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From: "141242068 at smail dot nju.edu.cn" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/114597] [GCC-14] Miscompilation of pointer assignment with inline assembly
Date: Fri, 05 Apr 2024 04:10:21 +0000	[thread overview]
Message-ID: <bug-114597-4-fe3fq4g7fk@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-114597-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114597

--- Comment #3 from wierton <141242068 at smail dot nju.edu.cn> ---
Thanks a lot, I have checked it out.

I'm still somewhat confused. Does the difference in compilation stem from GCC
interpreting "=m" and "=r" differently, leading it to assume that once "n.p" is
declared as an output operand without matched input declaration (eg. "=m"
expects "m", "=r" expects "r"), its value is expected to change?

```
asm("":"=m"(n.p):"r"(n.p)); // n.p is expected to change
asm("":"=r"(n.p):"r"(n.p)); // n.p can retain its value
asm("":"=m"(n.p):"m"(n.p)); // n.p can retain its value
```

Thanks in advance for any further explanation you can provide.

  parent reply	other threads:[~2024-04-05  4:10 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-05  3:42 [Bug c/114597] New: " 141242068 at smail dot nju.edu.cn
2024-04-05  3:52 ` [Bug c/114597] " pinskia at gcc dot gnu.org
2024-04-05  3:54 ` pinskia at gcc dot gnu.org
2024-04-05  4:10 ` 141242068 at smail dot nju.edu.cn [this message]
2024-04-05  6:03 ` xry111 at gcc dot gnu.org
2024-04-05  7:57 ` 141242068 at smail dot nju.edu.cn

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