-mips16 compilation issue

[Anoop]

I am using MIPS32 bit processor(24KEc) with mips16e support.

I have a codebase compiled with mips32r2. I need to reduce the code size and
hence I am trying to recompile with -mips16. 

Using GCC 4.8 with  -march=mips32r2   -mtune=mips32r2  -mips16  -mips32r2
-minterlink-mips16 compiler options. 

This gives me the following error while building some of the .so
/tmp/cc8ohIfv.s: Assembler messages:
/tmp/cc8ohIfv.s:119: Error: unrecognized opcode `wsbh'
/tmp/cc8ohIfv.s:119: Error: unrecognized opcode `rotr'

If I dont include -mips16 option, assembler  dont throw this error and
generated the .so successfully. I did an objdump on this .so and verified
that it doesnt have wsbh and rotr instructions. So These instructions are
generated only when I give -mips16 option and assembler doesn't understand
it. As I understand  wsbh and rotr are mips32r2 instruction(not in mips16
instruction set) the why compiler generated it in case of mips16? 

If I include -mips16 along with -mips32r2, does that mean that compiler will
generate  16 bit instructions where ever possible and rest will be 32bit
instructions(is it similar to thump2 in ARM?)? Is there a way wherein
compiler will generate only 16 bit instructions? 

It looks like I am missing something, please help me to understand better.


~Anoop



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