[ppc64] ICE: Region parameter out of range when substituting in region'b

[cuviper]

Trying to natively build powerpc64 as of 380100c, I get an ICE in stage 1:

Copying stage1 compiler (powerpc64-unknown-linux-gnu)
Building stage1 std artifacts (powerpc64-unknown-linux-gnu -> powerpc64-unknown-linux-gnu)
   Compiling core v0.0.0 (file:///home/jistone/rust/src/libcore)
error: internal compiler error: src/librustc/ty/subst.rs:411: Region parameter out of range when substituting in region'b (root type=Some((&&'b str,))) (index=1)

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.20.0-dev (380100c56 2017-06-20) running on powerpc64-unknown-linux-gnu

note: run with `RUST_BACKTRACE=1` for a backtrace

thread 'rustc' panicked at 'Box<Any>', src/librustc_errors/lib.rs:426
stack backtrace:
   0: rust_metadata_std_1ef34ef8b50021bf3e2b2bca3dfc146e
   1: rust_metadata_std_1ef34ef8b50021bf3e2b2bca3dfc146e
   2: rust_metadata_std_1ef34ef8b50021bf3e2b2bca3dfc146e
   3: rust_metadata_std_1ef34ef8b50021bf3e2b2bca3dfc146e
   4: rust_metadata_std_1ef34ef8b50021bf3e2b2bca3dfc146e
   5: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
   6: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
   7: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
   8: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
   9: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
  10: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
  11: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
  12: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
  13: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
  14: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
  15: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
  16: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
  17: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
  18: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
  19: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
  20: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
  21: <unknown>
  22: <unknown>
  23: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
  24: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
  25: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
  26: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
  27: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
  28: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
  29: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
  30: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
  31: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
  32: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
  33: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
  34: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
  35: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
  36: rust_metadata_rustc_e1561b4cf34be67f9773866f88239afd
  37: <unknown>
  38: <unknown>
  39: <unknown>
  40: <unknown>
  41: <unknown>
  42: <unknown>
  43: rust_metadata_std_1ef34ef8b50021bf3e2b2bca3dfc146e
  44: <unknown>
  45: rust_metadata_std_1ef34ef8b50021bf3e2b2bca3dfc146e
  46: <unknown>
  47: <unknown>

error: Could not compile `core`.

[cuviper]

FWIW beta (4795a8f) builds fine. I'll see if I can bisect it.

[cuviper]

I seem to be hitting unrelated issues when bisecting, so it may be regressing in and out lately...

It still ICEs on powerpc64 as of 47faf1d. I found that powerpc64le builds fine though, so this could be a general big-endian issue. If I get time I'll try s390x.

Also, the reported region sometimes changes, though still the same location. Most often I get:

error: internal compiler error: src/librustc/ty/subst.rs:411: Region parameter out of range when
    substituting in region 'b (root type=Some((&&'b str,))) (index=1)

But a few times I've seen:

error: internal compiler error: src/librustc/ty/subst.rs:411: Region parameter out of range when
    substituting in region 'a (root type=Some((str::pattern::StrSearcher<'a, 'b>,))) (index=0)

And the backtraces are still useless...

[arielb1]

@cuviper

Could you post the results of ../x.py build --verbose?

[cuviper]

rust42778-powerpc64-build-verbose.txt

That's doing a rebuild from the working dir of my prior attempts, so the only interesting piece is the stage1 libcore that ICEs. If you want the log of a complete build from scratch, I can get that too.

[arielb1]

I'm seeing a different error:

thread 'rustc' panicked at 'index out of bounds: the len is 17586 but the index is 270859', src/liballoc/vec.rs:1552

Could you compile with debuginfo to get a backtrace? That's the debuginfo setting in config.toml.

[cuviper]

Fresh build directory, debuginfo enabled: rust42778-powerpc64-build-verbose-2.txt

error: internal compiler error: src/librustc/ty/subst.rs:466: Type parameter `T/#0` (T/0) out of range when substituting (root type=Some((&mut [T], _))) substs=[]

Same dir just building again: rust42778-powerpc64-build-verbose-3.txt

error: internal compiler error: src/librustc/ty/subst.rs:411: Region parameter out of range when substituting in region 'a (root type=Some((str::pattern::StrSearcher<'a, 'b>,))) (index=0)

[arielb1]

Very odd. rustc compiled on x86-64 (both a rustc I hand-compiled and the official nightlies) works without any problems, but rustc compiled on powerpc64 crashes with all sorts of random errors. I wonder whether there is some sort of LLVM bug - the next beta uses LLVM 4.0.1, so I should check whether that fixes things.

Also, there shouldn't be any LLVM IR differences between a rustc compiled on powerpc and a rustc compiled on x86, so maybe I could do a diff

[cuviper]

We've seen weird differences between cross- and native-compiled rustc before for big-endian machines, which seems confirmed by powerpc64le working fine here. I'm still trying to get s390x access...

cc @nagisa who has found a few of these.

[arielb1]

@cuviper

The usual problem is that cross-compiled and native-compiled metadata end up being incompatible, so an x86-built ppc64 libcore is incompatible with a ppc-built ppc64 libcore. Through maybe we've ended up in a case where ppc can't decode its own metadata.

[nagisa]

Yes, my first suspect would be endianness issue. It could be fairly plausible that the metadata decoder is correct, but the encoder is not, hence the bug showing up on ppc-built stuff only.

[cuviper]

I got an s390x build, and it fared even worse. Tons of move errors on Copy types like this:

error[E0382]: use of moved value: `self`
    --> src/libcore/num/mod.rs:1412:28
     |
1412 |               (self << n) | (self >> (($BITS - n) % $BITS))
     |                ----          ^^^^ value used here after move
     |                |
     |                value moved here
...
2261 | /     uint_impl! { u16, u16, 16,
2262 | |         intrinsics::ctpop,
2263 | |         intrinsics::ctlz,
2264 | |         ctlz_nonzero,
...    |
2268 | |         intrinsics::sub_with_overflow,
2269 | |         intrinsics::mul_with_overflow }
     | |_______________________________________- in this macro invocation
     |
     = note: move occurs because `self` has type `u16`, which does not implement the `Copy` trait

before it finally ICEd:

thread 'rustc' panicked at 'assertion failed: self.qualif.intersects(Qualif::MUTABLE_INTERIOR)', src/librustc_mir/transform/qualify_consts.rs:732

I'm guessing that these particular errors and ICEs are not significant in themselves, only as signs of some more general corruption.

[arielb1]

Oddly enough, if I use an x86 stage0 to compile a powerpc stage1, or an powerpc stage0 to compile an x86 stage1, everything works fine, but if I use a powerpc stage0 to compile a powerpc stage1, the powerpc stage1 created is broken.

[arielb1]

I can't figure out a good way to debug this without a powerpc computer. So I'm gotta leave this alone unless anyone's going to help me track it down (e.g., ssh access to a fast(!) powerpc computer).