[Mlir-commits] [mlir] [MLIR][Affine] Check dependences during MDG init (PR #156422)

[Uday Bondhugula]

================
@@ -241,7 +241,55 @@ addNodeToMDG(Operation *nodeOp, MemRefDependenceGraph &mdg,
   return &node;
 }
 
-bool MemRefDependenceGraph::init() {
+/// Returns true if there may be a dependence on `memref` from srcNode's
+/// memory ops to dstNode's memory ops, while using the affine memory
+/// dependence analysis checks. The method assumes that there is at least one
+/// memory op in srcNode's loads and stores on `memref`, and similarly for
+/// `dstNode`. `srcNode.op` and `destNode.op` are expected to be nested in the
+/// same block and so the dependences are tested at the depth of that block.
+static bool mayDependence(const Node &srcNode, const Node &dstNode,
+                          Value memref) {
+  assert(srcNode.op->getBlock() == dstNode.op->getBlock());
+  if (!isa<AffineForOp>(srcNode.op) || !isa<AffineForOp>(dstNode.op))
+    return true;
+
+  // Non-affine stores, can't check. Conservatively, return true.
+  if (!srcNode.memrefStores.empty())
----------------
bondhugula wrote:

This method is not meant to deal with aliases since the code that comes later (after the call to this function) handles aliases. So we only need to handle the "same memref" scenario here.

https://github.com/llvm/llvm-project/pull/156422