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From: Segher Boessenkool <segher@kernel.crashing.org>
To: William Tambe <tambewilliam@gmail.com>
Cc: gcc-help <gcc-help@gcc.gnu.org>
Subject: Re: Make GCC move instructions between a multi-cycle instruction and the next instruction that depends on its result.
Date: Tue, 22 Feb 2022 18:22:53 -0600	[thread overview]
Message-ID: <20220223002253.GB614@gate.crashing.org> (raw)
In-Reply-To: <CAF8i9mM34-mLZoh4DrKbLsRNSR=S24zB39heVwv5MsxWjcWsiQ@mail.gmail.com>

On Tue, Feb 22, 2022 at 03:15:55PM -0600, William Tambe via Gcc-help wrote:
[snip]
> > Without above transformation, `add %4 %7` would cause the cpu to wait
> > on `div %4 %5` when it could have executed instructions that do not
> > depend on the result of "div".
> 
> How to implement above transformation such that GCC moves instructions
> between a multi-cycle instruction and the next instruction that
> depends on its result ?

GCC has a pretty advanced instruction scheduler.  You can start looking
at <https://gcc.gnu.org/onlinedocs/gccint/Scheduling.html> for example?


Segher

  reply	other threads:[~2022-02-23  0:23 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-22 19:00 William Tambe
2022-02-22 21:15 ` William Tambe
2022-02-23  0:22   ` Segher Boessenkool [this message]
2022-02-23  0:51     ` William Tambe
2022-02-23  7:25     ` AW: " stefan
2022-02-23 15:07       ` William Tambe

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