add more docs and fix some name

Author: PragmaTwice

mlir/include/mlir-c/Rewrite.h

@@ -303,11 +303,15 @@ MLIR_CAPI_EXPORTED void mlirIRRewriterDestroy(MlirRewriterBase rewriter);
 /// FrozenRewritePatternSet API
 //===----------------------------------------------------------------------===//
 
+/// Freeze the given MlirRewritePatternSet to a MlirFrozenRewritePatternSet.
+/// Note that the ownership of the input set is transferred into the frozen set
+/// after this call.
 MLIR_CAPI_EXPORTED MlirFrozenRewritePatternSet
-mlirFreezeRewritePattern(MlirRewritePatternSet op);
+mlirFreezeRewritePattern(MlirRewritePatternSet set);
 
+/// Destroy the given MlirFrozenRewritePatternSet.
 MLIR_CAPI_EXPORTED void
-mlirFrozenRewritePatternSetDestroy(MlirFrozenRewritePatternSet op);
+mlirFrozenRewritePatternSetDestroy(MlirFrozenRewritePatternSet set);
 
 MLIR_CAPI_EXPORTED MlirLogicalResult mlirApplyPatternsAndFoldGreedilyWithOp(
     MlirOperation op, MlirFrozenRewritePatternSet patterns,
@@ -368,6 +372,8 @@ mlirRewritePatternSetCreate(MlirContext context);
 MLIR_CAPI_EXPORTED void mlirRewritePatternSetDestroy(MlirRewritePatternSet set);
 
 /// Add the given MlirRewritePattern into a MlirRewritePatternSet.
+/// Note that the ownership of the pattern is transferred to the set after this
+/// call.
 MLIR_CAPI_EXPORTED void mlirRewritePatternSetAdd(MlirRewritePatternSet set,
                                                  MlirRewritePattern pattern);
 

mlir/lib/Bindings/Python/Rewrite.cpp

@@ -202,7 +202,11 @@ class PyRewritePatternSet {
     mlirRewritePatternSetAdd(set, pattern);
   }
 
-  PyFrozenRewritePatternSet freeze() { return mlirFreezeRewritePattern(set); }
+  PyFrozenRewritePatternSet freeze() {
+    MlirRewritePatternSet s = set;
+    set.ptr = nullptr;
+    return mlirFreezeRewritePattern(s);
+  }
 
 private:
   MlirRewritePatternSet set;

mlir/lib/CAPI/Transforms/Rewrite.cpp

@@ -291,15 +291,16 @@ wrap(mlir::FrozenRewritePatternSet *module) {
   return {module};
 }
 
-MlirFrozenRewritePatternSet mlirFreezeRewritePattern(MlirRewritePatternSet op) {
-  auto *m = new mlir::FrozenRewritePatternSet(std::move(*unwrap(op)));
-  op.ptr = nullptr;
+MlirFrozenRewritePatternSet
+mlirFreezeRewritePattern(MlirRewritePatternSet set) {
+  auto *m = new mlir::FrozenRewritePatternSet(std::move(*unwrap(set)));
+  set.ptr = nullptr;
   return wrap(m);
 }
 
-void mlirFrozenRewritePatternSetDestroy(MlirFrozenRewritePatternSet op) {
-  delete unwrap(op);
-  op.ptr = nullptr;
+void mlirFrozenRewritePatternSetDestroy(MlirFrozenRewritePatternSet set) {
+  delete unwrap(set);
+  set.ptr = nullptr;
 }
 
 MlirLogicalResult