gdb/47: Single-stepping on IA-64 ignores register rotation

[bob at virtualunlimited dot com]

>Number:         47
>Category:       gdb
>Synopsis:       Single-stepping on IA-64 ignores register rotation
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Apr 26 02:38:01 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:     bob@virtualunlimited.com
>Release:        gdb-5.0
>Organization:
>Environment:
ia64-suse-linux
>Description:
When trying to piece of vectorized code (with rotating registers and br.ctop as loop instruction) I noticed that single-stepping through the code ignores register rotation, i.e. stepping through the br.ctop instruction changes neither regular registers, predicate registers nor floating-point registers. Of course this makes it virtually impossible to single-step and debug that piece of code.
>How-To-Repeat:
Write any loop with br.ctop, for instance loading register r32 from an increasing address. Single-step through the routine, and see how the registers haven't rotated after each br.ctop.
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted: