[Mlir-commits] [mlir] [MLIR][Affine] Fix fusion in the presence of cyclic deps in source nests (PR #128397)

[llvmlistbot at llvm.org]

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@@ -447,3 +575,33 @@ bool mlir::affine::isTilingValid(ArrayRef<AffineForOp> loops) {
 
   return true;
 }
+
+bool mlir::affine::hasCyclicDependence(AffineForOp root) {
+  // Collect all the memory accesses in the source nest grouped by their
+  // immediate parent block.
+  DirectedOpGraph graph;
+  SmallVector<MemRefAccess> accesses;
+  root->walk([&](Operation *op) {
+    if (isa<AffineReadOpInterface, AffineWriteOpInterface>(op)) {
+      accesses.emplace_back(op);
+      graph.addNode(op);
+    }
+  });
+
+  // Construct the dependence graph for all the collected acccesses.
+  unsigned rootDepth = getNestingDepth(root);
+  for (const auto &accA : accesses) {
+    for (const auto &accB : accesses) {
+      if (accA.memref != accB.memref)
+        continue;
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patel-vimal wrote:

Are we not expecting aliases here?

https://github.com/llvm/llvm-project/pull/128397