This is the mail archive of the gcc@gcc.gnu.org mailing list for the GCC project.

Index Nav:	[Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav:	[Date Prev] [Date Next]	[Thread Prev] [Thread Next]
Other format:	[Raw text]

Re: Question about REG_OFFSET on big endian machines

From: Jim Wilson <wilson at specifixinc dot com>
To: Josef Zlomek <zlomj9am at artax dot karlin dot mff dot cuni dot cz>
Cc: gcc at gcc dot gnu dot org
Date: Thu, 06 May 2004 22:14:32 -0700
Subject: Re: Question about REG_OFFSET on big endian machines
References: <20040505184826.GA9613@artax.karlin.mff.cuni.cz>

Josef Zlomek wrote:

32-bit variable promoted to 64-bit register has a REG_OFFSET == 0.
When it is then accessed by SUBREG which is later converted to a REG
it gets a REG_OFFSET == 4 which is wrong for 32-bit variable in 32-bit
register.

This has come up before, when you tried writing a patch for PR 14084. See the thread at http://gcc.gnu.org/ml/gcc-patches/2004-02/msg01314.html

I think it is clear that the current REG_OFFSET support is broken, but it isn't clear to me whether your patch is the right fix. I never got around a more detailed investigation of the problem. I dropped the ball here. Also, your patch only fixed one place where we removed subregs, but we probably need to fix other places. -- Jim Wilson, GNU Tools Support, http://www.SpecifixInc.com

Follow-Ups:
- Re: Question about REG_OFFSET on big endian machines
  - From: Josef Zlomek

References:
- Question about REG_OFFSET on big endian machines
  - From: Josef Zlomek

Index Nav:	[Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav:	[Date Prev] [Date Next]	[Thread Prev] [Thread Next]