MS ABI: Mangle member pointer template arguments

Member pointers are mangled as they would be represented at runtime.
They can be a single integer literal, single decl, or a tuple with some
more numbers tossed in.  With Clang today, most of those numbers will be
zero because we reject pointers to members of virtual bases.

This change required moving VTableContextBase ownership from
CodeGenVTables to ASTContext, because mangling now depends on vtable
layout.

I also hoisted the inheritance model helpers up to be inline static
methods of MSInheritanceAttr.  This makes the AST code that deals with
member pointers much more readable.

MSVC doesn't appear to have stable manglings of null member pointers:
- Null data memptrs in function templates have a mangling collision with
  the first field of a non-polymorphic single inheritance class.
- The mangling of null data memptrs changes if you add casts.
- Large null function memptrs in class templates crash MSVC.

Clang uses the class template mangling for null data memptrs and the
function template mangling for null function memptrs to deal with this.

Reviewers: majnemer

Differential Revision: http://llvm-reviews.chandlerc.com/D2695

llvm-svn: 200857

1 files changed, 40 insertions, 77 deletions

diff --git a/clang/lib/CodeGen/MicrosoftCXXABI.cpp b/clang/lib/CodeGen/MicrosoftCXXABI.cpp
index 3433c8ca30c..c8d63af05c6 100644
--- a/clang/lib/CodeGen/MicrosoftCXXABI.cpp
+++ b/clang/lib/CodeGen/MicrosoftCXXABI.cpp
@@ -1327,44 +1327,6 @@ void MicrosoftCXXABI::EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
   CGF.EmitBlock(EndBlock);
 }
 
-// Member pointer helpers.
-static bool hasVBPtrOffsetField(MSInheritanceAttr::Spelling Inheritance) {
-  return Inheritance == MSInheritanceAttr::Keyword_unspecified_inheritance;
-}
-
-static bool hasOnlyOneField(bool IsMemberFunction,
-                            MSInheritanceAttr::Spelling Inheritance) {
-  if (IsMemberFunction)
-    return Inheritance <= MSInheritanceAttr::Keyword_single_inheritance;
-  return Inheritance <= MSInheritanceAttr::Keyword_multiple_inheritance;
-}
-
-// Only member pointers to functions need a this adjustment, since it can be
-// combined with the field offset for data pointers.
-static bool
-hasNonVirtualBaseAdjustmentField(bool IsMemberFunction,
-                                 MSInheritanceAttr::Spelling Inheritance) {
-  return IsMemberFunction &&
-         Inheritance >= MSInheritanceAttr::Keyword_multiple_inheritance;
-}
-
-static bool
-hasVirtualBaseAdjustmentField(MSInheritanceAttr::Spelling Inheritance) {
-  return Inheritance >= MSInheritanceAttr::Keyword_virtual_inheritance;
-}
-
-// Use zero for the field offset of a null data member pointer if we can
-// guarantee that zero is not a valid field offset, or if the member pointer has
-// multiple fields.  Polymorphic classes have a vfptr at offset zero, so we can
-// use zero for null.  If there are multiple fields, we can use zero even if it
-// is a valid field offset because null-ness testing will check the other
-// fields.
-static bool nullFieldOffsetIsZero(const CXXRecordDecl *RD) {
-  return RD->getMSInheritanceModel() >=
-             MSInheritanceAttr::Keyword_virtual_inheritance ||
-         (RD->hasDefinition() && RD->isPolymorphic());
-}
-
 bool MicrosoftCXXABI::isZeroInitializable(const MemberPointerType *MPT) {
   // Null-ness for function memptrs only depends on the first field, which is
   // the function pointer.  The rest don't matter, so we can zero initialize.
@@ -1376,8 +1338,8 @@ bool MicrosoftCXXABI::isZeroInitializable(const MemberPointerType *MPT) {
   // valid field offset.
   const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
   MSInheritanceAttr::Spelling Inheritance = RD->getMSInheritanceModel();
-  return (!hasVirtualBaseAdjustmentField(Inheritance) &&
-          nullFieldOffsetIsZero(RD));
+  return (!MSInheritanceAttr::hasVBTableOffsetField(Inheritance) &&
+          RD->nullFieldOffsetIsZero());
 }
 
 llvm::Type *
@@ -1390,12 +1352,12 @@ MicrosoftCXXABI::ConvertMemberPointerType(const MemberPointerType *MPT) {
   else
     fields.push_back(CGM.IntTy);  // FieldOffset
 
-  if (hasNonVirtualBaseAdjustmentField(MPT->isMemberFunctionPointer(),
-                                       Inheritance))
+  if (MSInheritanceAttr::hasNVOffsetField(MPT->isMemberFunctionPointer(),
+                                          Inheritance))
     fields.push_back(CGM.IntTy);
-  if (hasVBPtrOffsetField(Inheritance))
+  if (MSInheritanceAttr::hasVBPtrOffsetField(Inheritance))
     fields.push_back(CGM.IntTy);
-  if (hasVirtualBaseAdjustmentField(Inheritance))
+  if (MSInheritanceAttr::hasVBTableOffsetField(Inheritance))
     fields.push_back(CGM.IntTy);  // VirtualBaseAdjustmentOffset
 
   if (fields.size() == 1)
@@ -1413,18 +1375,18 @@ GetNullMemberPointerFields(const MemberPointerType *MPT,
     // FunctionPointerOrVirtualThunk
     fields.push_back(llvm::Constant::getNullValue(CGM.VoidPtrTy));
   } else {
-    if (nullFieldOffsetIsZero(RD))
+    if (RD->nullFieldOffsetIsZero())
       fields.push_back(getZeroInt());  // FieldOffset
     else
       fields.push_back(getAllOnesInt());  // FieldOffset
   }
 
-  if (hasNonVirtualBaseAdjustmentField(MPT->isMemberFunctionPointer(),
-                                       Inheritance))
+  if (MSInheritanceAttr::hasNVOffsetField(MPT->isMemberFunctionPointer(),
+                                          Inheritance))
     fields.push_back(getZeroInt());
-  if (hasVBPtrOffsetField(Inheritance))
+  if (MSInheritanceAttr::hasVBPtrOffsetField(Inheritance))
     fields.push_back(getZeroInt());
-  if (hasVirtualBaseAdjustmentField(Inheritance))
+  if (MSInheritanceAttr::hasVBTableOffsetField(Inheritance))
     fields.push_back(getAllOnesInt());
 }
 
@@ -1449,17 +1411,17 @@ MicrosoftCXXABI::EmitFullMemberPointer(llvm::Constant *FirstField,
 
   // Single inheritance class member pointer are represented as scalars instead
   // of aggregates.
-  if (hasOnlyOneField(IsMemberFunction, Inheritance))
+  if (MSInheritanceAttr::hasOnlyOneField(IsMemberFunction, Inheritance))
     return FirstField;
 
   llvm::SmallVector<llvm::Constant *, 4> fields;
   fields.push_back(FirstField);
 
-  if (hasNonVirtualBaseAdjustmentField(IsMemberFunction, Inheritance))
+  if (MSInheritanceAttr::hasNVOffsetField(IsMemberFunction, Inheritance))
     fields.push_back(llvm::ConstantInt::get(
       CGM.IntTy, NonVirtualBaseAdjustment.getQuantity()));
 
-  if (hasVBPtrOffsetField(Inheritance)) {
+  if (MSInheritanceAttr::hasVBPtrOffsetField(Inheritance)) {
     CharUnits Offs = CharUnits::Zero();
     if (RD->getNumVBases())
       Offs = getContext().getASTRecordLayout(RD).getVBPtrOffset();
@@ -1467,7 +1429,7 @@ MicrosoftCXXABI::EmitFullMemberPointer(llvm::Constant *FirstField,
   }
 
   // The rest of the fields are adjusted by conversions to a more derived class.
-  if (hasVirtualBaseAdjustmentField(Inheritance))
+  if (MSInheritanceAttr::hasVBTableOffsetField(Inheritance))
     fields.push_back(getZeroInt());
 
   return llvm::ConstantStruct::getAnon(fields);
@@ -1552,7 +1514,7 @@ MicrosoftCXXABI::BuildMemberPointer(const CXXRecordDecl *RD,
           getContext().getTargetInfo().getPointerWidth(0));
       uint64_t OffsetInVFTable = ML.Index * PointerWidth.getQuantity();
       llvm::raw_svector_ostream Out(ThunkName);
-      getMangleContext().mangleVirtualMemPtrThunk(MD, OffsetInVFTable, Out);
+      getMangleContext().mangleVirtualMemPtrThunk(MD, Out);
       Out.flush();
 
       llvm::Function *Thunk = EmitVirtualMemPtrThunk(MD, ThunkName.str());
@@ -1593,7 +1555,8 @@ MicrosoftCXXABI::EmitMemberPointerComparison(CodeGenFunction &CGF,
   // single icmp.
   const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
   MSInheritanceAttr::Spelling Inheritance = RD->getMSInheritanceModel();
-  if (hasOnlyOneField(MPT->isMemberFunctionPointer(), Inheritance))
+  if (MSInheritanceAttr::hasOnlyOneField(MPT->isMemberFunctionPointer(),
+                                         Inheritance))
     return Builder.CreateICmp(Eq, L, R);
 
   // Compare the first field.
@@ -1785,9 +1748,9 @@ MicrosoftCXXABI::EmitMemberDataPointerAddress(CodeGenFunction &CGF,
     // We need to extract values.
     unsigned I = 0;
     FieldOffset = Builder.CreateExtractValue(MemPtr, I++);
-    if (hasVBPtrOffsetField(Inheritance))
+    if (MSInheritanceAttr::hasVBPtrOffsetField(Inheritance))
       VBPtrOffset = Builder.CreateExtractValue(MemPtr, I++);
-    if (hasVirtualBaseAdjustmentField(Inheritance))
+    if (MSInheritanceAttr::hasVBTableOffsetField(Inheritance))
       VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(MemPtr, I++);
   }
 
@@ -1840,7 +1803,7 @@ MicrosoftCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF,
   CXXRecordDecl *SrcRD = SrcTy->getMostRecentCXXRecordDecl();
   CXXRecordDecl *DstRD = DstTy->getMostRecentCXXRecordDecl();
   if (IsReinterpret &&
-      nullFieldOffsetIsZero(SrcRD) == nullFieldOffsetIsZero(DstRD))
+      SrcRD->nullFieldOffsetIsZero() == DstRD->nullFieldOffsetIsZero())
     return Src;
 
   CGBuilderTy &Builder = CGF.Builder;
@@ -1870,15 +1833,15 @@ MicrosoftCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF,
   llvm::Value *VirtualBaseAdjustmentOffset = 0;
   llvm::Value *VBPtrOffset = 0;
   MSInheritanceAttr::Spelling SrcInheritance = SrcRD->getMSInheritanceModel();
-  if (!hasOnlyOneField(IsFunc, SrcInheritance)) {
+  if (!MSInheritanceAttr::hasOnlyOneField(IsFunc, SrcInheritance)) {
     // We need to extract values.
     unsigned I = 0;
     FirstField = Builder.CreateExtractValue(Src, I++);
-    if (hasNonVirtualBaseAdjustmentField(IsFunc, SrcInheritance))
+    if (MSInheritanceAttr::hasNVOffsetField(IsFunc, SrcInheritance))
       NonVirtualBaseAdjustment = Builder.CreateExtractValue(Src, I++);
-    if (hasVBPtrOffsetField(SrcInheritance))
+    if (MSInheritanceAttr::hasVBPtrOffsetField(SrcInheritance))
       VBPtrOffset = Builder.CreateExtractValue(Src, I++);
-    if (hasVirtualBaseAdjustmentField(SrcInheritance))
+    if (MSInheritanceAttr::hasVBTableOffsetField(SrcInheritance))
       VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(Src, I++);
   }
 
@@ -1902,19 +1865,19 @@ MicrosoftCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF,
   // Recompose dst from the null struct and the adjusted fields from src.
   MSInheritanceAttr::Spelling DstInheritance = DstRD->getMSInheritanceModel();
   llvm::Value *Dst;
-  if (hasOnlyOneField(IsFunc, DstInheritance)) {
+  if (MSInheritanceAttr::hasOnlyOneField(IsFunc, DstInheritance)) {
     Dst = FirstField;
   } else {
     Dst = llvm::UndefValue::get(DstNull->getType());
     unsigned Idx = 0;
     Dst = Builder.CreateInsertValue(Dst, FirstField, Idx++);
-    if (hasNonVirtualBaseAdjustmentField(IsFunc, DstInheritance))
+    if (MSInheritanceAttr::hasNVOffsetField(IsFunc, DstInheritance))
       Dst = Builder.CreateInsertValue(
         Dst, getValueOrZeroInt(NonVirtualBaseAdjustment), Idx++);
-    if (hasVBPtrOffsetField(DstInheritance))
+    if (MSInheritanceAttr::hasVBPtrOffsetField(DstInheritance))
       Dst = Builder.CreateInsertValue(
         Dst, getValueOrZeroInt(VBPtrOffset), Idx++);
-    if (hasVirtualBaseAdjustmentField(DstInheritance))
+    if (MSInheritanceAttr::hasVBTableOffsetField(DstInheritance))
       Dst = Builder.CreateInsertValue(
         Dst, getValueOrZeroInt(VirtualBaseAdjustmentOffset), Idx++);
   }
@@ -1955,15 +1918,15 @@ MicrosoftCXXABI::EmitMemberPointerConversion(const CastExpr *E,
   llvm::Constant *VirtualBaseAdjustmentOffset = 0;
   llvm::Constant *VBPtrOffset = 0;
   bool IsFunc = SrcTy->isMemberFunctionPointer();
-  if (!hasOnlyOneField(IsFunc, SrcInheritance)) {
+  if (!MSInheritanceAttr::hasOnlyOneField(IsFunc, SrcInheritance)) {
     // We need to extract values.
     unsigned I = 0;
     FirstField = Src->getAggregateElement(I++);
-    if (hasNonVirtualBaseAdjustmentField(IsFunc, SrcInheritance))
+    if (MSInheritanceAttr::hasNVOffsetField(IsFunc, SrcInheritance))
       NonVirtualBaseAdjustment = Src->getAggregateElement(I++);
-    if (hasVBPtrOffsetField(SrcInheritance))
+    if (MSInheritanceAttr::hasVBPtrOffsetField(SrcInheritance))
       VBPtrOffset = Src->getAggregateElement(I++);
-    if (hasVirtualBaseAdjustmentField(SrcInheritance))
+    if (MSInheritanceAttr::hasVBTableOffsetField(SrcInheritance))
       VirtualBaseAdjustmentOffset = Src->getAggregateElement(I++);
   }
 
@@ -1986,16 +1949,16 @@ MicrosoftCXXABI::EmitMemberPointerConversion(const CastExpr *E,
   // FIXME PR15713: Support conversions through virtually derived classes.
 
   // Recompose dst from the null struct and the adjusted fields from src.
-  if (hasOnlyOneField(IsFunc, DstInheritance))
+  if (MSInheritanceAttr::hasOnlyOneField(IsFunc, DstInheritance))
     return FirstField;
 
   llvm::SmallVector<llvm::Constant *, 4> Fields;
   Fields.push_back(FirstField);
-  if (hasNonVirtualBaseAdjustmentField(IsFunc, DstInheritance))
+  if (MSInheritanceAttr::hasNVOffsetField(IsFunc, DstInheritance))
     Fields.push_back(getConstantOrZeroInt(NonVirtualBaseAdjustment));
-  if (hasVBPtrOffsetField(DstInheritance))
+  if (MSInheritanceAttr::hasVBPtrOffsetField(DstInheritance))
     Fields.push_back(getConstantOrZeroInt(VBPtrOffset));
-  if (hasVirtualBaseAdjustmentField(DstInheritance))
+  if (MSInheritanceAttr::hasVBTableOffsetField(DstInheritance))
     Fields.push_back(getConstantOrZeroInt(VirtualBaseAdjustmentOffset));
   return llvm::ConstantStruct::getAnon(Fields);
 }
@@ -2026,11 +1989,11 @@ MicrosoftCXXABI::EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF,
     // We need to extract values.
     unsigned I = 0;
     FunctionPointer = Builder.CreateExtractValue(MemPtr, I++);
-    if (hasNonVirtualBaseAdjustmentField(MPT, Inheritance))
+    if (MSInheritanceAttr::hasNVOffsetField(MPT, Inheritance))
       NonVirtualBaseAdjustment = Builder.CreateExtractValue(MemPtr, I++);
-    if (hasVBPtrOffsetField(Inheritance))
+    if (MSInheritanceAttr::hasVBPtrOffsetField(Inheritance))
       VBPtrOffset = Builder.CreateExtractValue(MemPtr, I++);
-    if (hasVirtualBaseAdjustmentField(Inheritance))
+    if (MSInheritanceAttr::hasVBTableOffsetField(Inheritance))
       VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(MemPtr, I++);
   }