diff --git a/mlir/lib/Dialect/Affine/Transforms/LoopFusion.cpp b/mlir/lib/Dialect/Affine/Transforms/LoopFusion.cpp
--- a/mlir/lib/Dialect/Affine/Transforms/LoopFusion.cpp
+++ b/mlir/lib/Dialect/Affine/Transforms/LoopFusion.cpp
@@ -210,9 +210,9 @@
 
   MemRefDependenceGraph(Block &block) : block(block) {}
 
-  // Initializes the dependence graph based on operations in 'f'.
+  // Initializes the dependence graph based on operations in `block'.
   // Returns true on success, false otherwise.
-  bool init(Block *block);
+  bool init();
 
   // Returns the graph node for 'id'.
   Node *getNode(unsigned id) {
@@ -773,14 +773,14 @@
 // Assigns each node in the graph a node id based on program order in 'f'.
 // TODO: Add support for taking a Block arg to construct the
 // dependence graph at a different depth.
-bool MemRefDependenceGraph::init(Block *block) {
+bool MemRefDependenceGraph::init() {
   LLVM_DEBUG(llvm::dbgs() << "--- Initializing MDG ---\n");
   // Map from a memref to the set of ids of the nodes that have ops accessing
   // the memref.
   DenseMap<Value, SetVector<unsigned>> memrefAccesses;
 
   DenseMap<Operation *, unsigned> forToNodeMap;
-  for (Operation &op : *block) {
+  for (Operation &op : block) {
     if (auto forOp = dyn_cast<AffineForOp>(op)) {
       // Create graph node 'id' to represent top-level 'forOp' and record
       // all loads and store accesses it contains.
@@ -859,8 +859,8 @@
     for (Value value : opInst->getResults()) {
       for (Operation *user : value.getUsers()) {
         // Ignore users outside of the block.
-        if (block->getParent()->findAncestorOpInRegion(*user)->getBlock() !=
-            block)
+        if (block.getParent()->findAncestorOpInRegion(*user)->getBlock() !=
+            &block)
           continue;
         SmallVector<AffineForOp, 4> loops;
         getAffineForIVs(*user, &loops);
@@ -2032,8 +2032,10 @@
 /// Run fusion on `block`.
 void LoopFusion::runOnBlock(Block *block) {
   MemRefDependenceGraph g(*block);
-  if (!g.init(block))
+  if (!g.init()) {
+    LLVM_DEBUG(llvm::dbgs() << "MDG init failed");
     return;
+  }
 
   std::optional<unsigned> fastMemorySpaceOpt;
   if (fastMemorySpace.hasValue())