https://blog.csdn.net/weixin_43092232/article/details/106243657
https://blog.csdn.net/www_dong/article/details/117374370
代码验证:
龙芯3A5000验证
$ cat test.c
#include<stdio.h>
int add ( int d1, int d2 )
{
int d;
d = d1 + 1;
d = d + d2 + 2;
return d;
}
int add1 ( int d1, int d2 )
{
int d;
d = d1 + 10;
d = d + d2 + 20;
return d;
}
int main()
{
int a = 0, b = 0;
a = b + 1;
a = add(a, b);
a = a + 10;
b = add1(a, b);
b = a + b;
return 1;
}
桌面20.3系统
lihui@lihui-pc:~/community/build$ gcc -v
gcc version 8.3.0 (Loongnix 8.3.0-6.lnd.vec.33)
lihui@lihui-pc:~/community/build$ gdb/gdb -v
GNU gdb (GDB) 14.0.50.20230705-git
lihui@lihui-pc:~/community/build$ gcc -g test.c -o test
lihui@lihui-pc:~/community/build$ objdump -d test
00000001200006d0 <add>:
1200006d0: 02ff4063 addi.d $r3,$r3,-48(0xfd0)
1200006d4: 29c0a076 st.d $r22,$r3,40(0x28)
1200006d8: 02c0c076 addi.d $r22,$r3,48(0x30)
1200006dc: 0015008d move $r13,$r4
1200006e0: 001500ac move $r12,$r5
1200006e4: 004081ad slli.w $r13,$r13,0x0
1200006e8: 29bf72cd st.w $r13,$r22,-36(0xfdc)
1200006ec: 0040818c slli.w $r12,$r12,0x0
1200006f0: 29bf62cc st.w $r12,$r22,-40(0xfd8)
1200006f4: 28bf72cc ld.w $r12,$r22,-36(0xfdc)
1200006f8: 0280058c addi.w $r12,$r12,1(0x1)
1200006fc: 29bfb2cc st.w $r12,$r22,-20(0xfec)
120000700: 28bfb2cd ld.w $r13,$r22,-20(0xfec)
120000704: 28bf62cc ld.w $r12,$r22,-40(0xfd8)
120000708: 001031ac add.w $r12,$r13,$r12
12000070c: 0280098c addi.w $r12,$r12,2(0x2)
120000710: 29bfb2cc st.w $r12,$r22,-20(0xfec)
120000714: 28bfb2cc ld.w $r12,$r22,-20(0xfec)
120000718: 00150184 move $r4,$r12
12000071c: 28c0a076 ld.d $r22,$r3,40(0x28)
120000720: 02c0c063 addi.d $r3,$r3,48(0x30)
120000724: 4c000020 jirl $r0,$r1,0
0000000120000728 <add1>:
120000728: 02ff4063 addi.d $r3,$r3,-48(0xfd0)
12000072c: 29c0a076 st.d $r22,$r3,40(0x28)
120000730: 02c0c076 addi.d $r22,$r3,48(0x30)
120000734: 0015008d move $r13,$r4
120000738: 001500ac move $r12,$r5
12000073c: 004081ad slli.w $r13,$r13,0x0
120000740: 29bf72cd st.w $r13,$r22,-36(0xfdc)
120000744: 0040818c slli.w $r12,$r12,0x0
120000748: 29bf62cc st.w $r12,$r22,-40(0xfd8)
12000074c: 28bf72cc ld.w $r12,$r22,-36(0xfdc)
120000750: 0280298c addi.w $r12,$r12,10(0xa)
120000754: 29bfb2cc st.w $r12,$r22,-20(0xfec)
120000758: 28bfb2cd ld.w $r13,$r22,-20(0xfec)
12000075c: 28bf62cc ld.w $r12,$r22,-40(0xfd8)
120000760: 001031ac add.w $r12,$r13,$r12
120000764: 0280518c addi.w $r12,$r12,20(0x14)
120000768: 29bfb2cc st.w $r12,$r22,-20(0xfec)
12000076c: 28bfb2cc ld.w $r12,$r22,-20(0xfec)
120000770: 00150184 move $r4,$r12
120000774: 28c0a076 ld.d $r22,$r3,40(0x28)
120000778: 02c0c063 addi.d $r3,$r3,48(0x30)
12000077c: 4c000020 jirl $r0,$r1,0
0000000120000780 <main>:
120000780: 02ff8063 addi.d $r3,$r3,-32(0xfe0)
120000784: 29c06061 st.d $r1,$r3,24(0x18)
120000788: 29c04076 st.d $r22,$r3,16(0x10)
12000078c: 02c08076 addi.d $r22,$r3,32(0x20)
120000790: 29bfb2c0 st.w $r0,$r22,-20(0xfec)
120000794: 29bfa2c0 st.w $r0,$r22,-24(0xfe8)
120000798: 28bfa2cc ld.w $r12,$r22,-24(0xfe8)
12000079c: 0280058c addi.w $r12,$r12,1(0x1)
1200007a0: 29bfb2cc st.w $r12,$r22,-20(0xfec)
1200007a4: 28bfa2cd ld.w $r13,$r22,-24(0xfe8)
1200007a8: 28bfb2cc ld.w $r12,$r22,-20(0xfec)
1200007ac: 001501a5 move $r5,$r13
1200007b0: 00150184 move $r4,$r12
1200007b4: 57ff1fff bl -228(0xfffff1c) # 1200006d0 <add>
1200007b8: 0015008c move $r12,$r4
1200007bc: 29bfb2cc st.w $r12,$r22,-20(0xfec)
1200007c0: 28bfb2cc ld.w $r12,$r22,-20(0xfec)
1200007c4: 0280298c addi.w $r12,$r12,10(0xa)
1200007c8: 29bfb2cc st.w $r12,$r22,-20(0xfec)
1200007cc: 28bfa2cd ld.w $r13,$r22,-24(0xfe8)
1200007d0: 28bfb2cc ld.w $r12,$r22,-20(0xfec)
1200007d4: 001501a5 move $r5,$r13
1200007d8: 00150184 move $r4,$r12
1200007dc: 57ff4fff bl -180(0xfffff4c) # 120000728 <add1>
1200007e0: 0015008c move $r12,$r4
1200007e4: 29bfa2cc st.w $r12,$r22,-24(0xfe8)
1200007e8: 28bfa2cd ld.w $r13,$r22,-24(0xfe8)
1200007ec: 28bfb2cc ld.w $r12,$r22,-20(0xfec)
1200007f0: 001031ac add.w $r12,$r13,$r12
1200007f4: 29bfa2cc st.w $r12,$r22,-24(0xfe8)
1200007f8: 0280040c addi.w $r12,$r0,1(0x1)
1200007fc: 00150184 move $r4,$r12
120000800: 28c06061 ld.d $r1,$r3,24(0x18)
120000804: 28c04076 ld.d $r22,$r3,16(0x10)
120000808: 02c08063 addi.d $r3,$r3,32(0x20)
12000080c: 4c000020 jirl $r0,$r1,0
验证next
lihui@lihui-pc:~/community/build$ gdb/gdb test
...
(gdb) start
Temporary breakpoint 1 at 0x120000790: file test.c, line 20.
Starting program: /home/lihui/community/build/test
Temporary breakpoint 1, main () at test.c:20
20 int a = 0, b = 0;
(gdb) l
15 return d;
16 }
17
18 int main()
19 {
20 int a = 0, b = 0;
21 a = b + 1;
22 a = add(a, b);
23 a = a + 10;
24 b = add1(a, b);
(gdb) next
21 a = b + 1;
(gdb) next
22 a = add(a, b);
(gdb) next
23 a = a + 10;
(gdb) next
24 b = add1(a, b);
(gdb) next
25 b = a + b;
(gdb) next
26 return 1;
(gdb) next
27 }
...
验证step
lihui@lihui-pc:~/community/build$ gdb/gdb test
...
(gdb) start
..
Temporary breakpoint 1, main () at test.c:20
20 int a = 0, b = 0;
(gdb) step
21 a = b + 1;
(gdb) step
22 a = add(a, b);
(gdb) step
add (d1=1, d2=0) at test.c:5
5 d = d1 + 1;
(gdb) step
6 d = d + d2 + 2;
(gdb) step
7 return d;
(gdb) step
8 }
(gdb) step
main () at test.c:23
23 a = a + 10;
(gdb) step
24 b = add1(a, b);
(gdb) step
add1 (d1=14, d2=0) at test.c:13
13 d = d1 + 10;
(gdb) step
14 d = d + d2 + 20;
(gdb) step
15 return d;
(gdb) step
16 }
(gdb) step
main () at test.c:25
25 b = a + b;
(gdb) step
26 return 1;
(gdb) step
27 }
可以看到next命令遇到函数不进入，step遇到函数进入，符合预期。
验证nexti
lihui@lihui-pc:~/community/build$ gdb/gdb test
...
(gdb) start
Temporary breakpoint 1 at 0x120000790: file test.c, line 20.
Starting program: /home/lihui/community/build/test
Temporary breakpoint 1, main () at test.c:20
20 int a = 0, b = 0;
(gdb) nexti
20 int a = 0, b = 0;
(gdb) nexti
21 a = b + 1;
(gdb) nexti
0x000000012000079c 21 a = b + 1;
(gdb) nexti
0x00000001200007a0 21 a = b + 1;
(gdb) nexti
22 a = add(a, b);
(gdb) nexti
0x00000001200007a8 22 a = add(a, b);
(gdb) nexti
0x00000001200007ac 22 a = add(a, b);
(gdb) nexti
0x00000001200007b0 22 a = add(a, b);
(gdb) nexti
0x00000001200007b4 22 a = add(a, b);
(gdb) nexti
0x00000001200007b8 22 a = add(a, b);
(gdb) nexti
0x00000001200007bc 22 a = add(a, b);
(gdb) nexti
23 a = a + 10;
(gdb) nexti
0x00000001200007c4 23 a = a + 10;
(gdb) nexti
0x00000001200007c8 23 a = a + 10;
(gdb) nexti
24 b = add1(a, b);
(gdb) nexti
0x00000001200007d0 24 b = add1(a, b);
(gdb) nexti
0x00000001200007d4 24 b = add1(a, b);
(gdb) nexti
0x00000001200007d8 24 b = add1(a, b);
(gdb) nexti
0x00000001200007dc 24 b = add1(a, b);
(gdb) nexti
0x00000001200007e0 24 b = add1(a, b);
(gdb) nexti
0x00000001200007e4 24 b = add1(a, b);
(gdb) nexti
25 b = a + b;
(gdb) nexti
0x00000001200007ec 25 b = a + b;
(gdb) nexti
0x00000001200007f0 25 b = a + b;
(gdb) nexti
0x00000001200007f4 25 b = a + b;
(gdb) nexti
26 return 1;
(gdb) nexti
27 }
nexti是逐条指令执行，但是没有进入到add和add1函数，跳过了这两个函数继续执行下面的指令。
验证stepi
lihui@lihui-pc:~/community/build$ gdb/gdb test
...
(gdb) start
Temporary breakpoint 1 at 0x120000790: file test.c, line 20.
Starting program: /home/lihui/community/build/test
Temporary breakpoint 1, main () at test.c:20
20 int a = 0, b = 0;
(gdb) next
21 a = b + 1;
(gdb) next
22 a = add(a, b);
(gdb) stepi
0x00000001200007a8 22 a = add(a, b);
(gdb) stepi
0x00000001200007ac 22 a = add(a, b);
(gdb) stepi
0x00000001200007b0 22 a = add(a, b);
(gdb) stepi
0x00000001200007b4 22 a = add(a, b);
(gdb) stepi
add (d1=0, d2=0) at test.c:3
3 {
(gdb) stepi
0x00000001200006d4 3 {
(gdb) stepi
0x00000001200006d8 3 {
(gdb) stepi
0x00000001200006dc 3 {
(gdb) stepi
0x00000001200006e0 3 {
(gdb) stepi
0x00000001200006e4 3 {
(gdb) stepi
0x00000001200006e8 3 {
(gdb) stepi
0x00000001200006ec 3 {
(gdb) stepi
0x00000001200006f0 3 {
(gdb) stepi
5 d = d1 + 1;
(gdb) stepi
0x00000001200006f8 5 d = d1 + 1;
(gdb) stepi
0x00000001200006fc 5 d = d1 + 1;
(gdb) stepi
6 d = d + d2 + 2;
(gdb) stepi
0x0000000120000704 6 d = d + d2 + 2;
(gdb) stepi
0x0000000120000708 6 d = d + d2 + 2;
(gdb) stepi
6 d = d + d2 + 2;
(gdb) stepi
0x0000000120000710 6 d = d + d2 + 2;
(gdb) stepi
7 return d;
(gdb) stepi
8 }
(gdb) next
main () at test.c:23
23 a = a + 10;
(gdb) next
24 b = add1(a, b);
(gdb) stepi
0x00000001200007d0 24 b = add1(a, b);
(gdb) stepi
0x00000001200007d4 24 b = add1(a, b);
(gdb) stepi
0x00000001200007d8 24 b = add1(a, b);
(gdb) stepi
0x00000001200007dc 24 b = add1(a, b);
(gdb) stepi
add1 (d1=1, d2=0) at test.c:11
11 {
(gdb) stepi
0x000000012000072c 11 {
(gdb) stepi
0x0000000120000730 11 {
(gdb) stepi
0x0000000120000734 11 {
(gdb) stepi
0x0000000120000738 11 {
(gdb) stepi
0x000000012000073c 11 {
(gdb) stepi
0x0000000120000740 11 {
(gdb) stepi
0x0000000120000744 11 {
(gdb) stepi
0x0000000120000748 11 {
(gdb) stepi
13 d = d1 + 10;
(gdb) stepi
0x0000000120000750 13 d = d1 + 10;
(gdb) stepi
0x0000000120000754 13 d = d1 + 10;
(gdb) stepi
14 d = d + d2 + 20;
(gdb) stepi
0x000000012000075c 14 d = d + d2 + 20;
(gdb) stepi
0x0000000120000760 14 d = d + d2 + 20;
(gdb) stepi
14 d = d + d2 + 20;
(gdb) stepi
0x0000000120000768 14 d = d + d2 + 20;
(gdb) stepi
15 return d;
(gdb) stepi
16 }
(gdb) next
main () at test.c:25
25 b = a + b;
(gdb) next
26 return 1;
(gdb) next
27 }
可以看到stepi也是逐条指令执行，会进入到函数add和add1内部执行，符合预期