From: sotrdg sotrdg <euloanty@live.com>
To: Segher Boessenkool <segher@kernel.crashing.org>
Cc: "gcc@gcc.gnu.org" <gcc@gcc.gnu.org>,
"gcc-request@gcc.gnu.org" <gcc-request@gcc.gnu.org>,
"gcc-help@gcc.gnu.org" <gcc-help@gcc.gnu.org>
Subject: RE: __builtin_addc support??
Date: Wed, 27 Oct 2021 23:22:15 +0000 [thread overview]
Message-ID: <CH2PR02MB65221BD8700C18D2B585BB5DB2859@CH2PR02MB6522.namprd02.prod.outlook.com> (raw)
In-Reply-To: <20211027231641.GZ614@gate.crashing.org>
LOL
https://github.com/tearosccebe/fast_io/blob/4ca355fcbf31aa26a0259ad09671eaab899930fc/include/fast_io_core_impl/intrinsics.h#L366
You are wrong dude.
Give me solution for addcarry
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________________________________
From: Segher Boessenkool <segher@kernel.crashing.org>
Sent: Wednesday, October 27, 2021 7:16:41 PM
To: sotrdg sotrdg <euloanty@live.com>
Cc: gcc@gcc.gnu.org <gcc@gcc.gnu.org>; gcc-request@gcc.gnu.org <gcc-request@gcc.gnu.org>; gcc-help@gcc.gnu.org <gcc-help@gcc.gnu.org>
Subject: Re: __builtin_addc support??
On Wed, Oct 27, 2021 at 04:12:27PM +0000, sotrdg sotrdg via Gcc-help wrote:
> 79173 – add-with-carry and subtract-with-borrow support (x86_64 and others) (gnu.org)<https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79173>
>
> What I find quite interesting is things like this.
>
> Since llvm clang provides __builtin_addc __builtin_subc for all targets. Can we provide something similar? Since currently no solutions we can access carry flag besides x86
Why? We have __builtin_add_overflow, which is a smaller factor, and
enough to build up any bigger factors with. You can easily write the
same thing in standard C of course, which often is a better plan.
If you want exact machine insns as output, write those, i.e., write
assembler code, not C. Builtins are not there to please the "C is a
portable assembler" crowd: they are there to expose functionality you
cannot (conveniently) get using just pure standard C.
Segher
next prev parent reply other threads:[~2021-10-27 23:22 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-27 16:12 sotrdg sotrdg
2021-10-27 16:36 ` Paul Koning
2021-10-27 16:54 ` sotrdg sotrdg
2021-10-27 23:16 ` Segher Boessenkool
2021-10-27 23:22 ` sotrdg sotrdg [this message]
2021-10-27 23:23 ` sotrdg sotrdg
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