Any hope of compiling firefox port on ARM?

[bob prohaska]

For some time (years?) firefox compiles have failed with an error message
along the lines of

Assertion failed: (isReg() && "This is not a register operand!"), function getReg, file /usr/src/contrib/llvm/include/llvm/MC/MCInst.h, line 64.
c++: error: unable to execute command: Abort trap (core dumped)
c++: error: clang frontend command failed due to signal (use -v to see invocation)
FreeBSD clang version 4.0.0 (tags/RELEASE_400/final 297347) (based on LLVM 4.0.0)
Target: armv6--freebsd12.0-gnueabihf
Thread model: posix
InstalledDir: /usr/bin
c++: note: diagnostic msg: PLEASE submit a bug report to https://bugs.freebsd.org/submit/ and include the crash backtrace, preprocessed source, and associated run script.

Is there any hope of a fix, whether to clang or firefox?

Thanks for reading, and any insights...

bob prohaska