[CIR] Add support for constructors with VTT parameters (#156521)

This adds the support for implicit VTT arguments in constructors.

Author: andykaylor

clang/include/clang/CIR/MissingFeatures.h

@@ -132,10 +132,8 @@ struct MissingFeatures {
   // RecordType
   static bool skippedLayout() { return false; }
   static bool astRecordDeclAttr() { return false; }
-  static bool cxxSupport() { return false; }
   static bool recordZeroInit() { return false; }
   static bool zeroSizeRecordMembers() { return false; }
-  static bool recordLayoutVirtualBases() { return false; }
 
   // Various handling of deferred processing in CIRGenModule.
   static bool cgmRelease() { return false; }
@@ -148,7 +146,6 @@ struct MissingFeatures {
   static bool cxxabiUseARMMethodPtrABI() { return false; }
   static bool cxxabiUseARMGuardVarABI() { return false; }
   static bool cxxabiAppleARM64CXXABI() { return false; }
-  static bool cxxabiStructorImplicitParam() { return false; }
   static bool isDiscreteBitFieldABI() { return false; }
 
   // Address class
@@ -230,7 +227,6 @@ struct MissingFeatures {
   static bool globalViewIndices() { return false; }
   static bool globalViewIntLowering() { return false; }
   static bool hip() { return false; }
-  static bool implicitConstructorArgs() { return false; }
   static bool incrementProfileCounter() { return false; }
   static bool innermostEHScope() { return false; }
   static bool insertBuiltinUnpredictable() { return false; }

clang/lib/CIR/CodeGen/CIRGenBuilder.h

@@ -287,6 +287,10 @@ class CIRGenBuilderTy : public cir::CIRBaseBuilderTy {
   cir::ConstantOp getUInt32(uint32_t c, mlir::Location loc) {
     return getConstantInt(loc, getUInt32Ty(), c);
   }
+  cir::ConstantOp getSInt64(uint64_t c, mlir::Location loc) {
+    cir::IntType sInt64Ty = getSInt64Ty();
+    return cir::ConstantOp::create(*this, loc, cir::IntAttr::get(sInt64Ty, c));
+  }
 
   // Creates constant nullptr for pointer type ty.
   cir::ConstantOp getNullPtr(mlir::Type ty, mlir::Location loc) {
@@ -359,6 +363,18 @@ class CIRGenBuilderTy : public cir::CIRBaseBuilderTy {
     return Address(baseAddr, destType, addr.getAlignment());
   }
 
+  mlir::Value createVTTAddrPoint(mlir::Location loc, mlir::Type retTy,
+                                 mlir::Value addr, uint64_t offset) {
+    return cir::VTTAddrPointOp::create(*this, loc, retTy,
+                                       mlir::FlatSymbolRefAttr{}, addr, offset);
+  }
+
+  mlir::Value createVTTAddrPoint(mlir::Location loc, mlir::Type retTy,
+                                 mlir::FlatSymbolRefAttr sym, uint64_t offset) {
+    return cir::VTTAddrPointOp::create(*this, loc, retTy, sym, mlir::Value{},
+                                       offset);
+  }
+
   /// Cast the element type of the given address to a different type,
   /// preserving information like the alignment.
   Address createElementBitCast(mlir::Location loc, Address addr,
@@ -379,6 +395,23 @@ class CIRGenBuilderTy : public cir::CIRBaseBuilderTy {
                                /*mem_order=*/cir::MemOrderAttr{});
   }
 
+  cir::LoadOp createAlignedLoad(mlir::Location loc, mlir::Type ty,
+                                mlir::Value ptr, llvm::MaybeAlign align) {
+    if (ty != mlir::cast<cir::PointerType>(ptr.getType()).getPointee())
+      ptr = createPtrBitcast(ptr, ty);
+    uint64_t alignment = align ? align->value() : 0;
+    mlir::IntegerAttr alignAttr = getAlignmentAttr(alignment);
+    return cir::LoadOp::create(*this, loc, ptr, /*isDeref=*/false,
+                               /*isVolatile=*/false, alignAttr,
+                               /*mem_order=*/cir::MemOrderAttr{});
+  }
+
+  cir::LoadOp
+  createAlignedLoad(mlir::Location loc, mlir::Type ty, mlir::Value ptr,
+                    clang::CharUnits align = clang::CharUnits::One()) {
+    return createAlignedLoad(loc, ty, ptr, align.getAsAlign());
+  }
+
   cir::StoreOp createStore(mlir::Location loc, mlir::Value val, Address dst,
                            bool isVolatile = false,
                            mlir::IntegerAttr align = {},

clang/lib/CIR/CodeGen/CIRGenCXXABI.cpp

@@ -22,6 +22,20 @@ using namespace clang::CIRGen;
 
 CIRGenCXXABI::~CIRGenCXXABI() {}
 
+CIRGenCXXABI::AddedStructorArgCounts CIRGenCXXABI::addImplicitConstructorArgs(
+    CIRGenFunction &cgf, const CXXConstructorDecl *d, CXXCtorType type,
+    bool forVirtualBase, bool delegating, CallArgList &args) {
+  AddedStructorArgs addedArgs =
+      getImplicitConstructorArgs(cgf, d, type, forVirtualBase, delegating);
+  for (auto [idx, prefixArg] : llvm::enumerate(addedArgs.prefix))
+    args.insert(args.begin() + 1 + idx,
+                CallArg(RValue::get(prefixArg.value), prefixArg.type));
+  for (const auto &arg : addedArgs.suffix)
+    args.add(RValue::get(arg.value), arg.type);
+  return AddedStructorArgCounts(addedArgs.prefix.size(),
+                                addedArgs.suffix.size());
+}
+
 void CIRGenCXXABI::buildThisParam(CIRGenFunction &cgf,
                                   FunctionArgList &params) {
   const auto *md = cast<CXXMethodDecl>(cgf.curGD.getDecl());

clang/lib/CIR/CodeGen/CIRGenCXXABI.h

@@ -47,11 +47,67 @@ class CIRGenCXXABI {
   /// constructor/destructor Decl.
   virtual void emitCXXStructor(clang::GlobalDecl gd) = 0;
 
+  virtual mlir::Value
+  getVirtualBaseClassOffset(mlir::Location loc, CIRGenFunction &cgf,
+                            Address thisAddr, const CXXRecordDecl *classDecl,
+                            const CXXRecordDecl *baseClassDecl) = 0;
+
 public:
+  /// Similar to AddedStructorArgs, but only notes the number of additional
+  /// arguments.
+  struct AddedStructorArgCounts {
+    unsigned prefix = 0;
+    unsigned suffix = 0;
+    AddedStructorArgCounts() = default;
+    AddedStructorArgCounts(unsigned p, unsigned s) : prefix(p), suffix(s) {}
+    static AddedStructorArgCounts withPrefix(unsigned n) { return {n, 0}; }
+    static AddedStructorArgCounts withSuffix(unsigned n) { return {0, n}; }
+  };
+
+  /// Additional implicit arguments to add to the beginning (Prefix) and end
+  /// (Suffix) of a constructor / destructor arg list.
+  ///
+  /// Note that Prefix should actually be inserted *after* the first existing
+  /// arg; `this` arguments always come first.
+  struct AddedStructorArgs {
+    struct Arg {
+      mlir::Value value;
+      QualType type;
+    };
+    llvm::SmallVector<Arg, 1> prefix;
+    llvm::SmallVector<Arg, 1> suffix;
+    AddedStructorArgs() = default;
+    AddedStructorArgs(llvm::SmallVector<Arg, 1> p, llvm::SmallVector<Arg, 1> s)
+        : prefix(std::move(p)), suffix(std::move(s)) {}
+    static AddedStructorArgs withPrefix(llvm::SmallVector<Arg, 1> args) {
+      return {std::move(args), {}};
+    }
+    static AddedStructorArgs withSuffix(llvm::SmallVector<Arg, 1> args) {
+      return {{}, std::move(args)};
+    }
+  };
+
+  /// Build the signature of the given constructor or destructor vairant by
+  /// adding any required parameters. For convenience, ArgTys has been
+  /// initialized with the type of 'this'.
+  virtual AddedStructorArgCounts
+  buildStructorSignature(GlobalDecl gd,
+                         llvm::SmallVectorImpl<CanQualType> &argTys) = 0;
+
+  AddedStructorArgCounts
+  addImplicitConstructorArgs(CIRGenFunction &cgf, const CXXConstructorDecl *d,
+                             CXXCtorType type, bool forVirtualBase,
+                             bool delegating, CallArgList &args);
+
   clang::ImplicitParamDecl *getThisDecl(CIRGenFunction &cgf) {
     return cgf.cxxabiThisDecl;
   }
 
+  virtual AddedStructorArgs
+  getImplicitConstructorArgs(CIRGenFunction &cgf, const CXXConstructorDecl *d,
+                             CXXCtorType type, bool forVirtualBase,
+                             bool delegating) = 0;
+
   /// Emit the ABI-specific prolog for the function
   virtual void emitInstanceFunctionProlog(SourceLocation loc,
                                           CIRGenFunction &cgf) = 0;
@@ -144,6 +200,17 @@ class CIRGenCXXABI {
       CIRGenFunction &cgf, const CXXRecordDecl *vtableClass, BaseSubobject base,
       const CXXRecordDecl *nearestVBase) = 0;
 
+  /// Insert any ABI-specific implicit parameters into the parameter list for a
+  /// function. This generally involves extra data for constructors and
+  /// destructors.
+  ///
+  /// ABIs may also choose to override the return type, which has been
+  /// initialized with the type of 'this' if HasThisReturn(CGF.CurGD) is true or
+  /// the formal return type of the function otherwise.
+  virtual void addImplicitStructorParams(CIRGenFunction &cgf,
+                                         clang::QualType &resTy,
+                                         FunctionArgList &params) = 0;
+
   /// Checks if ABI requires to initialize vptrs for given dynamic class.
   virtual bool
   doStructorsInitializeVPtrs(const clang::CXXRecordDecl *vtableClass) = 0;
@@ -162,6 +229,18 @@ class CIRGenCXXABI {
 
   /// Gets the mangle context.
   clang::MangleContext &getMangleContext() { return *mangleContext; }
+
+  clang::ImplicitParamDecl *&getStructorImplicitParamDecl(CIRGenFunction &cgf) {
+    return cgf.cxxStructorImplicitParamDecl;
+  }
+
+  mlir::Value getStructorImplicitParamValue(CIRGenFunction &cgf) {
+    return cgf.cxxStructorImplicitParamValue;
+  }
+
+  void setStructorImplicitParamValue(CIRGenFunction &cgf, mlir::Value val) {
+    cgf.cxxStructorImplicitParamValue = val;
+  }
 };
 
 /// Creates and Itanium-family ABI

clang/lib/CIR/CodeGen/CIRGenCall.cpp

@@ -197,7 +197,10 @@ CIRGenTypes::arrangeCXXStructorDeclaration(GlobalDecl gd) {
   if (passParams)
     appendParameterTypes(*this, argTypes, fpt);
 
-  assert(!cir::MissingFeatures::implicitConstructorArgs());
+  // The structor signature may include implicit parameters.
+  [[maybe_unused]] CIRGenCXXABI::AddedStructorArgCounts addedArgs =
+      theCXXABI.buildStructorSignature(gd, argTypes);
+  assert(!cir::MissingFeatures::opCallCIRGenFuncInfoExtParamInfo());
 
   RequiredArgs required =
       (passParams && md->isVariadic() ? RequiredArgs(argTypes.size())
@@ -324,26 +327,27 @@ arrangeFreeFunctionLikeCall(CIRGenTypes &cgt, CIRGenModule &cgm,
 
 /// Arrange a call to a C++ method, passing the given arguments.
 ///
+/// extraPrefixArgs is the number of ABI-specific args passed after the `this`
+/// parameter.
 /// passProtoArgs indicates whether `args` has args for the parameters in the
 /// given CXXConstructorDecl.
 const CIRGenFunctionInfo &CIRGenTypes::arrangeCXXConstructorCall(
     const CallArgList &args, const CXXConstructorDecl *d, CXXCtorType ctorKind,
-    bool passProtoArgs) {
+    unsigned extraPrefixArgs, unsigned extraSuffixArgs, bool passProtoArgs) {
 
   // FIXME: Kill copy.
   llvm::SmallVector<CanQualType, 16> argTypes;
   for (const auto &arg : args)
     argTypes.push_back(astContext.getCanonicalParamType(arg.ty));
 
-  assert(!cir::MissingFeatures::implicitConstructorArgs());
   // +1 for implicit this, which should always be args[0]
-  unsigned totalPrefixArgs = 1;
+  unsigned totalPrefixArgs = 1 + extraPrefixArgs;
 
   CanQual<FunctionProtoType> fpt = getFormalType(d);
-  RequiredArgs required =
-      passProtoArgs
-          ? RequiredArgs::getFromProtoWithExtraSlots(fpt, totalPrefixArgs)
-          : RequiredArgs::All;
+  RequiredArgs required = passProtoArgs
+                              ? RequiredArgs::getFromProtoWithExtraSlots(
+                                    fpt, totalPrefixArgs + extraSuffixArgs)
+                              : RequiredArgs::All;
 
   GlobalDecl gd(d, ctorKind);
   if (theCXXABI.hasThisReturn(gd))