递归C++代码转RISC-V R64I汇编及参数传递错误排查

我需要将一段计算子集和的递归C++代码转换为RISC-V R64I汇编代码，目标支持两个测试用例：

• 测试用例1：数组{5,4,3}，预期输出12 9 8 5 7 4 3 0
• 测试用例2：数组{2,3}，预期输出5 2 3 0

目前已完成字符串与数字打印的部分，但递归函数subsetSums的参数传递存在错误，无法得到正确输出，请求协助排查并修正。

参考C++代码 #

#include <iostream>

using namespace std;

//==============testcase1==============
int arr[] = { 5, 4, 3 };
int n = 3;
//output: 12 9 8 5 7 4 3 0
//=====================================

//==============testcase2==============
//int arr[] = {2, 3};
//int n = 2;
//output: 5 2 3 0
//=====================================

// Prints sums of all subsets of arr[l..r]
void subsetSums(int arr[], int l, int r, int sum)
{
    // Print current subset
    if (l > r) {
        cout << sum << " ";
        return;
    }

    // Subset including arr[l]
    subsetSums(arr, l + 1, r, sum + arr[l]);

    // Subset excluding arr[l]
    subsetSums(arr, l + 1, r, sum);
}

// Driver code
int main()
{
    cout << "output: ";
    subsetSums(arr, 0, n - 1,0);
    return 0;
}

我编写的RISC-V汇编代码（含错误） #

# Reference: https://www.geeksforgeeks.org/print-sums-subsets-given-set/
.data
.align 4
# =========testcase1===========
arr: .word 5, 4, 3
n: .word 3
str: .string "output: "
space: .string " "
# output: 12 9 8 5 7 4 3 0
# ==============================

# =========testcase2===========
#arr: .word 2, 3
#n: .word 2
#str: .string "output: "
#space: .string " "
# output: 5 2 3 0
# ==============================

.text
.global _start
# Start your coding below, don't change anything upper except testing different testcase

_start:
   li a7, 4
   la a0, str
   ecall
   #load arr, 0, n, 0
   la a0, arr
   la a1, 0
   la a2, n
   la a3, 0
   jal subsetSums
   j end       # Jump to end of program
subsetSums:
   mv t0, a0
   mv t1, a1
   mv t2, a3
   # if l > r print sum
   blt a2, a1, sum
   add t3, a1, 0
   slli t3, t3, 2
   addi t3, a0, t3
   lw t4, 0(t3)
   add a3, t2, t3
   addi a1, t1, 1
   jal subsetSums
   addi a1, t1, 1
   add a3, t2, 0
   jal subsetSums

sum:
   mv t0, a3
   # Print sum
   li a7, 1
   addi a0, t0, 0
   ecall
   #Print 
   li a7, 4
   la a0, space
   ecall

   lw   ra, 0(sp) # Reload return address from stack
   addi sp, sp, 4 # Restore stack pointer
   jr x1

end:nop

错误代码段 #

subsetSums:
   mv t0, a0
   mv t1, a1
   mv t2, a3
   # if l > r print sum
   blt a2, a1, sum
   #BUG
   add t3, a1, 0
   slli t3, t3, 2
   addi t3, a0, t3
   lw t4, 0(t3)
   add a3, t2, t3
   addi a1, t1, 1
   jal subsetSums
   addi a1, t1, 1
   add a3, t2, 0
   jal subsetSums
   #BUG

我此前仅学习过基础的Hello World代码，从未接触过汇编语言，对当前问题无从下手。

内容的提问来源于stack exchange，提问作者Thitiwat Thongprasertsang