From: Anders Carlsson <andersca@mac.com>
Date: Sat, 5 Dec 2009 21:28:12 +0000 (+0000)
Subject: CodeGenModule::GenerateVtable now returns a pointer directly to the vtable and not... 
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=bb27d868ac3ca429bfe0f52c5f091f849368fff8;p=clang

CodeGenModule::GenerateVtable now returns a pointer directly to the vtable and not to the address point.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@90676 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/CGCXX.cpp b/lib/CodeGen/CGCXX.cpp
index c536350ad4..a2674b82d1 100644
--- a/lib/CodeGen/CGCXX.cpp
+++ b/lib/CodeGen/CGCXX.cpp
@@ -1682,8 +1682,7 @@ void CodeGenFunction::EmitCtorPrologue(const CXXConstructorDecl *CD,
   const CXXRecordDecl *ClassDecl = CD->getParent();
   
   // FIXME: Add vbase initialization
-  llvm::Value *LoadOfThis = 0;
-
+  
   for (CXXConstructorDecl::init_const_iterator B = CD->init_begin(),
        E = CD->init_end();
        B != E; ++B) {
@@ -1705,15 +1704,21 @@ void CodeGenFunction::EmitCtorPrologue(const CXXConstructorDecl *CD,
   if (!ClassDecl->isDynamicClass())
     return;
   
-  // Initialize the vtable pointer
-  if (!LoadOfThis)
-    LoadOfThis = LoadCXXThis();
+  // Initialize the vtable pointer.
+  // FIXME: This needs to initialize secondary vtable pointers too.
+  llvm::Value *ThisPtr = LoadCXXThis();
 
-  const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(VMContext);
+  llvm::Constant *Vtable = CGM.getVtableInfo().getVtable(ClassDecl);
+  uint64_t AddressPoint = CGM.getVtableInfo().getVtableAddressPoint(ClassDecl);
+
+  llvm::Value *VtableAddressPoint =
+    Builder.CreateConstInBoundsGEP2_64(Vtable, 0, AddressPoint);
+  
   llvm::Value *VtableField = 
-    Builder.CreateBitCast(LoadOfThis, Int8PtrTy->getPointerTo());
-  llvm::Value *vtable = CGM.getVtableInfo().getVtable(ClassDecl);
-  Builder.CreateStore(vtable, VtableField);
+    Builder.CreateBitCast(ThisPtr, 
+                          VtableAddressPoint->getType()->getPointerTo());
+  
+  Builder.CreateStore(VtableAddressPoint, VtableField);
 }
 
 /// EmitDtorEpilogue - Emit all code that comes at the end of class's
diff --git a/lib/CodeGen/CGVtable.cpp b/lib/CodeGen/CGVtable.cpp
index 8bf940b40c..e41712ecf9 100644
--- a/lib/CodeGen/CGVtable.cpp
+++ b/lib/CodeGen/CGVtable.cpp
@@ -1155,16 +1155,8 @@ llvm::Constant *CodeGenModule::GenerateVtable(const CXXRecordDecl *LayoutClass,
     if (Hidden)
       GV->setVisibility(llvm::GlobalVariable::HiddenVisibility);
   }
-  llvm::Constant *vtable = llvm::ConstantExpr::getBitCast(GV, Ptr8Ty);
-  llvm::Constant *AddressPointC;
-  uint32_t LLVMPointerWidth = getContext().Target.getPointerWidth(0);
-  AddressPointC = llvm::ConstantInt::get(llvm::Type::getInt64Ty(VMContext),
-                                         AddressPoint*LLVMPointerWidth/8);
-  vtable = llvm::ConstantExpr::getInBoundsGetElementPtr(vtable, &AddressPointC,
-                                                        1);
-
-  assert(vtable->getType() == Ptr8Ty);
-  return vtable;
+  
+  return GV;
 }
 
 namespace {
@@ -1184,12 +1176,13 @@ class VTTBuilder {
   llvm::LLVMContext &VMContext;
 
   /// BuildVtablePtr - Build up a referene to the given secondary vtable
-  llvm::Constant *BuildVtablePtr(llvm::Constant *vtbl,
-                                 const CXXRecordDecl *VtblClass,
+  llvm::Constant *BuildVtablePtr(llvm::Constant *Vtable,
+                                 const CXXRecordDecl *VtableClass,
                                  const CXXRecordDecl *RD,
                                  uint64_t Offset) {
-    int64_t AddressPoint;
-    AddressPoint = (*AddressPoints[VtblClass])[std::make_pair(RD, Offset)];    
+    int64_t AddressPoint = 
+      (*AddressPoints[VtableClass])[std::make_pair(RD, Offset)];
+    
     // FIXME: We can never have 0 address point.  Do this for now so gepping
     // retains the same structure.  Later we'll just assert.
     if (AddressPoint == 0)
@@ -1197,12 +1190,17 @@ class VTTBuilder {
     D1(printf("XXX address point for %s in %s layout %s at offset %d was %d\n",
               RD->getNameAsCString(), VtblClass->getNameAsCString(),
               Class->getNameAsCString(), (int)Offset, (int)AddressPoint));
-    uint32_t LLVMPointerWidth = CGM.getContext().Target.getPointerWidth(0);
-    llvm::Constant *init;
-    init = llvm::ConstantInt::get(llvm::Type::getInt64Ty(VMContext),
-                                  AddressPoint*LLVMPointerWidth/8);
-    init = llvm::ConstantExpr::getInBoundsGetElementPtr(vtbl, &init, 1);
-    return init;
+
+    llvm::Value *Idxs[] = {
+      llvm::ConstantInt::get(llvm::Type::getInt64Ty(VMContext), 0),
+      llvm::ConstantInt::get(llvm::Type::getInt64Ty(VMContext), AddressPoint)
+    };
+    
+    llvm::Constant *Init = 
+      llvm::ConstantExpr::getInBoundsGetElementPtr(Vtable, Idxs, 2);
+
+    const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(VMContext);
+    return llvm::ConstantExpr::getBitCast(Init, Int8PtrTy);
   }
 
   /// Secondary - Add the secondary vtable pointers to Inits.  Offset is the
@@ -1321,8 +1319,7 @@ public:
       VMContext(cgm.getModule().getContext()) {
     
     // First comes the primary virtual table pointer for the complete class...
-    ClassVtbl = cast<llvm::Constant>(CGM.getVtableInfo().getVtable(Class)
-                                     ->getOperand(0));
+    ClassVtbl = CGM.getVtableInfo().getVtable(Class);
     Inits.push_back(BuildVtablePtr(ClassVtbl, Class, Class, 0));
     
     // then the secondary VTTs...
@@ -1423,9 +1420,7 @@ llvm::Constant *CGVtableInfo::getVtable(const CXXRecordDecl *RD) {
 llvm::Constant *CGVtableInfo::getCtorVtable(const CXXRecordDecl *LayoutClass,
                                             const CXXRecordDecl *RD,
                                             uint64_t Offset) {
-  llvm::Constant *Vtable = CGM.GenerateVtable(LayoutClass, RD, Offset);
-  
-  return cast<llvm::Constant>(Vtable->getOperand(0));
+  return CGM.GenerateVtable(LayoutClass, RD, Offset);
 }
 
 void CGVtableInfo::MaybeEmitVtable(GlobalDecl GD) {