[Bug middle-end/27881] [4.1 Regression] Memory exhausted with -finline-functions on testsuite file alias3.C

["rguenth at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #10 from rguenth at gcc dot gnu dot org  2006-11-14 17:42 -------
It's true that the number of created calls is 2^N, but unfortunately the number
of created temporaries grows super-exponential:

 --param max-inline-recursive-depth-auto      grep 'struct X' t.C.t24.fixupcfg 
| wc -l
   1       3
   2      63
   3   16383 (!)

So it grows like n_i = (2*(n_{i-1}+1))**2 - 1 with n_1 = 3.
For 4 we would have 1073741823, for 5 we get 4611686018427387904 number
of temporaries ;)

Honza's patch (comment #8) fixes this on the mainline, but I guess porting that
back is not really an option.  We might instead lower the default value of
max-inline-recursive-depth[-auto], which is currently 8.

>From the above numbers a limit of 2 should be appropriate.  Or we can make
it count the number of functions inlined, not the depth, to avoid exponential
behavior with multiple calls to self.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27881