[InstCombine] Fix incorrect number of iterations

[dtcxzyw]

It is surprising to see a nonzero NumTwoIterations.

[llvmbot]

@llvm/pr-subscribers-llvm-transforms

Author: Yingwei Zheng (dtcxzyw)

Changes

It is surprising to see a nonzero NumTwoIterations.

---

Full diff: https://github.com/llvm/llvm-project/pull/140004.diff

1 Files Affected:

• (modified) llvm/lib/Transforms/InstCombine/InstructionCombining.cpp (+2-3)

diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 206d41e30db2c..a3cf665c4727a 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -5622,15 +5622,14 @@ 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");