[MLIR][LLVM] Support Recursive DITypes

mlir/include/mlir-c/Dialect/LLVM.h

@@ -229,10 +229,10 @@ MLIR_CAPI_EXPORTED MlirAttribute mlirLLVMDIBasicTypeAttrGet(
 
 /// Creates a LLVM DICompositeType attribute.
 MLIR_CAPI_EXPORTED MlirAttribute mlirLLVMDICompositeTypeAttrGet(
-    MlirContext ctx, unsigned int tag, MlirAttribute name, MlirAttribute file,
-    uint32_t line, MlirAttribute scope, MlirAttribute baseType, int64_t flags,
-    uint64_t sizeInBits, uint64_t alignInBits, intptr_t nElements,
-    MlirAttribute const *elements);
+    MlirContext ctx, unsigned int tag, MlirAttribute recId, MlirAttribute name,
+    MlirAttribute file, uint32_t line, MlirAttribute scope,
+    MlirAttribute baseType, int64_t flags, uint64_t sizeInBits,
+    uint64_t alignInBits, intptr_t nElements, MlirAttribute const *elements);
 
 /// Creates a LLVM DIDerivedType attribute.
 MLIR_CAPI_EXPORTED MlirAttribute mlirLLVMDIDerivedTypeAttrGet(

mlir/include/mlir/Dialect/LLVMIR/CMakeLists.txt

@@ -29,6 +29,8 @@ add_mlir_doc(LLVMIntrinsicOps LLVMIntrinsicOps Dialects/ -gen-op-doc)
 set(LLVM_TARGET_DEFINITIONS LLVMInterfaces.td)
 mlir_tablegen(LLVMInterfaces.h.inc -gen-op-interface-decls)
 mlir_tablegen(LLVMInterfaces.cpp.inc -gen-op-interface-defs)
+mlir_tablegen(LLVMAttrInterfaces.h.inc -gen-attr-interface-decls)
+mlir_tablegen(LLVMAttrInterfaces.cpp.inc -gen-attr-interface-defs)
 mlir_tablegen(LLVMTypeInterfaces.h.inc -gen-type-interface-decls)
 mlir_tablegen(LLVMTypeInterfaces.cpp.inc -gen-type-interface-defs)
 add_public_tablegen_target(MLIRLLVMInterfacesIncGen)

mlir/include/mlir/Dialect/LLVMIR/LLVMAttrDefs.td

@@ -10,6 +10,7 @@
 #define LLVMIR_ATTRDEFS
 
 include "mlir/Dialect/LLVMIR/LLVMDialect.td"
+include "mlir/Dialect/LLVMIR/LLVMInterfaces.td"
 include "mlir/IR/AttrTypeBase.td"
 include "mlir/IR/CommonAttrConstraints.td"
 
@@ -238,41 +239,43 @@ def LoopAnnotationAttr : LLVM_Attr<"LoopAnnotation", "loop_annotation"> {
 //===----------------------------------------------------------------------===//
 
 class LLVM_DIParameter<string summary, string default, string parseName,
-                       string printName = parseName>
+                       string errorCase, string printName = parseName>
     : AttrOrTypeParameter<"unsigned", "debug info " # summary> {
   let parser = [{ [&]() -> FailureOr<unsigned> {
     SMLoc tagLoc = $_parser.getCurrentLocation();
     StringRef name;
     if ($_parser.parseKeyword(&name))
       return failure();
 
-    if (unsigned tag = llvm::dwarf::get}] # parseName # [{(name))
-      return tag;
-    return $_parser.emitError(tagLoc)
-      << "invalid debug info }] # summary # [{ name: " << name;
+    unsigned tag = llvm::dwarf::get}] # parseName # [{(name);
+    if (tag == }] # errorCase # [{)
+      return $_parser.emitError(tagLoc)
+        << "invalid debug info }] # summary # [{ name: " << name;
+    return tag;
   }() }];
   let printer = "$_printer << llvm::dwarf::" # printName # "String($_self)";
   let defaultValue = default;
 }
 
 def LLVM_DICallingConventionParameter : LLVM_DIParameter<
-  "calling convention", /*default=*/"0", "CallingConvention", "Convention"
+  "calling convention", /*default=*/"0", "CallingConvention", /*errorCase=*/"0",
+  "Convention"
 >;
 
 def LLVM_DIEncodingParameter : LLVM_DIParameter<
-  "encoding", /*default=*/"0", "AttributeEncoding"
+  "encoding", /*default=*/"0", "AttributeEncoding", /*errorCase=*/"0"
 >;
 
 def LLVM_DILanguageParameter : LLVM_DIParameter<
-  "language", /*default=*/"", "Language"
+  "language", /*default=*/"", "Language", /*errorCase=*/"0"
 >;
 
 def LLVM_DITagParameter : LLVM_DIParameter<
-  "tag", /*default=*/"", "Tag"
+  "tag", /*default=*/"", "Tag", /*errorCase=*/"llvm::dwarf::DW_TAG_invalid"
 >;
 
 def LLVM_DIOperationEncodingParameter : LLVM_DIParameter<
-  "operation encoding", /*default=*/"", "OperationEncoding"
+  "operation encoding", /*default=*/"", "OperationEncoding", /*errorCase=*/"0"
 >;
 
 //===----------------------------------------------------------------------===//
@@ -357,9 +360,11 @@ def LLVM_DICompileUnitAttr : LLVM_Attr<"DICompileUnit", "di_compile_unit",
 //===----------------------------------------------------------------------===//
 
 def LLVM_DICompositeTypeAttr : LLVM_Attr<"DICompositeType", "di_composite_type",
-                                         /*traits=*/[], "DITypeAttr"> {
+                                         [LLVM_DIRecursiveTypeAttrInterface],
+                                         "DITypeAttr"> {
   let parameters = (ins
     LLVM_DITagParameter:$tag,
+    OptionalParameter<"DistinctAttr">:$recId,
     OptionalParameter<"StringAttr">:$name,
     OptionalParameter<"DIFileAttr">:$file,
     OptionalParameter<"uint32_t">:$line,
@@ -371,6 +376,21 @@ def LLVM_DICompositeTypeAttr : LLVM_Attr<"DICompositeType", "di_composite_type",
     OptionalArrayRefParameter<"DINodeAttr">:$elements
   );
   let assemblyFormat = "`<` struct(params) `>`";
+  let extraClassDeclaration = [{
+    /// Requirements of DIRecursiveTypeAttrInterface.
+    /// @{
+
+    /// Get whether this attr describes a recursive self reference.
+    bool isRecSelf() { return getTag() == 0; }
+
+    /// Get a copy of this type attr but with the recursive ID set to `recId`.
+    DIRecursiveTypeAttrInterface withRecId(DistinctAttr recId);
+
+    /// Build a rec-self instance using the provided `recId`.
+    static DIRecursiveTypeAttrInterface getRecSelf(DistinctAttr recId);
+
+    /// @}
+  }];
 }
 
 //===----------------------------------------------------------------------===//

mlir/include/mlir/Dialect/LLVMIR/LLVMAttrs.h

@@ -84,6 +84,8 @@ using linkage::Linkage;
 } // namespace LLVM
 } // namespace mlir
 
+#include "mlir/Dialect/LLVMIR/LLVMAttrInterfaces.h.inc"
+
 #define GET_ATTRDEF_CLASSES
 #include "mlir/Dialect/LLVMIR/LLVMOpsAttrDefs.h.inc"
 

mlir/include/mlir/Dialect/LLVMIR/LLVMInterfaces.td

@@ -6,7 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// This file defines op and type interfaces for the LLVM dialect in MLIR.
+// This file defines interfaces for the LLVM dialect in MLIR.
 //
 //===----------------------------------------------------------------------===//
 
@@ -319,4 +319,58 @@ def LLVM_PointerElementTypeInterface
   ];
 }
 
+//===----------------------------------------------------------------------===//
+// LLVM dialect attr interfaces.
+//===----------------------------------------------------------------------===//
+
+def LLVM_DIRecursiveTypeAttrInterface
+  : AttrInterface<"DIRecursiveTypeAttrInterface"> {
+  let description = [{
+    This attribute represents a DITypeAttr that is recursive. Only DITypeAttrs
+    that translate to LLVM DITypes that support mutation should implement this
+    interface.
+
+    There are two modes for conforming attributes:
+
+    1. "rec-decl":
+      - This attr is a recursive declaration identified by a recId.
+
+    2. "rec-self":
+      - This attr is considered a recursive self reference.
+      - This attr itself is a placeholder type that should be conceptually
+        replaced with the closest parent attr of the same type with the same
+        recId.
+
+    For example, to represent a linked list struct:
+
+      #rec_self = di_composite_type<recId = 0>
+      #ptr = di_derived_type<baseType: #rec_self, ...>
+      #field = di_derived_type<name = "next", baseType: #ptr, ...>
+      #rec = di_composite_type<recId = 0, name = "Node", elements: #field, ...>
+      #var = di_local_variable<type = #rec, ...>
+
+    Note that a rec-self without an outer rec-decl with the same recId is
+    conceptually the same as an "unbound" variable. The context needs to provide
+    meaning to the rec-self.
+  }];
+  let cppNamespace = "::mlir::LLVM";
+  let methods = [
+    InterfaceMethod<[{
+      Get whether this attr describes a recursive self reference.
+    }], "bool", "isRecSelf", (ins)>,
+    InterfaceMethod<[{
+      Get the recursive ID used for matching "rec-decl" with "rec-self".
+      If this attr instance is not recursive, return a null attribute.
+    }], "DistinctAttr", "getRecId", (ins)>,
+    InterfaceMethod<[{
+      Get a copy of this type attr but with the recursive ID set to `recId`.
+    }], "DIRecursiveTypeAttrInterface", "withRecId",
+    (ins "DistinctAttr":$recId)>,
+    StaticInterfaceMethod<[{
+      Build a rec-self instance using the provided `recId`.
+    }], "DIRecursiveTypeAttrInterface", "getRecSelf",
+    (ins "DistinctAttr":$recId)>
+  ];
+}
+
 #endif // LLVMIR_INTERFACES

mlir/lib/CAPI/Dialect/LLVM.cpp

@@ -152,18 +152,18 @@ MlirAttribute mlirLLVMDIBasicTypeAttrGet(MlirContext ctx, unsigned int tag,
 }
 
 MlirAttribute mlirLLVMDICompositeTypeAttrGet(
-    MlirContext ctx, unsigned int tag, MlirAttribute name, MlirAttribute file,
-    uint32_t line, MlirAttribute scope, MlirAttribute baseType, int64_t flags,
-    uint64_t sizeInBits, uint64_t alignInBits, intptr_t nElements,
-    MlirAttribute const *elements) {
+    MlirContext ctx, unsigned int tag, MlirAttribute recId, MlirAttribute name,
+    MlirAttribute file, uint32_t line, MlirAttribute scope,
+    MlirAttribute baseType, int64_t flags, uint64_t sizeInBits,
+    uint64_t alignInBits, intptr_t nElements, MlirAttribute const *elements) {
   SmallVector<Attribute> elementsStorage;
   elementsStorage.reserve(nElements);
 
   return wrap(DICompositeTypeAttr::get(
-      unwrap(ctx), tag, cast<StringAttr>(unwrap(name)),
-      cast<DIFileAttr>(unwrap(file)), line, cast<DIScopeAttr>(unwrap(scope)),
-      cast<DITypeAttr>(unwrap(baseType)), DIFlags(flags), sizeInBits,
-      alignInBits,
+      unwrap(ctx), tag, cast<DistinctAttr>(unwrap(recId)),
+      cast<StringAttr>(unwrap(name)), cast<DIFileAttr>(unwrap(file)), line,
+      cast<DIScopeAttr>(unwrap(scope)), cast<DITypeAttr>(unwrap(baseType)),
+      DIFlags(flags), sizeInBits, alignInBits,
       llvm::map_to_vector(unwrapList(nElements, elements, elementsStorage),
                           [](Attribute a) { return a.cast<DINodeAttr>(); })));
 }

mlir/lib/Dialect/LLVMIR/IR/LLVMAttrs.cpp

@@ -35,6 +35,7 @@ static LogicalResult parseExpressionArg(AsmParser &parser, uint64_t opcode,
 static void printExpressionArg(AsmPrinter &printer, uint64_t opcode,
                                ArrayRef<uint64_t> args);
 
+#include "mlir/Dialect/LLVMIR/LLVMAttrInterfaces.cpp.inc"
 #include "mlir/Dialect/LLVMIR/LLVMOpsEnums.cpp.inc"
 #define GET_ATTRDEF_CLASSES
 #include "mlir/Dialect/LLVMIR/LLVMOpsAttrDefs.cpp.inc"
@@ -185,6 +186,24 @@ void printExpressionArg(AsmPrinter &printer, uint64_t opcode,
   });
 }
 
+//===----------------------------------------------------------------------===//
+// DICompositeTypeAttr
+//===----------------------------------------------------------------------===//
+
+DIRecursiveTypeAttrInterface
+DICompositeTypeAttr::withRecId(DistinctAttr recId) {
+  return DICompositeTypeAttr::get(getContext(), getTag(), recId, getName(),
+                                  getFile(), getLine(), getScope(),
+                                  getBaseType(), getFlags(), getSizeInBits(),
+                                  getAlignInBits(), getElements());
+}
+
+DIRecursiveTypeAttrInterface
+DICompositeTypeAttr::getRecSelf(DistinctAttr recId) {
+  return DICompositeTypeAttr::get(recId.getContext(), 0, recId, {}, {}, 0, {},
+                                  {}, DIFlags(), 0, 0, {});
+}
+
 //===----------------------------------------------------------------------===//
 // TargetFeaturesAttr
 //===----------------------------------------------------------------------===//