error: couldn't load codegen backend "/usr/ports/lang/rust/work/rustc-1.37.0-src/build/armv6-unknown-freebsd/stage1/lib/rustlib/armv6-unknown-freebsd/codegen-backends/librustc_codegen_llvm-llvm.so": "/usr/ports/lang/rust/work/rustc-1.37.0-src/build/armv6-unknown-freebsd/stage1/lib/rustlib/armv6-unknown-freebsd/codegen-backends/librustc_codegen_llvm-llvm.so: Undefined symbol \"__clear_cache\""
__clear_cache is implemented in compiler-rt and was dropped upstream with [1]:
aa41e0d25f
For some unknown reason this is a problem on armv6. Bring back the
compiler-rt submodule for now to workaround this.
Submitted by: mikael.urankar_gmail.com
Differential Revision: https://reviews.freebsd.org/D21415
7589599b53