powerpc-unknown-linux-gnu fails to compile simple crates

[lu-zero]

Example:

Compiling rand v0.4.2
Expected no forward declarations!
!262 = <temporary!> !{}
scope points into the type hierarchy
!327 = !DILocation(line: 1, scope: !255)
scope points into the type hierarchy
!329 = distinct !DILexicalBlock(scope: !255, file: !256, line: 388, column: 8)
scope points into the type hierarchy
!346 = !DILocation(line: 388, scope: !255)
scope points into the type hierarchy
!351 = !DILocation(line: 404, scope: !255)
LLVM ERROR: Broken function found, compilation aborted!
error: Could not compile `rand`.

  nightly-powerpc-unknown-linux-gnu unchanged - rustc 1.28.0-nightly (cb20f68d0 2018-05-21)
  beta-powerpc-unknown-linux-gnu installed - rustc 1.27.0-beta.5 (84b5a46f8 2018-05-15)

Additionally I cannot install stable on powerpc and powerpc64le due rust-doc being not available.

[nikomatsakis]

@lu-zero think you can possibly bisect to find the source of the problem? The cargo-bisect-rustc tool may help:

https://github.com/rust-lang-nursery/cargo-bisect-rustc

[lu-zero]

rustc-1.24.0 seems working. Now I can build cargo-bisect-rustc and try.

If in the mean time you could unbreak 1.26.0 would be great btw :)

[lu-zero]

I used cargo-bisect-rustc as testcase.

nightly-2018-01-13 managed to build most of its dependencies and fail at num_cpus.

Expected no forward declarations!
!382 = <temporary!> !{}
LLVM ERROR: Broken function found, compilation aborted!
error: Could not compile `num_cpus`.

[lu-zero]

rustc-1.25.0 seems to work fine as well.

[Mark-Simulacrum]

I believe we're waiting on a bisection here to a nightly range or a specific PR. Given that we're T-3 weeks from release if that doesn't happen soon we'll want the bisection soon.

[lu-zero]

I gave @nikomatsakis access to the instance since I was unable to get a result less coarse than what I posted before.