[MLIR] Add an OpRewritePattern constructor that uses generated names

[ahmedsabie]

Summary

This constructor is useful to have since generated names affects the cost graph, and OpRewritePattern are often used with specific generatedNames in mind

[mehdi_amini]

No way to test/use it in tree?

[ahmedsabie]

Sorry forgot this never actually ended up getting pushed and it's my last day

mlir/include/mlir/IR/PatternMatch.h

 /// matching and rewriting against an instance of a derived operation class as
 /// opposed to a raw Operation.
 template <typename SourceOp> struct OpRewritePattern : public RewritePattern {
   /// Patterns must specify the root operation name they match against, and can
   /// also specify the benefit of the pattern matching.
   OpRewritePattern(MLIRContext *context, PatternBenefit benefit = 1)
       : RewritePattern(SourceOp::getOperationName(), benefit, context) {}
 
+  /// Patterns must specify the root operation name they match against, and can
+  /// also specify the benefit of the pattern matching.
+  /// `generatedNames` contains the names of operations that may be generated
+  /// during a successful rewrite.
+  OpRewritePattern(MLIRContext *context, ArrayRef<StringRef> generatedNames,
+                   PatternBenefit benefit = 1)
+      : RewritePattern(SourceOp::getOperationName(), generatedNames, benefit,
+                       context) {}
+
   /// Wrappers around the RewritePattern methods that pass the derived op type.
   void rewrite(Operation *op, PatternRewriter &rewriter) const final {
     rewrite(cast<SourceOp>(op), rewriter);
   }
   LogicalResult match(Operation *op) const final {
     return match(cast<SourceOp>(op));
   }
   LogicalResult matchAndRewrite(Operation *op,