On Nov 10, 2010, at 4:00 AM, David Brown wrote:
> Would it be possible to use the named address space syntax to implement
> reverse-endian data? Conversion between little-endian and big-endian data
> structures is something that turns up regularly in embedded systems, where
> you might well be using two different architectures with different
> endianness. Some compilers offer direct support for endian swapping, but gcc
> has no neat solution. You can use the __builtin_bswap32 (but no
> __builtin_bswap16?) function in recent versions of gcc, but you still need to
> handle the swapping explicitly.
>
> Named address spaces would give a very neat syntax for using such
> byte-swapped areas. Ideally you'd be able to write something like:
>
> __swapendian stuct { int a; short b; } data;
>
> and every access to data.a and data.b would be endian-swapped. You could
> also have __bigendian and __litteendian defined to __swapendian or blank
> depending on the native ordering of the target.
>
>
> I've started reading a little about how named address spaces work, but I
> don't know enough to see whether this is feasible or not.
>
>
> Another addition in a similar vein would be __nonaligned, for targets which
> cannot directly access non-aligned data. The loads and stores would be done
> byte-wise for slower but correct functionality.
Why not just handle this in the frontend during gimplification?
-Chris
