[mlir][capi] Add NameLoc

Add method to get NameLoc. Treat null child location as unknown to avoid
needing to create UnknownLoc in C API where child loc is not needed.

Differential Revision: https://reviews.llvm.org/D108678

Author: jpienaar

mlir/include/mlir-c/IR.h

@@ -162,6 +162,13 @@ MLIR_CAPI_EXPORTED MlirLocation mlirLocationFileLineColGet(
 MLIR_CAPI_EXPORTED MlirLocation mlirLocationCallSiteGet(MlirLocation callee,
                                                         MlirLocation caller);
 
+/// Creates a name location owned by the given context. Providing null location
+/// for childLoc is allowed and if childLoc is null location, then the behavior
+/// is the same as having unknown child location.
+MLIR_CAPI_EXPORTED MlirLocation mlirLocationNameGet(MlirContext context,
+                                                    MlirStringRef name,
+                                                    MlirLocation childLoc);
+
 /// Creates a location with unknown position owned by the given context.
 MLIR_CAPI_EXPORTED MlirLocation mlirLocationUnknownGet(MlirContext context);
 

mlir/lib/CAPI/IR/IR.cpp

@@ -15,6 +15,7 @@
 #include "mlir/IR/Attributes.h"
 #include "mlir/IR/BuiltinOps.h"
 #include "mlir/IR/Dialect.h"
+#include "mlir/IR/Location.h"
 #include "mlir/IR/Operation.h"
 #include "mlir/IR/Types.h"
 #include "mlir/IR/Verifier.h"
@@ -131,6 +132,15 @@ MlirLocation mlirLocationCallSiteGet(MlirLocation callee, MlirLocation caller) {
   return wrap(Location(CallSiteLoc::get(unwrap(callee), unwrap(caller))));
 }
 
+MlirLocation mlirLocationNameGet(MlirContext context, MlirStringRef name,
+                                 MlirLocation childLoc) {
+  if (mlirLocationIsNull(childLoc))
+    return wrap(
+        Location(NameLoc::get(Identifier::get(unwrap(name), unwrap(context)))));
+  return wrap(Location(NameLoc::get(
+      Identifier::get(unwrap(name), unwrap(context)), unwrap(childLoc))));
+}
+
 MlirLocation mlirLocationUnknownGet(MlirContext context) {
   return wrap(Location(UnknownLoc::get(unwrap(context))));
 }

mlir/test/CAPI/ir.c

@@ -19,6 +19,7 @@
 #include "mlir-c/Dialect/Standard.h"
 #include "mlir-c/IntegerSet.h"
 #include "mlir-c/Registration.h"
+#include "mlir-c/Support.h"
 
 #include <assert.h>
 #include <inttypes.h>
@@ -1703,6 +1704,10 @@ void testDiagnostics() {
           ctx, mlirStringRefCreateFromCString("other-file.c"), 2, 3),
       fileLineColLoc);
   mlirEmitError(callSiteLoc, "test diagnostics");
+  MlirLocation null = {0};
+  MlirLocation nameLoc =
+      mlirLocationNameGet(ctx, mlirStringRefCreateFromCString("named"), null);
+  mlirEmitError(nameLoc, "test diagnostics");
   mlirContextDetachDiagnosticHandler(ctx, id);
   mlirEmitError(unknownLoc, "more test diagnostics");
   // CHECK-LABEL: @test_diagnostics
@@ -1718,6 +1723,10 @@ void testDiagnostics() {
   // CHECK:   test diagnostics
   // CHECK:   loc(callsite("other-file.c":2:3 at "file.c":1:2))
   // CHECK: >> end of diagnostic (userData: 42)
+  // CHECK: processing diagnostic (userData: 42) <<
+  // CHECK:   test diagnostics
+  // CHECK:   loc("named")
+  // CHECK: >> end of diagnostic (userData: 42)
   // CHECK: deleting user data (userData: 42)
   // CHECK-NOT: processing diagnostic
   // CHECK:     more test diagnostics