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Re: optimization/2001: [3.2/3.3 regression] Inordinately long compile
- From: Brad Lucier <lucier at math dot purdue dot edu>
- To: s dot bosscher at student dot tudelft dot nl (Steven Bosscher)
- Cc: gcc-gnats at gcc dot gnu dot org, gcc-bugs at gcc dot gnu dot org, lucier at math dot purdue dot edu, nobody at gcc dot gnu dot org
- Date: Tue, 11 Mar 2003 21:36:08 -0500 (EST)
- Subject: Re: optimization/2001: [3.2/3.3 regression] Inordinately long compile
>
> http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=2001
>
> Brad, the last time you confirmed this ugly bug is 5 months ago, do you
> still see this? If so, maybe this is an Alpha-specific problem? On my
> ol' slow K6-2, I get a very reasonable compile time (with -march=i586
> -fPIC -O2 -fno-math-errno):
>
> Execution times (seconds)
...
> TOTAL : 9.66 0.34 11.80
Perhaps you were testing 3.4, where this is fixed? Or perhaps it requires
a large number of registers before gcc screws up. Here are the times I
now get, first for the 3.3 branch, then for 3.4:
popov-1734% gcc/cc1 -fPIC -fno-math-errno -O2 -mcpu=ev6 pi.i
__copysignf copysignf __copysign copysign __fabsf fabsf __fabs fabs __floorf __floor floorf floor ___H__20_pi ___init_proc ____20_pi
Execution times (seconds)
cfg construction : 0.24 ( 0%) usr 0.02 ( 3%) sys 0.50 ( 0%) wall
cfg cleanup : 0.94 ( 0%) usr 0.00 ( 0%) sys 0.50 ( 0%) wall
trivially dead code : 1.23 ( 0%) usr 0.00 ( 0%) sys 2.50 ( 1%) wall
life analysis : 13.07 ( 4%) usr 0.00 ( 0%) sys 12.50 ( 4%) wall
life info update : 1.95 ( 1%) usr 0.00 ( 0%) sys 3.00 ( 1%) wall
preprocessing : 0.06 ( 0%) usr 0.02 ( 4%) sys 0.00 ( 0%) wall
lexical analysis : 0.11 ( 0%) usr 0.04 ( 5%) sys 0.00 ( 0%) wall
parser : 0.30 ( 0%) usr 0.03 ( 5%) sys 0.50 ( 0%) wall
expand : 0.08 ( 0%) usr 0.01 ( 1%) sys 0.00 ( 0%) wall
varconst : 0.02 ( 0%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall
integration : 0.02 ( 0%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall
jump : 0.60 ( 0%) usr 0.00 ( 0%) sys 0.50 ( 0%) wall
CSE : 7.86 ( 2%) usr 0.00 ( 1%) sys 7.50 ( 2%) wall
global CSE : 4.63 ( 1%) usr 0.19 (29%) sys 5.00 ( 2%) wall
loop analysis : 0.14 ( 0%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall
CSE 2 : 3.78 ( 1%) usr 0.00 ( 0%) sys 3.50 ( 1%) wall
branch prediction : 1.52 ( 0%) usr 0.00 ( 1%) sys 1.50 ( 0%) wall
flow analysis : 0.20 ( 0%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall
combiner : 0.67 ( 0%) usr 0.00 ( 1%) sys 1.00 ( 0%) wall
if-conversion : 0.15 ( 0%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall
regmove : 0.59 ( 0%) usr 0.00 ( 0%) sys 0.50 ( 0%) wall
scheduling : 125.24 (39%) usr 0.03 ( 4%) sys 125.00 (39%) wall
local alloc : 1.24 ( 0%) usr 0.00 ( 0%) sys 1.50 ( 0%) wall
global alloc : 4.76 ( 1%) usr 0.09 (14%) sys 4.50 ( 1%) wall
reload CSE regs : 110.46 (34%) usr 0.11 (16%) sys 110.50 (34%) wall
flow 2 : 0.74 ( 0%) usr 0.00 ( 0%) sys 1.00 ( 0%) wall
if-conversion 2 : 0.07 ( 0%) usr 0.00 ( 0%) sys 0.50 ( 0%) wall
peephole 2 : 0.25 ( 0%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall
rename registers : 1.56 ( 0%) usr 0.00 ( 0%) sys 1.50 ( 0%) wall
scheduling 2 : 35.85 (11%) usr 0.08 (12%) sys 35.50 (11%) wall
reorder blocks : 0.04 ( 0%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall
shorten branches : 0.39 ( 0%) usr 0.00 ( 0%) sys 0.50 ( 0%) wall
final : 1.37 ( 0%) usr 0.03 ( 4%) sys 1.50 ( 0%) wall
rest of compilation : 0.33 ( 0%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall
TOTAL : 320.50 0.67 321.00
gcc/cc1 -fPIC -fno-math-errno -O2 -mcpu=ev6 pi.i
__copysignf copysignf __copysign copysign __fabsf fabsf __fabs fabs __floorf __floor floorf floor ___H__20_pi ___init_proc ____20_pi
Execution times (seconds)
cfg construction : 0.03 ( 1%) usr 0.00 ( 1%) sys 0.03 ( 1%) wall
cfg cleanup : 0.10 ( 2%) usr 0.00 ( 0%) sys 0.10 ( 2%) wall
trivially dead code : 0.10 ( 2%) usr 0.00 ( 0%) sys 0.10 ( 2%) wall
life analysis : 0.19 ( 5%) usr 0.00 ( 0%) sys 0.19 ( 4%) wall
life info update : 0.09 ( 2%) usr 0.00 ( 0%) sys 0.09 ( 2%) wall
alias analysis : 0.09 ( 2%) usr 0.00 ( 1%) sys 0.09 ( 2%) wall
register scan : 0.04 ( 1%) usr 0.00 ( 0%) sys 0.04 ( 1%) wall
rebuild jump labels : 0.02 ( 0%) usr 0.00 ( 0%) sys 0.02 ( 0%) wall
preprocessing : 0.07 ( 2%) usr 0.02 (12%) sys 0.10 ( 2%) wall
lexical analysis : 0.08 ( 2%) usr 0.04 (24%) sys 0.12 ( 3%) wall
parser : 0.31 ( 7%) usr 0.03 (19%) sys 0.34 ( 8%) wall
expand : 0.08 ( 2%) usr 0.00 ( 3%) sys 0.08 ( 2%) wall
varconst : 0.02 ( 0%) usr 0.00 ( 2%) sys 0.02 ( 0%) wall
integration : 0.02 ( 1%) usr 0.00 ( 1%) sys 0.02 ( 1%) wall
jump : 0.02 ( 1%) usr 0.00 ( 2%) sys 0.03 ( 1%) wall
CSE : 0.32 ( 8%) usr 0.00 ( 0%) sys 0.32 ( 7%) wall
global CSE : 0.59 (14%) usr 0.01 ( 9%) sys 0.61 (14%) wall
bypass jumps : 0.12 ( 3%) usr 0.01 ( 4%) sys 0.13 ( 3%) wall
CSE 2 : 0.12 ( 3%) usr 0.00 ( 0%) sys 0.12 ( 3%) wall
branch prediction : 0.05 ( 1%) usr 0.00 ( 1%) sys 0.05 ( 1%) wall
combiner : 0.13 ( 3%) usr 0.00 ( 1%) sys 0.14 ( 3%) wall
if-conversion : 0.02 ( 1%) usr 0.00 ( 1%) sys 0.02 ( 1%) wall
regmove : 0.05 ( 1%) usr 0.00 ( 0%) sys 0.05 ( 1%) wall
scheduling : 0.41 (10%) usr 0.00 ( 2%) sys 0.41 ( 9%) wall
local alloc : 0.11 ( 3%) usr 0.00 ( 0%) sys 0.11 ( 3%) wall
global alloc : 0.17 ( 4%) usr 0.01 ( 7%) sys 0.18 ( 4%) wall
reload CSE regs : 0.21 ( 5%) usr 0.00 ( 3%) sys 0.21 ( 5%) wall
flow 2 : 0.02 ( 0%) usr 0.00 ( 0%) sys 0.02 ( 0%) wall
if-conversion 2 : 0.05 ( 1%) usr 0.00 ( 0%) sys 0.05 ( 1%) wall
peephole 2 : 0.01 ( 0%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall
rename registers : 0.08 ( 2%) usr 0.00 ( 0%) sys 0.08 ( 2%) wall
scheduling 2 : 0.15 ( 3%) usr 0.00 ( 1%) sys 0.15 ( 3%) wall
reorder blocks : 0.10 ( 2%) usr 0.01 ( 7%) sys 0.12 ( 3%) wall
shorten branches : 0.02 ( 0%) usr 0.00 ( 0%) sys 0.02 ( 0%) wall
final : 0.08 ( 2%) usr 0.00 ( 1%) sys 0.08 ( 2%) wall
rest of compilation : 0.10 ( 2%) usr 0.00 ( 0%) sys 0.10 ( 2%) wall
TOTAL : 4.20 0.17 4.37
And the code generated by 3.3 is absolutely horrendous; I put the .s files at
http://www.math.purdue.edu/~lucier/GNATS/GNATS-6/pi-3.3.s.gz
and
http://www.math.purdue.edu/~lucier/GNATS/GNATS-6/pi-3.4.s.gz
The 3.4-generated code is a model of good behavior and decorum ;-).
The patch that fixed this for 3.4 was
http://gcc.gnu.org/ml/gcc-cvs/2003-02/msg00742.html
Perhaps it's in the RedHat 3.2 branch, too.
Brad