[flang-commits] [flang] [mlir] [mlir][IR] Move `match` and `rewrite` functions into separate class (PR #129861)

[Jacques Pienaar via flang-commits]

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@@ -528,24 +528,72 @@ class TypeConverter {
 // Conversion Patterns
 //===----------------------------------------------------------------------===//
 
+namespace detail {
+/// Helper class that derives from a ConversionRewritePattern class and
+/// provides separate `match` and `rewrite` entry points instead of a combined
+/// `matchAndRewrite`.
+template <typename PatternT>
+class ConversionSplitMatchAndRewriteImpl : public PatternT {
+  using PatternT::PatternT;
+
+  /// Rewrite the IR rooted at the specified operation with the result of
+  /// this pattern, generating any new operations with the specified
+  /// rewriter.
+  virtual void rewrite(typename PatternT::OperationT op,
+                       typename PatternT::OpAdaptor adaptor,
+                       ConversionPatternRewriter &rewriter) const {
+    // One of the two `rewrite` functions must be implemented.
+    llvm_unreachable("rewrite is not implemented");
+  }
+
+  virtual void rewrite(typename PatternT::OperationT op,
+                       typename PatternT::OneToNOpAdaptor adaptor,
+                       ConversionPatternRewriter &rewriter) const {
+    if constexpr (std::is_same<typename PatternT::OpAdaptor,
+                               ArrayRef<Value>>::value) {
+      rewrite(op, PatternT::getOneToOneAdaptorOperands(adaptor), rewriter);
+    } else {
+      SmallVector<Value> oneToOneOperands =
+          PatternT::getOneToOneAdaptorOperands(adaptor.getOperands());
+      rewrite(op, typename PatternT::OpAdaptor(oneToOneOperands, adaptor),
+              rewriter);
+    }
+  }
+
+  /// Attempt to match against code rooted at the specified operation,
+  /// which is the same operation code as getRootKind().
+  virtual LogicalResult match(typename PatternT::OperationT op) const = 0;
+
+  LogicalResult
+  matchAndRewrite(typename PatternT::OperationT op,
+                  typename PatternT::OpAdaptor adaptor,
+                  ConversionPatternRewriter &rewriter) const final {
+    llvm_unreachable("1:1 matchAndRewrite entry point is never used");
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jpienaar wrote:

I don't quite get this error message.

https://github.com/llvm/llvm-project/pull/129861