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From: Andrea Corallo <akrl@sdf.org>
To: "Nicolas Bértolo" <nicolasbertolo@gmail.com>
Cc: 41615@debbugs.gnu.org
Subject: bug#41615: [feature/native-comp] Dump prettier C code.
Date: Sun, 31 May 2020 20:00:29 +0000	[thread overview]
Message-ID: <xjftuzvkh7m.fsf@sdf.org> (raw)
In-Reply-To: <CAFnS-Okt=z_-qu4TmO+PfXSBBx4XidYCotRuGEmQuiur3HZ=4Q@mail.gmail.com> ("Nicolas Bértolo"'s message of "Sun, 31 May 2020 16:38:15 -0300")

Nicolas Bértolo <nicolasbertolo@gmail.com> writes:

>> The whole compilation is something like 5x faster here.
> Amazing.I took a closer look at the code that uses casts to bools and
> I think I found a
> bug.
>
> Casting to bool using an enum is equivalent to taking the lowest byte using
> a byte mask. This wrongly casts to "false" integers whose lowest byte is nil.
>
> bool cast_from_unsigned_long_long_to_bool (unsigned long long x)
> {
>   return (x & 0xFF);
> }
>
> The correct way to cast to bool is to mimic C semantics:
>
> bool cast_from_unsigned_long_long_to_bool (unsigned long long x)
> {
>   if (x != 0)
>     return true;
>   else
>     return false;
> }
>
> Am I right?

You are.

I never fixed it (is present also in the pure union cast mechanism)
because I had not time so far and practically I suspect is not a real
case of problematic code we generate.  But is *certanly* good to fix.

BTW If you are into the mood to dig into these... also sign extentions
probably should be handled ;)

Andrea

-- 
akrl@sdf.org





  reply	other threads:[~2020-05-31 20:00 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-30 15:08 bug#41615: [feature/native-comp] Dump prettier C code Nicolas Bértolo
2020-05-30 22:20 ` Nicolas Bértolo
2020-05-31 10:45   ` Andrea Corallo
2020-05-31 15:42     ` Nicolas Bértolo
2020-05-31 11:37   ` Andrea Corallo
2020-05-31 15:48     ` Andrea Corallo
2020-05-31 15:54     ` Nicolas Bértolo
2020-05-31 16:57       ` Andrea Corallo
2020-05-31 17:26         ` Nicolas Bértolo
2020-05-31 18:11           ` Andrea Corallo
2020-05-31 19:38             ` Nicolas Bértolo
2020-05-31 20:00               ` Andrea Corallo [this message]
2020-05-31 20:18                 ` Andrea Corallo
2020-06-01  7:19               ` Andrea Corallo
2020-06-01 12:25                 ` Nicolas Bértolo
2020-06-01 20:28                   ` Andrea Corallo
2020-06-01 23:11                     ` Nicolas Bértolo
2020-06-04  9:52                       ` Andrea Corallo

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