1 files changed, 121 insertions, 15 deletions

diff --git a/lib/AST/MicrosoftCXXABI.cpp b/lib/AST/MicrosoftCXXABI.cpp
index 51308ea0c0f5..6553e9d74943 100644
--- a/lib/AST/MicrosoftCXXABI.cpp
+++ b/lib/AST/MicrosoftCXXABI.cpp
@@ -13,6 +13,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "CXXABI.h"
+#include "clang/AST/Attr.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/DeclCXX.h"
 #include "clang/AST/RecordLayout.h"
@@ -27,13 +28,14 @@ class MicrosoftCXXABI : public CXXABI {
 public:
   MicrosoftCXXABI(ASTContext &Ctx) : Context(Ctx) { }
 
-  unsigned getMemberPointerSize(const MemberPointerType *MPT) const;
+  std::pair<uint64_t, unsigned>
+  getMemberPointerWidthAndAlign(const MemberPointerType *MPT) const;
 
   CallingConv getDefaultMethodCallConv(bool isVariadic) const {
-    if (!isVariadic && Context.getTargetInfo().getTriple().getArch() == llvm::Triple::x86)
+    if (!isVariadic &&
+        Context.getTargetInfo().getTriple().getArch() == llvm::Triple::x86)
       return CC_X86ThisCall;
-    else
-      return CC_C;
+    return CC_C;
   }
 
   bool isNearlyEmpty(const CXXRecordDecl *RD) const {
@@ -52,17 +54,121 @@ public:
 };
 }
 
-unsigned MicrosoftCXXABI::getMemberPointerSize(const MemberPointerType *MPT) const {
-  QualType Pointee = MPT->getPointeeType();
-  CXXRecordDecl *RD = MPT->getClass()->getAsCXXRecordDecl();
-  if (RD->getNumVBases() > 0) {
-    if (Pointee->isFunctionType())
-      return 3;
-    else
-      return 2;
-  } else if (RD->getNumBases() > 1 && Pointee->isFunctionType())
-    return 2;
-  return 1;
+// getNumBases() seems to only give us the number of direct bases, and not the
+// total.  This function tells us if we inherit from anybody that uses MI, or if
+// we have a non-primary base class, which uses the multiple inheritance model.
+static bool usesMultipleInheritanceModel(const CXXRecordDecl *RD) {
+  while (RD->getNumBases() > 0) {
+    if (RD->getNumBases() > 1)
+      return true;
+    assert(RD->getNumBases() == 1);
+    const CXXRecordDecl *Base =
+        RD->bases_begin()->getType()->getAsCXXRecordDecl();
+    if (RD->isPolymorphic() && !Base->isPolymorphic())
+      return true;
+    RD = Base;
+  }
+  return false;
+}
+
+static MSInheritanceModel MSInheritanceAttrToModel(attr::Kind Kind) {
+  switch (Kind) {
+  default: llvm_unreachable("expected MS inheritance attribute");
+  case attr::SingleInheritance:      return MSIM_Single;
+  case attr::MultipleInheritance:    return MSIM_Multiple;
+  case attr::VirtualInheritance:     return MSIM_Virtual;
+  case attr::UnspecifiedInheritance: return MSIM_Unspecified;
+  }
+}
+
+MSInheritanceModel CXXRecordDecl::getMSInheritanceModel() const {
+  if (Attr *IA = this->getAttr<MSInheritanceAttr>())
+    return MSInheritanceAttrToModel(IA->getKind());
+  // If there was no explicit attribute, the record must be defined already, and
+  // we can figure out the inheritance model from its other properties.
+  if (this->getNumVBases() > 0)
+    return MSIM_Virtual;
+  if (usesMultipleInheritanceModel(this))
+    return MSIM_Multiple;
+  return MSIM_Single;
+}
+
+// Returns the number of pointer and integer slots used to represent a member
+// pointer in the MS C++ ABI.
+//
+// Member function pointers have the following general form;  however, fields
+// are dropped as permitted (under the MSVC interpretation) by the inheritance
+// model of the actual class.
+//
+//   struct {
+//     // A pointer to the member function to call.  If the member function is
+//     // virtual, this will be a thunk that forwards to the appropriate vftable
+//     // slot.
+//     void *FunctionPointerOrVirtualThunk;
+//
+//     // An offset to add to the address of the vbtable pointer after (possibly)
+//     // selecting the virtual base but before resolving and calling the function.
+//     // Only needed if the class has any virtual bases or bases at a non-zero
+//     // offset.
+//     int NonVirtualBaseAdjustment;
+//
+//     // An offset within the vb-table that selects the virtual base containing
+//     // the member.  Loading from this offset produces a new offset that is
+//     // added to the address of the vb-table pointer to produce the base.
+//     int VirtualBaseAdjustmentOffset;
+//
+//     // The offset of the vb-table pointer within the object.  Only needed for
+//     // incomplete types.
+//     int VBTableOffset;
+//   };
+std::pair<unsigned, unsigned>
+MemberPointerType::getMSMemberPointerSlots() const {
+  const CXXRecordDecl *RD = this->getClass()->getAsCXXRecordDecl();
+  MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
+  unsigned Ptrs;
+  unsigned Ints = 0;
+  if (this->isMemberFunctionPointer()) {
+    // Member function pointers are a struct of a function pointer followed by a
+    // variable number of ints depending on the inheritance model used.  The
+    // function pointer is a real function if it is non-virtual and a vftable
+    // slot thunk if it is virtual.  The ints select the object base passed for
+    // the 'this' pointer.
+    Ptrs = 1;  // First slot is always a function pointer.
+    switch (Inheritance) {
+    case MSIM_Unspecified: ++Ints;  // VBTableOffset
+    case MSIM_Virtual:     ++Ints;  // VirtualBaseAdjustmentOffset
+    case MSIM_Multiple:    ++Ints;  // NonVirtualBaseAdjustment
+    case MSIM_Single:      break;   // Nothing
+    }
+  } else {
+    // Data pointers are an aggregate of ints.  The first int is an offset
+    // followed by vbtable-related offsets.
+    Ptrs = 0;
+    switch (Inheritance) {
+    case MSIM_Unspecified: ++Ints;  // VBTableOffset
+    case MSIM_Virtual:     ++Ints;  // VirtualBaseAdjustmentOffset
+    case MSIM_Multiple:             // Nothing
+    case MSIM_Single:      ++Ints;  // Field offset
+    }
+  }
+  return std::make_pair(Ptrs, Ints);
+}
+
+std::pair<uint64_t, unsigned> MicrosoftCXXABI::getMemberPointerWidthAndAlign(
+    const MemberPointerType *MPT) const {
+  const TargetInfo &Target = Context.getTargetInfo();
+  assert(Target.getTriple().getArch() == llvm::Triple::x86 ||
+         Target.getTriple().getArch() == llvm::Triple::x86_64);
+  unsigned Ptrs, Ints;
+  llvm::tie(Ptrs, Ints) = MPT->getMSMemberPointerSlots();
+  // The nominal struct is laid out with pointers followed by ints and aligned
+  // to a pointer width if any are present and an int width otherwise.
+  unsigned PtrSize = Target.getPointerWidth(0);
+  unsigned IntSize = Target.getIntWidth();
+  uint64_t Width = Ptrs * PtrSize + Ints * IntSize;
+  unsigned Align = Ptrs > 0 ? Target.getPointerAlign(0) : Target.getIntAlign();
+  Width = llvm::RoundUpToAlignment(Width, Align);
+  return std::make_pair(Width, Align);
 }
 
 CXXABI *clang::CreateMicrosoftCXXABI(ASTContext &Ctx) {