[Bug c++/28871] massive C++ compile time slowdown

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

------- Comment #2 from bkoz at gcc dot gnu dot org  2006-08-29 10:36 -------

More info.

I was able to take mainline libstdc++ sources, modify limits,
--disable-visibility and then run check-compile on the same machine/os/sources
with both 4_1-branch and mainline (20060827).

The time just to compile the libstdc++ testsuite is:

gcc-4_1-branch --disable-visibility
1626.889u 142.268s 34:30.18 85.4%       0+0k 0+0io 0pf+0w

gcc --disable-visibility
1713.939u 152.437s 32:24.81 95.9%       0+0k 0+0io 4pf+0w

gcc
1885.657u 126.063s 34:21.40 97.5%       0+0k 0+0io 0pf+0w

This is compiling with a PCH (which appears to be used from -Winvalid-pch and
-H), but no linking or executing. Still seems slower than I remember it being a
month ago, but I'll try to isolate more, and then come up with something simple
that can be used to fix this.

It does not look like the visibilty support impacts compile time. That's good.

These times are close enough to be a wash. So, I think we can remove the C++FE
from the list of slowdown candidates. (Which includes libstdc++, g++,
optmizers.)


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28871