[Mlir-commits] [mlir] [MLIR][SCF] Support permutation-based parallel loop fusion (PR #203207)

[Ivan Butygin]

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@@ -761,6 +771,147 @@ static std::optional<ParallelOp> interchangeLoops(OpBuilder &builder,
   return newOp;
 }
 
+struct LoopIV {
+  Value lBound, uBound, step;
+  bool operator!=(LoopIV const &other) const { return !(*this == other); }
+  bool operator==(LoopIV const &other) const {
+    return lBound == other.lBound && uBound == other.uBound &&
+           step == other.step;
+  }
+};
+
+template <>
+struct llvm::DenseMapInfo<LoopIV> {
+  static inline bool isEqual(const LoopIV &lhs, const LoopIV &rhs) {
+    return (lhs == rhs);
+  }
+
+  static inline unsigned getHashValue(const LoopIV &val) {
+    return llvm::hash_combine(
+        DenseMapInfo<mlir::Value>::getHashValue(val.lBound),
+        DenseMapInfo<mlir::Value>::getHashValue(val.uBound),
+        DenseMapInfo<mlir::Value>::getHashValue(val.step));
+  }
+};
+
+// Returns vector of candidate permutation indices vectors,
+// can be empty
+static SmallVector<SmallVector<int64_t>>
+computeCandidateInterchangePermutations(ParallelOp &firstPloop,
+                                        ParallelOp &secondPloop) {
+  SmallVector<SmallVector<int64_t>> extraResults;
+
+  // Check preconditions
+  if (firstPloop.getNumLoops() < 2 ||
+      firstPloop.getNumLoops() != secondPloop.getNumLoops())
+    return extraResults;
+
+  SmallVector<LoopIV> firstIVs(firstPloop.getNumLoops());
+  SmallVector<LoopIV> secondIVs(secondPloop.getNumLoops());
+  llvm::SmallSetVector<LoopIV, 6> unique;
+  for (unsigned index = 0; index < firstPloop.getNumLoops(); ++index) {
----------------
Hardcode84 wrote:

nit: `llvm::seq(firstPloop.getNumLoops())`

https://github.com/llvm/llvm-project/pull/203207