Proposal on how to study g++ compile-time regression and progression since 2.95.2 and initial analysis

[Neil Booth]

Loren James Rittle wrote:-

> addition, when one looks at the number of lines of non-blank code
> produced when $srcdir/gcc/testsuite/g++.old-deja/g++.other/headers1.C
> (which is not as exhaustive as the above standard header processing
> test but contains only those headers available under both 2.95.2 and
> 3.0) is preprocessed by each version of the compiler, 3.0 is only
> about 33% more lines than 2.95.2 (23618 verses 17225 lines).

I'd just like to point out that your comparison here is unfair - the
new preprocessor squelches enormous blocks of [vertical] whitespace
that 2.95.2 did not; thus I suspect that a fair comparison would have
the order of a 100% increase [if you removed redundant whitespace from
the 2.95.2 versions, say].

However, I also don't think that this is meaningful - most people will
be using the compiler on non-preprocessed source, and in that situation
g++ does not see whitespace at all with the now integrated preprocessor;
it just gets the meat as it were.

Neil.