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From: Paul Koning <paulkoning@comcast.net>
To: sotrdg sotrdg <euloanty@live.com>
Cc: GCC Development <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 12:36:43 -0400	[thread overview]
Message-ID: <058A01F7-6073-4F1D-994A-4D6748126173@comcast.net> (raw)
In-Reply-To: <CH2PR02MB65225B964A39D84CE8EF708CB2859@CH2PR02MB6522.namprd02.prod.outlook.com>



> On Oct 27, 2021, at 12:12 PM, sotrdg sotrdg via Gcc <gcc@gcc.gnu.org> 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

Certainly some other targets could do this.  The LLVM builtins explicitly expose carry, which isn't actually what you want (you'd want the carry flag in the condition code to be propagated).  Presumably optimization would eliminate those explicit arguments and reduce them to CC references.

	paul



  reply	other threads:[~2021-10-27 16:36 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 [this message]
2021-10-27 16:54   ` sotrdg sotrdg
2021-10-27 23:16 ` Segher Boessenkool
2021-10-27 23:22   ` sotrdg sotrdg
2021-10-27 23:23   ` sotrdg sotrdg

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