Instructions marked as alias with alias_id 0

[OBarronCS]

Work environment

Questions	Answers
Capstone module affected	Mips
Source of Capstone	git clone
Version/git commit	8ac2843 (HEAD, tag: 6.0.0-Alpha3)

I've run into some instructions in MIPS that have the .is_alias flag set to true, with the alias_id set to 0.

# bnez   $t0, 0x10
cstool -d mipsel "0x03 0x00 0x00 0x15"

 0  03 00 00 15  bnez   $t0, 0x10
        ID: 23 (bne)
        Is alias: 0 (invalid) with REAL operand set
        op_count: 2
                operands[0].type: REG = t0
                operands[0].is_reglist: false
                operands[1].type: IMM = 0x10
                operands[1].is_unsigned: true
        Groups: jump branch_relative HasStdEnc NotInMicroMips NotNanoMips 

This problem might be more widespread, but I have only encountered it in MIPS instructions. It is not the case for all instructions.

Other examples here: #2628 (search for the word invalid)

Expected behavior

If the instruction is marked as an alias, the alias_id should be a valid ID.

[OBarronCS]

A theory is that all aliases have the alias_id set to zero in mips?

[wargio]

I noticed this also on other instructions, tbh, i do not know why, probably missing a change to fix this, like lapc is an alias for addiupc but doesn't get resolved either.

$ ./build/cstool -r -d mipsel64r6 190040ec
 0  19 00 40 ec  lapc   $v0, 0x64
        ID: 99 (addiupc)
        Is alias: 0 (invalid) with REAL operand set
        op_count: 2
                operands[0].type: REG = v0
                operands[0].is_reglist: false
                operands[1].type: IMM = 0x64
                operands[1].is_unsigned: false
        Groups: HasStdEnc HasMips32r6 

[Rot127]

but doesn't get resolved either.

This indicates it is missing in LLVM. Which is annoying to fix. Because it is TableGen land.

[wargio]

It turns out it was my fault, and i forgot to implement the code that does that mapping.