to a function!");
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mtrofin wrote:

We can use what @alanzhao1 did [here](https://github.com/llvm/llvm-project/pull/158743/files#diff-1d202885a6953bfe78a07755de6bf6b35d4f4ecbb096fe4c3f5e2524ea70d1f5R188-R195) (once he lands it)

https://github.com/llvm/llvm-project/pull/160964