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Re: question about gcc rtx

From: Jeff Law <law at redhat dot com>
To: htio2 <wenbin dot leong at gmail dot com>, gcc-help at gcc dot gnu dot org
Date: Fri, 30 Oct 2015 08:32:55 -0600
Subject: Re: question about gcc rtx
Authentication-results: sourceware.org; auth=none
References: <1446193409431-1200050 dot post at n5 dot nabble dot com>

On 10/30/2015 02:23 AM, htio2 wrote:

Hi, how do I constraint the rtx to generate movsi Insn that only use odd
16bits register number (R1, R3, R5 ..) ? for register pairing (e.g R1 and R2
is a pair, R3 and R4 ...) .

Generally register pairing is handled by HARD_REGNO_MODE_OK and itsrelated macros. Many targets use register pairs to handle modes largerthan their word_size. ie, 64bit moves on 32 bit targets. I recommendlooking at other ports to see how that's handled.


Jeff

References:
- question about gcc rtx
  - From: htio2

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