[llvm] r224780 - DIBuilder: Similar to createPointerType, make createMemberPointerType take

[Adrian Prantl]

> On Dec 23, 2014, at 3:42 PM, David Blaikie <dblaikie at gmail.com> wrote:
> 
> 
> 
> On Tue, Dec 23, 2014 at 11:11 AM, Adrian Prantl <aprantl at apple.com <mailto:aprantl at apple.com>> wrote:
> Author: adrian
> Date: Tue Dec 23 13:11:47 2014
> New Revision: 224780
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=224780&view=rev <http://llvm.org/viewvc/llvm-project?rev=224780&view=rev>
> Log:
> DIBuilder: Similar to createPointerType, make createMemberPointerType take
> a size and alignment. Several assertions in DwarfDebug rely on all variable
> types to report back a size, or to be derived from a type with a size.
> 
> Are these reasonable assertions?

In my opinion, yes. I added them to sanity-check DW_OP_piece expressions.

> Does this change modify the resulting DWARF? (should we be putting a DW_AT_size on such things? I assume not, but haven't looked/compared/etc)

.. looking.. Actually it does, but that was unintentional. If want to keep the old behavior, we should extend this check to also include member function pointers.

/// constructTypeDIE - Construct derived type die from DIDerivedType.
void DwarfUnit::constructTypeDIE(DIE &Buffer, DIDerivedType DTy) {
  ...
 // Add size if non-zero (derived types might be zero-sized.)
  if (Size && Tag != dwarf::DW_TAG_pointer_type)
    addUInt(Buffer, dwarf::DW_AT_byte_size, None, Size);

I’ll do that — just to be consistent with the past. Specifying the size of a pointer in DWARF seems redundant as it should be specified by the target; assuming no target we want to support has more than one pointer size.

-- adrian

>  
> 
> Tested in CFE.
> 
> Modified:
>     llvm/trunk/include/llvm/IR/DIBuilder.h
>     llvm/trunk/lib/IR/DIBuilder.cpp
> 
> Modified: llvm/trunk/include/llvm/IR/DIBuilder.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/IR/DIBuilder.h?rev=224780&r1=224779&r2=224780&view=diff <http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/IR/DIBuilder.h?rev=224780&r1=224779&r2=224780&view=diff>
> ==============================================================================
> --- llvm/trunk/include/llvm/IR/DIBuilder.h (original)
> +++ llvm/trunk/include/llvm/IR/DIBuilder.h Tue Dec 23 13:11:47 2014
> @@ -172,8 +172,12 @@ namespace llvm {
> 
>      /// \brief Create debugging information entry for a pointer to member.
>      /// @param PointeeTy Type pointed to by this pointer.
> +    /// @param SizeInBits  Size.
> +    /// @param AlignInBits Alignment. (optional)
>      /// @param Class Type for which this pointer points to members of.
> -    DIDerivedType createMemberPointerType(DIType PointeeTy, DIType Class);
> +    DIDerivedType createMemberPointerType(DIType PointeeTy, DIType Class,
> +                                          uint64_t SizeInBits,
> +                                          uint64_t AlignInBits = 0);
> 
>      /// createReferenceType - Create debugging information entry for a c++
>      /// style reference or rvalue reference type.
> 
> Modified: llvm/trunk/lib/IR/DIBuilder.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/DIBuilder.cpp?rev=224780&r1=224779&r2=224780&view=diff <http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/DIBuilder.cpp?rev=224780&r1=224779&r2=224780&view=diff>
> ==============================================================================
> --- llvm/trunk/lib/IR/DIBuilder.cpp (original)
> +++ llvm/trunk/lib/IR/DIBuilder.cpp Tue Dec 23 13:11:47 2014
> @@ -328,14 +328,15 @@ DIBuilder::createPointerType(DIType Poin
>    return DIDerivedType(MDNode::get(VMContext, Elts));
>  }
> 
> -DIDerivedType DIBuilder::createMemberPointerType(DIType PointeeTy,
> -                                                 DIType Base) {
> +DIDerivedType
> +DIBuilder::createMemberPointerType(DIType PointeeTy, DIType Base,
> +                                   uint64_t SizeInBits, uint64_t AlignInBits) {
>    // Pointer types are encoded in DIDerivedType format.
>    Metadata *Elts[] = {HeaderBuilder::get(dwarf::DW_TAG_ptr_to_member_type)
>                            .concat(StringRef())
>                            .concat(0) // Line
> -                          .concat(0) // Size
> -                          .concat(0) // Align
> +                          .concat(SizeInBits) // Size
> +                          .concat(AlignInBits) // Align
>                            .concat(0) // Offset
>                            .concat(0) // Flags
>                            .get(VMContext),
> 
> 
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