[llvm-branch-commits] [mlir] [MLIR] Stop visiting unreachable blocks in the walkAndApplyPatterns driver (PR #154038)

[Jakub Kuderski via llvm-branch-commits]

================
@@ -98,13 +118,18 @@ void walkAndApplyPatterns(Operation *op,
       regionIt = region->begin();
       if (regionIt != region->end())
         blockIt = regionIt->begin();
+      if (!llvm::hasSingleElement(*region))
+        findReachableBlocks(*region, reachableBlocks);
     }
     // Advance the iterator to the next reachable operation.
     void advance() {
       assert(regionIt != region->end());
       hasVisitedRegions = false;
       if (blockIt == regionIt->end()) {
         regionIt++;
+        while (regionIt != region->end() &&
+               !reachableBlocks.contains(&*regionIt))
+          regionIt++;
----------------
kuhar wrote:

```suggestion
          ++regionIt;
```
Per https://llvm.org/docs/CodingStandards.html#prefer-preincrement

https://github.com/llvm/llvm-project/pull/154038