Getting LLVM/Clang to be 16 bit aligned

Question

I am working on a legacy project that has a large amount of files dating back to pre-OS X days. It's data has been 16 bit aligned for > 15 years. I would like to move to a full LLVM compilation but I can't seem to get 2 byte alignment working. Are there any compiler level options available for this? (previously using -malign-mac68k)

I am aware of the #pragma pack(2) option here. However that would require me to modify upwards of 1000 source files to include this. That it's a worst-case option, but it seems like a hack. Besides, if this is possible then surely there is a default option to set the alignment?

Answer 1

According to clang's sources, it does support mac68k alignment rules. It seems that right now you can enable it via "#pragma options align=mac68k" only. If you're ok with small clang hacking, then you can implement the cmdline option as well and submit the patch to clang.

Answer 2

I would suggest looking at #pragma pack (see http://msdn.microsoft.com/en-us/library/2e70t5y1%28v=vs.80%29.aspx and http://gcc.gnu.org/onlinedocs/gcc/Structure_002dPacking-Pragmas.html). It's relatively easy to use, and should work with any compiler Apple ships.