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From: "lienze at sourceware dot org" <sourceware-bugzilla@sourceware.org>
To: gdb-prs@sourceware.org
Subject: [Bug cli/24124] Command `b *804874e` sets breakpoint at 0xc480a - hex value of 804874
Date: Sun, 04 Sep 2022 08:45:13 +0000 [thread overview]
Message-ID: <bug-24124-4717-uW8IBu2Y1e@http.sourceware.org/bugzilla/> (raw)
In-Reply-To: <bug-24124-4717@http.sourceware.org/bugzilla/>
https://sourceware.org/bugzilla/show_bug.cgi?id=24124
--- Comment #4 from Enze Li <lienze at sourceware dot org> ---
(In reply to Tom Tromey from comment #3)
> (In reply to Enze Li from comment #2)
>
> > "804874e" is parsed as a floating point number because "en" stands for
> > "10^n". If there is no decimal number after "e", "e" will be ignored. "d"
> > and "f" are not as special as "e", that is why breakpoint address with a "d"
> > or "f" are recognized as illegal. This is my understanding.
>
> I think gdb's lexing here is weird, because it disagrees with C:
>
> prentzel. gcc --syntax-only q.c
> q.c:1:11: error: exponent has no digits
> 1 | float x = 80e;
> | ^~~
>
> (gdb) print 80e
> $1 = 80
> (gdb) ptype 80e
> type = double
>
> So not treating this as floating point (and rejecting the parse)
> might be fine.
>
> > In GDB, do users usually use decimal numbers to define the address of
> > breakpoints?
>
> No but nothing prohibits it.
>
> > Or, if only hexadecimal numbers are used to set the breakpoint
> > address, how about we restrict the value of the address to start with 0x?
>
> That's harder than it sounds because the text after the "*" is an
> arbitrary expression, not just an integer.
Hi Tom,
Thanks for your reply.
I have a proposed patch. FTR, I've posted here[1].
[1] https://sourceware.org/pipermail/gdb-patches/2022-September/191680.html
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prev parent reply other threads:[~2022-09-04 8:45 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-24124-4717@http.sourceware.org/bugzilla/>
2022-09-03 13:43 ` lienze at sourceware dot org
2022-09-03 21:15 ` tromey at sourceware dot org
2022-09-04 8:45 ` lienze at sourceware dot org [this message]
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