Re: 3.0 high priority: optimization/3083: C++ frontend consumesinacceptableamounts of CPU with -O3

[Gerald Pfeifer <pfeifer at dbai dot tuwien dot ac dot at>]

On Fri, 8 Jun 2001, Paolo Carlini wrote:
> please excuse me in advance for the naivety of my observation: are you
> fully aware of the fact that in the time span between Mitchell's fixes
> of about two monts ago and the following patch (of about one month ago):
>
>     http://gcc.gnu.org/ml/gcc-patches/2001-05/msg00233.html
>
> the -O3 option was broken?? (i.e. -O3 compilations were faster than
> they really would have been if -O3 was really working...)

Thanks for the pointer (and no, I wasn't aware of that). It seems,
however, that the performance regression I am seeing is unrelated.

Mark, it's the usual picture I've been observing too often recently:
GCC fails to bootstrap or my code base for weeks (or months), and
after that, something is broken. :-(

Obviously, a binary search is not too helpful in such a case :-(, but
nevertheless, here we are:

GCC versions
============

GCC 2.95.2
contrib/gcc_update -rgcc-3_0-branch -D2001-05-08
contrib/gcc_update -rgcc-3_0-branch -D2001-05-11
contrib/gcc_update -rgcc-3_0-branch -D2001-05-13
contrib/gcc_update -rgcc-3_0-branch -D2001-05-18
contrib/gcc_update -rgcc-3_0-branch -D2001-05-23
contrib/gcc_update -rgcc-3_0-branch -D2001-05-25
contrib/gcc_update -rgcc-3_0-branch -D2001-05-27
contrib/gcc_update -rgcc-3_0-branch -D2001-05-28

Results
=======

taygeta% \time gcc-2.95.2 -O3 -c generate.C
      129.70 real       119.54 user         1.63 sys

taygeta% \time /files/pfeifer/2001-05-08/bin/gcc -O3 -c generate.C
      303.02 real       268.33 user         3.41 sys

taygeta% \time /files/pfeifer/2001-05-11/bin/gcc -O3 -c generate.C
      279.83 real       266.28 user         3.25 sys

taygeta% \time /files/pfeifer/2001-05-13/bin/gcc -O3 -c generate.C
      279.17 real       267.39 user         3.00 sys

taygeta% \time /files/pfeifer/2001-05-18/bin/gcc -O3 -c generate.C
  generate.C: In member function `bool MODEL_GENERATOR::
    PropagatePositiveFromMustBeTrue(const GATOM&, GINTERPRET&)':
  generate.C:3484: Internal error: Segmentation fault
  Please submit a full bug report, with preprocessed source if appropriate.
      224.09 real       219.25 user         3.94 sys

taygeta% \time /files/pfeifer/2001-05-23/bin/gcc -O3 -c generate.C
  generate.C: In member function `bool MODEL_GENERATOR::
    PropagatePositiveFromMustBeTrue(const GATOM&, GINTERPRET&)':
  generate.C:3484: Internal error: Segmentation fault
  Please submit a full bug report, with preprocessed source if appropriate.
      227.05 real       221.61 user         4.12 sys

taygeta% \time /files/pfeifer/2001-05-25/bin/gcc -O3 -c generate.C
  generate.C: In member function `bool MODEL_GENERATOR::
    PropagatePositiveFromMustBeTrue(const GATOM&, GINTERPRET&)':
  generate.C:3484: Internal error: Segmentation fault
  Please submit a full bug report, with preprocessed source if appropriate.
      225.75 real       220.67 user         3.97 sys

taygeta% \time /files/pfeifer/2001-05-27/bin/gcc -O3 -c generate.C
      695.35 real       675.30 user         7.02 sys

taygeta% \time /files/pfeifer/2001-05-28/bin/gcc -O3 -c generate.C
      704.28 real       683.03 user         6.79 sys

Gerald