[Bug pch/71934] pch cannot be disabled so gcc cannot be position independent

[iains at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71934

--- Comment #27 from Iain Sandoe <iains at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #26)
> Note, the code to emit that relocation table isn't for free, besides that
> ~3% growth of the *.gch files it also slows down the PCH generation, e.g.
> for stdc++.h at -O2 -g on my box from ~3.45s to ~4.13s, so some 20%, I bet
> mainly to qsort the array of ~2.5 million pointers.

the one CS problem indirection cannot solve is having too many pointers ;).

Do you have a feel for what the growth in time is for the whole parse+output?

(we assume that PCH remains useful so long as the read-in is quicker than that,
right?)

> But upon PCH restore it shouldn't be noticeable, it is one size_t fread and
> one fseek when no relocation is needed.