From: HAO CHEN GUI <guihaoc@linux.ibm.com>
To: Jeff Law <jeffreyalaw@gmail.com>, gcc-patches <gcc-patches@gcc.gnu.org>
Cc: Segher Boessenkool <segher@kernel.crashing.org>,
David <dje.gcc@gmail.com>, "Kewen.Lin" <linkw@linux.ibm.com>,
Peter Bergner <bergner@linux.ibm.com>
Subject: Re: [PATCH-1, combine] Don't widen shift mode when target has rotate/mask instruction on original mode [PR93738]
Date: Fri, 21 Jul 2023 08:59:52 +0800 [thread overview]
Message-ID: <ddf571a3-a3c8-1d53-335a-4d182072cf9e@linux.ibm.com> (raw)
In-Reply-To: <514e6a6c-b357-f2ca-70ad-7af7cee6bfbe@gmail.com>
Hi Jeff,
在 2023/7/21 5:27, Jeff Law 写道:
> Wouldn't it make more sense to just try rotate/mask in the original mode before trying a shift in a widened mode? I'm not sure why we need a target hook here.
There is no change to try rotate/mask with the original mode when
expensive_optimizations is set. The subst widens the shift mode.
if (flag_expensive_optimizations)
{
/* Pass pc_rtx so no substitutions are done, just
simplifications. */
if (i1)
{
subst_low_luid = DF_INSN_LUID (i1);
i1src = subst (i1src, pc_rtx, pc_rtx, 0, 0, 0);
}
subst_low_luid = DF_INSN_LUID (i2);
i2src = subst (i2src, pc_rtx, pc_rtx, 0, 0, 0);
}
I don't know if the wider mode is helpful to other targets, so
I added the target hook.
Thanks
Gui Haochen
next prev parent reply other threads:[~2023-07-21 1:00 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-19 3:06 HAO CHEN GUI
2023-07-20 21:27 ` Jeff Law
2023-07-21 0:59 ` HAO CHEN GUI [this message]
2023-07-21 1:06 ` HAO CHEN GUI
2023-08-04 23:32 ` Jeff Law
2023-08-21 1:37 ` HAO CHEN GUI
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