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* [Bug gdb/12134] New: long double precision lost
@ 2010-10-18 21:08 jakub at redhat dot com
2023-12-30 20:36 ` [Bug gdb/12134] " ssbssa at sourceware dot org
0 siblings, 1 reply; 2+ messages in thread
From: jakub at redhat dot com @ 2010-10-18 21:08 UTC (permalink / raw)
To: gdb-prs
http://sourceware.org/bugzilla/show_bug.cgi?id=12134
Summary: long double precision lost
Product: gdb
Version: unknown
Status: NEW
Severity: normal
Priority: P2
Component: gdb
AssignedTo: unassigned@sourceware.org
ReportedBy: jakub@redhat.com
Target: x86_64-linux
double d = __DBL_DENORM_MIN__;
long double l1 = (long double) __DBL_DENORM_MIN__;
long double l2 = __LDBL_MIN__;
long double l3 = __LDBL_MIN__ * 0x1p200L;
int
main (void)
{
return 0;
}
gcc -g -o tt tt.c
gdb ./tt
b main
r
(gdb) p d
$1 = 4.9406564584124654e-324
(gdb) p l1
$2 = 4.9406564584124654417656879286822137e-324
(gdb) p l2
$3 = 0
(gdb) p l3
$4 = 0
(gdb) x/2gx &l2
0x600830 <l2>: 0x8000000000000000 0x0000000000000001
(gdb) x/2gx &l3
0x600840 <l3>: 0x8000000000000000 0x00000000000000c9
>From the above it seems that the long double value read from the vars is
somewhere in gdb internally cast to double, then probably cast back to long
double and printed (or goes through text representation or whatever), because
l2 and l3 definitely are not zero.
Also, it would be nice if p/x {d,l1,l2,l3} printed the double/long double vars
using ISO C99 hexadecimal notation (%a/%La for printf) and if hex float
literals could be used in gdb expressions.
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* [Bug gdb/12134] long double precision lost
2010-10-18 21:08 [Bug gdb/12134] New: long double precision lost jakub at redhat dot com
@ 2023-12-30 20:36 ` ssbssa at sourceware dot org
0 siblings, 0 replies; 2+ messages in thread
From: ssbssa at sourceware dot org @ 2023-12-30 20:36 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=12134
Hannes Domani <ssbssa at sourceware dot org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |ssbssa at sourceware dot org
Target Milestone|--- |8.1
Status|NEW |RESOLVED
Resolution|--- |FIXED
--- Comment #1 from Hannes Domani <ssbssa at sourceware dot org> ---
This works since gdb-8.1:
```
(gdb) p d
$1 = 4.9406564584124654e-324
(gdb) p l1
$2 = 4.94065645841246544177e-324
(gdb) p l2
$3 = 3.36210314311209350626e-4932
(gdb) p l3
$4 = 5.40269144938955163113e-4872
```
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2010-10-18 21:08 [Bug gdb/12134] New: long double precision lost jakub at redhat dot com
2023-12-30 20:36 ` [Bug gdb/12134] " ssbssa at sourceware dot org
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