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Author: nikic

llvm/lib/Analysis/ScalarEvolution.cpp

@@ -9200,9 +9200,13 @@ ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromICmp(
     if (!EnableFiniteLoopControl || !ControllingFiniteLoop ||
         !isLoopInvariant(RHS, L)) {
       // Otherwise, perform the addition in a wider type, to avoid overflow.
+      // If the LHS is an addrec with the appropriate nowrap flag, the
+      // extension will be sunk into it and the exit count can be analyzed.
       auto *OldType = dyn_cast<IntegerType>(LHS->getType());
       if (!OldType)
         break;
+      // Prefer doubling the bitwidth over adding a single bit to make it more
+      // likely that we use a legal type.
       auto *NewType =
           Type::getIntNTy(OldType->getContext(), OldType->getBitWidth() * 2);
       if (ICmpInst::isSigned(Pred)) {