Re: WIP: Faster Expression Processing v4

On 2017-03-27 09:33:43 -0400, Tom Lane wrote:
> Andres Freund <andres(at)anarazel(dot)de> writes:
> > Checking for this isn't entirely pretty - see my attached attempt at
> > doing so. I considered hiding
> > __attribute__((optimize("no-crossjumping"))) in execInterpExpr.c behind
> > a macro (like PG_DISABLE_CROSSJUMPING), but I don't really think that
> > makes things better.
>
> I think it would, primarily because if we find out that some other compiler
> spells this differently, we could handle it totally within configure.

I'm unconvinced that we could sensibly map different compiler's options
on the same option name - I'd be surprised if they would have a similar
enough effect.

> Isn't our practice to put __attribute__ at the end of a function
> declaration or definition, not in the middle someplace?

We could move it to the declaration - which doesn't seem like an
improvement here, given that it's about optimization not API changes -
but in definitions you can't move it after the function name:
static Datum
ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
#ifdef HAVE_FUNCATTR_NO_CROSSJUMPING
__attribute__((optimize("no-crossjumping")))
#endif
:
/home/andres/src/postgresql/src/backend/executor/execExprInterp.c:279:1: error: attributes should be specified before the declarator in a function definition

Greetings,

Andres Freund