First pass at abstracting out a class for the target C++ ABI.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@173514 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 159 insertions, 0 deletions

diff --git a/include/clang/Basic/TargetCXXABI.h b/include/clang/Basic/TargetCXXABI.h
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+//===--- TargetCXXABI.h - C++ ABI Target Configuration ----------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// \brief Defines the TargetCXXABI class, which abstracts details of the
+/// C++ ABI that we're targeting.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TARGETCXXABI_H
+#define LLVM_CLANG_TARGETCXXABI_H
+
+#include "llvm/ADT/Triple.h"
+#include "llvm/Support/ErrorHandling.h"
+
+namespace clang {
+
+/// \brief The basic abstraction for the target C++ ABI.
+class TargetCXXABI {
+public:
+  /// \brief The basic C++ ABI kind.
+  enum Kind {
+    /// The generic Itanium ABI is the standard ABI of most open-source
+    /// and Unix-like platforms.  It is the primary ABI targeted by
+    /// many compilers, including Clang and GCC.
+    ///
+    /// It is documented here:
+    ///   http://www.codesourcery.com/public/cxx-abi/
+    GenericItanium,
+
+    /// The generic ARM ABI is a modified version of the Itanium ABI
+    /// proposed by ARM for use on ARM-based platforms.
+    ///
+    /// These changes include:
+    ///   - the representation of member function pointers is adjusted
+    ///     to not conflict with the 'thumb' bit of ARM function pointers;
+    ///   - constructors and destructors return 'this';
+    ///   - guard variables are smaller;
+    ///   - inline functions are never key functions;
+    ///   - array cookies have a slightly different layout;
+    ///   - additional convenience functions are specified;
+    ///   - and more!
+    ///
+    /// It is documented here:
+    ///    http://infocenter.arm.com
+    ///                    /help/topic/com.arm.doc.ihi0041c/IHI0041C_cppabi.pdf
+    GenericARM,
+
+    /// The iOS ABI is a partial implementation of the ARM ABI.
+    /// Several of the features of the ARM ABI were not fully implemented
+    /// in the compilers that iOS was launched with.
+    ///
+    /// Essentially, the iOS ABI includes the ARM changes to:
+    ///   - member function pointers,
+    ///   - guard variables,
+    ///   - array cookies, and
+    ///   - constructor/destructor signatures.
+    iOS,
+
+    /// The Microsoft ABI is the ABI used by Microsoft Visual Studio (and
+    /// compatible compilers).
+    ///
+    /// FIXME: should this be split into Win32 and Win64 variants?
+    ///
+    /// Only scattered and incomplete official documentation exists.
+    Microsoft
+  };
+
+private:
+  // Right now, this class is passed around as a cheap value type.
+  // If you add more members, especially non-POD members, please
+  // audit the users to pass it by reference instead.
+  Kind TheKind;
+
+public:
+  /// A bogus initialization of the platform ABI.
+  TargetCXXABI() : TheKind(GenericItanium) {}
+
+  TargetCXXABI(Kind kind) : TheKind(kind) {}
+
+  void set(Kind kind) {
+    TheKind = kind;
+  }
+
+  Kind getKind() const { return TheKind; }
+
+  /// \brief Does this ABI generally fall into the Itanium family of ABIs?
+  bool isItaniumFamily() const {
+    switch (getKind()) {
+    case GenericItanium:
+    case GenericARM:
+    case iOS:
+      return true;
+
+    case Microsoft:
+      return false;
+    }
+    llvm_unreachable("bad ABI kind");
+  }
+
+  /// \brief Is this ABI an MSVC-compatible ABI?
+  bool isMicrosoft() const {
+    switch (getKind()) {
+    case GenericItanium:
+    case GenericARM:
+    case iOS:
+      return false;
+
+    case Microsoft:
+      return true;
+    }
+    llvm_unreachable("bad ABI kind");
+  }
+
+  /// \brief Is the default C++ member function calling convention
+  /// the same as the default calling convention?
+  bool isMemberFunctionCCDefault() const {
+    // Right now, this is always true for Microsoft.
+    return !isMicrosoft();
+  }
+
+  /// \brief Does this ABI have different entrypoints for complete-object
+  /// and base-subobject constructors?
+  bool hasConstructorVariants() const {
+    return isItaniumFamily();
+  }
+
+  /// \brief Does this ABI have different entrypoints for complete-object
+  /// and base-subobject destructors?
+  bool hasDestructorVariants() const {
+    return isItaniumFamily();
+  }
+
+  /// \brief Does this ABI allow virtual bases to be primary base classes?
+  bool hasPrimaryVBases() const {
+    return isItaniumFamily();
+  }
+
+  /// Try to parse an ABI name, returning false on error.
+  bool tryParse(llvm::StringRef name);
+
+  friend bool operator==(const TargetCXXABI &left, const TargetCXXABI &right) {
+    return left.getKind() == right.getKind();
+  }
+
+  friend bool operator!=(const TargetCXXABI &left, const TargetCXXABI &right) {
+    return !(left == right);
+  }
+};
+
+}  // end namespace clang
+
+#endif