[llvm] [IR] Introduce `llvm.experimental.hot()` (PR #84850)

[Vitaly Buka via llvm-commits]

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@@ -7276,6 +7276,12 @@ void SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I,
     setValue(&I, getValue(I.getArgOperand(0)));
     return;
 
+  case Intrinsic::experimental_hot:
+    // Default lowering to false. It's intended to be lowered as soon as profile
+    // is avalible to unblock other optimizations.
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vitalybuka wrote:

I guess we sill want some default lowering, e.g. for `-opt-bisect-limit=` working when we stop pipeline before the PGO based pass.

https://github.com/llvm/llvm-project/pull/84850