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Date: Mon, 07 Aug 2017 21:02:00 -0000
To: pinskia@gmail.com
Subject: Re: [PATCH] [Aarch64] Optimize subtract in shift counts
Cc: gcc-patches@gcc.gnu.org, Michael.Collison@arm.com, nd@arm.com
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From: kenner@vlsi1.ultra.nyu.edu (Richard Kenner)
X-SW-Source: 2017-08/txt/msg00550.txt.bz2

> That is simplify:
> (SHIFT A (32 - B)) -> (SHIFT A (AND (NEG B) 31))
> etc.

I think you need SHIFT_COUNT_TRUNCATED to be true for this to be
valid, but this is exactly what I was getting at in my last message.