Compilation time has more than doubled on some Polyhedron tests

[Tobias Schlüter]

Dominique Dhumieres wrote:
> On an AMD, the 20060105 build gives
>  tree SSA verifier     :   9.55 (50%) usr   0.09 (23%) sys   9.62 (48%) wall      19 kB ( 0%) ggc
>  tree STMT verifier    :   1.56 ( 8%) usr   0.00 ( 0%) sys   1.61 ( 8%) wall       0 kB ( 0%) ggc
> TOTAL                 :  19.26             0.40            19.91   129144 kB

> The 20060106 build gives
>  tree SSA verifier     :  18.53 (55%) usr   0.05 (13%) sys  18.54 (54%) wall      19 kB ( 0%) ggc
>  tree STMT verifier    :   2.36 ( 7%) usr   0.00 ( 0%) sys   2.28 ( 7%) wall       0 kB ( 0%) ggc
> TOTAL                 :  33.82             0.38            34.64   194932 kB

So it looks like the bulk of the change is accounted for in the tree-checking.

(As for the answer to my question about --enable checking, with -ftime-report
the compiler is quite explicit about this:
> Extra diagnostic checks enabled; compiler may run slowly.
> Configure with --disable-checking to disable checks.
Unless --disable-checking is given, these checks are enabled everywhere but in
releases.)

> Not knowing what to look for, I'll need further directives about
> what to do next.

If you want a faster compiler, you can always build with --disable-checking.
But since we're probably performing redundant checks, I've added Richard
Günther to CC:, who seems to be the only person who committed changes during
that timeframe, maybe he has an idea where we're now excessively checking trees.

Thanks,
- Tobi