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Re: Compiling c++ template is very slow.
On 03/09/2018 06:51 AM, Richard Biener wrote:
On Fri, Mar 9, 2018 at 11:32 AM, Richard Biener
<richard.guenther@gmail.com> wrote:
callgrind shows that propagate_binfo_offsets recursing
to self very many times is likely the issue. Your templates
build a very deep inheritance chain and it seems that
the binfo offset propagation ends up being exponential here.
I would have expected that any bases have already correct
offsets so we don't need the recursion to bases of bases?
Ah, so in this case we have offset of 1 because sizeof is
always nonzero. So the issue might just be that
BINFO_OFFSET is not relative to the parent?
Correct, it's relative to the complete object.
doens't improve things. We call this functions millions of times
creating millions of INTEGER_CSTs. Can BINFO_OFFSET be
non-constant?
No. (if it's a vbase, it shows the offset in the complete object, IIRC,
and there's other data to let code generation know some vtable
inspection is needed when the dynamic type is unknown).
nathan
--
Nathan Sidwell