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Date: Sun, 9 Jul 2023 17:37:36 -0400 (EDT)
From: Hans-Peter Nilsson <hp@bitrange.com>
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To: Manolis Tsamis <manolis.tsamis@vrull.eu>
cc: gcc-patches@gcc.gnu.org, Richard Biener <richard.guenther@gmail.com>, 
    Philipp Tomsich <philipp.tomsich@vrull.eu>, 
    Jeff Law <jeffreyalaw@gmail.com>
Subject: Re: [PATCH v2] Implement new RTL optimizations pass:
 fold-mem-offsets.
In-Reply-To: <20230615172817.3587006-1-manolis.tsamis@vrull.eu>
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On Thu, 15 Jun 2023, Manolis Tsamis wrote:

> This is a new RTL pass that tries to optimize memory offset calculations
> by moving them from add immediate instructions to the memory loads/stores.
> For example it can transform this:
> 
>   addi t4,sp,16
>   add  t2,a6,t4
>   shl  t3,t2,1
>   ld   a2,0(t3)
>   addi a2,1
>   sd   a2,8(t2)
> 
> into the following (one instruction less):
> 
>   add  t2,a6,sp
>   shl  t3,t2,1
>   ld   a2,32(t3)
>   addi a2,1
>   sd   a2,24(t2)
> 
> Although there are places where this is done already, this pass is more
> powerful and can handle the more difficult cases that are currently not
> optimized. Also, it runs late enough and can optimize away unnecessary
> stack pointer calculations.

It punts on all "use" insns that are not SET.
Why not use single_set there too?

brgds, H-P