On 08/14/2015 02:02 AM, Richard Biener wrote:
On Fri, Aug 14, 2015 at 3:04 AM, Mikhail Maltsev <malts...@gmail.com> wrote:
The second part removes all global state accesses (i.e. accesses to cfun and
it's members) from dominance.c. This requires to change lots of code, but I hope
that this is a step in right direction (if my understanding of ongoing
re-architecture w.r.t. to global state is correct).
For now this second part lacks a changelog entry, but it's very "mechanical". I
will, of course, write it if the patch gets approved.
So the last time I did similar refactoring I wondered if we can somehow avoid
the "noise" in non-IPA passes. Ideas I came up with are
a) Inherit gimple/rtl pass classes from a class which is initialized with the
function the pass operates on and provides methods like
bool dom_info_available_p (..) { return dom_info_available_p (fn, ...); }
thus wraps APIs working on a specific function.
b) Do sth similar but make it work with overloads and clever (no idea what!)
C++ that disables them if this_fn cannot be looked up
template <disable-me-if-this_fn-cannot_be_lookedup-at-instantiation-place>
bool dom_info_available_p (..., struct function *fn = this_fn);
all of the above would of course require that passes make all their
implementation
be methods of their pass class. So even more refactoring.
Note that we do not have any IPA pass which accesses dominators, so the
implicit 'cfun' use was ok. The cases I refactored were those where we had
to push/pop_cfun () in IPA passes (which can be expensive) because it
used APIs with implicit cfun.
Overall I'm not sure we want all APIs using 'cfun' to be refactored.
It is after
all useless noise to callers if all callers are effectively using 'cfun'.
And since the main driver for eliminating global state is David's work
on the JIT, perhaps see if any of this helps David in a noticeable way
before giving it a yea/nea.
Jeff
