[Mlir-commits] [mlir] [RegionUtils] replace uses in nested regions when isolating from above (PR #180548)

[Scott Manley]

https://github.com/rscottmanley created https://github.com/llvm/llvm-project/pull/180548

When making a region IsolatedFromAbove, replace uses in any region within the parent region, not just the immediate parent region.

>From c74923e7e73c26ab947101be965023f3d6d0901f Mon Sep 17 00:00:00 2001
From: Scott Manley <scmanley at nvidia.com>
Date: Mon, 9 Feb 2026 07:36:37 -0800
Subject: [PATCH] [RegionUtils] replace uses in nested regions when isolating
 from above

When making a region IsolatedFromAbove, replace uses in any region
within the parent region, not just the immediate parent region.
---
 mlir/lib/Transforms/Utils/RegionUtils.cpp     | 10 +++++++-
 .../Transforms/make-isolated-from-above.mlir  | 25 +++++++++++++++++++
 2 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/mlir/lib/Transforms/Utils/RegionUtils.cpp b/mlir/lib/Transforms/Utils/RegionUtils.cpp
index 5406a51d2ab7f..87125beafa065 100644
--- a/mlir/lib/Transforms/Utils/RegionUtils.cpp
+++ b/mlir/lib/Transforms/Utils/RegionUtils.cpp
@@ -156,9 +156,17 @@ SmallVector<Value> mlir::makeRegionIsolatedFromAbove(
 
   // Create a mapping between the captured values and the new arguments added.
   IRMapping map;
+  Operation *regionParentOp = region.getParentOp();
   auto replaceIfFn = [&](OpOperand &use) {
-    return use.getOwner()->getBlock()->getParent() == ®ion;
+    Operation *parentOp = use.getOwner()->getParentOp();
+    while (parentOp) {
+      if (parentOp == regionParentOp)
+        return true;
+      parentOp = parentOp->getParentOp();
+    }
+    return false;
   };
+
   for (auto [arg, capturedVal] :
        llvm::zip(newEntryBlockArgs.take_back(finalCapturedValues.size()),
                  finalCapturedValues)) {
diff --git a/mlir/test/Transforms/make-isolated-from-above.mlir b/mlir/test/Transforms/make-isolated-from-above.mlir
index a9d4325944fd9..3b0084d6e0007 100644
--- a/mlir/test/Transforms/make-isolated-from-above.mlir
+++ b/mlir/test/Transforms/make-isolated-from-above.mlir
@@ -113,3 +113,28 @@ func.func @make_isolated_from_above_multiple_blocks(%arg0 : index, %arg1 : index
 //  CLONE2-NEXT:       cf.br ^bb1
 //       CLONE2:     ^bb1:
 //       CLONE2:       "foo.yield"(%[[C0]], %[[C1]], %[[D0]], %[[D1]], %[[B0]])
+
+
+// -----
+
+// CHECK-LABEL: func @make_isolated_from_above_nested_region
+//  CHECK-SAME:     %[[ARG0:[a-zA-Z0-9]+]]: memref<8xindex>
+//       CHECK:   %[[C1:.+]] = arith.constant 1 : index
+//       CHECK:   %[[C8:.+]] = arith.constant 8 : index
+//       CHECK:   test.isolated_one_region_op %[[C1]], %[[ARG0]], %[[C8]]
+//       CHECK:   ^bb0(%[[B0:[a-zA-Z0-9]+]]: index, %[[B1:[a-zA-Z0-9]+]]: memref<8xindex>, %[[B2:[a-zA-Z0-9]+]]: index)
+//       CHECK:     scf.for %arg4 = %[[B0]] to %[[B2]] step %[[B0]]
+//       CHECK:       memref.store %[[B0]], %[[B1]][%arg4] : memref<8xindex>
+//       CHECK:     "foo.yield"() : () -> ()
+
+func.func @make_isolated_from_above_nested_region(%arg0 : memref<8xindex>) {
+  %c1 = arith.constant 1 : index
+  %c8 = arith.constant 8 : index
+  "test.one_region_with_operands_op"() ({
+    scf.for %arg1 = %c1 to %c8 step %c1 {
+      memref.store %c1, %arg0[%arg1] : memref<8xindex>
+    }
+    "foo.yield"() : () -> ()
+  }) : () -> ()
+  return
+}