From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-io0-x243.google.com ([2607:f8b0:4001:c06::243]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1fsd4k-0000tB-9P for barebox@lists.infradead.org; Thu, 23 Aug 2018 00:02:11 +0000 Received: by mail-io0-x243.google.com with SMTP id y10-v6so2886613ioa.10 for ; Wed, 22 Aug 2018 17:01:56 -0700 (PDT) MIME-Version: 1.0 References: <20180821062603.17393-1-andrew.smirnov@gmail.com> <20180821062603.17393-20-andrew.smirnov@gmail.com> <20180822070940.2bgr6uraeoeewy7h@pengutronix.de> In-Reply-To: <20180822070940.2bgr6uraeoeewy7h@pengutronix.de> From: Andrey Smirnov Date: Wed, 22 Aug 2018 17:01:41 -0700 Message-ID: List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: [PATCH 19/22] bbu: Remove logical negation in barebox_update_handler_exists() To: Sascha Hauer Cc: Barebox List On Wed, Aug 22, 2018 at 12:09 AM Sascha Hauer wrote: > > On Mon, Aug 20, 2018 at 11:26:00PM -0700, Andrey Smirnov wrote: > > Returning !bbu_find_handler() from barebox_update_handler_exists() > > would return the opposite result from what the name of that funciton > > implies. Drop the "!" to make it behave as expected. > > > > Signed-off-by: Andrey Smirnov > > --- > > common/bbu.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/common/bbu.c b/common/bbu.c > > index 11e44f4a7..69ccac68a 100644 > > --- a/common/bbu.c > > +++ b/common/bbu.c > > @@ -151,7 +151,7 @@ bool barebox_update_handler_exists(struct bbu_data *data) > > if (!data->handler_name) > > return false; > > > > - return !bbu_find_handler(data->handler_name); > > + return bbu_find_handler(data->handler_name); > > As bbu_find_handler() returns a pointer maybe better '!!' or > bbu_find_handler() != NULL? > That shouldn't be necessary since barebox_update_handler_exists() returns bool(real type name is _Bool) which explicitly specifies that a cast of any scalar value to it would be normalized to 1 or 0 (as per C99 standard from whence it came). Otherwise you'd be able to end up in a situation where bool1 && bool2 && (bool1 != bool2) evaluates to true. To give you more concrete example, here's what the last portion of that function compiles to on AArch64: 2924: 97ffff5e bl 269c 2928: f100001f cmp x0, #0x0 292c: 1a9f07e0 cset w0, ne // ne = any 2930: f9400bf3 ldr x19, [sp, #16] 2934: a8c27bfd ldp x29, x30, [sp], #32 2938: d65f03c0 ret 293c: 52800020 mov w0, #0x1 // #1 2940: 17fffffc b 2930 2944: 52800000 mov w0, #0x0 // #0 2948: 17fffffa b 2930 and on AArch32 (Thumb): 18e0: f7ff ff48 bl 1774 18e4: 3000 adds r0, #0 18e6: bf18 it ne 18e8: 2001 movne r0, #1 18ea: bd10 pop {r4, pc} 18ec: 2001 movs r0, #1 18ee: e7fc b.n 18ea as you can see both cases already have code to explicitly convert the result of the function to 0/1. I am more than happy to add ether !! or != NULL if you still think that'd be better, it just I don't think it will have any practical effect. Thanks, Andrey Smirnov _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox