On Tue, 30 Nov 2010, Julian Brown wrote:
* defaults.h (VECTOR_ELEMENTS_BIG_ENDIAN): Define.
Apart from the point that new target macros should be hooks, the *very first* thing to do with any new macro or hook is to write the .texi documentation, which appears to be missing from this patch. This is best done before making any consequent code changes. That documentation needs to make clear:
* What the effects are on the semantics of GNU C code (that uses generic vector extensions - which in 4.6 include subscripting), if any.
* What the effects are on the semantics of GENERIC and GIMPLE using vector types, if any. If the semantics of memory references to such types are affected, or the semantics of any other existing GENERIC or GIMPLE operation (most likely any operations that may exist involving lane numbers) then you need to make clear how, and ensure that any documentation / comments for that operation are updated as well; the patch submission needs to make clear how you have audited all existing code for correctness given such a change - any code mentioning a GENERIC or GIMPLE code may do transformations assuming particular semantics.
* Likewise, for all machine-independent RTL operations.
* For UNSPECs the documentation issue doesn't arise, but the audit is still relevant.