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

[Adrian Prantl]

> On Dec 23, 2014, at 3:55 PM, Adrian Prantl <aprantl at apple.com> wrote:
> 
> 
>> On Dec 23, 2014, at 3:42 PM, David Blaikie <dblaikie at gmail.com <mailto: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.

I wonder if that clang-upc frontend falls into that category.
> 
> -- 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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