On Mon, Sep 27, 2021 at 10:40 AM Steve Dower <steve.do...@python.org> wrote:
> On 9/27/2021 5:51 PM, Eric Snow wrote: > > Possible solutions: > > > > 1. always default to "on" (the annoyance for contributors isn't big > enough?) > > 2. default to "on" if it's a PGO build (and "off" otherwise) > > Just to air my concerns regarding option 2 (which I've already spoken to > Eric about): I feel this option is completely orthogonal to whether PGO > is used or not, and ought to be discoverable independently. > > Essentially, it should be its own configure-time option, and should be > included somewhere in sysconfig.get_config_var(...). > > If we went with #2, there's no reliable way to detect whether > profile-guided optimisations were used on all CPython builds, which > means there'd be no reliable way to detect whether frozen modules are > going to be enabled by default or not. Adding a separate option handles > this case. > > (My overall preference is for #3, FWIW) > When I proposed #2, I used "PGO" as a proxy for "best optimization mode". On UNIX, this is `./configure --enable-optimizations`, which doesn't mention PGO -- IIUC it turns on PGO and LTO, if they're available. So my *actual* proposal (call it #2') is to use a separate compile-time flag, which is set by `./configure --enable-optimizations` regardless of whether PGO/LTO are possible, and which on Windows can be set by `PCbuild\build.bat --pgo` (we could add another flag to disable it, but who'd want to?). -- --Guido van Rossum (python.org/~guido) *Pronouns: he/him **(why is my pronoun here?)* <http://feministing.com/2015/02/03/how-using-they-as-a-singular-pronoun-can-change-the-world/>
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