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Date: Mon, 03 Dec 2007 16:19:00 -0000
From: Andrew Cagney <cagney@redhat.com>
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To: Mark Wielaard <mwielaar@redhat.com>
CC: frysk@sourceware.org
Subject: Re: [SCM]  master: Use libunwind cursor to get at CFA.
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mark@sourceware.org wrote:
>     frysk-core/frysk/stack/ChangeLog
>     2007-12-03  Mark Wielaard  <mwielaard@redhat.com>
>     
>            * LibunwindFrame.java (getFrameIdentifier): Get CFA from cursor.
>   

This isn't right.

The confusion comes from what libunwind considers to be the cursor's 
CFA.  It returns what you're more likely to recognize as the  
inner-to-cursor's CFA and not the cursor''s CFA.  Effectively the 
current frame's SP, in fact:

    case UNW_X86_64_CFA:
    case UNW_X86_64_RSP:
      if (write)
        return -UNW_EREADONLYREG;
      *valp = c->dwarf.cfa;
      return 0;

Andrew