On 13 May 2015 at 22:06, Richard Henderson <r...@twiddle.net> wrote: > On 05/13/2015 01:54 PM, Peter Maydell wrote: >> We don't seem to be very consistent about what type we're using for >> mmu_idx. In the TCG backends changed in patch 1 (and in the >> prototype of this helper which we've just removed) we used 'int'; >> in the return type of get_mmuidx() we use 'unsigned'; and here we're >> using size_t... > > Yes, we previously used "int", but we only allow small positive values. I > could have continued to use "int", but I thought "unsigned" more approprate > most places that it's actually used. > > As for here, we're about to pass mmu_idx to several array references. In the > past this has been known to help the compiler realize it doesn't need an > additional zero-extension. That said, in this case with gcc 4.9, it doesn't > seem to affect code generation in any way except register allocation. I can > change it back if you prefer.
I don't mind use of unsigned; I do think size_t is very odd. If the compiler needs an array index to be size_t to generate decent code then it's pretty broken, because almost nobody uses size_t for array indexes (indeed signed is probably more common than unsigned types I would hae thought). thanks -- PMM
