[SLU][profcheck] Propagate profile for branches on injected conditions. (#164476)

This patch addresses the profile of 2 branches:

- one that compares the 2 limits, for which we have no information (the C1, C2, see https://reviews.llvm.org/D136233)
- one that is conditioned on a condition for which we have a profile, so we reuse it



Issue #147390

Author: mtrofin

llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp

@@ -3203,10 +3203,15 @@ injectPendingInvariantConditions(NonTrivialUnswitchCandidate Candidate, Loop &L,
   Builder.SetInsertPoint(TI);
   auto *InvariantBr =
       Builder.CreateCondBr(InjectedCond, InLoopSucc, CheckBlock);
+  // We don't know anything about the relation between the limits.
+  setExplicitlyUnknownBranchWeightsIfProfiled(
+      *InvariantBr, *InvariantBr->getParent()->getParent(), DEBUG_TYPE);
 
   Builder.SetInsertPoint(CheckBlock);
-  Builder.CreateCondBr(TI->getCondition(), TI->getSuccessor(0),
-                       TI->getSuccessor(1));
+  Builder.CreateCondBr(
+      TI->getCondition(), TI->getSuccessor(0), TI->getSuccessor(1),
+      !ProfcheckDisableMetadataFixes ? TI->getMetadata(LLVMContext::MD_prof)
+                                     : nullptr);
   TI->eraseFromParent();
 
   // Fixup phis.