1622856 - .mozbuild/clang 9 with experimental-new-pass-manager loops for ever when compiling nsStyleStruct.cpp on macOS

Status: RESOLVED FIXED

(Firefox Build System :: Toolchains, defect)

Description

[Jeff Muizelaar [:jrmuizel]]

Seems like a recent change started causing this.

Comment 1

[Nathan Froyd [:froydnj]]

Going to guess this is dmajor's compiler changes.

Comment 2

[Jeff Muizelaar [:jrmuizel]]

I believe using the same compiler on an older version of m-c does work

Comment 3

[(Away)]

Can you check whether ac_add_options --disable-new-pass-manager fixes it?

Comment 4

[Jeff Muizelaar [:jrmuizel]]

What are the clang arguments that correspond to that?

Comment 5

[Jeff Muizelaar [:jrmuizel]]

Yeah, using the same compiler:
8ab81c8e93adff2d4187aabf1ddcfcae8bfc4e16 finishes building
6199f7b91e8bde7b7965585842d7a72e2e406e3e does not

Comment 6

[(Away)]

-fno-experimental-new-pass-manager

Comment 7

[Jeff Muizelaar [:jrmuizel]]

Removing -fexperimental-new-pass-manager does seem to fix the problem

Comment 8

[(Away)]

I think we should disable the flag on mac hosts, I have no ability to repro/debug issues there, and not even the ability to test on try. And even if we did find the underlying issue this time, there could be further instances down the road and I don't want to waste more developer time.

Comment 9

[Jeff Muizelaar [:jrmuizel]]

For the record, what's the bug that added the flag?

Comment 10

[Mark Banner (:standard8)]

Workaround for those building locally that are hitting this, add this to your .mozconfig:

ac_add_options --disable-new-pass-manager

Comment 11

[(Away)]

Attachment: Disable new pass manager on Mac hosts

Several developers have reported hangs on native Mac builds. I think we should default-off the flag on Mac hosts. Even if we could fix the current hangs, without coverage in CI for this build configuration, we're asking for more trouble down the road.

Comment 12

[(Away)]

Jeff, since you have a mac and have worked with upstream before, I'm sure LLVM would appreciate a bug with a reduced repro. You'd probably want to test with trunk though so I understand if it's too annoying or time-consuming.

Comment 13

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/ad204b01a300
Disable new pass manager on Mac hosts r=firefox-build-system-reviewers,rstewart

Comment 14

[Arthur Iakab [arthur_iakab]]

https://hg.mozilla.org/mozilla-central/rev/ad204b01a300

Comment 15

[Jeff Muizelaar [:jrmuizel]]

I was able to reproduce with clang trunk. Currently it looks like it's the nsStyleDisplay copy constructor that causes the problems.

Comment 16

[(Away)]

I think this might be the same as bug 1622168, which I can reproduce since that doesn't require a mac host. I ran creduce overnight and it gave me a reasonable file so I don't mind taking over the filing this upstream if you haven't already.

Comment 17

[Jeff Muizelaar [:jrmuizel]]

I haven't filed anything upstream yet.

Comment 18

[(Away)]

I filed https://bugs.llvm.org/show_bug.cgi?id=45253.