[mlir][CAPI] Allow specifying pass manager anchor

This adds a new function for creating pass managers that takes an
argument for the anchor string.

Reviewed By: mehdi_amini

Differential Revision: https://reviews.llvm.org/D136404

Author: rkayaith

mlir/include/mlir-c/Pass.h

@@ -51,9 +51,13 @@ DEFINE_C_API_STRUCT(MlirOpPassManager, void);
 // PassManager/OpPassManager APIs.
 //===----------------------------------------------------------------------===//
 
-/// Create a new top-level PassManager.
+/// Create a new top-level PassManager with the default anchor.
 MLIR_CAPI_EXPORTED MlirPassManager mlirPassManagerCreate(MlirContext ctx);
 
+/// Create a new top-level PassManager anchored on `anchorOp`.
+MLIR_CAPI_EXPORTED MlirPassManager
+mlirPassManagerCreateOnOperation(MlirContext ctx, MlirStringRef anchorOp);
+
 /// Destroy the provided PassManager.
 MLIR_CAPI_EXPORTED void mlirPassManagerDestroy(MlirPassManager passManager);
 

mlir/lib/CAPI/IR/Pass.cpp

@@ -24,6 +24,11 @@ MlirPassManager mlirPassManagerCreate(MlirContext ctx) {
   return wrap(new PassManager(unwrap(ctx)));
 }
 
+MlirPassManager mlirPassManagerCreateOnOperation(MlirContext ctx,
+                                                 MlirStringRef anchorOp) {
+  return wrap(new PassManager(unwrap(ctx), unwrap(anchorOp)));
+}
+
 void mlirPassManagerDestroy(MlirPassManager passManager) {
   delete unwrap(passManager);
 }

mlir/test/CAPI/pass.c

@@ -140,7 +140,8 @@ static void dontPrint(MlirStringRef str, void *userData) {
 
 void testPrintPassPipeline() {
   MlirContext ctx = mlirContextCreate();
-  MlirPassManager pm = mlirPassManagerCreate(ctx);
+  MlirPassManager pm = mlirPassManagerCreateOnOperation(
+      ctx, mlirStringRefCreateFromCString("any"));
   // Populate the pass-manager
   MlirOpPassManager nestedModulePm = mlirPassManagerGetNestedUnder(
       pm, mlirStringRefCreateFromCString("builtin.module"));
@@ -150,7 +151,7 @@ void testPrintPassPipeline() {
   mlirOpPassManagerAddOwnedPass(nestedFuncPm, printOpStatPass);
 
   // Print the top level pass manager
-  //      CHECK: Top-level: builtin.module(
+  //      CHECK: Top-level: any(
   // CHECK-SAME:   builtin.module(func.func(print-op-stats{json=false}))
   // CHECK-SAME: )
   fprintf(stderr, "Top-level: ");