When performing a derived-to-base cast that we know will not change the offset, we don't need to null check the input pointer. Fixes PR5965.
llvm-svn: 94942
diff --git a/clang/lib/CodeGen/CGClass.cpp b/clang/lib/CodeGen/CGClass.cpp
index eaebf14..1b337eb 100644
--- a/clang/lib/CodeGen/CGClass.cpp
+++ b/clang/lib/CodeGen/CGClass.cpp
@@ -67,51 +67,6 @@
return llvm::ConstantInt::get(PtrDiffTy, Offset);
}
-static llvm::Value *GetBaseClassOffset(CodeGenFunction &CGF,
- llvm::Value *BaseValue,
- const CXXRecordDecl *ClassDecl,
- const CXXRecordDecl *BaseClassDecl) {
- CXXBasePaths Paths(/*FindAmbiguities=*/false,
- /*RecordPaths=*/true, /*DetectVirtual=*/false);
- if (!const_cast<CXXRecordDecl *>(ClassDecl)->
- isDerivedFrom(const_cast<CXXRecordDecl *>(BaseClassDecl), Paths)) {
- assert(false && "Class must be derived from the passed in base class!");
- return 0;
- }
-
- unsigned Start = 0;
- llvm::Value *VirtualOffset = 0;
-
- const CXXBasePath &Path = Paths.front();
- const CXXRecordDecl *VBase = 0;
- for (unsigned i = 0, e = Path.size(); i != e; ++i) {
- const CXXBasePathElement& Element = Path[i];
- if (Element.Base->isVirtual()) {
- Start = i+1;
- QualType VBaseType = Element.Base->getType();
- VBase = cast<CXXRecordDecl>(VBaseType->getAs<RecordType>()->getDecl());
- }
- }
- if (VBase)
- VirtualOffset =
- CGF.GetVirtualBaseClassOffset(BaseValue, ClassDecl, VBase);
-
- uint64_t Offset =
- ComputeNonVirtualBaseClassOffset(CGF.getContext(), Paths, Start);
-
- if (!Offset)
- return VirtualOffset;
-
- const llvm::Type *PtrDiffTy =
- CGF.ConvertType(CGF.getContext().getPointerDiffType());
- llvm::Value *NonVirtualOffset = llvm::ConstantInt::get(PtrDiffTy, Offset);
-
- if (VirtualOffset)
- return CGF.Builder.CreateAdd(VirtualOffset, NonVirtualOffset);
-
- return NonVirtualOffset;
-}
-
// FIXME: This probably belongs in CGVtable, but it relies on
// the static function ComputeNonVirtualBaseClassOffset, so we should make that
// a CodeGenModule member function as well.
@@ -162,7 +117,37 @@
// Just cast back.
return Builder.CreateBitCast(Value, BasePtrTy);
}
+
+ CXXBasePaths Paths(/*FindAmbiguities=*/false,
+ /*RecordPaths=*/true, /*DetectVirtual=*/false);
+ if (!const_cast<CXXRecordDecl *>(Class)->
+ isDerivedFrom(const_cast<CXXRecordDecl *>(BaseClass), Paths)) {
+ assert(false && "Class must be derived from the passed in base class!");
+ return 0;
+ }
+
+ unsigned Start = 0;
+ llvm::Value *VirtualOffset = 0;
+
+ const CXXBasePath &Path = Paths.front();
+ const CXXRecordDecl *VBase = 0;
+ for (unsigned i = 0, e = Path.size(); i != e; ++i) {
+ const CXXBasePathElement& Element = Path[i];
+ if (Element.Base->isVirtual()) {
+ Start = i+1;
+ QualType VBaseType = Element.Base->getType();
+ VBase = cast<CXXRecordDecl>(VBaseType->getAs<RecordType>()->getDecl());
+ }
+ }
+
+ uint64_t Offset =
+ ComputeNonVirtualBaseClassOffset(getContext(), Paths, Start);
+ if (!Offset && !VBase) {
+ // Just cast back.
+ return Builder.CreateBitCast(Value, BasePtrTy);
+ }
+
llvm::BasicBlock *CastNull = 0;
llvm::BasicBlock *CastNotNull = 0;
llvm::BasicBlock *CastEnd = 0;
@@ -179,15 +164,27 @@
EmitBlock(CastNotNull);
}
- const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(VMContext);
+ if (VBase)
+ VirtualOffset = GetVirtualBaseClassOffset(Value, Class, VBase);
- llvm::Value *Offset = GetBaseClassOffset(*this, Value, Class, BaseClass);
+ const llvm::Type *PtrDiffTy = ConvertType(getContext().getPointerDiffType());
+ llvm::Value *NonVirtualOffset = 0;
+ if (Offset)
+ NonVirtualOffset = llvm::ConstantInt::get(PtrDiffTy, Offset);
- if (Offset) {
- // Apply the offset.
- Value = Builder.CreateBitCast(Value, Int8PtrTy);
- Value = Builder.CreateGEP(Value, Offset, "add.ptr");
- }
+ llvm::Value *BaseOffset;
+ if (VBase) {
+ if (NonVirtualOffset)
+ BaseOffset = Builder.CreateAdd(VirtualOffset, NonVirtualOffset);
+ else
+ BaseOffset = VirtualOffset;
+ } else
+ BaseOffset = NonVirtualOffset;
+
+ // Apply the base offset.
+ const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(getLLVMContext());
+ Value = Builder.CreateBitCast(Value, Int8PtrTy);
+ Value = Builder.CreateGEP(Value, BaseOffset, "add.ptr");
// Cast back.
Value = Builder.CreateBitCast(Value, BasePtrTy);