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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/115019] wraparound bug with with -O3 and int128
Date: Fri, 10 May 2024 01:54:54 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D115019

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #2)
> /app/example.cpp:36:24: runtime error: negation of
> 0x80000000000000000000000000000000 cannot be represented in type '__int12=
8';
> cast to an unsigned type to negate this value to itself

Once I fix that with:
```
static char *itoa128(char *buf, __int128_t v)
{
  if (v < 0) {
    buf =3D utoa128(buf, -(__uint128_t)v);
```

GCC behavior is what you expect.=