將C轉換爲MIPS

Question

我正在用MIPS編寫一個程序，但無法圍繞下面的語句寫下下面的語句。我如何在MIPS指令集中編寫這樣的邏輯語句？

return a > b ? a : b; 

Answer 1

• return：一些值返回到被叫方（如果表達呈現）。
• A ? B : C：這是條件運算符。如果A爲真（非零），則評估B。否則，評估C。

如果a和b簽署的32位整數，它應該是這樣的：

# assuming 
# a = $t0 
# b = $t1 
# return value = $v0 

slt $t2, $t1, $t0  # $t2 = (b < a) 
beq $t2, $zero, nottrue # if (!(a > b)) goto nottrue 
addui $v0, $t0, $zero # return value = a (not harmful even if executed when jump is taken) 
jr $ra     # return 
sll $zero, $zero, 0  # nop: prevent instruction after branch from being executed 
nottrue: 
addui $v0, $t1, $zero # return value = b 
jr $ra     # return 
sll $zero, $zero, 0  # nop: prevent instruction after branch from being executed