[MLIR] Expose LocationAttrs in the C API

[youngar]

Summary

This patch adds three functions to the C API:

• mlirAttributeIsALocation: returns true if the attribute is a LocationAttr, false otherwise.
• mlirLocationGetAttribute: returns the underlying LocationAttr of a Location.
• mlirLocationFromAttribute: gets a Location from a LocationAttr.

[mikeurbach]

I think this looks good to me. Not sure why the pre-merge tests failed...

Also don't know who should be added as a reviewer. Looking at the git history, maybe @mehdi_amini, @ftynse, @rriddle, or @Mogball could take a look?

[youngar]

Apparently you should not upload patches created --no-prefix to phabricator. This fixes the issues, namely unintended file moving, which resulted from that.

mlir/include/mlir-c/BuiltinAttributes.h

 #ifdef __cplusplus
 extern "C" {
 #endif
 
 /// Returns an empty attribute.
 MLIR_CAPI_EXPORTED MlirAttribute mlirAttributeGetNull(void);
 
 //===----------------------------------------------------------------------===//
+// Location attribute.
+//===----------------------------------------------------------------------===//
+
+MLIR_CAPI_EXPORTED bool mlirAttributeIsALocation(MlirAttribute attr);
+
+//===----------------------------------------------------------------------===//
 // Affine map attribute.
 //===----------------------------------------------------------------------===//
 
 /// Checks whether the given attribute is an affine map attribute.
 MLIR_CAPI_EXPORTED bool mlirAttributeIsAAffineMap(MlirAttribute attr);
 
 /// Creates an affine map attribute wrapping the given map. The attribute
 /// belongs to the same context as the affine map.

mlir/include/mlir-c/IR.h

 /// Takes a dialect registry owned by the caller and destroys it.
 MLIR_CAPI_EXPORTED void
 mlirDialectRegistryDestroy(MlirDialectRegistry registry);
 
 //===----------------------------------------------------------------------===//
 // Location API.
 //===----------------------------------------------------------------------===//
 
+/// Returns the underlying location attribute of this location.
+MLIR_CAPI_EXPORTED MlirAttribute
+mlirLocationGetAttribute(MlirLocation location);
+
+/// Creates a location from a location attribute.
+MLIR_CAPI_EXPORTED MlirLocation
+mlirLocationFromAttribute(MlirAttribute attribute);
+
 /// Creates an File/Line/Column location owned by the given context.
 MLIR_CAPI_EXPORTED MlirLocation mlirLocationFileLineColGet(
     MlirContext context, MlirStringRef filename, unsigned line, unsigned col);
 
 /// Creates a call site location with a callee and a caller.
 MLIR_CAPI_EXPORTED MlirLocation mlirLocationCallSiteGet(MlirLocation callee,
                                                         MlirLocation caller);
 

mlir/lib/CAPI/IR/BuiltinAttributes.cpp

 #include "mlir/IR/BuiltinAttributes.h"
 #include "mlir/IR/BuiltinTypes.h"
 
 using namespace mlir;
 
 MlirAttribute mlirAttributeGetNull() { return {nullptr}; }
 
 //===----------------------------------------------------------------------===//
+// Location attribute.
+//===----------------------------------------------------------------------===//
+
+bool mlirAttributeIsALocation(MlirAttribute attr) {
+  return unwrap(attr).isa<LocationAttr>();
+}
+
+//===----------------------------------------------------------------------===//
 // Affine map attribute.
 //===----------------------------------------------------------------------===//
 
 bool mlirAttributeIsAAffineMap(MlirAttribute attr) {
   return unwrap(attr).isa<AffineMapAttr>();
 }
 
 MlirAttribute mlirAffineMapAttrGet(MlirAffineMap map) {

mlir/lib/CAPI/IR/IR.cpp

 void mlirOpPrintingFlagsUseLocalScope(MlirOpPrintingFlags flags) {
   unwrap(flags)->useLocalScope();
 }
 
 //===----------------------------------------------------------------------===//
 // Location API.
 //===----------------------------------------------------------------------===//
 
+MlirAttribute mlirLocationGetAttribute(MlirLocation location) {
+  return wrap(LocationAttr(unwrap(location)));
+}
+
+MlirLocation mlirLocationFromAttribute(MlirAttribute attribute) {
+  return wrap(Location(unwrap(attribute).cast<LocationAttr>()));
+}
+
 MlirLocation mlirLocationFileLineColGet(MlirContext context,
                                         MlirStringRef filename, unsigned line,
                                         unsigned col) {
   return wrap(Location(
       FileLineColLoc::get(unwrap(context), unwrap(filename), line, col)));
 }
 
 MlirLocation mlirLocationCallSiteGet(MlirLocation callee, MlirLocation caller) {

mlir/test/CAPI/ir.c

if (mlirDenseUInt8ResourceElementsAttrGetValue(uint8Blob, 1) != 1 ||
       mlirDenseInt64ResourceElementsAttrGetValue(int64Blob, 1) != 1 ||
       fabsf(mlirDenseF32ArrayGetElement(floatArray, 1) - 1.0f) > 1E-6f ||
       fabsf(mlirDenseFloatResourceElementsAttrGetValue(floatsBlob, 1) - 1.0f) >
           1e-6 ||
       fabs(mlirDenseDoubleResourceElementsAttrGetValue(doublesBlob, 1) - 1.0f) >
           1e-6)
     return 23;
 
+  MlirLocation loc = mlirLocationUnknownGet(ctx);
+  MlirAttribute locAttr = mlirLocationGetAttribute(loc);
+  if (!mlirAttributeIsALocation(locAttr))
+    return 24;
+
   return 0;
 }
 
 int printAffineMap(MlirContext ctx) {
   MlirAffineMap emptyAffineMap = mlirAffineMapEmptyGet(ctx);
   MlirAffineMap affineMap = mlirAffineMapZeroResultGet(ctx, 3, 2);
   MlirAffineMap constAffineMap = mlirAffineMapConstantGet(ctx, 2);
   MlirAffineMap multiDimIdentityAffineMap =

 
 void testDiagnostics(void) {
   MlirContext ctx = mlirContextCreate();
   MlirDiagnosticHandlerID id = mlirContextAttachDiagnosticHandler(
       ctx, errorHandler, (void *)42, deleteUserData);
   fprintf(stderr, "@test_diagnostics\n");
   MlirLocation unknownLoc = mlirLocationUnknownGet(ctx);
   mlirEmitError(unknownLoc, "test diagnostics");
+  MlirAttribute unknownAttr = mlirLocationGetAttribute(unknownLoc);
+  MlirLocation unknownClone = mlirLocationFromAttribute(unknownAttr);
+  mlirEmitError(unknownClone, "test clone");
   MlirLocation fileLineColLoc = mlirLocationFileLineColGet(
       ctx, mlirStringRefCreateFromCString("file.c"), 1, 2);
   mlirEmitError(fileLineColLoc, "test diagnostics");
   MlirLocation callSiteLoc = mlirLocationCallSiteGet(
       mlirLocationFileLineColGet(
           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");
   MlirLocation locs[2] = {nameLoc, callSiteLoc};
   MlirAttribute nullAttr = {0};
   MlirLocation fusedLoc = mlirLocationFusedGet(ctx, 2, locs, nullAttr);
   mlirEmitError(fusedLoc, "test diagnostics");
   mlirContextDetachDiagnosticHandler(ctx, id);
   mlirEmitError(unknownLoc, "more test diagnostics");
   // CHECK-LABEL: @test_diagnostics
   // CHECK: processing diagnostic (userData: 42) <<
   // CHECK:   test diagnostics
   // CHECK:   loc(unknown)
+  // CHECK: processing diagnostic (userData: 42) <<
+  // CHECK:   test clone
+  // CHECK:   loc(unknown)
   // CHECK: >> end of diagnostic (userData: 42)
   // CHECK: processing diagnostic (userData: 42) <<
   // CHECK:   test diagnostics
   // CHECK:   loc("file.c":1:2)
   // CHECK: >> end of diagnostic (userData: 42)
   // CHECK: processing diagnostic (userData: 42) <<
   // CHECK:   test diagnostics
   // CHECK:   loc(callsite("other-file.c":2:3 at "file.c":1:2))