Re: 3.0 compiled application twice as slow as 2.95.3 compiled application (execution time)

[Daniel Berlin <dan at cgsoftware dot com>]

Carlo Wood <carlo@alinoe.com> writes:

If people can get me preprocessed source to some of these things that
are *much* (ie 2x the time) along with all the test data needed to
reproduce, i'll happily look into it.


> I surely hope 3.1 will be faster.  Working with Real Life(tm) code
> one would almost want to develop with 2.95.3 and only use 3.0 to
> test if it works...  Actually, I already find myself doing that.
> 
> 3.0 compiles much slower, but the resulting code also runs much
> slower.

Try --param max-inline-insns=100, and see if both are still true.
>  For example:
> 
> Using 3.0:
> 
> ~/c++/libcw/src/libcwd/testsuite>time tst_bfd_shared
> STABS   : address 0x804bc6a corresponds to bfd.cc:111
> NOTICE  : called from bfd.cc:111
> STABS   : address 0x804bc7a corresponds to bfd.cc:119
> NOTICE  : called from bfd.cc:119
> STABS   : address 0x804bc8a corresponds to bfd.cc:127
> NOTICE  : called from bfd.cc:127
> STABS   : address 0x804bdae corresponds to bfd.cc:159
> NOTICE  : called from bfd.cc:159
> STABS   : address 0x401a5f30 corresponds to libc-start.c:129
> NOTICE  : called from libc-start.c:129
> STABS   : Warning: Address 0x804b870 in section .text does not have a line number, perhaps the unit containing the function
>           `_start' wasn't compiled with flag -g
> NOTICE  : called from <unknown location>
> 	 
> real    0m1.691s
> user    0m1.450s
> sys     0m0.080s
> 
> Using 2.95.3:
> 
> ~/c++/libcw/src/libcwd/testsuite>time tst_bfd_shared
> STABS   : address 0x804bc22 corresponds to bfd.cc:111
> NOTICE  : called from bfd.cc:111
> STABS   : address 0x804bc36 corresponds to bfd.cc:119
> NOTICE  : called from bfd.cc:119
> STABS   : address 0x804bc4e corresponds to bfd.cc:127
> NOTICE  : called from bfd.cc:127
> STABS   : address 0x804bd8b corresponds to bfd.cc:159
> NOTICE  : called from bfd.cc:159
> STABS   : address 0x40132f30 corresponds to libc-start.c:129
> NOTICE  : called from libc-start.c:129
> STABS   : Warning: Address 0x804b810 in section .text does not have a line number, perhaps the unit containing the function
>           `_start' wasn't compiled with flag -g
> NOTICE  : called from <unknown location>
> 
> real    0m0.795s
> user    0m0.750s
> sys     0m0.040s
> 
> That's a factor of TWO execution time.  100% slower :/
> 
> -- 
> Carlo Wood <carlo@alinoe.com>

-- 
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