compilation with sancov and multiple codegen units results in SIGSEGV: invalid memory reference; nightly-2017-12-26 regression

[frewsxcv]

git clone https://github.com/rust-fuzz/targets.git
cd targets
export RUSTFLAGS="-C codegen-units=16 -C passes=sancov -C llvm-args=-sanitizer-coverage-level=3 -Z sanitizer=address -C opt-level=3"
cargo build --verbose

error: Could not compile `getopts`.

Caused by:
  process didn't exit successfully: `rustc --crate-name getopts /Users/corey/.cargo/registry/src/github.com-1ecc6299db9ec823/getopts-0.2.15/src/lib.rs --crate-type lib --emit=dep-info,link -C debuginfo=2 -C metadata=e4fe6dbb6aba3ffd -C extra-filename=-e4fe6dbb6aba3ffd --out-dir /private/tmp/targets/target/debug/deps -L dependency=/private/tmp/targets/target/debug/deps --cap-lints allow -C passes=sancov -C llvm-args=-sanitizer-coverage-level=3 -Z sanitizer=address -C opt-level=3` (signal: 11, SIGSEGV: invalid memory reference)

EDIT: updated RUSTFLAGS to include -C codegen-units=16 since rust-fuzz/targets master was updated to use -C codegen-units=1

[frewsxcv]

if i add -C codegen-units=1 to RUSTFLAGS, it compiles fine. so i'm going to assume this started happening after #46910 merged

[frewsxcv]

another possibly related issue #45220

[frewsxcv]

this might be the issue upstream https://bugs.llvm.org/show_bug.cgi?id=32700

[nikomatsakis]

So, am I correctly inferring from this that this is (most likely) not a rustc bug, but rather a bug in LLVM?

[nikomatsakis]

@frewsxcv can you get a backtrace, by any chance?