On Mon, Mar 22, 2021 at 12:39:28PM +0800, Gergő Érdi wrote:

I'd love to have this in a GHC 8.10 release: https://mail.haskell.org/pipermail/ghc-devs/2021-March/019629.html

This is already in 9.0, 9.2 and master, but it is a rather non-trivial change, given all the new work that went into the String case. So I am not sure it is small/simple enough to make for a compelling backport. There's a lot of recent activity in this space. See also https://gitlab.haskell.org/ghc/ghc/-/merge_requests/5259, which is not yet merged into master, and might still be eta-reduced one more step). I don't know whether such optimisation tweaks (not a bugfix) are in scope for backporting, we certainly need to be confident they'll not cause any new problems. FWIW, 5259 is dramatically simpler... Of course we also have https://gitlab.haskell.org/ghc/ghc/-/merge_requests/4890 in much the same territory, but there we're still blocked on someone figuring out what's going on with the 20% compile-time hit with T13056, and whether that's acceptable or not... -- Viktor.

The commit message from https://gitlab.haskell.org/ghc/ghc/-/commit/f10d11fa49fa9a7a506c4fdbdf86521c... , makes the changes to string seem required. Applying the commit on its own doesn't apply cleanly and pulls in quite a bit of extra dependent commits. Just applying the elem rules appears rather risky. Thus will I agree that having that would be a nice fix to have, the amount of necessary code changes makes me rather uncomfortable for a minor release :-/ On Mon, Mar 22, 2021 at 1:58 PM Gergő Érdi wrote:

Thanks, that makes it less appealing. In the original thread, I got no further replies after my email announcing my "discovery" of that commit, so I thought that was the whole story.

On Mon, Mar 22, 2021, 13:53 Viktor Dukhovni wrote:

...

On Mon, Mar 22, 2021 at 12:39:28PM +0800, Gergő Érdi wrote:

...

I'd love to have this in a GHC 8.10 release: https://mail.haskell.org/pipermail/ghc-devs/2021-March/019629.html

This is already in 9.0, 9.2 and master, but it is a rather non-trivial change, given all the new work that went into the String case. So I am not sure it is small/simple enough to make for a compelling backport.

There's a lot of recent activity in this space. See also https://gitlab.haskell.org/ghc/ghc/-/merge_requests/5259, which is not yet merged into master, and might still be eta-reduced one more step).

I don't know whether such optimisation tweaks (not a bugfix) are in scope for backporting, we certainly need to be confident they'll not cause any new problems. FWIW, 5259 is dramatically simpler...

Of course we also have https://gitlab.haskell.org/ghc/ghc/-/merge_requests/4890 in much the same territory, but there we're still blocked on someone figuring out what's going on with the 20% compile-time hit with T13056, and whether that's acceptable or not...

-- Viktor. _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs

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More like abandoned backport attempt :D On Wed, Mar 24, 2021 at 7:29 PM Andreas Klebinger wrote:

Yes, only changing the rule did indeed cause regressions. Whichwhen not including the string changes. I don't think it's worth having one without the other.

But it seems you already backported this? See https://gitlab.haskell.org/ghc/ghc/-/merge_requests/5263

Cheers Andreas Am 22/03/2021 um 07:02 schrieb Moritz Angermann:

The commit message from https://gitlab.haskell.org/ghc/ghc/-/commit/f10d11fa49fa9a7a506c4fdbdf86521c...,

makes the changes to string seem required. Applying the commit on its own doesn't apply cleanly and pulls in quite a bit of extra dependent commits. Just applying the elem rules appears rather risky. Thus will I agree that having that would be a nice fix to have, the amount of necessary code changes makes me rather uncomfortable for a minor release :-/

On Mon, Mar 22, 2021 at 1:58 PM Gergő Érdi wrote:

...

Thanks, that makes it less appealing. In the original thread, I got no further replies after my email announcing my "discovery" of that commit, so I thought that was the whole story.

On Mon, Mar 22, 2021, 13:53 Viktor Dukhovni wrote:

...

On Mon, Mar 22, 2021 at 12:39:28PM +0800, Gergő Érdi wrote:

...

I'd love to have this in a GHC 8.10 release: https://mail.haskell.org/pipermail/ghc-devs/2021-March/019629.html

This is already in 9.0, 9.2 and master, but it is a rather non-trivial change, given all the new work that went into the String case. So I am not sure it is small/simple enough to make for a compelling backport.

There's a lot of recent activity in this space. See also https://gitlab.haskell.org/ghc/ghc/-/merge_requests/5259, which is not yet merged into master, and might still be eta-reduced one more step).

I don't know whether such optimisation tweaks (not a bugfix) are in scope for backporting, we certainly need to be confident they'll not cause any new problems. FWIW, 5259 is dramatically simpler...

Of course we also have https://gitlab.haskell.org/ghc/ghc/-/merge_requests/4890 in much the same territory, but there we're still blocked on someone figuring out what's going on with the 20% compile-time hit with T13056, and whether that's acceptable or not...

-- Viktor. _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs

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Thanks! I’ll make sure not to forget that one. I’m afraid 8.10 will be delayed yet again a bit as we find ourselves in docker purgatory. On Tue, 23 Mar 2021 at 2:18 PM, Phyx wrote:

Hi,

I currently have https://gitlab.haskell.org/ghc/ghc/-/merge_requests/5055 marked for backports but don't know if it was done or not.

Thanks, Tamar

Sent from my Mobile

On Mon, Mar 22, 2021, 04:33 Moritz Angermann wrote:

...

Hi there!

Does anyone have any backports they'd like to see for consideration for 8.10.5?

Cheers, Moritz _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs