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[Bug ipa/63671] [5 Regression] 21% tramp3d-v4 performance hit due to -fdevirtualize
- From: "hubicka at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Mon, 24 Nov 2014 16:39:05 +0000
- Subject: [Bug ipa/63671] [5 Regression] 21% tramp3d-v4 performance hit due to -fdevirtualize
- Auto-submitted: auto-generated
- References: <bug-63671-4 at http dot gcc dot gnu dot org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63671
--- Comment #15 from Jan Hubicka <hubicka at gcc dot gnu.org> ---
The performance regression seems solved on my setup (Trevor, can you double
check?).
-Ofast -fdevirtualize:
Time spent in iteration: 4.11598
-Ofast -fno-devirtualize
Time spent in iteration: 4.17063
-Ofast -fno-devirtualize -fno-icf
Time spent in iteration: 3.34953
GCC 4.7:
Time spent in iteration: 5.53831
GCC 4.8:
Time spent in iteration: 3.4625
GCC 4.9:
Time spent in iteration: 2.79834
$ size 4.7 4.9 devirt nodevirt
text data bss dec hex filename
785615 1204 2904 789723 c0cdb 4.7
620822 1268 3320 625410 98b02 4.8
615847 1180 3160 620187 9769b 4.9
680881 1228 3064 685173 a7475 devirt
650161 1228 3064 654453 9fc75 nodevirt
681709 1228 3064 686001 a77b1 tramp-devirt-noicf
So 4.9 still outperforms mainline; ICF confuse inliner and moreover
devirtualization accounts 5% of code for no visible benefits.