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digitalmars.D.bugs - [Issue 4155] New: return of NaN to temporary fails equality test

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=4155

           Summary: return of NaN to temporary fails equality test
           Product: D
           Version: unspecified
          Platform: Other
        OS/Version: Windows
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody puremagic.com
        ReportedBy: melvin.curran googlemail.com


--- Comment #0 from melvin.curran googlemail.com 2010-05-03 09:06:03 PDT ---
The problem is found in both DMD 1.059 and 2.044 and is demonstrated by the
following program - every answer should be false, but that is not the case.

import std.stdio;

T getnan(T)() { return T.nan; }

void main()
{
    float  f = 0.0;
    double d = 0.0;
    real   r = 0.0;

    writefln("before assigning NaN, float:%s, double:%s, real:%s", f, d, r);

    f = getnan!(float)();
    d = getnan!(double)();
    r = getnan!(real)();

    writefln(" float test, literal:%s, assign:%s, temporary:%s", (float.nan ==
0), (f == 0), (getnan!(float)() == 0));
    writefln("double test, literal:%s, assign:%s, temporary:%s", (double.nan ==
0), (d == 0), (getnan!(double)() == 0));
    writefln("  real test, literal:%s, assign:%s, temporary:%s", (real.nan ==
0), (r == 0), (getnan!(real)() == 0));
}

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next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=4155


yebblies <yebblies gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |pull
                 CC|                            |yebblies gmail.com
           Platform|Other                       |x86
         AssignedTo|nobody puremagic.com        |yebblies gmail.com
         OS/Version|Windows                     |All
           Severity|normal                      |critical


--- Comment #1 from yebblies <yebblies gmail.com> 2012-02-24 01:42:51 EST ---
https://github.com/D-Programming-Language/dmd/pull/760

When T is a float or double, and in memory, dmd loads it to gp registers,
doubles it, then tests for zero.  When it's in ST(0), dmd uses fucompp to test
but the code that tests the flags is unaware of this and doesn't check the zero
flag to see if it was a nan comparison.

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prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=4155


yebblies <yebblies gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Version|unspecified                 |D1 & D2


--- Comment #2 from yebblies <yebblies gmail.com> 2012-02-27 03:37:25 EST ---
New pull

https://github.com/D-Programming-Language/dmd/pull/769

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prev sibling next sibling parent d-bugmail puremagic.com writes:
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--- Comment #3 from github-bugzilla puremagic.com 2012-04-27 18:21:45 PDT ---
Commit pushed to dmd-1.x at https://github.com/D-Programming-Language/dmd

https://github.com/D-Programming-Language/dmd/commit/ac10c87904a73311eba93143d1aa92988227be49
add yebblies fix Issue 4155 - return of NaN to temporary fails equality test

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--- Comment #4 from github-bugzilla puremagic.com 2012-04-27 18:21:57 PDT ---
Commit pushed to master at https://github.com/D-Programming-Language/dmd

https://github.com/D-Programming-Language/dmd/commit/e1d597875183f58464ac44b8eb5d3d28f1f90170
add yebblies fix Issue 4155 - return of NaN to temporary fails equality test

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prev sibling parent d-bugmail puremagic.com writes:
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Walter Bright <bugzilla digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |bugzilla digitalmars.com
         Resolution|                            |FIXED


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