ref: 2a6e8ef42d269906883ea1b3f1b43dfb13c557a0 dir: /src/cmd/as/target/powerpc/opers.dat/
imm5 AIMM5 imm8 AIMM8 imm16 AIMM16 imm32 AIMM32 imm64 AIMM64 sym ASYM string ASTR