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

Kevin Buettner
Fri Apr 27 16:18:00 GMT 2001

The following reply was made to PR gdb/47; it has been noted by GNATS.

From: Kevin Buettner <>
Subject: Re: gdb/47: Single-stepping on IA-64 ignores register rotation
Date: Fri, 27 Apr 2001 16:13:16 -0700

 On Apr 26,  9:31am, wrote:
 > >Synopsis:       Single-stepping on IA-64 ignores register rotation
 > >Release:        gdb-5.0
 > >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.
 It isn't clear to me which version of gdb Suse is including in their
 IA-64 Linux distribution.  In any event, I would appreciate it if you'd
 try again with the current development sources since I implemented
 register rotation support quite some time ago.  If it still doesn't
 work for you, I'd appreciate it if you'd send me a test case to look

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