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# Assignment2: RISC-V Toolchain
contributed by < `Cheng Yu` >
###### tags: `Computer Architure`
## Bubble sort
Choose bubble sort assembly code from [王傑世](https://hackmd.io/4-oWQOprRnCLu3ZeJy31kA?view)
### Rewrite C code
```cpp
void BBSort(int *arr, int size) {
for (int i = 0; i < size; ++i)
for (int j = 0; j < size - i; ++j)
if (arr[j] < arr[j + 1]) {
int temp = arr[j];
arr[j] = arr[j + 1];
arr[j + 1] = temp;
}
}
int _start()
{
int arr[] = {2, 3, 7, 4, 1};
int size = 5;
BBSort(arr, size - 1);
volatile char* tx = (volatile char*) 0x40002000;
for (int i = 0; i < size; ++i) {
*tx = arr[i] + '0';
*tx = '\n';
}
return 0;
}
```
Then we can run the following instructions
```
$ riscv-none-embed-gcc -march=rv32i -mabi=ilp32 -O3 -nostdlib bubble_sort.c -o bubble_sort
$ ./emu-rv32i bubble_sort
```
O0
ELF file header
```
Disassembly of section .text:
00010054 <BBSort>:
10054: fd010113 addi sp,sp,-48
10058: 02812623 sw s0,44(sp)
1005c: 03010413 addi s0,sp,48
10060: fca42e23 sw a0,-36(s0)
10064: fcb42c23 sw a1,-40(s0)
10068: fe042623 sw zero,-20(s0)
1006c: 0c80006f j 10134 <BBSort+0xe0>
10070: fe042423 sw zero,-24(s0)
10074: 0a00006f j 10114 <BBSort+0xc0>
10078: fe842783 lw a5,-24(s0)
1007c: 00279793 slli a5,a5,0x2
10080: fdc42703 lw a4,-36(s0)
10084: 00f707b3 add a5,a4,a5
10088: 0007a703 lw a4,0(a5)
1008c: fe842783 lw a5,-24(s0)
10090: 00178793 addi a5,a5,1
10094: 00279793 slli a5,a5,0x2
10098: fdc42683 lw a3,-36(s0)
1009c: 00f687b3 add a5,a3,a5
100a0: 0007a783 lw a5,0(a5)
100a4: 06f75263 bge a4,a5,10108 <BBSort+0xb4>
100a8: fe842783 lw a5,-24(s0)
100ac: 00279793 slli a5,a5,0x2
100b0: fdc42703 lw a4,-36(s0)
100b4: 00f707b3 add a5,a4,a5
100b8: 0007a783 lw a5,0(a5)
100bc: fef42223 sw a5,-28(s0)
100c0: fe842783 lw a5,-24(s0)
100c4: 00178793 addi a5,a5,1
100c8: 00279793 slli a5,a5,0x2
100cc: fdc42703 lw a4,-36(s0)
100d0: 00f70733 add a4,a4,a5
100d4: fe842783 lw a5,-24(s0)
100d8: 00279793 slli a5,a5,0x2
100dc: fdc42683 lw a3,-36(s0)
100e0: 00f687b3 add a5,a3,a5
100e4: 00072703 lw a4,0(a4)
100e8: 00e7a023 sw a4,0(a5)
100ec: fe842783 lw a5,-24(s0)
100f0: 00178793 addi a5,a5,1
100f4: 00279793 slli a5,a5,0x2
100f8: fdc42703 lw a4,-36(s0)
100fc: 00f707b3 add a5,a4,a5
10100: fe442703 lw a4,-28(s0)
10104: 00e7a023 sw a4,0(a5)
10108: fe842783 lw a5,-24(s0)
1010c: 00178793 addi a5,a5,1
10110: fef42423 sw a5,-24(s0)
10114: fd842703 lw a4,-40(s0)
10118: fec42783 lw a5,-20(s0)
1011c: 40f707b3 sub a5,a4,a5
10120: fe842703 lw a4,-24(s0)
10124: f4f74ae3 blt a4,a5,10078 <BBSort+0x24>
10128: fec42783 lw a5,-20(s0)
1012c: 00178793 addi a5,a5,1
10130: fef42623 sw a5,-20(s0)
10134: fec42703 lw a4,-20(s0)
10138: fd842783 lw a5,-40(s0)
1013c: f2f74ae3 blt a4,a5,10070 <BBSort+0x1c>
10140: 00000013 nop
10144: 02c12403 lw s0,44(sp)
10148: 03010113 addi sp,sp,48
1014c: 00008067 ret
00010150 <_start>:
10150: fd010113 addi sp,sp,-48
10154: 02112623 sw ra,44(sp)
10158: 02812423 sw s0,40(sp)
1015c: 03010413 addi s0,sp,48
10160: 000107b7 lui a5,0x10
10164: 2307a583 lw a1,560(a5) # 10230 <_start+0xe0>
10168: 23078713 addi a4,a5,560
1016c: 00472603 lw a2,4(a4)
10170: 23078713 addi a4,a5,560
10174: 00872683 lw a3,8(a4)
10178: 23078713 addi a4,a5,560
1017c: 00c72703 lw a4,12(a4)
10180: 23078793 addi a5,a5,560
10184: 0107a783 lw a5,16(a5)
10188: fcb42823 sw a1,-48(s0)
1018c: fcc42a23 sw a2,-44(s0)
10190: fcd42c23 sw a3,-40(s0)
10194: fce42e23 sw a4,-36(s0)
10198: fef42023 sw a5,-32(s0)
1019c: 00500793 li a5,5
101a0: fef42423 sw a5,-24(s0)
101a4: fe842783 lw a5,-24(s0)
101a8: fff78713 addi a4,a5,-1
101ac: fd040793 addi a5,s0,-48
101b0: 00070593 mv a1,a4
101b4: 00078513 mv a0,a5
101b8: e9dff0ef jal ra,10054 <BBSort>
101bc: 400027b7 lui a5,0x40002
101c0: fef42223 sw a5,-28(s0)
101c4: fe042623 sw zero,-20(s0)
101c8: 0440006f j 1020c <_start+0xbc>
101cc: fec42783 lw a5,-20(s0)
101d0: 00279793 slli a5,a5,0x2
101d4: ff040713 addi a4,s0,-16
101d8: 00f707b3 add a5,a4,a5
101dc: fe07a783 lw a5,-32(a5) # 40001fe0 <__global_pointer$+0x3fff059c>
101e0: 0ff7f793 andi a5,a5,255
101e4: 03078793 addi a5,a5,48
101e8: 0ff7f713 andi a4,a5,255
101ec: fe442783 lw a5,-28(s0)
101f0: 00e78023 sb a4,0(a5)
101f4: fe442783 lw a5,-28(s0)
101f8: 00a00713 li a4,10
101fc: 00e78023 sb a4,0(a5)
10200: fec42783 lw a5,-20(s0)
10204: 00178793 addi a5,a5,1
10208: fef42623 sw a5,-20(s0)
1020c: fec42703 lw a4,-20(s0)
10210: fe842783 lw a5,-24(s0)
10214: faf74ce3 blt a4,a5,101cc <_start+0x7c>
10218: 00000793 li a5,0
1021c: 00078513 mv a0,a5
10220: 02c12083 lw ra,44(sp)
10224: 02812403 lw s0,40(sp)
10228: 03010113 addi sp,sp,48
1022c: 00008067 ret
```
size
```
text data bss dec hex filename
496 0 0 496 1f0 bubble_sort
```
O3
```
Disassembly of section .text:
00010054 <BBSort>:
10054: 02b05a63 blez a1,10088 <BBSort+0x34>
10058: 00259613 slli a2,a1,0x2
1005c: 00c50633 add a2,a0,a2
10060: 00050793 mv a5,a0
10064: 0007a703 lw a4,0(a5)
10068: 0047a683 lw a3,4(a5)
1006c: 00d75663 bge a4,a3,10078 <BBSort+0x24>
10070: 00d7a023 sw a3,0(a5)
10074: 00e7a223 sw a4,4(a5)
10078: 00478793 addi a5,a5,4
1007c: fec794e3 bne a5,a2,10064 <BBSort+0x10>
10080: ffc60613 addi a2,a2,-4
10084: fcc51ee3 bne a0,a2,10060 <BBSort+0xc>
10088: 00008067 ret
0001008c <_start>:
1008c: 000107b7 lui a5,0x10
10090: 21478793 addi a5,a5,532 # 10214 <_start+0x188>
10094: 0007a703 lw a4,0(a5)
10098: 0047a683 lw a3,4(a5)
1009c: 0087a583 lw a1,8(a5)
100a0: 00c7a603 lw a2,12(a5)
100a4: 0107a783 lw a5,16(a5)
100a8: fe010113 addi sp,sp,-32
100ac: 00e12623 sw a4,12(sp)
100b0: 00d12823 sw a3,16(sp)
100b4: 00b12a23 sw a1,20(sp)
100b8: 00c12c23 sw a2,24(sp)
100bc: 00f12e23 sw a5,28(sp)
100c0: 00d75663 bge a4,a3,100cc <_start+0x40>
100c4: 00d12623 sw a3,12(sp)
100c8: 00e12823 sw a4,16(sp)
100cc: 01012783 lw a5,16(sp)
100d0: 01412703 lw a4,20(sp)
100d4: 00e7dc63 bge a5,a4,100ec <_start+0x60>
100d8: 00078693 mv a3,a5
100dc: 00e12823 sw a4,16(sp)
100e0: 00f12a23 sw a5,20(sp)
100e4: 00070793 mv a5,a4
100e8: 00068713 mv a4,a3
100ec: 01812603 lw a2,24(sp)
100f0: 00c75c63 bge a4,a2,10108 <_start+0x7c>
100f4: 00070693 mv a3,a4
100f8: 00c12a23 sw a2,20(sp)
100fc: 00e12c23 sw a4,24(sp)
10100: 00060713 mv a4,a2
10104: 00068613 mv a2,a3
10108: 01c12683 lw a3,28(sp)
1010c: 0ed64c63 blt a2,a3,10204 <_start+0x178>
10110: 00c12683 lw a3,12(sp)
10114: 00f6dc63 bge a3,a5,1012c <_start+0xa0>
10118: 00078593 mv a1,a5
1011c: 00f12623 sw a5,12(sp)
10120: 00d12823 sw a3,16(sp)
10124: 00068793 mv a5,a3
10128: 00058693 mv a3,a1
1012c: 00e7dc63 bge a5,a4,10144 <_start+0xb8>
10130: 00078593 mv a1,a5
10134: 00e12823 sw a4,16(sp)
10138: 00f12a23 sw a5,20(sp)
1013c: 00070793 mv a5,a4
10140: 00058713 mv a4,a1
10144: 0ac74863 blt a4,a2,101f4 <_start+0x168>
10148: 00f6dc63 bge a3,a5,10160 <_start+0xd4>
1014c: 00078613 mv a2,a5
10150: 00f12623 sw a5,12(sp)
10154: 00d12823 sw a3,16(sp)
10158: 00068793 mv a5,a3
1015c: 00060693 mv a3,a2
10160: 00e7d863 bge a5,a4,10170 <_start+0xe4>
10164: 00f12a23 sw a5,20(sp)
10168: 00e12823 sw a4,16(sp)
1016c: 00070793 mv a5,a4
10170: 00f6d663 bge a3,a5,1017c <_start+0xf0>
10174: 00f12623 sw a5,12(sp)
10178: 00d12823 sw a3,16(sp)
1017c: 00c12683 lw a3,12(sp)
10180: 400027b7 lui a5,0x40002
10184: 00a00713 li a4,10
10188: 03068693 addi a3,a3,48
1018c: 0ff6f693 andi a3,a3,255
10190: 00d78023 sb a3,0(a5) # 40002000 <__global_pointer$+0x3fff05d8>
10194: 00e78023 sb a4,0(a5)
10198: 01012683 lw a3,16(sp)
1019c: 00000513 li a0,0
101a0: 03068693 addi a3,a3,48
101a4: 0ff6f693 andi a3,a3,255
101a8: 00d78023 sb a3,0(a5)
101ac: 00e78023 sb a4,0(a5)
101b0: 01412683 lw a3,20(sp)
101b4: 03068693 addi a3,a3,48
101b8: 0ff6f693 andi a3,a3,255
101bc: 00d78023 sb a3,0(a5)
101c0: 00e78023 sb a4,0(a5)
101c4: 01812683 lw a3,24(sp)
101c8: 03068693 addi a3,a3,48
101cc: 0ff6f693 andi a3,a3,255
101d0: 00d78023 sb a3,0(a5)
101d4: 00e78023 sb a4,0(a5)
101d8: 01c12683 lw a3,28(sp)
101dc: 03068693 addi a3,a3,48
101e0: 0ff6f693 andi a3,a3,255
101e4: 00d78023 sb a3,0(a5)
101e8: 00e78023 sb a4,0(a5)
101ec: 02010113 addi sp,sp,32
101f0: 00008067 ret
101f4: 00e12c23 sw a4,24(sp)
101f8: 00c12a23 sw a2,20(sp)
101fc: 00060713 mv a4,a2
10200: f49ff06f j 10148 <_start+0xbc>
10204: 00c12e23 sw a2,28(sp)
10208: 00d12c23 sw a3,24(sp)
1020c: 00068613 mv a2,a3
10210: f01ff06f j 10110 <_start+0x84>
```
size
```
text data bss dec hex filename
468 0 0 468 1d4 bubble_sort
```
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