Description
| Bugzilla Link | 51251 |
| Version | trunk |
| OS | Linux |
| Attachments | Test asm file containing every MIPS16 instruction, The output of calling llvm-mc on the attached asm source |
Extended Description
It would appear that LLVM does not recognize many MIPS16 instructions.
The attached assembly file is a test I made that contains, as far as I can tell, every MIPS16 instruction. I can build it with GCC 9.3 without any issues using the following command on Ubuntu 20.04 64-bit (Windows 10 WSL).
mipsel-linux-gnu-gcc -march=mips32r2 -mips16 <source> -o <obj file>
However, trying to build it with Clang or LLVM-MC fails with many "instruction requires a CPU feature not currently enabled" or "invalid operand for instruction" errors. I have not yet verified that the instructions that do not cause errors are correctly encoded, but a cursory look suggests that they are not (they might be using the MIPS32 forms instead).
llvm-mc -arch=mipsel -mcpu=mips32r2 -mattr=+mips16 -show-encoding -show-inst <source>
--OR--
clang -target mipsel-linux-gnu-musl -march=mips32r2 -mips16 -c <source> -o <obj file>
I cloned and built my version of LLVM and Clang on 27 July, 2021; however, I believe this issue has been present for a long time. It is present on LLVM 10 that is available on Ubuntu 20.04.