From: "Stefan Kanthak" <stefan.kanthak@nexgo.de>
To: "Eric Botcazou" <botcazou@adacore.com>
Cc: <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH] Better __ashlDI3, __ashrDI3 and __lshrDI3 functions, plus fixed __bswapsi2 function
Date: Tue, 10 Nov 2020 20:44:32 +0100 [thread overview]
Message-ID: <003190C0741B4AF0B73E189026EADC84@H270> (raw)
In-Reply-To: <7786108.h9Zq5u0u6d@fomalhaut>
Eric Botcazou <botcazou@adacore.com> wrote:
>> The implementation of the __ashlDI3(), __ashrDI3() and __lshrDI3() functions
>> is rather bad, it yields bad machine code at least on i386 and AMD64. Since
>> GCC knows how to shift integers twice the register size these functions can
>> be written as one-liners.
>
> These functions are precisely meant to be used when GCC cannot do that.
On which processor(s) is GCC unable to generate code for DWtype shifts?
JFTR: if GCC were not able to generate code for DWtype addition and subtraction
it would also need __[u]addDI3() and __[u]subDI3() functions ... which
are but missing from libgcc.a
Stefan Kanthak
next prev parent reply other threads:[~2020-11-10 19:49 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-10 17:59 Stefan Kanthak
2020-11-10 18:08 ` Eric Botcazou
2020-11-10 19:44 ` Stefan Kanthak [this message]
2020-11-10 20:14 ` Jakub Jelinek
2020-11-10 21:09 ` Jeff Law
2020-11-10 21:17 ` Jakub Jelinek
2020-11-10 23:42 ` Jeff Law
2020-11-24 0:21 ` Jeff Law
2020-11-10 22:12 ` Jeff Law
2020-11-10 22:01 ` Jeff Law
2020-11-11 0:00 ` Andreas Schwab
2020-11-24 13:57 ` Stefan Kanthak
2020-11-24 14:34 ` Andreas Schwab
2020-11-24 15:40 ` Stefan Kanthak
2020-11-24 15:49 ` Andreas Schwab
2020-11-25 18:53 ` Jeff Law
2020-11-25 20:22 ` Stefan Kanthak
2020-11-25 20:42 ` Jakub Jelinek
2020-11-25 21:22 ` Stefan Kanthak
2020-11-25 22:06 ` Jeff Law
2020-11-25 23:06 ` Stefan Kanthak
2020-11-25 20:44 ` Jeff Law
2020-11-10 18:09 ` Jakub Jelinek
2020-11-10 18:32 ` Jeff Law
2020-11-10 18:26 ` Jakub Jelinek
2020-11-10 23:48 ` Jeff Law
2020-11-10 23:53 ` Jakub Jelinek
2020-11-11 8:33 ` Stefan Kanthak
2020-11-11 9:55 ` Jakub Jelinek
2020-11-11 17:54 ` Joseph Myers
2020-11-23 23:01 ` Jeff Law
2020-11-30 1:06 ` Jeff Law
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