1526476 - Infinite loop during --enable-debug --disable-optimize ARM build

Status: RESOLVED WORKSFORME

(Firefox Build System :: General, enhancement)

Description

[Bobby Holley (:bholley)]

Attachment: .mozconfig

On both mac and linux of [1], an android build with the attached mozconfig stalls out indefinitely, with one process pegged at 100% CPU.

The profile is entirely within llvm::SelectionDAG::Combine. Some googling found [2], which may or may not be the source here. Some additional googling also suggests that this function is prone to infinite loops [3].

A build with --enable-optimize works fine.

[1] https://hg.mozilla.org/mozilla-central/rev/00432a450b3af67c4d5711810691b27093880c62
[2] https://reviews.llvm.org/D53190?id=169371
[3] https://groups.google.com/forum/#!topic/llvm-dev/kFWEyf_r6Rg

Comment 1

[Nick Alexander :nalexander [he/him]]

That's annoying. Could you dump your clang and clang++ versions, Bobby? Not much to do immediately, but might as well try to track offending versions.

Comment 2

[Bobby Holley (:bholley)]

(In reply to Nick Alexander :nalexander [he/him] from comment #1)

That's annoying. Could you dump your clang and clang++ versions, Bobby? Not much to do immediately, but might as well try to track offending versions.

It's what was downloaded from ./mach bootstrap:

clang version 7.0.1 (tags/RELEASE_701/final) (llvm/tags/RELEASE_701/final 349247)

Comment 3

[Mike Hommey [:glandium]]

We upgraded to clang 8, which means you should get that version from mach bootstrap now. Presumably, that llvm bug is fixed in that version. Can you check?

Comment 4

[Bobby Holley (:bholley)]

(In reply to Mike Hommey [:glandium] from comment #3)

We upgraded to clang 8, which means you should get that version from mach bootstrap now. Presumably, that llvm bug is fixed in that version. Can you check?

Yep, works now. Thank you!