* Re: [gnu-prog-discuss] Reproducible builds [not found] ` <87r3ifkepm.fsf@gnu.org> @ 2015-12-22 3:32 ` Stefan Monnier 2015-12-22 16:39 ` Ludovic Courtès 0 siblings, 1 reply; 3+ messages in thread From: Stefan Monnier @ 2015-12-22 3:32 UTC (permalink / raw) To: Ludovic Courtès; +Cc: emacs-devel BTW, in https://reproducible.debian.net/index_issues.html I fail to see one issue that should affect Emacs: the result depends on ordering of independent commands. So in sequential builds, this does not manifest itself, but in parallel builds the result becomes non-deterministic. The way this shows up in Emacs is that depending on how the byte-compilations get ordered, all the (require '<foo>) will either load the corresponding <foo>.el or the <foo>.elc. In many cases, the end result is 100% identical, but if <foo>.el includes functions defined with defsubst then the result can be different because in one case the defsubst's source will be inlined and in the other the defsubst's byte-code will be inlined. The easiest way to solve this problem is probably to get rid of the "source-level inlining". IIRC this is already partly the case for lexical-binding reasons: we can't inline (at the source-level) lexical-binding code in dynamic-binding code (nor vice versa), so when the binding style disagrees we forcefully byte-compile the defsubst to make sure the inlining is done on the byte-code (where the binding-style is not a problem any more). So we could simply always forcefully byte-compile the defsubst, even when the binding styles agree. Of course, there can be other differences depending on all kinds of weird tings you can do with eval-when-compile and friends, but in practice this should hopefully never be an issue. Still, it would be good to *test* that there aren't other such issues. We could also reduce/eliminate those problems by adding dependencies in the makefile so that (require '<foo>) always gets the .elc file, but this would reduce the available parallelism during compilation, and it's hard to do in general: many packages have circular requires. Stefan ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [gnu-prog-discuss] Reproducible builds 2015-12-22 3:32 ` [gnu-prog-discuss] Reproducible builds Stefan Monnier @ 2015-12-22 16:39 ` Ludovic Courtès 2015-12-23 1:08 ` John Wiegley 0 siblings, 1 reply; 3+ messages in thread From: Ludovic Courtès @ 2015-12-22 16:39 UTC (permalink / raw) To: Stefan Monnier; +Cc: emacs-devel Stefan Monnier <monnier@IRO.UMontreal.CA> skribis: > The way this shows up in Emacs is that depending on how the > byte-compilations get ordered, all the (require '<foo>) will either load > the corresponding <foo>.el or the <foo>.elc. Guile works similarly, so depending on ordering, when a file is compiled, you might be evaluating dependent modules or running a compiled version thereof. In practice, it doesn’t matter since both are semantically equivalent. > In many cases, the end result is 100% identical, but if <foo>.el > includes functions defined with defsubst then the result can be > different because in one case the defsubst's source will be inlined and > in the other the defsubst's byte-code will be inlined. So the .elc file itself can contain inlined source in some cases? (In Guile ‘define-inlinable’ is implemented as a macro, there’s no magic taking place.) > The easiest way to solve this problem is probably to get rid of the > "source-level inlining". IIRC this is already partly the case for > lexical-binding reasons: we can't inline (at the source-level) > lexical-binding code in dynamic-binding code (nor vice versa), so when > the binding style disagrees we forcefully byte-compile the defsubst to > make sure the inlining is done on the byte-code (where the binding-style > is not a problem any more). So we could simply always forcefully > byte-compile the defsubst, even when the binding styles agree. It would be important to make inlining works the same regardless of whether the defsubst-providing module is being evaluated or not, indeed. Thanks, Ludo’. ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [gnu-prog-discuss] Reproducible builds 2015-12-22 16:39 ` Ludovic Courtès @ 2015-12-23 1:08 ` John Wiegley 0 siblings, 0 replies; 3+ messages in thread From: John Wiegley @ 2015-12-23 1:08 UTC (permalink / raw) To: Ludovic Courtès; +Cc: Stefan Monnier, emacs-devel >>>>> Ludovic Courtès <ludo@gnu.org> writes: > It would be important to make inlining works the same regardless of whether > the defsubst-providing module is being evaluated or not, indeed. Agreed. -- John Wiegley GPG fingerprint = 4710 CF98 AF9B 327B B80F http://newartisans.com 60E1 46C4 BD1A 7AC1 4BA2 ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2015-12-23 1:08 UTC | newest] Thread overview: 3+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- [not found] <1450695354.3591.18.camel@invergo.net> [not found] ` <1450710479.31597.40.camel@Renee-desktop.suse> [not found] ` <87r3ifkepm.fsf@gnu.org> 2015-12-22 3:32 ` [gnu-prog-discuss] Reproducible builds Stefan Monnier 2015-12-22 16:39 ` Ludovic Courtès 2015-12-23 1:08 ` John Wiegley
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