[mlir] [dataflow] further optimize dataflow compile time

Optimize dataflow compilation time by skipping initialization
of irrelevant operations

Author: cxy-1993

mlir/include/mlir/Analysis/DataFlowFramework.h

@@ -658,6 +658,12 @@ class DataFlowAnalysis {
     return solver.getOrCreateState<StateT>(anchor);
   }
 
+  /// Add irrelevant program point.
+  template <typename PointT>
+  void addIrrelevantPoint(PointT point) {
+    irrelevantPoints.insert(ProgramPoint(point));
+  }
+
   /// Get a read-only analysis state for the given point and create a dependency
   /// on `dependent`. If the return state is updated elsewhere, this analysis is
   /// re-invoked on the dependent.
@@ -695,6 +701,9 @@ class DataFlowAnalysis {
   StringRef debugName;
 #endif // LLVM_ENABLE_ABI_BREAKING_CHECKS
 
+  /// Program points shouldn't analyzed by this analysis.
+  DenseSet<ProgramPoint> irrelevantPoints;
+
 private:
   /// The parent data-flow solver.
   DataFlowSolver &solver;

mlir/lib/Analysis/DataFlow/DenseAnalysis.cpp

@@ -104,6 +104,10 @@ void AbstractDenseForwardDataFlowAnalysis::visitCallOperation(
 
 LogicalResult
 AbstractDenseForwardDataFlowAnalysis::processOperation(Operation *op) {
+  // Skip irrelavant program points.
+  if (irrelevantPoints.contains(ProgramPoint(op)))
+    return;
+
   ProgramPoint *point = getProgramPointAfter(op);
   // If the containing block is not executable, bail out.
   if (op->getBlock() != nullptr &&
@@ -333,6 +337,10 @@ void AbstractDenseBackwardDataFlowAnalysis::visitCallOperation(
 
 LogicalResult
 AbstractDenseBackwardDataFlowAnalysis::processOperation(Operation *op) {
+  // Skip irrelavant program points.
+  if (irrelevantPoints.contains(ProgramPoint(op)))
+    return;
+
   ProgramPoint *point = getProgramPointBefore(op);
   // If the containing block is not executable, bail out.
   if (op->getBlock() != nullptr &&

mlir/test/lib/Analysis/DataFlow/TestDenseBackwardDataFlowAnalysis.cpp

@@ -147,6 +147,7 @@ LogicalResult NextAccessAnalysis::visitOperation(Operation *op,
 
 void NextAccessAnalysis::buildOperationEquivalentLatticeAnchor(Operation *op) {
   if (isMemoryEffectFree(op)) {
+    addIrrelevantPoint(op);
     unionLatticeAnchors<NextAccess>(getProgramPointBefore(op),
                                     getProgramPointAfter(op));
   }

mlir/test/lib/Analysis/DataFlow/TestDenseForwardDataFlowAnalysis.cpp

@@ -154,6 +154,7 @@ LogicalResult LastModifiedAnalysis::visitOperation(
 void LastModifiedAnalysis::buildOperationEquivalentLatticeAnchor(
     Operation *op) {
   if (isMemoryEffectFree(op)) {
+    addIrrelevantPoint(op);
     unionLatticeAnchors<LastModification>(getProgramPointBefore(op),
                                           getProgramPointAfter(op));
   }