[CIR] Data member pointer comparison and casts (llvm#1268)

This PR adds CIRGen and LLVM lowering support for the following language
features related to pointers to data members:

  - Comparisons between pointers to data members.
  - Casting from pointers to data members to boolean.
  - Reinterpret casts between pointers to data members.

clang/include/clang/CIR/Dialect/IR/CIROps.td

@@ -123,6 +123,7 @@ def CK_FloatComplexToIntegralComplex
 def CK_IntegralComplexCast : I32EnumAttrCase<"int_complex", 23>;
 def CK_IntegralComplexToFloatComplex
     : I32EnumAttrCase<"int_complex_to_float_complex", 24>;
+def CK_MemberPtrToBoolean : I32EnumAttrCase<"member_ptr_to_bool", 25>;
 
 def CastKind : I32EnumAttr<
     "CastKind",
@@ -135,7 +136,7 @@ def CastKind : I32EnumAttr<
      CK_FloatComplexToReal, CK_IntegralComplexToReal, CK_FloatComplexToBoolean,
      CK_IntegralComplexToBoolean, CK_FloatComplexCast,
      CK_FloatComplexToIntegralComplex, CK_IntegralComplexCast,
-     CK_IntegralComplexToFloatComplex]> {
+     CK_IntegralComplexToFloatComplex, CK_MemberPtrToBoolean]> {
   let cppNamespace = "::cir";
 }
 

clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp

@@ -932,7 +932,12 @@ class ScalarExprEmitter : public StmtVisitor<ScalarExprEmitter, mlir::Value> {
     };
 
     if (const MemberPointerType *MPT = LHSTy->getAs<MemberPointerType>()) {
-      assert(0 && "not implemented");
+      assert(E->getOpcode() == BO_EQ || E->getOpcode() == BO_NE);
+      mlir::Value lhs = CGF.emitScalarExpr(E->getLHS());
+      mlir::Value rhs = CGF.emitScalarExpr(E->getRHS());
+      cir::CmpOpKind kind = ClangCmpToCIRCmp(E->getOpcode());
+      Result =
+          Builder.createCompare(CGF.getLoc(E->getExprLoc()), kind, lhs, rhs);
     } else if (!LHSTy->isAnyComplexType() && !RHSTy->isAnyComplexType()) {
       BinOpInfo BOInfo = emitBinOps(E);
       mlir::Value LHS = BOInfo.LHS;
@@ -1741,8 +1746,11 @@ mlir::Value ScalarExprEmitter::VisitCastExpr(CastExpr *CE) {
     auto Ty = mlir::cast<cir::DataMemberType>(CGF.convertType(DestTy));
     return Builder.getNullDataMemberPtr(Ty, CGF.getLoc(E->getExprLoc()));
   }
-  case CK_ReinterpretMemberPointer:
-    llvm_unreachable("NYI");
+  case CK_ReinterpretMemberPointer: {
+    mlir::Value src = Visit(E);
+    return Builder.createBitcast(CGF.getLoc(E->getExprLoc()), src,
+                                 CGF.convertType(DestTy));
+  }
   case CK_BaseToDerivedMemberPointer:
   case CK_DerivedToBaseMemberPointer: {
     mlir::Value src = Visit(E);
@@ -1875,8 +1883,12 @@ mlir::Value ScalarExprEmitter::VisitCastExpr(CastExpr *CE) {
     return emitPointerToBoolConversion(Visit(E), E->getType());
   case CK_FloatingToBoolean:
     return emitFloatToBoolConversion(Visit(E), CGF.getLoc(E->getExprLoc()));
-  case CK_MemberPointerToBoolean:
-    llvm_unreachable("NYI");
+  case CK_MemberPointerToBoolean: {
+    mlir::Value memPtr = Visit(E);
+    return Builder.createCast(CGF.getLoc(CE->getSourceRange()),
+                              cir::CastKind::member_ptr_to_bool, memPtr,
+                              CGF.convertType(DestTy));
+  }
   case CK_FloatingComplexToReal:
   case CK_IntegralComplexToReal:
   case CK_FloatingComplexToBoolean:

clang/lib/CIR/Dialect/IR/CIRDialect.cpp

@@ -530,6 +530,11 @@ LogicalResult cir::CastOp::verify() {
       return success();
     }
 
+    // Handle the data member pointer types.
+    if (mlir::isa<cir::DataMemberType>(srcType) &&
+        mlir::isa<cir::DataMemberType>(resType))
+      return success();
+
     // This is the only cast kind where we don't want vector types to decay
     // into the element type.
     if ((!mlir::isa<cir::VectorType>(getSrc().getType()) ||
@@ -705,6 +710,13 @@ LogicalResult cir::CastOp::verify() {
              << "requires !cir.complex<!cir.float> type for result";
     return success();
   }
+  case cir::CastKind::member_ptr_to_bool: {
+    if (!mlir::isa<cir::DataMemberType>(srcType))
+      return emitOpError() << "requires !cir.data_member type for source";
+    if (!mlir::isa<cir::BoolType>(resType))
+      return emitOpError() << "requires !cir.bool type for result";
+    return success();
+  }
   }
 
   llvm_unreachable("Unknown CastOp kind?");

clang/lib/CIR/Dialect/Transforms/TargetLowering/CIRCXXABI.h

@@ -97,6 +97,19 @@ class CIRCXXABI {
   virtual mlir::Value
   lowerDerivedDataMember(cir::DerivedDataMemberOp op, mlir::Value loweredSrc,
                          mlir::OpBuilder &builder) const = 0;
+
+  virtual mlir::Value lowerDataMemberCmp(cir::CmpOp op, mlir::Value loweredLhs,
+                                         mlir::Value loweredRhs,
+                                         mlir::OpBuilder &builder) const = 0;
+
+  virtual mlir::Value
+  lowerDataMemberBitcast(cir::CastOp op, mlir::Type loweredDstTy,
+                         mlir::Value loweredSrc,
+                         mlir::OpBuilder &builder) const = 0;
+
+  virtual mlir::Value
+  lowerDataMemberToBoolCast(cir::CastOp op, mlir::Value loweredSrc,
+                            mlir::OpBuilder &builder) const = 0;
 };
 
 /// Creates an Itanium-family ABI.

clang/lib/CIR/Dialect/Transforms/TargetLowering/ItaniumCXXABI.cpp

@@ -73,6 +73,18 @@ class ItaniumCXXABI : public CIRCXXABI {
   mlir::Value lowerDerivedDataMember(cir::DerivedDataMemberOp op,
                                      mlir::Value loweredSrc,
                                      mlir::OpBuilder &builder) const override;
+
+  mlir::Value lowerDataMemberCmp(cir::CmpOp op, mlir::Value loweredLhs,
+                                 mlir::Value loweredRhs,
+                                 mlir::OpBuilder &builder) const override;
+
+  mlir::Value lowerDataMemberBitcast(cir::CastOp op, mlir::Type loweredDstTy,
+                                     mlir::Value loweredSrc,
+                                     mlir::OpBuilder &builder) const override;
+
+  mlir::Value
+  lowerDataMemberToBoolCast(cir::CastOp op, mlir::Value loweredSrc,
+                            mlir::OpBuilder &builder) const override;
 };
 
 } // namespace
@@ -89,18 +101,23 @@ bool ItaniumCXXABI::classifyReturnType(LowerFunctionInfo &FI) const {
   return false;
 }
 
-mlir::Type ItaniumCXXABI::lowerDataMemberType(
-    cir::DataMemberType type, const mlir::TypeConverter &typeConverter) const {
+static mlir::Type getABITypeForDataMember(LowerModule &lowerMod) {
   // Itanium C++ ABI 2.3:
   //   A pointer to data member is an offset from the base address of
   //   the class object containing it, represented as a ptrdiff_t
-  const clang::TargetInfo &target = LM.getTarget();
+  const clang::TargetInfo &target = lowerMod.getTarget();
   clang::TargetInfo::IntType ptrdiffTy =
       target.getPtrDiffType(clang::LangAS::Default);
-  return cir::IntType::get(type.getContext(), target.getTypeWidth(ptrdiffTy),
+  return cir::IntType::get(lowerMod.getMLIRContext(),
+                           target.getTypeWidth(ptrdiffTy),
                            target.isTypeSigned(ptrdiffTy));
 }
 
+mlir::Type ItaniumCXXABI::lowerDataMemberType(
+    cir::DataMemberType type, const mlir::TypeConverter &typeConverter) const {
+  return getABITypeForDataMember(LM);
+}
+
 mlir::TypedAttr ItaniumCXXABI::lowerDataMemberConstant(
     cir::DataMemberAttr attr, const mlir::DataLayout &layout,
     const mlir::TypeConverter &typeConverter) const {
@@ -175,6 +192,33 @@ ItaniumCXXABI::lowerDerivedDataMember(cir::DerivedDataMemberOp op,
                              /*isDerivedToBase=*/false, builder);
 }
 
+mlir::Value ItaniumCXXABI::lowerDataMemberCmp(cir::CmpOp op,
+                                              mlir::Value loweredLhs,
+                                              mlir::Value loweredRhs,
+                                              mlir::OpBuilder &builder) const {
+  return builder.create<cir::CmpOp>(op.getLoc(), op.getKind(), loweredLhs,
+                                    loweredRhs);
+}
+
+mlir::Value
+ItaniumCXXABI::lowerDataMemberBitcast(cir::CastOp op, mlir::Type loweredDstTy,
+                                      mlir::Value loweredSrc,
+                                      mlir::OpBuilder &builder) const {
+  return builder.create<cir::CastOp>(op.getLoc(), loweredDstTy,
+                                     cir::CastKind::bitcast, loweredSrc);
+}
+
+mlir::Value
+ItaniumCXXABI::lowerDataMemberToBoolCast(cir::CastOp op, mlir::Value loweredSrc,
+                                         mlir::OpBuilder &builder) const {
+  // Itanium C++ ABI 2.3:
+  //   A NULL pointer is represented as -1.
+  auto nullAttr = cir::IntAttr::get(getABITypeForDataMember(LM), -1);
+  auto nullValue = builder.create<cir::ConstantOp>(op.getLoc(), nullAttr);
+  return builder.create<cir::CmpOp>(op.getLoc(), cir::CmpOpKind::ne, loweredSrc,
+                                    nullValue);
+}
+
 CIRCXXABI *CreateItaniumCXXABI(LowerModule &LM) {
   switch (LM.getCXXABIKind()) {
   // Note that AArch64 uses the generic ItaniumCXXABI class since it doesn't

clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp

@@ -1299,8 +1299,18 @@ mlir::LogicalResult CIRToLLVMCastOpLowering::matchAndRewrite(
   }
   case cir::CastKind::bitcast: {
     auto dstTy = castOp.getType();
-    auto llvmSrcVal = adaptor.getOperands().front();
     auto llvmDstTy = getTypeConverter()->convertType(dstTy);
+
+    if (mlir::isa<cir::DataMemberType>(castOp.getSrc().getType())) {
+      mlir::Value loweredResult = lowerMod->getCXXABI().lowerDataMemberBitcast(
+          castOp, llvmDstTy, src, rewriter);
+      rewriter.replaceOp(castOp, loweredResult);
+      return mlir::success();
+    }
+    if (mlir::isa<cir::MethodType>(castOp.getSrc().getType()))
+      llvm_unreachable("NYI");
+
+    auto llvmSrcVal = adaptor.getOperands().front();
     rewriter.replaceOpWithNewOp<mlir::LLVM::BitcastOp>(castOp, llvmDstTy,
                                                        llvmSrcVal);
     return mlir::success();
@@ -1324,6 +1334,16 @@ mlir::LogicalResult CIRToLLVMCastOpLowering::matchAndRewrite(
                                                              llvmSrcVal);
     break;
   }
+  case cir::CastKind::member_ptr_to_bool: {
+    mlir::Value loweredResult;
+    if (mlir::isa<cir::MethodType>(castOp.getSrc().getType()))
+      llvm_unreachable("NYI");
+    else
+      loweredResult = lowerMod->getCXXABI().lowerDataMemberToBoolCast(
+          castOp, src, rewriter);
+    rewriter.replaceOp(castOp, loweredResult);
+    break;
+  }
   default: {
     return castOp.emitError("Unhandled cast kind: ")
            << castOp.getKindAttrName();
@@ -2902,6 +2922,14 @@ mlir::LogicalResult CIRToLLVMCmpOpLowering::matchAndRewrite(
     mlir::ConversionPatternRewriter &rewriter) const {
   auto type = cmpOp.getLhs().getType();
 
+  if (mlir::isa<cir::DataMemberType>(type)) {
+    assert(lowerMod && "lowering module is not available");
+    mlir::Value loweredResult = lowerMod->getCXXABI().lowerDataMemberCmp(
+        cmpOp, adaptor.getLhs(), adaptor.getRhs(), rewriter);
+    rewriter.replaceOp(cmpOp, loweredResult);
+    return mlir::success();
+  }
+
   // Lower to LLVM comparison op.
   // if (auto intTy = mlir::dyn_cast<cir::IntType>(type)) {
   if (mlir::isa<cir::IntType, mlir::IntegerType>(type)) {
@@ -4087,6 +4115,7 @@ void populateCIRToLLVMConversionPatterns(
                                           argsVarMap, patterns.getContext());
   patterns.add<
       // clang-format off
+      CIRToLLVMCastOpLowering,
       CIRToLLVMLoadOpLowering,
       CIRToLLVMStoreOpLowering,
       CIRToLLVMGlobalOpLowering,
@@ -4096,14 +4125,14 @@ void populateCIRToLLVMConversionPatterns(
   patterns.add<
       // clang-format off
       CIRToLLVMBaseDataMemberOpLowering,
+      CIRToLLVMCmpOpLowering,
       CIRToLLVMDerivedDataMemberOpLowering,
       CIRToLLVMGetRuntimeMemberOpLowering
       // clang-format on
       >(converter, patterns.getContext(), lowerModule);
   patterns.add<
       // clang-format off
       CIRToLLVMPtrStrideOpLowering,
-      CIRToLLVMCastOpLowering,
       CIRToLLVMInlineAsmOpLowering
       // clang-format on
       >(converter, patterns.getContext(), dataLayout);
@@ -4132,7 +4161,6 @@ void populateCIRToLLVMConversionPatterns(
       CIRToLLVMCallOpLowering,
       CIRToLLVMCatchParamOpLowering,
       CIRToLLVMClearCacheOpLowering,
-      CIRToLLVMCmpOpLowering,
       CIRToLLVMCmpThreeWayOpLowering,
       CIRToLLVMComplexCreateOpLowering,
       CIRToLLVMComplexImagOpLowering,

clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.h

@@ -232,16 +232,18 @@ class CIRToLLVMBrCondOpLowering
 };
 
 class CIRToLLVMCastOpLowering : public mlir::OpConversionPattern<cir::CastOp> {
+  cir::LowerModule *lowerMod;
   mlir::DataLayout const &dataLayout;
 
   mlir::Type convertTy(mlir::Type ty) const;
 
 public:
   CIRToLLVMCastOpLowering(const mlir::TypeConverter &typeConverter,
                           mlir::MLIRContext *context,
+                          cir::LowerModule *lowerModule,
                           mlir::DataLayout const &dataLayout)
-      : OpConversionPattern(typeConverter, context), dataLayout(dataLayout) {}
-  using mlir::OpConversionPattern<cir::CastOp>::OpConversionPattern;
+      : OpConversionPattern(typeConverter, context), lowerMod(lowerModule),
+        dataLayout(dataLayout) {}
 
   mlir::LogicalResult
   matchAndRewrite(cir::CastOp op, OpAdaptor,
@@ -649,8 +651,15 @@ class CIRToLLVMShiftOpLowering
 };
 
 class CIRToLLVMCmpOpLowering : public mlir::OpConversionPattern<cir::CmpOp> {
+  cir::LowerModule *lowerMod;
+
 public:
-  using mlir::OpConversionPattern<cir::CmpOp>::OpConversionPattern;
+  CIRToLLVMCmpOpLowering(const mlir::TypeConverter &typeConverter,
+                         mlir::MLIRContext *context,
+                         cir::LowerModule *lowerModule)
+      : OpConversionPattern(typeConverter, context), lowerMod(lowerModule) {
+    setHasBoundedRewriteRecursion();
+  }
 
   mlir::LogicalResult
   matchAndRewrite(cir::CmpOp op, OpAdaptor,

clang/test/CIR/CodeGen/pointer-to-data-member-cast.cpp

@@ -70,3 +70,29 @@ auto derived_to_base_zero_offset(int Derived::*ptr) -> int Base1::* {
   // LLVM-NEXT: %[[#ret:]] = load i64, ptr %[[#ret_slot]]
   // LLVM-NEXT: ret i64 %[[#ret]]
 }
+
+struct Foo {
+  int a;
+};
+
+struct Bar {
+  int a;
+};
+
+bool to_bool(int Foo::*x) {
+  return x;
+}
+
+// CIR-LABEL: @_Z7to_boolM3Fooi
+//      CIR:   %[[#x:]] = cir.load %{{.+}} : !cir.ptr<!cir.data_member<!s32i in !ty_Foo>>, !cir.data_member<!s32i in !ty_Foo>
+// CIR-NEXT:   %{{.+}} = cir.cast(member_ptr_to_bool, %[[#x]] : !cir.data_member<!s32i in !ty_Foo>), !cir.bool
+//      CIR: }
+
+auto bitcast(int Foo::*x) {
+  return reinterpret_cast<int Bar::*>(x);
+}
+
+// CIR-LABEL: @_Z7bitcastM3Fooi
+//      CIR:   %[[#x:]] = cir.load %{{.+}} : !cir.ptr<!cir.data_member<!s32i in !ty_Foo>>, !cir.data_member<!s32i in !ty_Foo>
+// CIR-NEXT:   %{{.+}} = cir.cast(bitcast, %[[#x]] : !cir.data_member<!s32i in !ty_Foo>), !cir.data_member<!s32i in !ty_Bar>
+//      CIR: }

clang/test/CIR/CodeGen/pointer-to-data-member-cmp.cpp

@@ -0,0 +1,44 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -std=c++17 -fclangir -emit-cir %s -o %t.cir
+// RUN: FileCheck --input-file=%t.cir --check-prefix=CIR %s
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -std=c++17 -fclangir -emit-llvm %s -o %t.ll
+// RUN: FileCheck --input-file=%t.ll --check-prefix=LLVM %s
+
+struct Foo {
+  int a;
+};
+
+struct Bar {
+  int a;
+};
+
+bool eq(int Foo::*x, int Foo::*y) {
+  return x == y;
+}
+
+// CIR-LABEL: @_Z2eqM3FooiS0_
+//      CIR:   %[[#x:]] = cir.load %{{.+}} : !cir.ptr<!cir.data_member<!s32i in !ty_Foo>>, !cir.data_member<!s32i in !ty_Foo>
+// CIR-NEXT:   %[[#y:]] = cir.load %{{.+}} : !cir.ptr<!cir.data_member<!s32i in !ty_Foo>>, !cir.data_member<!s32i in !ty_Foo>
+// CIR-NEXT:   %{{.+}} = cir.cmp(eq, %[[#x]], %[[#y]]) : !cir.data_member<!s32i in !ty_Foo>, !cir.bool
+//      CIR: }
+
+// LLVM-LABEL: @_Z2eqM3FooiS0_
+//      LLVM:   %[[#x:]] = load i64, ptr %{{.+}}, align 8
+// LLVM-NEXT:   %[[#y:]] = load i64, ptr %{{.+}}, align 8
+// LLVM-NEXT:   %{{.+}} = icmp eq i64 %[[#x]], %[[#y]]
+//      LLVM: }
+
+bool ne(int Foo::*x, int Foo::*y) {
+  return x != y;
+}
+
+// CIR-LABEL: @_Z2neM3FooiS0_
+//      CIR:   %[[#x:]] = cir.load %{{.+}} : !cir.ptr<!cir.data_member<!s32i in !ty_Foo>>, !cir.data_member<!s32i in !ty_Foo>
+// CIR-NEXT:   %[[#y:]] = cir.load %{{.+}} : !cir.ptr<!cir.data_member<!s32i in !ty_Foo>>, !cir.data_member<!s32i in !ty_Foo>
+// CIR-NEXT:   %{{.+}} = cir.cmp(ne, %[[#x]], %[[#y]]) : !cir.data_member<!s32i in !ty_Foo>, !cir.bool
+//      CIR: }
+
+// LLVM-LABEL: @_Z2neM3FooiS0_
+//      LLVM:   %[[#x:]] = load i64, ptr %{{.+}}, align 8
+// LLVM-NEXT:   %[[#y:]] = load i64, ptr %{{.+}}, align 8
+// LLVM-NEXT:   %{{.+}} = icmp ne i64 %[[#x]], %[[#y]]
+//      LLVM: }