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.intel_syntax noprefix
.globl main
main:
mov rax, 5
add rax, 20
sub rax, 4
ret
$ cc -g -o tmp tmp.s
$ gdb ./tmp
(gdb) b main
Breakpoint 1 at 0x1125: file tmp.s, line 4.
(gdb) r
Starting program:
Breakpoint 1, main () at tmp.s:4
4 mov rax, 5
(gdb) n
5 add rax, 20
(gdb) p $rax
$1 = 5
(gdb) n
6 sub rax, 4
(gdb) p $rax
$2 = 25
(gdb) n
main () at tmp.s:7
7 ret
(gdb) p $rax
$3 = 21
#include <stdio.h>
#include <stdlib.h>
int main(int argc, char **argv) {
if (argc != 2) {
fprintf(stderr, "引数の個数が正しくありません\n");
return 1;
}
char *p = argv[1];
printf(".intel_syntax noprefix\n");
printf(".globl main\n");
printf("main:\n");
printf(" mov rax, %ld\n", strtol(p, &p, 10));
while (*p) {
if (*p == '+') {
p++;
printf(" add rax, %ld\n", strtol(p, &p, 10));
continue;
}
if (*p == '-') {
p++;
printf(" sub rax, %ld\n", strtol(p, &p, 10));
continue;
}
fprintf(stderr, "予期しない文字です: '%c'\n", *p);
return 1;
}
printf(" ret\n");
return 0;
}
$ gdb ./9cc
(gdb) b main
Breakpoint 1 at 0x401bac: file 9cc.c, line 5.
(gdb) r '5+20-4'
Starting program: /home/yoshio/rui_ueyama/9cc/9cc '5+20-4'
Breakpoint 1, main (argc=2, argv=0x7fffffffdfe8) at 9cc.c:5
5 if (argc != 2) {
(gdb) n
10 char *p = argv[1];
(gdb)
12 printf(".intel_syntax noprefix\n");
(gdb) p p
$1 = 0x7fffffffe389 "5+20-4"
(gdb) n
.intel_syntax noprefix
13 printf(".globl main\n");
(gdb)
.globl main
14 printf("main:\n");
(gdb)
main:
15 printf(" mov rax, %ld\n", strtol(p, &p, 10));
(gdb)
mov rax, 5
17 while (*p) {
(gdb) p p
$2 = 0x7fffffffe38a "+20-4"
(gdb) n
18 if (*p == '+') {
(gdb)
19 p++;
(gdb)
20 printf(" add rax, %ld\n", strtol(p, &p, 10));
(gdb) p p
$3 = 0x7fffffffe38b "20-4"
(gdb) n
add rax, 20
21 continue;
(gdb) p p
$4 = 0x7fffffffe38d "-4"
(gdb) n
17 while (*p) {
(gdb)
18 if (*p == '+') {
(gdb)
24 if (*p == '-') {
(gdb)
25 p++;
(gdb)
26 printf(" sub rax, %ld\n", strtol(p, &p, 10));
(gdb) p p
$5 = 0x7fffffffe38e "4"
(gdb) n
sub rax, 4
27 continue;
(gdb) p p
$6 = 0x7fffffffe38f ""
(gdb) n
17 while (*p) {
(gdb)
33 printf(" ret\n");
(gdb)
ret
34 return 0;
(gdb)
35 }
(gdb)
