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Re: inserting instructions into prologue/epilogue

From: Nathan Sidwell <nathan at codesourcery dot com>
To: Gunther Nikl <gni at gecko dot de>
Cc: gcc at gcc dot gnu dot org
Date: Wed, 03 Aug 2005 15:50:09 +0100
Subject: Re: inserting instructions into prologue/epilogue
References: <20050803144045.GA19698@lorien.int.gecko.de>

Gunther Nikl wrote:

Hello!

I am trying to add instructions into function prologue/epilogue. These
instructions shall save and load "fixed" registers to avoid assembly.

Register saving in the prologue appears to work. The restore code in the
epilogue aborts in flow.c/propagate_one_insn with

"Attempt to delete prologue/epilogue insn"

unless the stackslot was marked with MEM_VOLATILE_P. I don't think thats
the proper fix.

you can add a (USE reg) after the restore in the prologue. Then flow considers the register, and the preceding load, to be live at that point.

nathan
--
Nathan Sidwell    ::   http://www.codesourcery.com   ::     CodeSourcery LLC
nathan@codesourcery.com    ::     http://www.planetfall.pwp.blueyonder.co.uk

Follow-Ups:
- Re: inserting instructions into prologue/epilogue
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References:
- inserting instructions into prologue/epilogue
  - From: Gunther Nikl

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