Old idioms, new widths
Nothing about comparison changes when the operands come from narrow loads — by the time slt or xor sees them, they're proper 32-bit values, courtesy of the load's extension. The skill is simply recognizing your control-chapter idioms with lbus in front. Two quick specimens:
s32 is_dark(u8 *p) {
return *p < 40;
}
lbu v0, 0(a0)
slti t6, v0, 40 # boolean: loaded byte < 40
or v0, t6, zero
jr ra
nop
s32 below_zero(s8 *p) {
return *p < 0;
}
lb v0, 0(a0)
slti t6, v0, 0 # sign test on the sign-extended byte
or v0, t6, zero
jr ra
nop
Worth a pause on each:
is_dark uses slti — a signed compare — on a u8. Legal and correct: a zero-extended byte is 0…255, comfortably positive, so signed and unsigned comparison agree and IDO picks the signed one. Don't let a slti talk you out of a u8 declaration when the load says lbu.below_zero only works because lb sign-extended: the byte's bit 7 became bit 31, and slti …, 0 reads it. The same C on a u8 would be meaningless (never true) — the compiler would fold it to zero. Load signedness and comparison meaning are welded together.
The target compares two loaded bytes for equality and returns the boolean — the branch-free materialization pattern, fed by two loads.
Your task
Write func_80206670 to reproduce the target assembly.