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Date: Tue, 9 May 2023 20:45:09 +0000
From: Joseph Myers <joseph@codesourcery.com>
To: Roger Sayle <roger@nextmovesoftware.com>
CC: 'GCC Patches' <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH] Add RTX codes for BITREVERSE and COPYSIGN.
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On Sat, 6 May 2023, Roger Sayle wrote:

> An analysis of backend UNSPECs reveals that two of the most common UNSPECs
> across target backends are for copysign and bit reversal.  This patch
> adds RTX codes for these expressions to allow their representation to
> be standardized, and them to optimized by the middle-end RTL optimizers.

Note we have bug 50481 requesting (target-independent) built-in functions 
for bit reversal (so this patch could be useful as a basis for 
implementing such built-in functions, with appropriate lowering or libgcc 
implementation for targets without relevant instructions).

-- 
Joseph S. Myers
joseph@codesourcery.com