ref: b953ac1cdd26aad71a91905475ce2ff1a0a9cbc8 dir: /src/cmd/as/target/powerpc/opers.dat/
imm2 AIMM2 imm5 AIMM5 imm8 AIMM8 imm16 AIMM16 imm32 AIMM32 imm64 AIMM64 sym ASYM string ASTR