Closed Durun closed 3 years ago
gcc最適化オプションは
gcc -O0 # 最適化なし gcc -O3 # 最適化あり
objdump 逆アセンブル https://linuxcommand.net/objdump/
objdump -d file.out
場所: https://github.com/Durun/sysdev.lec/tree/main/exc-collatz
gcc -O0 collatz.c -o O0.out gcc -O3 collatz.c -o O3.out
objdump -d o0.out > o0.asm objdump -d o3.out > o3.asm
o0.asm, o3.asmを比較
0000000000001159 <collatz>: 1159: 55 push %rbp 115a: 48 89 e5 mov %rsp,%rbp 115d: 48 83 ec 10 sub $0x10,%rsp 1161: 89 7d fc mov %edi,-0x4(%rbp) 1164: 83 7d fc 01 cmpl $0x1,-0x4(%rbp) 1168: 75 07 jne 1171 <collatz+0x18> 116a: b8 01 00 00 00 mov $0x1,%eax 116f: eb 32 jmp 11a3 <collatz+0x4a> 1171: 8b 45 fc mov -0x4(%rbp),%eax 1174: 83 e0 01 and $0x1,%eax 1177: 85 c0 test %eax,%eax 1179: 74 15 je 1190 <collatz+0x37> 117b: 8b 55 fc mov -0x4(%rbp),%edx 117e: 89 d0 mov %edx,%eax 1180: 01 c0 add %eax,%eax 1182: 01 d0 add %edx,%eax 1184: 83 c0 01 add $0x1,%eax 1187: 89 c7 mov %eax,%edi 1189: e8 cb ff ff ff callq 1159 <collatz> 118e: eb 13 jmp 11a3 <collatz+0x4a> 1190: 8b 45 fc mov -0x4(%rbp),%eax 1193: 89 c2 mov %eax,%edx 1195: c1 ea 1f shr $0x1f,%edx 1198: 01 d0 add %edx,%eax 119a: d1 f8 sar %eax 119c: 89 c7 mov %eax,%edi 119e: e8 b6 ff ff ff callq 1159 <collatz> 11a3: c9 leaveq 11a4: c3 retq
00000000000011e0 <collatz>: 11e0: 83 ff 01 cmp $0x1,%edi 11e3: 74 21 je 1206 <collatz+0x26> 11e5: 0f 1f 00 nopl (%rax) 11e8: 40 f6 c7 01 test $0x1,%dil 11ec: 74 0a je 11f8 <collatz+0x18> 11ee: 8d 7c 7f 01 lea 0x1(%rdi,%rdi,2),%edi 11f2: 40 f6 c7 01 test $0x1,%dil 11f6: 75 f6 jne 11ee <collatz+0xe> 11f8: 89 f8 mov %edi,%eax 11fa: c1 e8 1f shr $0x1f,%eax 11fd: 01 c7 add %eax,%edi 11ff: d1 ff sar %edi 1201: 83 ff 01 cmp $0x1,%edi 1204: 75 e2 jne 11e8 <collatz+0x8> 1206: b8 01 00 00 00 mov $0x1,%eax 120b: c3 retq 120c: 0f 1f 40 00 nopl 0x0(%rax)
Durun
commented
3 years ago Durun
commented
3 years ago
作業記録 コラッツ予想
gcc最適化オプションは
objdump 逆アセンブル https://linuxcommand.net/objdump/
作業
場所: https://github.com/Durun/sysdev.lec/tree/main/exc-collatz
o0.asm, o3.asmを比較
最適化なし
最適化あり
違い