On Fri, 2013-11-01 at 22:57 +0100, Jakub Jelinek wrote:
> On Fri, Nov 01, 2013 at 05:47:14PM -0400, Andrew MacLeod wrote:
> > On 11/01/2013 05:41 PM, Jakub Jelinek wrote:
> > >On Fri, Nov 01, 2013 at 05:36:34PM -0400, Andrew MacLeod wrote:
> > >> static inline void
> > >>! gimple_call_set_lhs (gimple gs, tree lhs)
> > >> {
> > >>- GIMPLE_CHECK (gs, GIMPLE_CALL);
>
> The checking you are removing here.
>
> > What checking? There ought to be no checking at all in this
> > example... gimple_build_call_vec returns a gimple_call, and
> > gimple_call_set_lhs() doesn't have to check anything because it
> > only accepts gimple_call's.. so there is no checking other than the
> > usual "does my parameter match" that the compiler has to do...
>
> and want to replace it by checking of the types at compile time.
> The problem is that it uglifies the source too much, and, when you
> actually don't have a gimple_call but supposedly a base class of it,
> I expect you'd do as_a which is not only further uglification, but has
> runtime cost also for --enable-checking=release.
I can have a look next week at every call to gimple_call_set_lhs in the
tree, and see to what extent we know at compile-time that the initial
arg is indeed a call (of the ones I quickly grepped just now, most are
from gimple_build_call and friends, but one was from a gimple_copy).
FWIW I did some performance testing of the is_a/as_a code in the earlier
version of the patch, and it didn't have a noticable runtime cost
compared to the GIMPLE_CHECK in the existing code:
Size of compiler executable:
http://gcc.gnu.org/ml/gcc-patches/2013-08/msg01920.html
Compile times:
http://gcc.gnu.org/ml/gcc-patches/2013-09/msg00171.html
Dave
