On Wed, 13 Nov 2013, Martin Jambor wrote:
> Hi,
>
> On Wed, Nov 13, 2013 at 10:49:09AM +0100, Jakub Jelinek wrote:
> > Hi!
> >
> > void f1 (void) {}
> > __attribute__((target ("avx"))) void f2 (void) {}
> > __attribute__((target ("avx2"))) void f3 (void) {}
> > __attribute__((target ("sse3"))) void f4 (void) {}
> > __attribute__((target ("ssse3"))) void f5 (void) {}
> > __attribute__((target ("sse4"))) void f6 (void) {}
> > takes about 3 seconds to compile at -O2, because set_cfun is terribly
> > expensive and there are hundreds of such calls.
> > The following patch is just a quick change to avoid some of them:
> > execute_function_todo starts with:
> > unsigned int flags = (size_t)data;
> > flags &= ~cfun->last_verified;
> > if (!flags)
> > return;
> > and if flags is initially zero, it does nothing.
> > Similarly, execute_function_dump has the whole body surrounded by
> > if (dump_file && current_function_decl)
> > and thus if dump_file is NULL, there is nothing to do.
> > So IMHO in neither case (which happens pretty frequently) we need to
> > set_cfun to every function during IPA.
> >
> > Also, I wonder if we couldn't defer the expensive ira_init, if the info
> > computed by it is used only during RTL optimization passes (haven't verified
> > it yet), then supposedly we could just remember using some target hook
> > what the last state was when we did ira_init last time, and call ira_init
> > again at the start of expansion or so if it is different from the
> > last time.
>
> I was wondering whether the expensive parts of set_cfun could only be
> run in pass_all_optimizations (and the -Og equivalent) but not when
> changing functions in early and IPA passes.
Sounds like a hack ;)
Better get things working without the cfun/current_function_decl globals.
Wasn't there someone replacing all implicit uses with explicit ones
for stuff like n_basic_blocks?
Richard.
