MS ABI: Implement x86_64 RTTI

Summary:
The RTTI scheme for x86_64 is largely the same as the one for i386.

Differences are largely limited to avoiding load-time relocations by
replacing pointers to RTTI metadata with the difference of that data
relative to the load address of the module.

Interestingly, this precludes the possibility of successfully using RTTI
data from another DLL.  The ImageBase reference is always relative to
the current DLL.

Differential Revision: http://reviews.llvm.org/D4148

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@211041 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/MicrosoftRTTI.cpp

@@ -51,6 +51,43 @@ using namespace CodeGen;
 //   vbtable.  The names of the BaseClassDescriptors have all of their fields
 //   mangled into them so they can be aggressively deduplicated by the linker.
 
+static bool isImageRelative(CodeGenModule &CGM) {
+  return CGM.getTarget().getPointerWidth(/*AddressSpace=*/0) == 64;
+}
+
+static llvm::Type *getImageRelativeType(CodeGenModule &CGM,
+                                        llvm::Type *PtrType) {
+  if (!isImageRelative(CGM))
+    return PtrType;
+  return CGM.IntTy;
+}
+
+static llvm::GlobalVariable *getImageBase(CodeGenModule &CGM) {
+  StringRef Name = "__ImageBase";
+  if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(Name))
+    return GV;
+
+  return new llvm::GlobalVariable(CGM.getModule(), CGM.Int8Ty,
+                                  /*isConstant=*/true,
+                                  llvm::GlobalValue::ExternalLinkage,
+                                  /*Initializer=*/nullptr, Name);
+}
+
+static llvm::Constant *getImageRelativeConstant(CodeGenModule &CGM,
+                                                llvm::Constant *PtrVal) {
+  if (!isImageRelative(CGM))
+    return PtrVal;
+
+  llvm::Constant *ImageBaseAsInt =
+      llvm::ConstantExpr::getPtrToInt(getImageBase(CGM), CGM.IntPtrTy);
+  llvm::Constant *PtrValAsInt =
+      llvm::ConstantExpr::getPtrToInt(PtrVal, CGM.IntPtrTy);
+  llvm::Constant *Diff =
+      llvm::ConstantExpr::getSub(PtrValAsInt, ImageBaseAsInt,
+                                 /*HasNUW=*/true, /*HasNSW=*/true);
+  return llvm::ConstantExpr::getTrunc(Diff, CGM.IntTy);
+}
+
 // 5 routines for constructing the llvm types for MS RTTI structs.
 static llvm::StructType *getClassHierarchyDescriptorType(CodeGenModule &CGM);
 
@@ -72,13 +109,15 @@ static llvm::StructType *getBaseClassDescriptorType(CodeGenModule &CGM) {
   if (auto Type = CGM.getModule().getTypeByName(Name))
     return Type;
   llvm::Type *FieldTypes[] = {
-      CGM.Int8PtrTy,
+      getImageRelativeType(CGM, CGM.Int8PtrTy),
       CGM.IntTy,
       CGM.IntTy,
       CGM.IntTy,
       CGM.IntTy,
       CGM.IntTy,
-      getClassHierarchyDescriptorType(CGM)->getPointerTo()};
+      getImageRelativeType(
+          CGM, getClassHierarchyDescriptorType(CGM)->getPointerTo()),
+  };
   return llvm::StructType::create(CGM.getLLVMContext(), FieldTypes, Name);
 }
 
@@ -92,7 +131,10 @@ static llvm::StructType *getClassHierarchyDescriptorType(CodeGenModule &CGM) {
     CGM.IntTy,
     CGM.IntTy,
     CGM.IntTy,
-    getBaseClassDescriptorType(CGM)->getPointerTo()->getPointerTo()};
+    getImageRelativeType(
+        CGM,
+        getBaseClassDescriptorType(CGM)->getPointerTo()->getPointerTo()),
+  };
   Type->setBody(FieldTypes);
   return Type;
 }
@@ -101,13 +143,21 @@ static llvm::StructType *getCompleteObjectLocatorType(CodeGenModule &CGM) {
   static const char Name[] = "MSRTTICompleteObjectLocator";
   if (auto Type = CGM.getModule().getTypeByName(Name))
     return Type;
+  llvm::StructType *Type = llvm::StructType::create(CGM.getLLVMContext(), Name);
   llvm::Type *FieldTypes[] = {
     CGM.IntTy,
     CGM.IntTy,
     CGM.IntTy,
-    CGM.Int8PtrTy,
-    getClassHierarchyDescriptorType(CGM)->getPointerTo() };
-  return llvm::StructType::create(CGM.getLLVMContext(), FieldTypes, Name);
+    getImageRelativeType(CGM, CGM.Int8PtrTy),
+    getImageRelativeType(
+        CGM, getClassHierarchyDescriptorType(CGM)->getPointerTo()),
+    getImageRelativeType(CGM, Type),
+  };
+  llvm::ArrayRef<llvm::Type *> FieldTypesRef(
+      std::begin(FieldTypes),
+      isImageRelative(CGM) ? std::end(FieldTypes) : std::end(FieldTypes) - 1);
+  Type->setBody(FieldTypesRef);
+  return Type;
 }
 
 static llvm::GlobalVariable *getTypeInfoVTable(CodeGenModule &CGM) {
@@ -288,9 +338,11 @@ llvm::GlobalVariable *MSRTTIBuilder::getClassHierarchyDescriptor() {
     llvm::ConstantInt::get(CGM.IntTy, 0), // Unknown
     llvm::ConstantInt::get(CGM.IntTy, Flags),
     llvm::ConstantInt::get(CGM.IntTy, Classes.size()),
-    llvm::ConstantExpr::getInBoundsGetElementPtr(
-        getBaseClassArray(Classes),
-        llvm::ArrayRef<llvm::Value *>(GEPIndices))};
+    getImageRelativeConstant(CGM,
+                             llvm::ConstantExpr::getInBoundsGetElementPtr(
+                                 getBaseClassArray(Classes),
+                                 llvm::ArrayRef<llvm::Value *>(GEPIndices))),
+  };
   CHD->setInitializer(llvm::ConstantStruct::get(Type, Fields));
   return CHD;
 }
@@ -308,7 +360,8 @@ MSRTTIBuilder::getBaseClassArray(SmallVectorImpl<MSRTTIClass> &Classes) {
   // mode) bytes of padding.  We provide a pointer sized amount of padding by
   // adding +1 to Classes.size().  The sections have pointer alignment and are
   // marked pick-any so it shouldn't matter.
-  auto PtrType = getBaseClassDescriptorType(CGM)->getPointerTo();
+  auto PtrType = getImageRelativeType(
+      CGM, getBaseClassDescriptorType(CGM)->getPointerTo());
   auto ArrayType = llvm::ArrayType::get(PtrType, Classes.size() + 1);
   auto BCA = new llvm::GlobalVariable(Module, ArrayType,
       /*Constant=*/true, Linkage, /*Initializer=*/nullptr, MangledName.c_str());
@@ -316,8 +369,9 @@ MSRTTIBuilder::getBaseClassArray(SmallVectorImpl<MSRTTIClass> &Classes) {
   // Initialize the BaseClassArray.
   SmallVector<llvm::Constant *, 8> BaseClassArrayData;
   for (MSRTTIClass &Class : Classes)
-    BaseClassArrayData.push_back(getBaseClassDescriptor(Class));
-  BaseClassArrayData.push_back(llvm::ConstantPointerNull::get(PtrType));
+    BaseClassArrayData.push_back(
+        getImageRelativeConstant(CGM, getBaseClassDescriptor(Class)));
+  BaseClassArrayData.push_back(llvm::Constant::getNullValue(PtrType));
   BCA->setInitializer(llvm::ConstantArray::get(ArrayType, BaseClassArrayData));
   return BCA;
 }
@@ -354,13 +408,16 @@ MSRTTIBuilder::getBaseClassDescriptor(const MSRTTIClass &Class) {
 
   // Initialize the BaseClassDescriptor.
   llvm::Constant *Fields[] = {
-    CGM.getMSTypeDescriptor(Context.getTypeDeclType(Class.RD)),
+    getImageRelativeConstant(
+        CGM, CGM.getMSTypeDescriptor(Context.getTypeDeclType(Class.RD))),
     llvm::ConstantInt::get(CGM.IntTy, Class.NumBases),
     llvm::ConstantInt::get(CGM.IntTy, Class.OffsetInVBase),
     llvm::ConstantInt::get(CGM.IntTy, VBPtrOffset),
     llvm::ConstantInt::get(CGM.IntTy, OffsetInVBTable),
     llvm::ConstantInt::get(CGM.IntTy, Class.Flags),
-    MSRTTIBuilder(CGM, Class.RD).getClassHierarchyDescriptor()};
+    getImageRelativeConstant(
+        CGM, MSRTTIBuilder(CGM, Class.RD).getClassHierarchyDescriptor()),
+  };
   BCD->setInitializer(llvm::ConstantStruct::get(Type, Fields));
   return BCD;
 }
@@ -395,12 +452,18 @@ MSRTTIBuilder::getCompleteObjectLocator(const VPtrInfo *Info) {
 
   // Initialize the CompleteObjectLocator.
   llvm::Constant *Fields[] = {
-    llvm::ConstantInt::get(CGM.IntTy, 0), // IsDeltaEncoded
+    llvm::ConstantInt::get(CGM.IntTy, isImageRelative(CGM)),
     llvm::ConstantInt::get(CGM.IntTy, OffsetToTop),
     llvm::ConstantInt::get(CGM.IntTy, VFPtrOffset),
-    CGM.getMSTypeDescriptor(Context.getTypeDeclType(RD)),
-    getClassHierarchyDescriptor()};
-  COL->setInitializer(llvm::ConstantStruct::get(Type, Fields));
+    getImageRelativeConstant(
+        CGM, CGM.getMSTypeDescriptor(Context.getTypeDeclType(RD))),
+    getImageRelativeConstant(CGM, getClassHierarchyDescriptor()),
+    getImageRelativeConstant(CGM, COL),
+  };
+  llvm::ArrayRef<llvm::Constant *> FieldsRef(Fields);
+  if (!isImageRelative(CGM))
+    FieldsRef = FieldsRef.slice(0, FieldsRef.size() - 1);
+  COL->setInitializer(llvm::ConstantStruct::get(Type, FieldsRef));
   return COL;
 }