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Re: The speed of the compiler, was: Re: Combine four insns
Diego Novillo wrote:
On 10-08-09 10:54 , Toon Moene wrote:
Most of these "compiles" are -O0 -g compiles, for obvious reasons (why
spend time on optimization when you don't even know the code is
correct ?)
Internally, we have been working on build time improvements for a few
months. We are not looking at just the compiler, but the entire toolchain.
As I've posted in other threads, our main consumer of compilation time
is the C++ front end. Hands down. It consistently takes between 70%
and 80% of compilation time across the board. Furthermore, this is
independent from the optimization level. The optimizers never take more
than 10-15% of total compilation time, on average.
As I pointed out in my 2007 GCC Summit talk, the Fortran Front End
*already* (i.e., before anyone approved it) performs optimization on the
Front End internal representation of a Fortran program / subroutine.
Is this also true for C++ ? In that case it might be useful to curb
Front End optimizations when -O0 is given ...
Or is there a reason why the C++ Front End has to do so much work (even
when not bothering with language specific optimizations) ?
--
Toon Moene - e-mail: toon@moene.org - phone: +31 346 214290
Saturnushof 14, 3738 XG Maartensdijk, The Netherlands
At home: http://moene.org/~toon/; weather: http://moene.org/~hirlam/
Progress of GNU Fortran: http://gcc.gnu.org/gcc-4.5/changes.html#Fortran