[CIR] Add basic support for data member pointers #170939

andykaylor · 2025-12-05T22:38:13Z

This adds the minimum support for C++ data member pointer variables.

llvmbot · 2025-12-05T22:38:47Z

@llvm/pr-subscribers-clangir

Author: Andy Kaylor (andykaylor)

Changes

This adds the minimum support for C++ data member pointer variables.

Patch is 37.69 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/170939.diff

26 Files Affected:

(modified) clang/include/clang/CIR/Dialect/IR/CIRAttrs.h (+1)
(modified) clang/include/clang/CIR/Dialect/IR/CIRAttrs.td (+51)
(modified) clang/include/clang/CIR/Dialect/IR/CIRTypeConstraints.td (+9-1)
(modified) clang/include/clang/CIR/Dialect/IR/CIRTypes.td (+31-1)
(modified) clang/include/clang/CIR/MissingFeatures.h (+5)
(modified) clang/lib/CIR/CodeGen/CIRGenBuilder.h (+5)
(modified) clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp (+2-5)
(modified) clang/lib/CIR/CodeGen/CIRGenModule.cpp (+20)
(modified) clang/lib/CIR/CodeGen/CIRGenModule.h (+2)
(modified) clang/lib/CIR/CodeGen/CIRGenTypes.cpp (+15)
(modified) clang/lib/CIR/Dialect/IR/CIRAttrs.cpp (+32)
(modified) clang/lib/CIR/Dialect/IR/CIRDialect.cpp (+6)
(modified) clang/lib/CIR/Dialect/IR/CIRTypes.cpp (+20)
(modified) clang/lib/CIR/Dialect/Transforms/CMakeLists.txt (+3)
(added) clang/lib/CIR/Dialect/Transforms/TargetLowering/CIRCXXABI.cpp (+20)
(added) clang/lib/CIR/Dialect/Transforms/TargetLowering/CIRCXXABI.h (+55)
(added) clang/lib/CIR/Dialect/Transforms/TargetLowering/CMakeLists.txt (+20)
(added) clang/lib/CIR/Dialect/Transforms/TargetLowering/LowerItaniumCXXABI.cpp (+90)
(added) clang/lib/CIR/Dialect/Transforms/TargetLowering/LowerModule.cpp (+87)
(added) clang/lib/CIR/Dialect/Transforms/TargetLowering/LowerModule.h (+55)
(modified) clang/lib/CIR/Lowering/DirectToLLVM/CMakeLists.txt (+5)
(modified) clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp (+31-3)
(modified) clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.h (+2)
(added) clang/test/CIR/CodeGen/pointer-to-data-member.cpp (+35)
(added) clang/test/CIR/IR/invalid-data-member.cir (+27)
(modified) clang/utils/TableGen/CIRLoweringEmitter.cpp (+5-2)

diff --git a/clang/include/clang/CIR/Dialect/IR/CIRAttrs.h b/clang/include/clang/CIR/Dialect/IR/CIRAttrs.h
index 03a6a97dc8c2e..858d4d6350bed 100644
--- a/clang/include/clang/CIR/Dialect/IR/CIRAttrs.h
+++ b/clang/include/clang/CIR/Dialect/IR/CIRAttrs.h
@@ -35,6 +35,7 @@ namespace cir {
 class ArrayType;
 class BoolType;
 class ComplexType;
+class DataMemberType;
 class IntType;
 class MethodType;
 class PointerType;
diff --git a/clang/include/clang/CIR/Dialect/IR/CIRAttrs.td b/clang/include/clang/CIR/Dialect/IR/CIRAttrs.td
index 98d4636dafc29..c0279a0b20670 100644
--- a/clang/include/clang/CIR/Dialect/IR/CIRAttrs.td
+++ b/clang/include/clang/CIR/Dialect/IR/CIRAttrs.td
@@ -447,6 +447,57 @@ def CIR_ConstPtrAttr : CIR_Attr<"ConstPtr", "ptr", [TypedAttrInterface]> {
   }];
 }
 
+//===----------------------------------------------------------------------===//
+// DataMemberAttr
+//===----------------------------------------------------------------------===//
+
+def CIR_DataMemberAttr : CIR_Attr<"DataMember", "data_member", [
+  TypedAttrInterface
+]> {
+  let summary = "Holds a constant data member pointer value";
+  let parameters = (ins AttributeSelfTypeParameter<
+                            "", "cir::DataMemberType">:$type,
+                        OptionalParameter<
+                            "std::optional<unsigned>">:$member_index);
+  let description = [{
+    A data member attribute is a literal attribute that represents a constant
+    pointer-to-data-member value.
+
+    The `member_index` parameter represents the index of the pointed-to member
+    within its containing record. It is an optional parameter; lack of this
+    parameter indicates a null pointer-to-data-member value.
+
+    Example:
+    ```
+    #ptr = #cir.data_member<1> : !cir.data_member<!s32i in !rec_22Point22>
+
+    #null = #cir.data_member<null> : !cir.data_member<!s32i in !rec_22Point22>
+    ```
+  }];
+
+  let builders = [
+    AttrBuilderWithInferredContext<(ins "cir::DataMemberType":$type), [{
+      return $_get(type.getContext(), type, std::nullopt);
+    }]>,
+    AttrBuilderWithInferredContext<(ins "cir::DataMemberType":$type,
+                                        "unsigned":$member_index), [{
+      return $_get(type.getContext(), type, member_index);
+    }]>,
+  ];
+
+  let genVerifyDecl = 1;
+
+  let assemblyFormat = [{
+    `<` ($member_index^):(`null`)? `>`
+  }];
+
+  let extraClassDeclaration = [{
+    bool isNullPtr() const {
+      return !getMemberIndex().has_value();
+    }
+  }];
+}
+
 //===----------------------------------------------------------------------===//
 // GlobalViewAttr
 //===----------------------------------------------------------------------===//
diff --git a/clang/include/clang/CIR/Dialect/IR/CIRTypeConstraints.td b/clang/include/clang/CIR/Dialect/IR/CIRTypeConstraints.td
index ddca98eac93ab..89762249ed0c4 100644
--- a/clang/include/clang/CIR/Dialect/IR/CIRTypeConstraints.td
+++ b/clang/include/clang/CIR/Dialect/IR/CIRTypeConstraints.td
@@ -309,6 +309,13 @@ def CIR_AnyFloatOrVecOfFloatType
     let cppFunctionName = "isFPOrVectorOfFPType";
 }
 
+//===----------------------------------------------------------------------===//
+// Data member type predicates
+//===----------------------------------------------------------------------===//
+
+def CIR_AnyDataMemberType : CIR_TypeBase<"::cir::DataMemberType",
+    "data member type">;
+
 //===----------------------------------------------------------------------===//
 // VPtr type predicates
 //===----------------------------------------------------------------------===//
@@ -322,7 +329,8 @@ def CIR_PtrToVPtr : CIR_PtrToType<CIR_AnyVPtrType>;
 //===----------------------------------------------------------------------===//
 
 defvar CIR_ScalarTypes = [
-    CIR_AnyBoolType, CIR_AnyIntType, CIR_AnyFloatType, CIR_AnyPtrType
+    CIR_AnyBoolType, CIR_AnyIntType, CIR_AnyFloatType, CIR_AnyPtrType,
+    CIR_AnyDataMemberType, CIR_AnyVPtrType
 ];
 
 def CIR_AnyScalarType : AnyTypeOf<CIR_ScalarTypes, "cir scalar type"> {
diff --git a/clang/include/clang/CIR/Dialect/IR/CIRTypes.td b/clang/include/clang/CIR/Dialect/IR/CIRTypes.td
index 3e062add6633a..59b97f0c6d39a 100644
--- a/clang/include/clang/CIR/Dialect/IR/CIRTypes.td
+++ b/clang/include/clang/CIR/Dialect/IR/CIRTypes.td
@@ -305,6 +305,36 @@ def CIR_PointerType : CIR_Type<"Pointer", "ptr", [
   }];
 }
 
+//===----------------------------------------------------------------------===//
+// CIR_DataMemberType
+//===----------------------------------------------------------------------===//
+
+def CIR_DataMemberType : CIR_Type<"DataMember", "data_member",
+    [DeclareTypeInterfaceMethods<DataLayoutTypeInterface>]
+> {
+  let summary = "CIR type that represents a pointer-to-data-member in C++";
+  let description = [{
+    `cir.data_member` models a pointer-to-data-member in C++. Values of this
+    type are essentially offsets of the pointed-to member within one of its
+    containing record.
+  }];
+
+  let parameters = (ins "mlir::Type":$member_ty,
+                        "cir::RecordType":$class_ty);
+
+  let builders = [
+    TypeBuilderWithInferredContext<(ins
+      "mlir::Type":$member_ty, "cir::RecordType":$class_ty
+    ), [{
+      return $_get(member_ty.getContext(), member_ty, class_ty);
+    }]>,
+  ];
+
+  let assemblyFormat = [{
+    `<` $member_ty `in` $class_ty `>`
+  }];
+}
+
 //===----------------------------------------------------------------------===//
 // CIR_VPtrType
 //===----------------------------------------------------------------------===//
@@ -693,7 +723,7 @@ def CIRRecordType : Type<
 def CIR_AnyType : AnyTypeOf<[
   CIR_VoidType, CIR_BoolType, CIR_ArrayType, CIR_VectorType, CIR_IntType,
   CIR_AnyFloatType, CIR_PointerType, CIR_FuncType, CIR_RecordType,
-  CIR_ComplexType, CIR_VPtrType
+  CIR_ComplexType, CIR_VPtrType, CIR_DataMemberType
 ]>;
 
 #endif // CLANG_CIR_DIALECT_IR_CIRTYPES_TD
diff --git a/clang/include/clang/CIR/MissingFeatures.h b/clang/include/clang/CIR/MissingFeatures.h
index b8df0528ea18d..51d18750e72ac 100644
--- a/clang/include/clang/CIR/MissingFeatures.h
+++ b/clang/include/clang/CIR/MissingFeatures.h
@@ -189,6 +189,10 @@ struct MissingFeatures {
   static bool globalCtorLexOrder() { return false; }
   static bool globalCtorAssociatedData() { return false; }
 
+  // LowerModule handling
+  static bool lowerModuleCodeGenOpts() { return false; }
+  static bool lowerModuleLangOpts() { return false; }
+
   // Misc
   static bool aarch64SIMDIntrinsics() { return false; }
   static bool aarch64SMEIntrinsics() { return false; }
@@ -293,6 +297,7 @@ struct MissingFeatures {
   static bool lowerModeOptLevel() { return false; }
   static bool loweringPrepareX86CXXABI() { return false; }
   static bool loweringPrepareAArch64XXABI() { return false; }
+  static bool makeTripleAlwaysPresent() { return false; }
   static bool maybeHandleStaticInExternC() { return false; }
   static bool mergeAllConstants() { return false; }
   static bool metaDataNode() { return false; }
diff --git a/clang/lib/CIR/CodeGen/CIRGenBuilder.h b/clang/lib/CIR/CodeGen/CIRGenBuilder.h
index 85b38120169fd..bf13eeeaea60a 100644
--- a/clang/lib/CIR/CodeGen/CIRGenBuilder.h
+++ b/clang/lib/CIR/CodeGen/CIRGenBuilder.h
@@ -189,6 +189,11 @@ class CIRGenBuilderTy : public cir::CIRBaseBuilderTy {
     return getType<cir::RecordType>(nameAttr, kind);
   }
 
+  cir::DataMemberAttr getDataMemberAttr(cir::DataMemberType ty,
+                                        unsigned memberIndex) {
+    return cir::DataMemberAttr::get(ty, memberIndex);
+  }
+
   // Return true if the value is a null constant such as null pointer, (+0.0)
   // for floating-point or zero initializer
   bool isNullValue(mlir::Attribute attr) const {
diff --git a/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp b/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
index 3e9d3db768bea..c6f88c4f1f627 100644
--- a/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
@@ -640,11 +640,8 @@ class ScalarExprEmitter : public StmtVisitor<ScalarExprEmitter, mlir::Value> {
   }
 
   mlir::Value VisitUnaryAddrOf(const UnaryOperator *e) {
-    if (llvm::isa<MemberPointerType>(e->getType())) {
-      cgf.cgm.errorNYI(e->getSourceRange(), "Address of member pointer");
-      return builder.getNullPtr(cgf.convertType(e->getType()),
-                                cgf.getLoc(e->getExprLoc()));
-    }
+    if (llvm::isa<MemberPointerType>(e->getType()))
+      return cgf.cgm.emitMemberPointerConstant(e);
 
     return cgf.emitLValue(e->getSubExpr()).getPointer();
   }
diff --git a/clang/lib/CIR/CodeGen/CIRGenModule.cpp b/clang/lib/CIR/CodeGen/CIRGenModule.cpp
index 1d8e4a3b444ee..281418848c351 100644
--- a/clang/lib/CIR/CodeGen/CIRGenModule.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenModule.cpp
@@ -1464,6 +1464,26 @@ void CIRGenModule::emitExplicitCastExprType(const ExplicitCastExpr *e,
          "emitExplicitCastExprType");
 }
 
+mlir::Value CIRGenModule::emitMemberPointerConstant(const UnaryOperator *e) {
+  assert(!cir::MissingFeatures::cxxABI());
+
+  mlir::Location loc = getLoc(e->getSourceRange());
+
+  const auto *decl = cast<DeclRefExpr>(e->getSubExpr())->getDecl();
+
+  // A member function pointer.
+  if (const auto *methodDecl = dyn_cast<CXXMethodDecl>(decl)) {
+    errorNYI(e->getSourceRange(), "emitMemberPointerConstant: method pointer");
+    return {};
+  }
+
+  // Otherwise, a member data pointer.
+  auto ty = mlir::cast<cir::DataMemberType>(convertType(e->getType()));
+  const auto *fieldDecl = cast<FieldDecl>(decl);
+  return cir::ConstantOp::create(
+      builder, loc, builder.getDataMemberAttr(ty, fieldDecl->getFieldIndex()));
+}
+
 void CIRGenModule::emitDeclContext(const DeclContext *dc) {
   for (Decl *decl : dc->decls()) {
     // Unlike other DeclContexts, the contents of an ObjCImplDecl at TU scope
diff --git a/clang/lib/CIR/CodeGen/CIRGenModule.h b/clang/lib/CIR/CodeGen/CIRGenModule.h
index d7aee8ebf4d7a..f167102864893 100644
--- a/clang/lib/CIR/CodeGen/CIRGenModule.h
+++ b/clang/lib/CIR/CodeGen/CIRGenModule.h
@@ -481,6 +481,8 @@ class CIRGenModule : public CIRGenTypeCache {
   /// the given type. This is usually, but not always, an LLVM null constant.
   mlir::TypedAttr emitNullConstantForBase(const CXXRecordDecl *record);
 
+  mlir::Value emitMemberPointerConstant(const UnaryOperator *e);
+
   llvm::StringRef getMangledName(clang::GlobalDecl gd);
 
   void emitTentativeDefinition(const VarDecl *d);
diff --git a/clang/lib/CIR/CodeGen/CIRGenTypes.cpp b/clang/lib/CIR/CodeGen/CIRGenTypes.cpp
index efc2c6c0ba500..da15b3626b349 100644
--- a/clang/lib/CIR/CodeGen/CIRGenTypes.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenTypes.cpp
@@ -481,6 +481,21 @@ mlir::Type CIRGenTypes::convertType(QualType type) {
     break;
   }
 
+  case Type::MemberPointer: {
+    const auto *mpt = cast<MemberPointerType>(ty);
+
+    mlir::Type memberTy = convertType(mpt->getPointeeType());
+    auto clsTy = mlir::cast<cir::RecordType>(
+        convertType(QualType(mpt->getQualifier().getAsType(), 0)));
+    if (mpt->isMemberDataPointer()) {
+      resultType = cir::DataMemberType::get(memberTy, clsTy);
+    } else {
+      assert(!cir::MissingFeatures::methodType());
+      cgm.errorNYI(SourceLocation(), "MethodType");
+    }
+    break;
+  }
+
   case Type::FunctionNoProto:
   case Type::FunctionProto:
     resultType = convertFunctionTypeInternal(type);
diff --git a/clang/lib/CIR/Dialect/IR/CIRAttrs.cpp b/clang/lib/CIR/Dialect/IR/CIRAttrs.cpp
index ee296f171e0d9..59d7765198f9e 100644
--- a/clang/lib/CIR/Dialect/IR/CIRAttrs.cpp
+++ b/clang/lib/CIR/Dialect/IR/CIRAttrs.cpp
@@ -269,6 +269,38 @@ ConstComplexAttr::verify(function_ref<InFlightDiagnostic()> emitError,
   return success();
 }
 
+//===----------------------------------------------------------------------===//
+// DataMemberAttr definitions
+//===----------------------------------------------------------------------===//
+
+LogicalResult
+DataMemberAttr::verify(function_ref<InFlightDiagnostic()> emitError,
+                       cir::DataMemberType ty,
+                       std::optional<unsigned> memberIndex) {
+  // DataMemberAttr without a given index represents a null value.
+  if (!memberIndex.has_value())
+    return success();
+
+  cir::RecordType recTy = ty.getClassTy();
+  if (recTy.isIncomplete())
+    return emitError()
+           << "incomplete 'cir.record' cannot be used to build a non-null "
+              "data member pointer";
+
+  unsigned memberIndexValue = memberIndex.value();
+  if (memberIndexValue >= recTy.getNumElements())
+    return emitError()
+           << "member index of a #cir.data_member attribute is out of range";
+
+  mlir::Type memberTy = recTy.getMembers()[memberIndexValue];
+  if (memberTy != ty.getMemberTy())
+    return emitError()
+           << "member type of a #cir.data_member attribute must match the "
+              "attribute type";
+
+  return success();
+}
+
 //===----------------------------------------------------------------------===//
 // CIR ConstArrayAttr
 //===----------------------------------------------------------------------===//
diff --git a/clang/lib/CIR/Dialect/IR/CIRDialect.cpp b/clang/lib/CIR/Dialect/IR/CIRDialect.cpp
index 396d97ddd794e..56b69ec81dc34 100644
--- a/clang/lib/CIR/Dialect/IR/CIRDialect.cpp
+++ b/clang/lib/CIR/Dialect/IR/CIRDialect.cpp
@@ -357,6 +357,12 @@ static LogicalResult checkConstantTypes(mlir::Operation *op, mlir::Type opType,
     return success();
   }
 
+  if (isa<cir::DataMemberAttr>(attrType)) {
+    // More detailed type verifications are already done in
+    // DataMemberAttr::verify. Don't need to repeat here.
+    return success();
+  }
+
   if (isa<cir::ZeroAttr>(attrType)) {
     if (isa<cir::RecordType, cir::ArrayType, cir::VectorType, cir::ComplexType>(
             opType))
diff --git a/clang/lib/CIR/Dialect/IR/CIRTypes.cpp b/clang/lib/CIR/Dialect/IR/CIRTypes.cpp
index bb87056048ec5..9a37a4f4e3996 100644
--- a/clang/lib/CIR/Dialect/IR/CIRTypes.cpp
+++ b/clang/lib/CIR/Dialect/IR/CIRTypes.cpp
@@ -750,6 +750,26 @@ BoolType::getABIAlignment(const ::mlir::DataLayout &dataLayout,
   return 1;
 }
 
+//===----------------------------------------------------------------------===//
+//  DataMemberType Definitions
+//===----------------------------------------------------------------------===//
+
+llvm::TypeSize
+DataMemberType::getTypeSizeInBits(const ::mlir::DataLayout &dataLayout,
+                                  ::mlir::DataLayoutEntryListRef params) const {
+  // FIXME: consider size differences under different ABIs
+  assert(!MissingFeatures::cxxABI());
+  return llvm::TypeSize::getFixed(64);
+}
+
+uint64_t
+DataMemberType::getABIAlignment(const ::mlir::DataLayout &dataLayout,
+                                ::mlir::DataLayoutEntryListRef params) const {
+  // FIXME: consider alignment differences under different ABIs
+  assert(!MissingFeatures::cxxABI());
+  return 8;
+}
+
 //===----------------------------------------------------------------------===//
 //  VPtrType Definitions
 //===----------------------------------------------------------------------===//
diff --git a/clang/lib/CIR/Dialect/Transforms/CMakeLists.txt b/clang/lib/CIR/Dialect/Transforms/CMakeLists.txt
index 3fc5b06b74e4d..e3b7106c1d6b9 100644
--- a/clang/lib/CIR/Dialect/Transforms/CMakeLists.txt
+++ b/clang/lib/CIR/Dialect/Transforms/CMakeLists.txt
@@ -1,3 +1,5 @@
+add_subdirectory(TargetLowering)
+
 add_clang_library(MLIRCIRTransforms
   CIRCanonicalize.cpp
   CIRSimplify.cpp
@@ -21,4 +23,5 @@ add_clang_library(MLIRCIRTransforms
 
   MLIRCIR
   MLIRCIRInterfaces
+  MLIRCIRTargetLowering
 )
diff --git a/clang/lib/CIR/Dialect/Transforms/TargetLowering/CIRCXXABI.cpp b/clang/lib/CIR/Dialect/Transforms/TargetLowering/CIRCXXABI.cpp
new file mode 100644
index 0000000000000..86cf7ebdc8f50
--- /dev/null
+++ b/clang/lib/CIR/Dialect/Transforms/TargetLowering/CIRCXXABI.cpp
@@ -0,0 +1,20 @@
+//===- CIRCXXABI.cpp ------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file partially mimics clang/lib/CodeGen/CGCXXABI.cpp. The queries are
+// adapted to operate on the CIR dialect, however.
+//
+//===----------------------------------------------------------------------===//
+
+#include "CIRCXXABI.h"
+
+namespace cir {
+
+CIRCXXABI::~CIRCXXABI() {}
+
+} // namespace cir
diff --git a/clang/lib/CIR/Dialect/Transforms/TargetLowering/CIRCXXABI.h b/clang/lib/CIR/Dialect/Transforms/TargetLowering/CIRCXXABI.h
new file mode 100644
index 0000000000000..fa14375a6edb8
--- /dev/null
+++ b/clang/lib/CIR/Dialect/Transforms/TargetLowering/CIRCXXABI.h
@@ -0,0 +1,55 @@
+//===----- CIRCXXABI.h - Interface to C++ ABIs for CIR Dialect --*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file partially mimics the CodeGen/CGCXXABI.h class. The main difference
+// is that this is adapted to operate on the CIR dialect.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef CLANG_LIB_CIR_DIALECT_TRANSFORMS_TARGETLOWERING_CIRCXXABI_H
+#define CLANG_LIB_CIR_DIALECT_TRANSFORMS_TARGETLOWERING_CIRCXXABI_H
+
+#include "mlir/Transforms/DialectConversion.h"
+#include "clang/CIR/Dialect/IR/CIRTypes.h"
+
+namespace cir {
+
+// Forward declarations.
+class LowerModule;
+
+class CIRCXXABI {
+  friend class LowerModule;
+
+protected:
+  LowerModule &lm;
+
+  CIRCXXABI(LowerModule &lm) : lm(lm) {}
+
+public:
+  virtual ~CIRCXXABI();
+
+  /// Lower the given data member pointer type to its ABI type. The returned
+  /// type is also a CIR type.
+  virtual mlir::Type
+  lowerDataMemberType(cir::DataMemberType type,
+                      const mlir::TypeConverter &typeConverter) const = 0;
+
+  /// Lower the given data member pointer constant to a constant of the ABI
+  /// type. The returned constant is represented as an attribute as well.
+  virtual mlir::TypedAttr
+  lowerDataMemberConstant(cir::DataMemberAttr attr,
+                          const mlir::DataLayout &layout,
+                          const mlir::TypeConverter &typeConverter) const = 0;
+};
+
+/// Creates an Itanium-family ABI.
+CIRCXXABI *createItaniumCXXABI(LowerModule &lm);
+
+} // namespace cir
+
+#endif // CLANG_LIB_CIR_DIALECT_TRANSFORMS_TARGETLOWERING_CIRCXXABI_H
diff --git a/clang/lib/CIR/Dialect/Transforms/TargetLowering/CMakeLists.txt b/clang/lib/CIR/Dialect/Transforms/TargetLowering/CMakeLists.txt
new file mode 100644
index 0000000000000..158c42e729536
--- /dev/null
+++ b/clang/lib/CIR/Dialect/Transforms/TargetLowering/CMakeLists.txt
@@ -0,0 +1,20 @@
+add_clang_library(MLIRCIRTargetLowering
+  CIRCXXABI.cpp
+  LowerModule.cpp
+  LowerItaniumCXXABI.cpp
+
+  DEPENDS
+  clangBasic
+
+  LINK_COMPONENTS
+  TargetParser
+
+  LINK_LIBS PUBLIC
+
+  clangBasic
+  MLIRIR
+  MLIRPass
+  MLIRDLTIDialect
+  MLIRCIR
+  MLIRCIRInterfaces
+)
diff --git a/clang/lib/CIR/Dialect/Transforms/TargetLowering/LowerItaniumCXXABI.cpp b/clang/lib/CIR/Dialect/Transforms/TargetLowering/LowerItaniumCXXABI.cpp
new file mode 100644
index 0000000000000..1e2c9b68f3a6e
--- /dev/null
+++ b/clang/lib/CIR/Dialect/Transforms/TargetLowering/LowerItaniumCXXABI.cpp
@@ -0,0 +1,90 @@
+//===---- LowerItaniumCXXABI.cpp - Emit CIR code Itanium-specific code  ---===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This provides CIR lowering logic targeting the Itanium C++ ABI. The class in
+// this file generates records that follow the Itanium C++ ABI, which is
+// documented at:
+//  https://itanium-cxx-abi.github.io/cxx-abi/abi.html
+//  https://itanium-cxx-abi.github.io/cxx-abi/abi-eh.html
+//
+// It also supports the closely-related ARM ABI, doc...
[truncated]

llvmbot · 2025-12-05T22:38:47Z

@llvm/pr-subscribers-clang

Author: Andy Kaylor (andykaylor)

Changes

This adds the minimum support for C++ data member pointer variables.

Patch is 37.69 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/170939.diff

26 Files Affected:

(modified) clang/include/clang/CIR/Dialect/IR/CIRAttrs.h (+1)
(modified) clang/include/clang/CIR/Dialect/IR/CIRAttrs.td (+51)
(modified) clang/include/clang/CIR/Dialect/IR/CIRTypeConstraints.td (+9-1)
(modified) clang/include/clang/CIR/Dialect/IR/CIRTypes.td (+31-1)
(modified) clang/include/clang/CIR/MissingFeatures.h (+5)
(modified) clang/lib/CIR/CodeGen/CIRGenBuilder.h (+5)
(modified) clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp (+2-5)
(modified) clang/lib/CIR/CodeGen/CIRGenModule.cpp (+20)
(modified) clang/lib/CIR/CodeGen/CIRGenModule.h (+2)
(modified) clang/lib/CIR/CodeGen/CIRGenTypes.cpp (+15)
(modified) clang/lib/CIR/Dialect/IR/CIRAttrs.cpp (+32)
(modified) clang/lib/CIR/Dialect/IR/CIRDialect.cpp (+6)
(modified) clang/lib/CIR/Dialect/IR/CIRTypes.cpp (+20)
(modified) clang/lib/CIR/Dialect/Transforms/CMakeLists.txt (+3)
(added) clang/lib/CIR/Dialect/Transforms/TargetLowering/CIRCXXABI.cpp (+20)
(added) clang/lib/CIR/Dialect/Transforms/TargetLowering/CIRCXXABI.h (+55)
(added) clang/lib/CIR/Dialect/Transforms/TargetLowering/CMakeLists.txt (+20)
(added) clang/lib/CIR/Dialect/Transforms/TargetLowering/LowerItaniumCXXABI.cpp (+90)
(added) clang/lib/CIR/Dialect/Transforms/TargetLowering/LowerModule.cpp (+87)
(added) clang/lib/CIR/Dialect/Transforms/TargetLowering/LowerModule.h (+55)
(modified) clang/lib/CIR/Lowering/DirectToLLVM/CMakeLists.txt (+5)
(modified) clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp (+31-3)
(modified) clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.h (+2)
(added) clang/test/CIR/CodeGen/pointer-to-data-member.cpp (+35)
(added) clang/test/CIR/IR/invalid-data-member.cir (+27)
(modified) clang/utils/TableGen/CIRLoweringEmitter.cpp (+5-2)

diff --git a/clang/include/clang/CIR/Dialect/IR/CIRAttrs.h b/clang/include/clang/CIR/Dialect/IR/CIRAttrs.h
index 03a6a97dc8c2e..858d4d6350bed 100644
--- a/clang/include/clang/CIR/Dialect/IR/CIRAttrs.h
+++ b/clang/include/clang/CIR/Dialect/IR/CIRAttrs.h
@@ -35,6 +35,7 @@ namespace cir {
 class ArrayType;
 class BoolType;
 class ComplexType;
+class DataMemberType;
 class IntType;
 class MethodType;
 class PointerType;
diff --git a/clang/include/clang/CIR/Dialect/IR/CIRAttrs.td b/clang/include/clang/CIR/Dialect/IR/CIRAttrs.td
index 98d4636dafc29..c0279a0b20670 100644
--- a/clang/include/clang/CIR/Dialect/IR/CIRAttrs.td
+++ b/clang/include/clang/CIR/Dialect/IR/CIRAttrs.td
@@ -447,6 +447,57 @@ def CIR_ConstPtrAttr : CIR_Attr<"ConstPtr", "ptr", [TypedAttrInterface]> {
   }];
 }
 
+//===----------------------------------------------------------------------===//
+// DataMemberAttr
+//===----------------------------------------------------------------------===//
+
+def CIR_DataMemberAttr : CIR_Attr<"DataMember", "data_member", [
+  TypedAttrInterface
+]> {
+  let summary = "Holds a constant data member pointer value";
+  let parameters = (ins AttributeSelfTypeParameter<
+                            "", "cir::DataMemberType">:$type,
+                        OptionalParameter<
+                            "std::optional<unsigned>">:$member_index);
+  let description = [{
+    A data member attribute is a literal attribute that represents a constant
+    pointer-to-data-member value.
+
+    The `member_index` parameter represents the index of the pointed-to member
+    within its containing record. It is an optional parameter; lack of this
+    parameter indicates a null pointer-to-data-member value.
+
+    Example:
+    ```
+    #ptr = #cir.data_member<1> : !cir.data_member<!s32i in !rec_22Point22>
+
+    #null = #cir.data_member<null> : !cir.data_member<!s32i in !rec_22Point22>
+    ```
+  }];
+
+  let builders = [
+    AttrBuilderWithInferredContext<(ins "cir::DataMemberType":$type), [{
+      return $_get(type.getContext(), type, std::nullopt);
+    }]>,
+    AttrBuilderWithInferredContext<(ins "cir::DataMemberType":$type,
+                                        "unsigned":$member_index), [{
+      return $_get(type.getContext(), type, member_index);
+    }]>,
+  ];
+
+  let genVerifyDecl = 1;
+
+  let assemblyFormat = [{
+    `<` ($member_index^):(`null`)? `>`
+  }];
+
+  let extraClassDeclaration = [{
+    bool isNullPtr() const {
+      return !getMemberIndex().has_value();
+    }
+  }];
+}
+
 //===----------------------------------------------------------------------===//
 // GlobalViewAttr
 //===----------------------------------------------------------------------===//
diff --git a/clang/include/clang/CIR/Dialect/IR/CIRTypeConstraints.td b/clang/include/clang/CIR/Dialect/IR/CIRTypeConstraints.td
index ddca98eac93ab..89762249ed0c4 100644
--- a/clang/include/clang/CIR/Dialect/IR/CIRTypeConstraints.td
+++ b/clang/include/clang/CIR/Dialect/IR/CIRTypeConstraints.td
@@ -309,6 +309,13 @@ def CIR_AnyFloatOrVecOfFloatType
     let cppFunctionName = "isFPOrVectorOfFPType";
 }
 
+//===----------------------------------------------------------------------===//
+// Data member type predicates
+//===----------------------------------------------------------------------===//
+
+def CIR_AnyDataMemberType : CIR_TypeBase<"::cir::DataMemberType",
+    "data member type">;
+
 //===----------------------------------------------------------------------===//
 // VPtr type predicates
 //===----------------------------------------------------------------------===//
@@ -322,7 +329,8 @@ def CIR_PtrToVPtr : CIR_PtrToType<CIR_AnyVPtrType>;
 //===----------------------------------------------------------------------===//
 
 defvar CIR_ScalarTypes = [
-    CIR_AnyBoolType, CIR_AnyIntType, CIR_AnyFloatType, CIR_AnyPtrType
+    CIR_AnyBoolType, CIR_AnyIntType, CIR_AnyFloatType, CIR_AnyPtrType,
+    CIR_AnyDataMemberType, CIR_AnyVPtrType
 ];
 
 def CIR_AnyScalarType : AnyTypeOf<CIR_ScalarTypes, "cir scalar type"> {
diff --git a/clang/include/clang/CIR/Dialect/IR/CIRTypes.td b/clang/include/clang/CIR/Dialect/IR/CIRTypes.td
index 3e062add6633a..59b97f0c6d39a 100644
--- a/clang/include/clang/CIR/Dialect/IR/CIRTypes.td
+++ b/clang/include/clang/CIR/Dialect/IR/CIRTypes.td
@@ -305,6 +305,36 @@ def CIR_PointerType : CIR_Type<"Pointer", "ptr", [
   }];
 }
 
+//===----------------------------------------------------------------------===//
+// CIR_DataMemberType
+//===----------------------------------------------------------------------===//
+
+def CIR_DataMemberType : CIR_Type<"DataMember", "data_member",
+    [DeclareTypeInterfaceMethods<DataLayoutTypeInterface>]
+> {
+  let summary = "CIR type that represents a pointer-to-data-member in C++";
+  let description = [{
+    `cir.data_member` models a pointer-to-data-member in C++. Values of this
+    type are essentially offsets of the pointed-to member within one of its
+    containing record.
+  }];
+
+  let parameters = (ins "mlir::Type":$member_ty,
+                        "cir::RecordType":$class_ty);
+
+  let builders = [
+    TypeBuilderWithInferredContext<(ins
+      "mlir::Type":$member_ty, "cir::RecordType":$class_ty
+    ), [{
+      return $_get(member_ty.getContext(), member_ty, class_ty);
+    }]>,
+  ];
+
+  let assemblyFormat = [{
+    `<` $member_ty `in` $class_ty `>`
+  }];
+}
+
 //===----------------------------------------------------------------------===//
 // CIR_VPtrType
 //===----------------------------------------------------------------------===//
@@ -693,7 +723,7 @@ def CIRRecordType : Type<
 def CIR_AnyType : AnyTypeOf<[
   CIR_VoidType, CIR_BoolType, CIR_ArrayType, CIR_VectorType, CIR_IntType,
   CIR_AnyFloatType, CIR_PointerType, CIR_FuncType, CIR_RecordType,
-  CIR_ComplexType, CIR_VPtrType
+  CIR_ComplexType, CIR_VPtrType, CIR_DataMemberType
 ]>;
 
 #endif // CLANG_CIR_DIALECT_IR_CIRTYPES_TD
diff --git a/clang/include/clang/CIR/MissingFeatures.h b/clang/include/clang/CIR/MissingFeatures.h
index b8df0528ea18d..51d18750e72ac 100644
--- a/clang/include/clang/CIR/MissingFeatures.h
+++ b/clang/include/clang/CIR/MissingFeatures.h
@@ -189,6 +189,10 @@ struct MissingFeatures {
   static bool globalCtorLexOrder() { return false; }
   static bool globalCtorAssociatedData() { return false; }
 
+  // LowerModule handling
+  static bool lowerModuleCodeGenOpts() { return false; }
+  static bool lowerModuleLangOpts() { return false; }
+
   // Misc
   static bool aarch64SIMDIntrinsics() { return false; }
   static bool aarch64SMEIntrinsics() { return false; }
@@ -293,6 +297,7 @@ struct MissingFeatures {
   static bool lowerModeOptLevel() { return false; }
   static bool loweringPrepareX86CXXABI() { return false; }
   static bool loweringPrepareAArch64XXABI() { return false; }
+  static bool makeTripleAlwaysPresent() { return false; }
   static bool maybeHandleStaticInExternC() { return false; }
   static bool mergeAllConstants() { return false; }
   static bool metaDataNode() { return false; }
diff --git a/clang/lib/CIR/CodeGen/CIRGenBuilder.h b/clang/lib/CIR/CodeGen/CIRGenBuilder.h
index 85b38120169fd..bf13eeeaea60a 100644
--- a/clang/lib/CIR/CodeGen/CIRGenBuilder.h
+++ b/clang/lib/CIR/CodeGen/CIRGenBuilder.h
@@ -189,6 +189,11 @@ class CIRGenBuilderTy : public cir::CIRBaseBuilderTy {
     return getType<cir::RecordType>(nameAttr, kind);
   }
 
+  cir::DataMemberAttr getDataMemberAttr(cir::DataMemberType ty,
+                                        unsigned memberIndex) {
+    return cir::DataMemberAttr::get(ty, memberIndex);
+  }
+
   // Return true if the value is a null constant such as null pointer, (+0.0)
   // for floating-point or zero initializer
   bool isNullValue(mlir::Attribute attr) const {
diff --git a/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp b/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
index 3e9d3db768bea..c6f88c4f1f627 100644
--- a/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
@@ -640,11 +640,8 @@ class ScalarExprEmitter : public StmtVisitor<ScalarExprEmitter, mlir::Value> {
   }
 
   mlir::Value VisitUnaryAddrOf(const UnaryOperator *e) {
-    if (llvm::isa<MemberPointerType>(e->getType())) {
-      cgf.cgm.errorNYI(e->getSourceRange(), "Address of member pointer");
-      return builder.getNullPtr(cgf.convertType(e->getType()),
-                                cgf.getLoc(e->getExprLoc()));
-    }
+    if (llvm::isa<MemberPointerType>(e->getType()))
+      return cgf.cgm.emitMemberPointerConstant(e);
 
     return cgf.emitLValue(e->getSubExpr()).getPointer();
   }
diff --git a/clang/lib/CIR/CodeGen/CIRGenModule.cpp b/clang/lib/CIR/CodeGen/CIRGenModule.cpp
index 1d8e4a3b444ee..281418848c351 100644
--- a/clang/lib/CIR/CodeGen/CIRGenModule.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenModule.cpp
@@ -1464,6 +1464,26 @@ void CIRGenModule::emitExplicitCastExprType(const ExplicitCastExpr *e,
          "emitExplicitCastExprType");
 }
 
+mlir::Value CIRGenModule::emitMemberPointerConstant(const UnaryOperator *e) {
+  assert(!cir::MissingFeatures::cxxABI());
+
+  mlir::Location loc = getLoc(e->getSourceRange());
+
+  const auto *decl = cast<DeclRefExpr>(e->getSubExpr())->getDecl();
+
+  // A member function pointer.
+  if (const auto *methodDecl = dyn_cast<CXXMethodDecl>(decl)) {
+    errorNYI(e->getSourceRange(), "emitMemberPointerConstant: method pointer");
+    return {};
+  }
+
+  // Otherwise, a member data pointer.
+  auto ty = mlir::cast<cir::DataMemberType>(convertType(e->getType()));
+  const auto *fieldDecl = cast<FieldDecl>(decl);
+  return cir::ConstantOp::create(
+      builder, loc, builder.getDataMemberAttr(ty, fieldDecl->getFieldIndex()));
+}
+
 void CIRGenModule::emitDeclContext(const DeclContext *dc) {
   for (Decl *decl : dc->decls()) {
     // Unlike other DeclContexts, the contents of an ObjCImplDecl at TU scope
diff --git a/clang/lib/CIR/CodeGen/CIRGenModule.h b/clang/lib/CIR/CodeGen/CIRGenModule.h
index d7aee8ebf4d7a..f167102864893 100644
--- a/clang/lib/CIR/CodeGen/CIRGenModule.h
+++ b/clang/lib/CIR/CodeGen/CIRGenModule.h
@@ -481,6 +481,8 @@ class CIRGenModule : public CIRGenTypeCache {
   /// the given type. This is usually, but not always, an LLVM null constant.
   mlir::TypedAttr emitNullConstantForBase(const CXXRecordDecl *record);
 
+  mlir::Value emitMemberPointerConstant(const UnaryOperator *e);
+
   llvm::StringRef getMangledName(clang::GlobalDecl gd);
 
   void emitTentativeDefinition(const VarDecl *d);
diff --git a/clang/lib/CIR/CodeGen/CIRGenTypes.cpp b/clang/lib/CIR/CodeGen/CIRGenTypes.cpp
index efc2c6c0ba500..da15b3626b349 100644
--- a/clang/lib/CIR/CodeGen/CIRGenTypes.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenTypes.cpp
@@ -481,6 +481,21 @@ mlir::Type CIRGenTypes::convertType(QualType type) {
     break;
   }
 
+  case Type::MemberPointer: {
+    const auto *mpt = cast<MemberPointerType>(ty);
+
+    mlir::Type memberTy = convertType(mpt->getPointeeType());
+    auto clsTy = mlir::cast<cir::RecordType>(
+        convertType(QualType(mpt->getQualifier().getAsType(), 0)));
+    if (mpt->isMemberDataPointer()) {
+      resultType = cir::DataMemberType::get(memberTy, clsTy);
+    } else {
+      assert(!cir::MissingFeatures::methodType());
+      cgm.errorNYI(SourceLocation(), "MethodType");
+    }
+    break;
+  }
+
   case Type::FunctionNoProto:
   case Type::FunctionProto:
     resultType = convertFunctionTypeInternal(type);
diff --git a/clang/lib/CIR/Dialect/IR/CIRAttrs.cpp b/clang/lib/CIR/Dialect/IR/CIRAttrs.cpp
index ee296f171e0d9..59d7765198f9e 100644
--- a/clang/lib/CIR/Dialect/IR/CIRAttrs.cpp
+++ b/clang/lib/CIR/Dialect/IR/CIRAttrs.cpp
@@ -269,6 +269,38 @@ ConstComplexAttr::verify(function_ref<InFlightDiagnostic()> emitError,
   return success();
 }
 
+//===----------------------------------------------------------------------===//
+// DataMemberAttr definitions
+//===----------------------------------------------------------------------===//
+
+LogicalResult
+DataMemberAttr::verify(function_ref<InFlightDiagnostic()> emitError,
+                       cir::DataMemberType ty,
+                       std::optional<unsigned> memberIndex) {
+  // DataMemberAttr without a given index represents a null value.
+  if (!memberIndex.has_value())
+    return success();
+
+  cir::RecordType recTy = ty.getClassTy();
+  if (recTy.isIncomplete())
+    return emitError()
+           << "incomplete 'cir.record' cannot be used to build a non-null "
+              "data member pointer";
+
+  unsigned memberIndexValue = memberIndex.value();
+  if (memberIndexValue >= recTy.getNumElements())
+    return emitError()
+           << "member index of a #cir.data_member attribute is out of range";
+
+  mlir::Type memberTy = recTy.getMembers()[memberIndexValue];
+  if (memberTy != ty.getMemberTy())
+    return emitError()
+           << "member type of a #cir.data_member attribute must match the "
+              "attribute type";
+
+  return success();
+}
+
 //===----------------------------------------------------------------------===//
 // CIR ConstArrayAttr
 //===----------------------------------------------------------------------===//
diff --git a/clang/lib/CIR/Dialect/IR/CIRDialect.cpp b/clang/lib/CIR/Dialect/IR/CIRDialect.cpp
index 396d97ddd794e..56b69ec81dc34 100644
--- a/clang/lib/CIR/Dialect/IR/CIRDialect.cpp
+++ b/clang/lib/CIR/Dialect/IR/CIRDialect.cpp
@@ -357,6 +357,12 @@ static LogicalResult checkConstantTypes(mlir::Operation *op, mlir::Type opType,
     return success();
   }
 
+  if (isa<cir::DataMemberAttr>(attrType)) {
+    // More detailed type verifications are already done in
+    // DataMemberAttr::verify. Don't need to repeat here.
+    return success();
+  }
+
   if (isa<cir::ZeroAttr>(attrType)) {
     if (isa<cir::RecordType, cir::ArrayType, cir::VectorType, cir::ComplexType>(
             opType))
diff --git a/clang/lib/CIR/Dialect/IR/CIRTypes.cpp b/clang/lib/CIR/Dialect/IR/CIRTypes.cpp
index bb87056048ec5..9a37a4f4e3996 100644
--- a/clang/lib/CIR/Dialect/IR/CIRTypes.cpp
+++ b/clang/lib/CIR/Dialect/IR/CIRTypes.cpp
@@ -750,6 +750,26 @@ BoolType::getABIAlignment(const ::mlir::DataLayout &dataLayout,
   return 1;
 }
 
+//===----------------------------------------------------------------------===//
+//  DataMemberType Definitions
+//===----------------------------------------------------------------------===//
+
+llvm::TypeSize
+DataMemberType::getTypeSizeInBits(const ::mlir::DataLayout &dataLayout,
+                                  ::mlir::DataLayoutEntryListRef params) const {
+  // FIXME: consider size differences under different ABIs
+  assert(!MissingFeatures::cxxABI());
+  return llvm::TypeSize::getFixed(64);
+}
+
+uint64_t
+DataMemberType::getABIAlignment(const ::mlir::DataLayout &dataLayout,
+                                ::mlir::DataLayoutEntryListRef params) const {
+  // FIXME: consider alignment differences under different ABIs
+  assert(!MissingFeatures::cxxABI());
+  return 8;
+}
+
 //===----------------------------------------------------------------------===//
 //  VPtrType Definitions
 //===----------------------------------------------------------------------===//
diff --git a/clang/lib/CIR/Dialect/Transforms/CMakeLists.txt b/clang/lib/CIR/Dialect/Transforms/CMakeLists.txt
index 3fc5b06b74e4d..e3b7106c1d6b9 100644
--- a/clang/lib/CIR/Dialect/Transforms/CMakeLists.txt
+++ b/clang/lib/CIR/Dialect/Transforms/CMakeLists.txt
@@ -1,3 +1,5 @@
+add_subdirectory(TargetLowering)
+
 add_clang_library(MLIRCIRTransforms
   CIRCanonicalize.cpp
   CIRSimplify.cpp
@@ -21,4 +23,5 @@ add_clang_library(MLIRCIRTransforms
 
   MLIRCIR
   MLIRCIRInterfaces
+  MLIRCIRTargetLowering
 )
diff --git a/clang/lib/CIR/Dialect/Transforms/TargetLowering/CIRCXXABI.cpp b/clang/lib/CIR/Dialect/Transforms/TargetLowering/CIRCXXABI.cpp
new file mode 100644
index 0000000000000..86cf7ebdc8f50
--- /dev/null
+++ b/clang/lib/CIR/Dialect/Transforms/TargetLowering/CIRCXXABI.cpp
@@ -0,0 +1,20 @@
+//===- CIRCXXABI.cpp ------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file partially mimics clang/lib/CodeGen/CGCXXABI.cpp. The queries are
+// adapted to operate on the CIR dialect, however.
+//
+//===----------------------------------------------------------------------===//
+
+#include "CIRCXXABI.h"
+
+namespace cir {
+
+CIRCXXABI::~CIRCXXABI() {}
+
+} // namespace cir
diff --git a/clang/lib/CIR/Dialect/Transforms/TargetLowering/CIRCXXABI.h b/clang/lib/CIR/Dialect/Transforms/TargetLowering/CIRCXXABI.h
new file mode 100644
index 0000000000000..fa14375a6edb8
--- /dev/null
+++ b/clang/lib/CIR/Dialect/Transforms/TargetLowering/CIRCXXABI.h
@@ -0,0 +1,55 @@
+//===----- CIRCXXABI.h - Interface to C++ ABIs for CIR Dialect --*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file partially mimics the CodeGen/CGCXXABI.h class. The main difference
+// is that this is adapted to operate on the CIR dialect.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef CLANG_LIB_CIR_DIALECT_TRANSFORMS_TARGETLOWERING_CIRCXXABI_H
+#define CLANG_LIB_CIR_DIALECT_TRANSFORMS_TARGETLOWERING_CIRCXXABI_H
+
+#include "mlir/Transforms/DialectConversion.h"
+#include "clang/CIR/Dialect/IR/CIRTypes.h"
+
+namespace cir {
+
+// Forward declarations.
+class LowerModule;
+
+class CIRCXXABI {
+  friend class LowerModule;
+
+protected:
+  LowerModule &lm;
+
+  CIRCXXABI(LowerModule &lm) : lm(lm) {}
+
+public:
+  virtual ~CIRCXXABI();
+
+  /// Lower the given data member pointer type to its ABI type. The returned
+  /// type is also a CIR type.
+  virtual mlir::Type
+  lowerDataMemberType(cir::DataMemberType type,
+                      const mlir::TypeConverter &typeConverter) const = 0;
+
+  /// Lower the given data member pointer constant to a constant of the ABI
+  /// type. The returned constant is represented as an attribute as well.
+  virtual mlir::TypedAttr
+  lowerDataMemberConstant(cir::DataMemberAttr attr,
+                          const mlir::DataLayout &layout,
+                          const mlir::TypeConverter &typeConverter) const = 0;
+};
+
+/// Creates an Itanium-family ABI.
+CIRCXXABI *createItaniumCXXABI(LowerModule &lm);
+
+} // namespace cir
+
+#endif // CLANG_LIB_CIR_DIALECT_TRANSFORMS_TARGETLOWERING_CIRCXXABI_H
diff --git a/clang/lib/CIR/Dialect/Transforms/TargetLowering/CMakeLists.txt b/clang/lib/CIR/Dialect/Transforms/TargetLowering/CMakeLists.txt
new file mode 100644
index 0000000000000..158c42e729536
--- /dev/null
+++ b/clang/lib/CIR/Dialect/Transforms/TargetLowering/CMakeLists.txt
@@ -0,0 +1,20 @@
+add_clang_library(MLIRCIRTargetLowering
+  CIRCXXABI.cpp
+  LowerModule.cpp
+  LowerItaniumCXXABI.cpp
+
+  DEPENDS
+  clangBasic
+
+  LINK_COMPONENTS
+  TargetParser
+
+  LINK_LIBS PUBLIC
+
+  clangBasic
+  MLIRIR
+  MLIRPass
+  MLIRDLTIDialect
+  MLIRCIR
+  MLIRCIRInterfaces
+)
diff --git a/clang/lib/CIR/Dialect/Transforms/TargetLowering/LowerItaniumCXXABI.cpp b/clang/lib/CIR/Dialect/Transforms/TargetLowering/LowerItaniumCXXABI.cpp
new file mode 100644
index 0000000000000..1e2c9b68f3a6e
--- /dev/null
+++ b/clang/lib/CIR/Dialect/Transforms/TargetLowering/LowerItaniumCXXABI.cpp
@@ -0,0 +1,90 @@
+//===---- LowerItaniumCXXABI.cpp - Emit CIR code Itanium-specific code  ---===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This provides CIR lowering logic targeting the Itanium C++ ABI. The class in
+// this file generates records that follow the Itanium C++ ABI, which is
+// documented at:
+//  https://itanium-cxx-abi.github.io/cxx-abi/abi.html
+//  https://itanium-cxx-abi.github.io/cxx-abi/abi-eh.html
+//
+// It also supports the closely-related ARM ABI, doc...
[truncated]

andykaylor · 2025-12-05T22:39:42Z

I realize this is a fairly big change. I am hoping that enough of it is boilerplate for it to still be manageable. If necessary, I can split the dialect changes out to a separate PR.

github-actions · 2025-12-05T22:57:50Z

🐧 Linux x64 Test Results

112620 tests passed
4087 tests skipped

✅ The build succeeded and all tests passed.

[CIR] Add basic support for data member pointers

381cf78

This adds the minimum support for C++ data member pointer variables.

andykaylor requested review from Lancern, bcardosolopes, erichkeane, lanza and xlauko December 5, 2025 22:38

llvmbot added clang Clang issues not falling into any other category ClangIR Anything related to the ClangIR project labels Dec 5, 2025

Fix build warning

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[CIR] Add basic support for data member pointers #170939

[CIR] Add basic support for data member pointers #170939

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