On Wed, Sep 21, 2011 at 5:23 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > None of that stuff is inlinable or constant-foldable today, nor would it > be with the patch that Peter was proposing AFAICS, because none of the > flags will ever be compile time constant values.
I was referring to transformations like this which I believe compilers are already capable of doing: v = ...; while (...) if (v) { if (a < b) ... else ....; } else { if (a > b) ... else ...; } turning it into code that looks like: if (v) { while (....) if (a<b) ... else ...; } else { while (....) if (a>b) ... else ...; } which may not look like much -- especially with branch prediction -- but then it's much more likely to be able to unroll the loop and do clever instruction scheduling and so on than if there's an extra branch in the middle of the loop. But if there's a function call to an external function called through a function pointer in the middle of the loop then the whole endeavour would be for naught. -- greg -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers