https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103733
--- Comment #2 from Jan Engelhardt <jengelh at inai dot de> ---
== New input ==
$ cat x.cpp
struct S {
char b[16];
#if __cplusplus >= 202000L
bool operator==(const S &) const = default;
#else
inline bool operator==(const S &o) const { return __builtin_memcmp(b,
o.b, sizeof(b)); }
#endif
};
bool fff(const S &a, const S &b) { return a == b; }
== Observed ==
$ ./xgcc -B. -c /dev/shm/x.cpp -O2 && objdump -d x.o
0000000000000000 <_Z3fffRK1SS1_>: C++17
0: 48 8b 17 mov (%rdi),%rdx
3: 48 8b 47 08 mov 0x8(%rdi),%rax
7: 48 33 16 xor (%rsi),%rdx
a: 48 33 46 08 xor 0x8(%rsi),%rax
e: 48 09 d0 or %rdx,%rax
11: 0f 95 c0 setne %al
14: c3 ret
0000000000000000 <_Z3fffRK1SS1_>: C++20
0: 31 c0 xor %eax,%eax
2: 66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1)
8: 0f b6 14 06 movzbl (%rsi,%rax,1),%edx
c: 38 14 07 cmp %dl,(%rdi,%rax,1)
f: 75 17 jne 28 <_Z3fffRK1SS1_+0x28>
11: 48 83 c0 01 add $0x1,%rax
15: 48 83 f8 10 cmp $0x10,%rax
19: 75 ed jne 8 <_Z3fffRK1SS1_+0x8>
1b: b8 01 00 00 00 mov $0x1,%eax
20: c3 ret
21: 0f 1f 80 00 00 00 00 nopl 0x0(%rax)
28: 31 c0 xor %eax,%eax
2a: c3 ret
