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[Bug middle-end/63338] Compiling large amounts of large switch cases takes a large amount of time
- From: "rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Tue, 23 Sep 2014 08:26:41 +0000
- Subject: [Bug middle-end/63338] Compiling large amounts of large switch cases takes a large amount of time
- Auto-submitted: auto-generated
- References: <bug-63338-4 at http dot gcc dot gnu dot org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63338
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |WAITING
Last reconfirmed| |2014-09-23
Ever confirmed|0 |1
--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
And what compiler options? With -O1 on x86_64-linux it takes around 1m30s to
compile with GCC 4.8 with the biggest offenders being
alias stmt walking : 64.95 (70%) usr 0.15 (12%) sys 65.11 (69%) wall
0 kB ( 0%) ggc
tree SSA incremental : 11.83 (13%) usr 0.18 (14%) sys 12.04 (13%) wall
47726 kB (12%) ggc
tree copy propagation : 4.12 ( 4%) usr 0.00 ( 0%) sys 4.13 ( 4%) wall
515 kB ( 0%) ggc
TOTAL : 92.99 1.29 94.23
383497 kB
with GCC 4.9 this improves to
alias stmt walking : 55.67 (66%) usr 0.26 (18%) sys 55.95 (65%) wall
0 kB ( 0%) ggc
tree copy propagation : 4.90 ( 6%) usr 0.01 ( 1%) sys 4.94 ( 6%) wall
522 kB ( 0%) ggc
tree SSA incremental : 10.89 (13%) usr 0.20 (14%) sys 11.02 (13%) wall
47751 kB (12%) ggc
TOTAL : 83.95 1.45 85.55
390402 kB
most time is spent in early local cleanups at -O1.
With -O2 GCC 4.9 takes 95s.