On Tue, May 30, 2017 at 11:35 AM, Richard Sandiford <richard.sandif...@linaro.org> wrote: > Yuri Gribov <tetra2...@gmail.com> writes: >> On Tue, May 30, 2017 at 7:35 AM, Richard Sandiford >> <richard.sandif...@linaro.org> wrote: >>> Yuri Gribov <tetra2...@gmail.com> writes: >>>> From 330209f721a598ec393dcb5d62de3457ee282153 Mon Sep 17 00:00:00 2001 >>>> From: Yury Gribov <tetra2...@gmail.com> >>>> Date: Fri, 26 May 2017 07:53:10 +0100 >>>> Subject: [PATCH 3/4] Added bool conversion for wide_ints. >>>> >>>> gcc/ >>>> 2017-05-26 Yury Gribov <tetra2...@gmail.com> >>>> >>>> * wide-int.cc (wi::zero_p_large): New method. >>>> * wide-int.h (wi::zero_p): New method. >>> >>> Do you still need this bit? It looks like it isn't used by the other >>> parts of the series. >>> >>> The idea was that wi::eq_p (x, 0) (or just x == 0, if x is a >>> wide-int-based type) is supposed to be as fast as a dedicated zero check. >>> It'd be OK to have a helper function anyway, but it should probably be >>> defined using wi::eq_p. >>> >>> The zero_p_large fallback can never return true, since a zero of >>> any precision will have a length of 1. >> >> Thanks Richard, I'll update the patch. The bool check is used in >> successive patch (4/4), in >> widest_int mask = wi::to_widest (@2); >> bool mask_all_ones_p = !(mask & (mask + 1)); > > Ah, OK. That's equivalent to mask == -1 (or wi::eq_p (@2, -1), to avoid > the temporary).
Hm, is it? Current check ensures that N consecutive LSBs are set, not that all bits are set. Perhaps variable name should be changed to reflect this better. > I think it'd be better to use one of those instead. > There's an argument that if ! is defined, it should return an integer > of the same precision as the argument. True. Perhaps I should make separate wide_int operator !() and bool operator bool() -I
