Fix nested dominance relationship between parent results and child operations.

This modifies DominanceInfo::properlyDominates(Value *value, Operation *op) to return false if the value is defined by a parent operation of 'op'. This prevents using values defined by the parent operation from within any child regions.

PiperOrigin-RevId: 269934920

1 files changed, 7 insertions, 1 deletions

diff --git a/mlir/lib/Analysis/Dominance.cpp b/mlir/lib/Analysis/Dominance.cpp
index ead8d7e070c..71caa3eec42 100644
--- a/mlir/lib/Analysis/Dominance.cpp
+++ b/mlir/lib/Analysis/Dominance.cpp
@@ -128,8 +128,14 @@ bool DominanceInfo::properlyDominates(Operation *a, Operation *b) {
 
 /// Return true if value A properly dominates operation B.
 bool DominanceInfo::properlyDominates(Value *a, Operation *b) {
-  if (auto *aInst = a->getDefiningOp())
+  if (auto *aInst = a->getDefiningOp()) {
+    // The values defined by an operation do *not* dominate any nested
+    // operations.
+    if (aInst->getParentRegion() != b->getParentRegion() &&
+        aInst->isAncestor(b))
+      return false;
     return properlyDominates(aInst, b);
+  }
 
   // block arguments properly dominate all operations in their own block, so
   // we use a dominates check here, not a properlyDominates check.