[llvm-commits] [126245] Fix http://lists.cs.uiuc.edu/pipermail/llvm-commits/ Week-of-Mon-20070416/047943.html

[Devang Patel]

On Apr 17, 2007, at 11:15 PM, Duncan Sands wrote:

> Hi Devang,
>
>> if
>> 	(StartOffsetInBits > FirstUnallocatedByte*8)
>>
>> is true then
>> 	
>> 	(StartOffsetFromByteBoundry == 0)
>>
>> is always true. If so, we could simply this even further. In other
>> words, if we need pad bytes for a new field then it always starts at
>> byte boundary. Can you think of an example where this is not true ?
>
> yes, this need not be true in Ada, where bitfields can be placed
> wherever you like,

Is it true for very first bitfield also ?

> for example
>
>   type Second_Bitfield_Not_At_Bitoffset_Zero is record
>      A : Character;
>      B : Integer;
>   end record;
>   for Second_Bitfield_Not_At_Bitoffset_Zero use record
>      A at 0 range 0 .. 7;
>      B at 0 range 27 .. 64;
>   end record;

so here, range is not value  range. In that case size of B
should be 64. No?

-
Devang

>
>   -- "gaps__second_bitfield_not_at_bitoffset_zero", size 72
>   --   Fields:
>   --     "a", size  8, offset 0, bit offset 0
>   --     "b", size 32, offset 0, bit offset 27
>
> Best wishes,
>
> Duncan.