RISC-V assembler should accept compressed shift hints with 0 immediates #150304
Description
Currently if you try to assemble any of these instructions Clang will complain:
asm.s:49864:13: error: immediate must be an integer in the range [1, 63]
c.srli x14, 0x0
^
asm.s:50440:12: error: immediate must be an integer in the range [1, 63]
c.srai x9, 0x0
^
asm.s:188:12: error: immediate must be an integer in the range [1, 63]
c.slli x1, 0x0
^
These compressed shift instructions with a 0 immediate are HINTs, but I don't think that means you shouldn't be allowed to assemble them. You can assemble c.nop hints for example c.nop 1.
There probably isn't a practical use for this yet seeing as no meaning has been assigned to these hints (they are designated for custom use), but it would be nice if there was some valid syntax for representing them.