[Bug cli/16242] New: print format for hex float

[Bug cli/16242] New: print format for hex float

[schwab@linux-m68k.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16242

            Bug ID: 16242
           Summary: print format for hex float
           Product: gdb
           Version: HEAD
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: cli
          Assignee: unassigned at sourceware dot org
          Reporter: schwab@linux-m68k.org

There should be a print format for displaying float values in hex.  /x doesn't
work, it converts the value to integer first.

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[Bug cli/16242] print format for hex float

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16242

--- Comment #5 from Tom Tromey <tromey at sourceware dot org> ---
This has been filed a few times; I'm picking this one as the canonical
bug since it mentions the /z thing.

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[Bug cli/16242] print format for hex float

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16242

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ubizjak at gmail dot com

--- Comment #6 from Tom Tromey <tromey at sourceware dot org> ---
*** Bug 25983 has been marked as a duplicate of this bug. ***

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[Bug cli/16242] print format for hex float

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16242

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |sogartary at yahoo dot com

--- Comment #7 from Tom Tromey <tromey at sourceware dot org> ---
*** Bug 15318 has been marked as a duplicate of this bug. ***

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[Bug cli/16242] print format for hex float

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16242

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |i.kerseymer at gmail dot com

--- Comment #8 from Tom Tromey <tromey at sourceware dot org> ---
*** Bug 16687 has been marked as a duplicate of this bug. ***

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[Bug cli/16242] print format for hex float

[schwab@linux-m68k.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16242

--- Comment #9 from Andreas Schwab <schwab@linux-m68k.org> ---
/z is really the same as /x, just with padding.

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[Bug cli/16242] print format for hex float

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16242

--- Comment #10 from Tom Tromey <tromey at sourceware dot org> ---
This is a bit of a pain to implement, since according to gnulib
some host printf implementations don't support %a.

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[Bug cli/16242] print format for hex float

[b7.10110111 at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16242

--- Comment #11 from Ruslan <b7.10110111 at gmail dot com> ---
Doesn't gnulib already provide an implementation of sprintf function family? Or
do you mean gnulib's sprintf doesn't implement %a on some architectures?

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[Bug cli/16242] print format for hex float

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16242

--- Comment #12 from Tom Tromey <tromey at sourceware dot org> ---
Actually I misread the gnulib docs -- it does fix this.
I didn't check to see if gdb already uses this module.

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[Bug cli/16242] print format for hex float

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16242

--- Comment #13 from Tom Tromey <tromey at sourceware dot org> ---
I added sprintf-posix to gdb's gnulib list and re-imported,
and there weren't any changes.  So I suppose it was already
pulled in.

Docs are here btw:
https://www.gnu.org/software/gnulib/manual/html_node/sprintf.html

So I think we're ok using %a for ordinary things.
However there's also the question of target-float.c.

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[Bug cli/16242] print format for hex float

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16242

--- Comment #14 from Tom Tromey <tromey at sourceware dot org> ---
(In reply to Tom Tromey from comment #13)
> I added sprintf-posix to gdb's gnulib list and re-imported,
> and there weren't any changes.  So I suppose it was already
> pulled in.

LOL I used the wrong tree.
This pulls in a bunch more stuff, so I wonder whether it's
appropriate at this stage.

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[Bug cli/16242] print format for hex float

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16242

--- Comment #15 from Tom Tromey <tromey at sourceware dot org> ---
Actually I've come around to the idea that p/x should just
reinterpret the bits and print those exactly.
It's what the manual implies, for one thing.

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[Bug cli/16242] print format for hex float

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16242

--- Comment #16 from Tom Tromey <tromey at sourceware dot org> ---
https://sourceware.org/pipermail/gdb-patches/2022-February/185967.html

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[Bug cli/16242] print format for hex float

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16242

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at sourceware dot org   |tromey at sourceware dot org

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[Bug cli/16242] print format for hex float

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16242

--- Comment #17 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Tom Tromey <tromey@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=56262a931b7ca8ee3ec9104bc7e9e0b40cf3d64e

commit 56262a931b7ca8ee3ec9104bc7e9e0b40cf3d64e
Author: Tom Tromey <tromey@adacore.com>
Date:   Thu Feb 17 13:43:59 2022 -0700

    Change how "print/x" displays floating-point value

    Currently, "print/x" will display a floating-point value by first
    casting it to an integer type.  This yields weird results like:

        (gdb) print/x 1.5
        $1 = 0x1

    This has confused users multiple times -- see PR gdb/16242, where
    there are several dups.  I've also seen some confusion from this
    internally at AdaCore.

    The manual says:

        'x'
             Regard the bits of the value as an integer, and print the integer
             in hexadecimal.

    ... which seems more useful.  So, perhaps what happened is that this
    was incorrectly implemented (or maybe correctly implemented and then
    regressed, as there don't seem to be any tests).

    This patch fixes the bug.

    There was a previous discussion where we agreed to preserve the old
    behavior:

        https://sourceware.org/legacy-ml/gdb-patches/2017-06/msg00314.html

    However, I think it makes more sense to follow the manual.

    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=16242

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[Bug cli/16242] print format for hex float

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16242

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|NEW                         |RESOLVED
   Target Milestone|---                         |12.1

--- Comment #18 from Tom Tromey <tromey at sourceware dot org> ---
Fixed.

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[Bug cli/16242] print format for hex float

[schwab@linux-m68k.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16242

Andreas Schwab <schwab@linux-m68k.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|FIXED                       |---
             Status|RESOLVED                    |REOPENED

--- Comment #19 from Andreas Schwab <schwab@linux-m68k.org> ---
That isn't hex float, though.

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[Bug cli/16242] print format for hex float

[brobecker at gnat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16242

Joel Brobecker <brobecker at gnat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|12.1                        |---
                 CC|                            |brobecker at gnat dot com

--- Comment #20 from Joel Brobecker <brobecker at gnat dot com> ---
Since this ticket has been re-opened, I've removed the target-milestone, as
this isn't a blocking change for GDB 12 release.

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[Bug cli/16242] print format for hex float

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16242

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|tromey at sourceware dot org       |unassigned at sourceware dot org

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[Bug cli/16242] print format for hex float

[nchatz314 at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16242

Nikolaos Chatzikonstantinou <nchatz314 at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |nchatz314 at gmail dot com

--- Comment #21 from Nikolaos Chatzikonstantinou <nchatz314 at gmail dot com> ---
If this is of any help, if you add the following python script and source it,

    import gdb

    class Hexfloat (gdb.Function):
      """Converts a float to a hex representation."""

      def __init__ (self):
        super (Hexfloat, self).__init__ ("hexfloat")

      def invoke (self, x):
        return float.hex(float(x))

    Hexfloat()

you can get what you want (I think) with

    (gdb) p $hexfloat(123.4567)
    $1 = "0x1.edd3a92a30553p+6"

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[Bug cli/16242] print format for hex float

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16242

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |elson.wei at gmail dot com

--- Comment #22 from Tom Tromey <tromey at sourceware dot org> ---
*** Bug 20506 has been marked as a duplicate of this bug. ***

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[Bug cli/16242] print format for hex float

[ssbssa at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16242

--- Comment #23 from Hannes Domani <ssbssa at sourceware dot org> ---
*** Bug 21907 has been marked as a duplicate of this bug. ***

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