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Re: [PATCH] Optimize zero_extend into paradoxical subreg

From: Richard Henderson <rth at redhat dot com>
To: Roger Sayle <roger at eyesopen dot com>
Cc: Richard dot Earnshaw at arm dot com, gcc-patches at gcc dot gnu dot org
Date: Sun, 29 Sep 2002 11:05:20 -0700
Subject: Re: [PATCH] Optimize zero_extend into paradoxical subreg
References: <200209281629.g8SGTI207508@pc960.cambridge.arm.com> <Pine.LNX.4.33.0209281022040.15924-100000@www.eyesopen.com>

On Sat, Sep 28, 2002 at 11:03:04AM -0600, Roger Sayle wrote:
> In an ideal world we probably wouldn't need LOAD_EXTEND_OP,
> target patterns would appropriately recognize "(zero_extend (mem ...))""

Many targets do.  This is not particularly difficult on load/store
architectures; merely a matter of making zero_extendsidi (or whatever)
recognize memory inputs.

> and GCC would recognize"(?rshift (?lshift ...))" as extend insns.

It does, in combine.

r~

References:
- Re: [PATCH] Optimize zero_extend into paradoxical subreg
  - From: Richard Earnshaw
- Re: [PATCH] Optimize zero_extend into paradoxical subreg
  - From: Roger Sayle

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