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Re: Variable tracking (location lists support) - part 1
- From: Vladimir Makarov <vmakarov at redhat dot com>
- To: law at redhat dot com
- Cc: "Joseph S. Myers" <jsm at polyomino dot org dot uk>, Josef Zlomek <zlomj9am at artax dot karlin dot mff dot cuni dot cz>, gcc-patches at gcc dot gnu dot org
- Date: Thu, 29 Jan 2004 16:06:17 -0500
- Subject: Re: Variable tracking (location lists support) - part 1
- References: <200401292010.i0TKA7rI008229@speedy.slc.redhat.com>
law@redhat.com wrote:
In message <Pine.LNX.4.58.0401291957130.23288@digraph.polyomino.org.uk>, "Josep
h S. Myers" writes:
>On Thu, 29 Jan 2004, Josef Zlomek wrote:
>
>> Without location lists, GDB printed some wierd values when debugging
>> optimized code. GDB with support of location lists (GDB 6.0.1 and newer)
>> shows correct values of variables even when debugging optimized code
>> even with -fomit-frame-pointer (when !frame_pointer_needed a special locati
>on
>> list for describing the changes of stack pointer is emitted).
>
>Does this mean that some targets that didn't previously should now have
>-fomit-frame-pointer enabled at -O? (The documentation saying
>"@option{-O} also turns on @option{-fomit-frame-pointer} on machines where
>doing so does not interfere with debugging.".)
That would be a significant step forward -- being able to turn on FP
elimination for ia32 is probably the easiest way to get a measureable
performance improvement I can think of :-)
Yes, that is true. As I remember the improvement was 1.5-2% for pentium4 on SPECINT2000.
Vlad