Re: GCC 8.3.0 vs. 9.0.1

Hi,

On 2019-05-07 10:28:16 -0700, Peter Geoghegan wrote:
> On Tue, May 7, 2019 at 10:06 AM Tom Lane <[email protected]> wrote:
> > Given the described test setup, I'd put basically no stock in these
> > numbers.  It's unlikely that this test case's performance is CPU-bound
> > per se; more likely, I/O and lock contention are dominant factors.
> > So I'm afraid whatever they're measuring is a more-or-less chance
> > effect rather than a real system-wide code improvement.
> 
> Or a compiler bug. Link-time optimizations give the compiler a view of
> the program as a whole, not just a single TU at a time. This enables
> it to perform additional aggressive optimization.

Note that the flags described don't enable LTO.

Greetings,

Andres Freund