http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57218
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2013-05-10
CC| |hubicka at gcc dot gnu.org
Target Milestone|--- |4.8.1
Summary|Excessive inlining even at |[4.8/4.9 Regression]
|-Os |Excessive inlining even at
| |-Os
Ever confirmed|0 |1
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed.
Deciding on inlining of small functions. Starting with size 47.
Enqueueing calls of std.isra.0/8.
Estimating body: std.isra.0/8
Known to be false: not inlined, op1 changed, op2 changed
size:11 time:20
Estimating body: std.isra.0/8
Known to be false: not inlined, op1 changed, op2 changed
size:11 time:20
Estimating body: std.isra.0/8
Known to be false: not inlined, op1 changed, op2 changed
size:11 time:20
enqueuing call __sinit/1 -> std.isra.0/8, badness -36092160
enqueuing call __sinit/1 -> std.isra.0/8, badness -36092160
enqueuing call __sinit/1 -> std.isra.0/8, badness -36092160
Enqueueing calls of __sinit/1.
Estimating body: std.isra.0/8
Known to be false: not inlined, op1 changed, op2 changed
size:11 time:20
Considering std.isra.0 with 21 size
to be inlined into __sinit in newlib/libc/stdio/findfp.c:79
Estimated growth after inlined into all is +0 insns.
Estimated badness is -36092160, frequency 0.39.
Badness calculation for __sinit/1 -> std.isra.0/8
size growth 7, time 20 big_speedup
-36092160: guessed profile. frequency 0.389000, benefit 23.529411%, time
w/o inlining 34, time w inlining 26 overall growth 0 (current) 0 (original)
Accounting size:7.00, time:2.72 on predicate:(op0[ref offset:
640] == 0)
Processing frequency std.isra.0
Called by __sinit that is normal or hot
Inlined into __sinit which now has time 26 and size 33,net change of +7.
So the reason is that it can eliminate the body of 'std' after inlining
it three times and it computes that the cost of doing that (3 * 7 is
the same as the cost of the offline body).
And that's because
ptr_1(D)->_p = 0B;
freq:1.00 size: 1 time: 1
50% will be eliminated by inlining
Accounting size:0.50, time:0.50 on predicate:(not inlined)
Accounting size:0.50, time:0.50 on predicate:(true)
ptr_1(D)->_r = 0;
freq:1.00 size: 1 time: 1
50% will be eliminated by inlining
Accounting size:0.50, time:0.50 on predicate:(not inlined)
Accounting size:0.50, time:0.50 on predicate:(true)
...
the inliner thinks that it is likely that initializations via parameters
are eliminated by inlining:
Inline summary for std.isra.0/8 inlinable
self time: 29
global time: 0
self size: 21
global size: 0
self stack: 0
global stack: 0
size:7.000000, time:7.000000, predicate:(true)
size:10.000000, time:9.000000, predicate:(not inlined)
calls:
memset/3 function body not available
loop depth: 0 freq:1000 size: 4 time: 13 callee size: 0 stack: 0
op1 is compile time invariant
op2 is compile time invariant
not sure why we have that (not inlined) predicate size stuff but use
'self size' when accounting against inlining multiple times.
The above seems to suggest that GCC will _always_ inline a function
with just initializers twice when the body can be eliminated then.
