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Re: Compilation performance comparison of 3.5.0 and TreeSSA trees on MICO sources as requested in: [tree-ssa] Merge status 2004-05-03
- From: Andrew Pinski <pinskia at physics dot uc dot edu>
- To: Mike Stump <mrs at apple dot com>
- Cc: Diego Novillo <dnovillo at redhat dot com>, "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>, Karel Gardas <kgardas at objectsecurity dot com>, Andrew Pinski <pinskia at physics dot uc dot edu>
- Date: Tue, 4 May 2004 17:20:43 -0400
- Subject: Re: Compilation performance comparison of 3.5.0 and TreeSSA trees on MICO sources as requested in: [tree-ssa] Merge status 2004-05-03
- References: <D5503AFA-9E0F-11D8-B137-003065A77310@apple.com>
On May 4, 2004, at 17:13, Mike Stump wrote:
On Tuesday, May 4, 2004, at 01:50 PM, Karel Gardas wrote:
MICO doesn't look good. I've compared todays source trees:
File 350-O0 TSSA-O0 Delta% 350-O2 TSSA-O2
Sum 523.2 649.36 -19.43 774.7 904.11 -14.31
Conclusion: compile time regressions for both -O0 and -O2 compilation.
Thanks. While I'll happily take the 14% hit for optimized code, the
20% drop for -O0 I want to bitch about. Last time we lost 34% in one
tiny patch, we lost, and the work went in anyway. That was almost ok,
as we just reverted the work that caused the regression in our tree.
However, we have no ability to `revert' treessa for -O0 to gain the
20% back.
I'd like ask people to see if there is anyway to get that back. If
not all of it, part of it?
Yes there is a way, it is called do some optimizations at -O0. The
problem with the tree-ssa,
the RTL which is generated for an unoptimized run is just huge compared
to what the mainline
was/is. Simple things like DCE will help a lot on the compile time and
code size.
Thanks,
Andrew Pinski