On Thu, Jan 19, 2012 at 1:24 PM, Torvald Riegel <trie...@redhat.com> wrote:
>> The spec does say that all function should be regparm(2), but I agree >> that the above is less confusing. The attribute is ignored, but >> perhaps a comment would clear this confusion even more. > > Uros, thanks for spotting the vararg issue. This looks okay to me, but > Richard Henderson will have to OK this. > > If regparm(2) cannot work with variadic functions on x86, then I'd > prefer removing the regparm. beginTransaction was switched to being > variadic to allow communicating which kinds of versions a compiler has > generated for the transaction's code (besides the default > instrumentation that we have right now). I'd believe Ulrich Drepper's > experience that making this variadic is better than restricting this to > 64b (minus 10 bits or so already in use). > > BTW, would regparm(2) optimize on any arch/platform besides 32b x86? > What about x32? No, regparm is effective only on x86_32. x32 strictly follows x86_64 ABI. > Note that if we remove the regparm, we should also remove it on the > other functions associated with txn begin (GTM_beginTransaction etc.). No, this is not needed. The patch adds the move that loads %eax with the first parameter from function arguments and pass it via regparm ABI to GTM_beginTransaction. OTOH, in GTM_beginTransaction we can still access other variable arguments through the pointer to CFA. Uros.
