[MLIR] Add reduction interface with tester to mlir-reduce (llvm#166096)

Currently, we don't have support for patterns that need access to a
`Tester` instance in `mlir-reduce`. This PR adds
`DialectReductionPatternWithTesterInterface` to the set of supported
interfaces. Dialects can implement this interface to inject the tester
into their pattern classes.

Author: aidint

mlir/include/mlir/Reducer/ReductionPatternInterface.h

@@ -10,6 +10,7 @@
 #define MLIR_REDUCER_REDUCTIONPATTERNINTERFACE_H
 
 #include "mlir/IR/DialectInterface.h"
+#include "mlir/Reducer/Tester.h"
 
 namespace mlir {
 
@@ -47,10 +48,17 @@ class DialectReductionPatternInterface
   /// replacing an operation with a constant.
   virtual void populateReductionPatterns(RewritePatternSet &patterns) const = 0;
 
+  /// This method extends `populateReductionPatterns` by allowing reduction
+  /// patterns to use a `Tester` instance. Some reduction patterns may need to
+  /// run tester to determine whether certain transformations preserve the
+  /// "interesting" behavior of the program. This is mostly useful when pattern
+  /// should choose between multiple modifications.
+  virtual void populateReductionPatternsWithTester(RewritePatternSet &patterns,
+                                                   Tester &tester) const {}
+
 protected:
   DialectReductionPatternInterface(Dialect *dialect) : Base(dialect) {}
 };
-
 } // namespace mlir
 
 #endif // MLIR_REDUCER_REDUCTIONPATTERNINTERFACE_H

mlir/include/mlir/Reducer/Tester.h

@@ -36,6 +36,9 @@ class Tester {
     Untested,
   };
 
+  Tester() = default;
+  Tester(const Tester &) = default;
+
   Tester(StringRef testScript, ArrayRef<std::string> testScriptArgs);
 
   /// Runs the interestingness testing script on a MLIR test case file. Returns
@@ -46,6 +49,9 @@ class Tester {
   /// Return whether the file in the given path is interesting.
   Interestingness isInteresting(StringRef testCase) const;
 
+  void setTestScript(StringRef script) { testScript = script; }
+  void setTestScriptArgs(ArrayRef<std::string> args) { testScriptArgs = args; }
+
 private:
   StringRef testScript;
   ArrayRef<std::string> testScriptArgs;

mlir/lib/Reducer/ReductionTreePass.cpp

@@ -175,9 +175,12 @@ class ReductionPatternInterfaceCollection
   using Base::Base;
 
   // Collect the reduce patterns defined by each dialect.
-  void populateReductionPatterns(RewritePatternSet &pattern) const {
-    for (const DialectReductionPatternInterface &interface : *this)
+  void populateReductionPatterns(RewritePatternSet &pattern,
+                                 Tester &tester) const {
+    for (const DialectReductionPatternInterface &interface : *this) {
       interface.populateReductionPatterns(pattern);
+      interface.populateReductionPatternsWithTester(pattern, tester);
+    }
   }
 };
 
@@ -201,15 +204,21 @@ class ReductionTreePass
 private:
   LogicalResult reduceOp(ModuleOp module, Region &region);
 
+  Tester tester;
   FrozenRewritePatternSet reducerPatterns;
 };
 
 } // namespace
 
 LogicalResult ReductionTreePass::initialize(MLIRContext *context) {
+  tester.setTestScript(testerName);
+  tester.setTestScriptArgs(testerArgs);
+
   RewritePatternSet patterns(context);
+
   ReductionPatternInterfaceCollection reducePatternCollection(context);
-  reducePatternCollection.populateReductionPatterns(patterns);
+  reducePatternCollection.populateReductionPatterns(patterns, tester);
+
   reducerPatterns = std::move(patterns);
   return success();
 }
@@ -244,11 +253,10 @@ void ReductionTreePass::runOnOperation() {
 }
 
 LogicalResult ReductionTreePass::reduceOp(ModuleOp module, Region &region) {
-  Tester test(testerName, testerArgs);
   switch (traversalModeId) {
   case TraversalMode::SinglePath:
     return findOptimal<ReductionNode::iterator<TraversalMode::SinglePath>>(
-        module, region, reducerPatterns, test);
+        module, region, reducerPatterns, tester);
   default:
     return module.emitError() << "unsupported traversal mode detected";
   }