Back out r101911 and see if it makes the bots happy.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@101921 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGClass.cpp b/lib/CodeGen/CGClass.cpp
index b2991ad..a21af41 100644
--- a/lib/CodeGen/CGClass.cpp
+++ b/lib/CodeGen/CGClass.cpp
@@ -1549,7 +1549,6 @@
 void
 CodeGenFunction::InitializeVTablePointer(BaseSubobject Base, 
                                          const CXXRecordDecl *NearestVBase,
-                                         uint64_t BaseOffsetFromNearestVBase,
                                          llvm::Constant *VTable,
                                          const CXXRecordDecl *VTableClass) {
   const CXXRecordDecl *RD = Base.getBase();
@@ -1577,31 +1576,21 @@
       Builder.CreateConstInBoundsGEP2_64(VTable, 0, AddressPoint);
   }
 
-  llvm::Value *VTableField = LoadCXXThis();
-
   // Compute where to store the address point.
-  uint64_t NonVirtualOffset = BaseOffsetFromNearestVBase;
+  llvm::Value *VTableField;
+  
+  if (CodeGenVTables::needsVTTParameter(CurGD) && NearestVBase) {
+    // We need to use the virtual base offset offset because the virtual base
+    // might have a different offset in the most derived class.
+    VTableField = GetAddressOfBaseClass(LoadCXXThis(), VTableClass, RD, 
+                                        /*NullCheckValue=*/false);
+  } else {
+    const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGM.getLLVMContext());
 
-  llvm::Value *VirtualOffset = 0;
-  if (NearestVBase) {
-    if (!CodeGenVTables::needsVTTParameter(CurGD)) {
-      // Just get the vbase offset in the complete class.
-      const ASTRecordLayout &Layout = 
-        getContext().getASTRecordLayout(VTableClass);
-
-      NonVirtualOffset += Layout.getVBaseClassOffset(NearestVBase);
-    } else {
-      // We need to use the virtual base offset offset because the virtual base
-      // might have a different offset in the most derived class.
-      VirtualOffset = GetVirtualBaseClassOffset(VTableField,
-                                                VTableClass, NearestVBase);
-    }
-  }
-
-  if (NonVirtualOffset || VirtualOffset)
+    VTableField = Builder.CreateBitCast(LoadCXXThis(), Int8PtrTy);
     VTableField = 
-      ApplyNonVirtualAndVirtualOffset(*this, VTableField,
-                                      NonVirtualOffset, VirtualOffset);
+      Builder.CreateConstInBoundsGEP1_64(VTableField, Base.getBaseOffset() / 8);  
+  }
 
   // Finally, store the address point.
   const llvm::Type *AddressPointPtrTy =
@@ -1613,7 +1602,6 @@
 void
 CodeGenFunction::InitializeVTablePointers(BaseSubobject Base, 
                                           const CXXRecordDecl *NearestVBase,
-                                          uint64_t BaseOffsetFromNearestVBase,
                                           bool BaseIsNonVirtualPrimaryBase,
                                           llvm::Constant *VTable,
                                           const CXXRecordDecl *VTableClass,
@@ -1622,8 +1610,7 @@
   // been set.
   if (!BaseIsNonVirtualPrimaryBase) {
     // Initialize the vtable pointer for this base.
-    InitializeVTablePointer(Base, NearestVBase, BaseOffsetFromNearestVBase,
-                            VTable, VTableClass);
+    InitializeVTablePointer(Base, NearestVBase, VTable, VTableClass);
   }
   
   const CXXRecordDecl *RD = Base.getBase();
@@ -1660,7 +1647,6 @@
     
     InitializeVTablePointers(BaseSubobject(BaseDecl, BaseOffset), 
                              I->isVirtual() ? BaseDecl : NearestVBase,
-                             I->isVirtual() ? 0 : BaseOffsetFromNearestVBase,
                              BaseDeclIsNonVirtualPrimaryBase, 
                              VTable, VTableClass, VBases);
   }
@@ -1677,7 +1663,6 @@
   // Initialize the vtable pointers for this class and all of its bases.
   VisitedVirtualBasesSetTy VBases;
   InitializeVTablePointers(BaseSubobject(RD, 0), /*NearestVBase=*/0, 
-                           /*BaseOffsetFromNearestVBase=*/0,
                            /*BaseIsNonVirtualPrimaryBase=*/false, 
                            VTable, RD, VBases);
 }