Yuri Gribov <tetra2...@gmail.com> writes: > 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.
Sorry, yeah, was going off the variable name rather than what the test actually did... >> 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() Why not just a comparison? It seems clearer IMO. Thanks, Richard
