[cfe-commits] r77332 - in /cfe/trunk: lib/CodeGen/CGCXX.cpp lib/CodeGen/CGExpr.cpp lib/CodeGen/CodeGenFunction.h test/CodeGenCXX/constructor-init.cpp

[Chris Lattner]

On Jul 28, 2009, at 10:38 AM, Fariborz Jahanian wrote:
> Author: fjahanian
> Date: Tue Jul 28 12:38:28 2009
> New Revision: 77332
>
> URL: http://llvm.org/viewvc/llvm-project?rev=77332&view=rev
> Log:
> More work toward data member access ir-gen.

Nice.  :)

> +llvm::Value *CodeGenFunction::AddressCXXOfBaseClass(llvm::Value  
> *BaseValue,
> +                                                CXXRecordDecl  
> *ClassDecl,
> +                                                CXXRecordDecl  
> *BaseClassDecl) {
> +  if (ClassDecl == BaseClassDecl)
> +    return BaseValue;
> +
> +  // Accessing a member of the base class. Must add delata to
> +  // the load of 'this'.
> +  // FIXME. Once type layout is complete, this will probably change.
> +  const ASTRecordLayout &Layout =
> +  getContext().getASTRecordLayout(ClassDecl);
> +  llvm::Type *I8Ptr =  
> VMContext.getPointerTypeUnqual(llvm::Type::Int8Ty);
> +  unsigned Idx = 0;
> +  for (CXXRecordDecl::base_class_const_iterator i =
> +         ClassDecl->bases_begin(),
> +         e = ClassDecl->bases_end(); i != e; ++i, ++Idx) {
> +    if (!i->isVirtual()) {
> +        const CXXRecordDecl *Base =
> +        cast<CXXRecordDecl>(i->getType()->getAsRecordType()- 
> >getDecl());
> +        if (Base == BaseClassDecl)
> +          break;
> +    }
> +  }

Please split this out into a static function that return Idx, as per  
the previous email.

> +  uint64_t Offset = Layout.getFieldOffset(Idx) / 8;

Maybe there should be a getFieldOffsetInBytes() method?

> +  llvm::Value *OffsetVal =  
> llvm::ConstantInt::get(llvm::Type::Int32Ty, Offset);

will this work with large (64-bit) offsets on x86-64?  Maybe this  
should use pointertype instead?

>
>     CVRQualifiers = PTy->getPointeeType().getCVRQualifiers();
> +    if (CXXThisExpr *ThisExpr = dyn_cast<CXXThisExpr>(BaseExpr)) {
> +      QualType ClassTy = ThisExpr->getType();
> +      ClassTy = ClassTy->getPointeeType();
> +      CXXRecordDecl *ClassDecl =
> +        cast<CXXRecordDecl>(ClassTy->getAsRecordType()->getDecl());

I'm seeing a lot of this sort of code.  Can you add a method on Type,  
something like "getCXXRecordDeclForPointerType()" that returns a  
CXXRecordDecl if the type is a pointer to record type?

It would basically be:

   if (PointerType *PT = X->getAsPointerType())
     if (RecordType *RT = PT->getPointeeType()->getAsRecordType())
       return dyn_cast<CXXRecordDecl>(RT);
   return 0;

Please make use of this helper in various other places, it seems that  
it could significantly simplify a lot of the code you've been working  
on lately.

-Chris