-ffixed option in llvm-gcc

Hi
  I am trying to register shadow a global variable using -ffixed option in llvm-gcc. I am able to accomplish this using gcc however llvm-gcc seems to ignore this option and generate code using the register.

command line:
>gcc -Wall -m64 -O3 -pthread -ftls-model=initial-exec -ffixed-r12 test.c -o test
>objdump -d ./test | grep r12

>llvm-gcc -Wall -m64 -O3 -pthread -ftls-model=initial-exec -ffixed-r12 test.c -o test
>objdump -d ./test | grep r12
....
... //uses r12 register

I was wondering if "-ffixed" option is not supported by llvm-gcc. If so I was wondering what is the best approach to register shadow a global variable in llvm.

Best,
--Hari

LLVM doesn’t support -ffixed and global register variables.

/jakob