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Re: SImode -> DImode optimizations

From: Richard Henderson <rth at redhat dot com>
To: gcc at gcc dot gnu dot org
Date: Fri, 22 Feb 2002 01:31:33 -0800
Subject: Re: SImode -> DImode optimizations
References: <20020222050238.GG1054@bubble.sa.bigpond.net.au>

On Fri, Feb 22, 2002 at 03:32:38PM +1030, Alan Modra wrote:
> What's the correct way to let gcc know that SImode insn patterns
> leave the high part of a reg in a known state?

Create additional patterns that also contain the zero_extend.  I.e.

  (set (match_operand:DI 0 "gpc_reg_operand" "=r")
       (zero_extend:DI
	 (rotate:SI (match_operand:SI 1 "gpc_reg_operand" "r")
		    (match_operand:SI 2 "reg_or_cint_operand" "ri"))))


r~

References:
- SImode -> DImode optimizations
  - From: Alan Modra

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