[InstCombine] Fix incorrect number of iterations (llvm#140004)

Author: dtcxzyw

llvm/lib/Transforms/InstCombine/InstructionCombining.cpp

@@ -5663,15 +5663,14 @@ static bool combineInstructionsOverFunction(
   // Iterate while there is work to do.
   unsigned Iteration = 0;
   while (true) {
-    ++Iteration;
-
-    if (Iteration > Opts.MaxIterations && !VerifyFixpoint) {
+    if (Iteration >= Opts.MaxIterations && !VerifyFixpoint) {
       LLVM_DEBUG(dbgs() << "\n\n[IC] Iteration limit #" << Opts.MaxIterations
                         << " on " << F.getName()
                         << " reached; stopping without verifying fixpoint\n");
       break;
     }
 
+    ++Iteration;
     ++NumWorklistIterations;
     LLVM_DEBUG(dbgs() << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on "
                       << F.getName() << "\n");