[Mlir-commits] [mlir] [mlir][scf] Expose isPerfectlyNestedForLoops (PR #152115)

[Mehdi Amini]

================
@@ -1512,3 +1512,47 @@ FailureOr<scf::ForallOp> mlir::normalizeForallOp(RewriterBase &rewriter,
   rewriter.replaceOp(forallOp, normalizedForallOp);
   return normalizedForallOp;
 }
+
+bool mlir::isPerfectlyNestedForLoops(
+    MutableArrayRef<LoopLikeOpInterface> loops) {
+  assert(!loops.empty() && "unexpected empty loop nest");
+  if (loops.size() == 1) {
+    return isa_and_nonnull<scf::ForOp>(loops.front().getOperation());
+  }
+  for (auto [outerLoop, innerLoop] :
+       llvm::zip_equal(loops.drop_back(), loops.drop_front())) {
+    auto outerFor = dyn_cast_or_null<scf::ForOp>(outerLoop.getOperation());
+    auto innerFor = dyn_cast_or_null<scf::ForOp>(innerLoop.getOperation());
+    if (!outerFor || !innerFor) {
+      return false;
+    }
+    auto outerBBArgs = outerFor.getRegionIterArgs();
+    auto innerIterArgs = innerFor.getInitArgs();
+    if (outerBBArgs.size() != innerIterArgs.size()) {
+      return false;
+    }
+
+    for (auto [outerBBArg, innerIterArg] :
+         llvm::zip_equal(outerBBArgs, innerIterArgs)) {
+      if (!llvm::hasSingleElement(outerBBArg.getUses()) ||
+          innerIterArg != outerBBArg) {
+        return false;
+      }
----------------
joker-eph wrote:

```suggestion
          innerIterArg != outerBBArg)
        return false;
```

https://github.com/llvm/llvm-project/pull/152115