tdep/1503: hppa-tdep recognition of std-with-modify is busted

[mec dot gnu at mindspring dot com]

>Number:         1503
>Category:       tdep
>Synopsis:       hppa-tdep recognition of std-with-modify is busted
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Jan 09 03:18:00 UTC 2004
>Closed-Date:
>Last-Modified:
>Originator:     mec.gnu@mindspring.com
>Release:        gdb 6.0
>Organization:
>Environment:
target = native, host = hppa2.0-hp-hpux11.11
>Description:
This code has a problem:

  hppa_frame_find_saved_regs
  ...
    /* A std has explicit post_modify_forms.  */
    else if ((inst & 0xfc00000c0) == 0x70000008)
      frame_saved_regs[reg] = get_frame_base (frame_info);
    else
      ...

The problem is that "0xfc00000c0" is 9 hex digits long.  gcc 3.3.2 throws a warning (but gcc 3.2-7-rh does not) and the code turns into an "if (0)".

This code was introduced in hppa-tdep.c version 1.1.1.10 on 1999-08-31.

>How-To-Repeat:
That is tough.  It doesn't happen with HP ansi c and HP aCC on my test system, using a gcov'ed version of gdb on the whole test suite.
>Fix:
Don't just change the instruction.  That "if" test is way suspicious.  There are two forms of std, and it handles only one form.  It doesn't handle non-zero immediate displacemnts.  The code in the "else" actually probably does a better job.

Someone who knows their way around pa-risc instruction set and the ABI has to look at this.  That might be me, in the future.

PA-RISC instruction set:

http://h21007.www2.hp.com/dspp/tech/tech_TechDocumentDetailPage_IDX/1,1701,2533,00.html
page 7-136 (page 138 in chapter 7 of the PDF)
>Release-Note:
>Audit-Trail:
>Unformatted: