[Bug c/35712] New: decimal float literal constant zero loses significant trailing zeroes

[Bug c/35712] New: decimal float literal constant zero loses significant trailing zeroes

[janis at gcc dot gnu dot org]

Decimal floating point types support significant trailing zeroes to
specify how much precision a value has.  Trailing zeroes are relevant
even for values of zero; for example, rounding 1.e-11dd to 10 places
after the decimal point results in 0.e-10dd.

The draft Technical Report N1241 for ISO/IEC TR 24732 doesn't specify
this directly, but section 9.5 "Formatted input/output specifiers"
shows expected output for five different representations of zero:
0, -0, 0.000000, 0e-07, and 0e+02.

Currently GCC converts all decimal float literal values of zero to
0.DF, 0.DD, or 0.DL.

I'm testing a patch to fix this but want a PR to record the issue.


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           Summary: decimal float literal constant zero loses significant
                    trailing zeroes
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: janis at gcc dot gnu dot org
        ReportedBy: janis at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35712

[Bug c/35712] decimal float literal constant zero loses significant trailing zeroes

[janis at gcc dot gnu dot org]

------- Comment #1 from janis at gcc dot gnu dot org  2008-04-03 23:50 -------
Subject: Bug 35712

Author: janis
Date: Thu Apr  3 23:49:35 2008
New Revision: 133881

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=133881
Log:
2008-04-03  Janis Johnson  <janis187@us.ibm.com>

gcc/
        PR c/35712
        * dfp.c (decimal_from_decnumber): Retain trailing zeroes for
          decimal-float literal constant zero.

testsuite/
        PR c/35712
        * gcc.dg/dfp/constants-zero.c: New test.


Added:
    trunk/gcc/testsuite/gcc.dg/dfp/constants-zero.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/dfp.c
    trunk/gcc/testsuite/ChangeLog


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35712

[Bug c/35712] decimal float literal constant zero loses significant trailing zeroes

[bergner at gcc dot gnu dot org]

------- Comment #2 from bergner at gcc dot gnu dot org  2008-06-23 19:59 -------
Janis, is this fixed so we can close this bugzilla?


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35712

[Bug c/35712] decimal float literal constant zero loses significant trailing zeroes

[janis at gcc dot gnu dot org]

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janis at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2008-09-11 16:55:59
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35712

[Bug c/35712] decimal float literal constant zero loses significant trailing zeroes

[janis at gcc dot gnu dot org]

------- Comment #3 from janis at gcc dot gnu dot org  2008-09-11 16:56 -------
Fixed in mainline.  It's not a regression so the fix has not been applied to
4.3.


-- 

janis at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35712

[Bug c/35712] decimal float literal constant zero loses significant trailing zeroes

[janis at gcc dot gnu dot org]

------- Comment #4 from janis at gcc dot gnu dot org  2008-09-18 18:35 -------
Subject: Bug 35712

Author: janis
Date: Thu Sep 18 18:33:58 2008
New Revision: 140466

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=140466
Log:
        Backport from mainline:
        2008-04-03  Janis Johnson  <janis187@us.ibm.com>
gcc/
        PR c/35712
        * dfp.c (decimal_from_decnumber): Retain trailing zeroes for
        decimal-float literal constant zero.
testsuite/
        PR c/35712
        * gcc.dg/dfp/constants-zero.c: New test.

Added:
    branches/gcc-4_3-branch/gcc/testsuite/gcc.dg/dfp/constants-zero.c
Modified:
    branches/gcc-4_3-branch/gcc/ChangeLog
    branches/gcc-4_3-branch/gcc/dfp.c
    branches/gcc-4_3-branch/gcc/testsuite/ChangeLog


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35712

[Bug c/35712] decimal float literal constant zero loses significant trailing zeroes

[rguenth at gcc dot gnu dot org]

-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.3.2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35712