optimization/8361: [3.3/3.4 regression] C++ compile-time performance regression

[Gerald Pfeifer]

I have now tested Mark's fix for PR 8361 and while that does not affect
non-optimizing performance, the difference for -O3 is noticable.

Below are the results of the 3.3-branch from 03/15 versus 03/24 (without
explicit --disable-checking):

  % \time /files/pfeifer/gcc-3.3-0315/bin/g++ -c generate.ii
       28.50 real        27.57 user         0.75 sys
  % \time /files/pfeifer/gcc-3.3-0324/bin/g++ -c generate.ii
       28.70 real        27.42 user         0.69 sys

No difference for non-optimizing compilation...

  % \time /files/pfeifer/gcc-3.3-0315/bin/g++ -O3 -c generate.ii
      109.55 real       105.85 user         3.06 sys
  % \time /files/pfeifer/gcc-3.3-0324/bin/g++ -O3 -c generate.ii
       81.28 real        77.41 user         3.55 sys

...but a nice speedup for -O3!

Gerald