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digitalmars.D.bugs - [Issue 7376] New: floating point bug

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=7376

           Summary: floating point bug
           Product: D
           Version: D2
          Platform: x86_64
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody puremagic.com
        ReportedBy: iteronvexor gmail.com



As discussed in this thread:
http://www.digitalmars.com/pnews/read.php?server=news.digitalmars.com&group=digitalmars.D.learn&artnum=31864

Shorter version of the bug:

import std.stdio;

void calculate1(float a, float b)
{
       float s1 = 1.0f - a;

       float s2 = a * b;
       writeln(s2);
       writeln(a * b);
}

void calculate2(float a, float b)
{
       float s1 = 1.0 - a;
       float s2 = a * b;
       writeln(s2);
       writeln(a * b);
}

void calculate3(double a, double b)
{
       double s1 = 1.0 - a;
       double s2 = a * b;
       writeln(s2);
       writeln(a * b);
}

int main()
{      
       writeln("calculate1:");
       calculate1(0.75f,2.0f);
       writeln("calculate2:");
       calculate2(0.75f,2.0f);
       writeln("calculate3:");
       calculate3(0.75f,2.0f);
       return 0;
}


-------------------------------------------------
+       The complete output
-------------------------------------------------

calculate1:
1.5
1.5
calculate2:
0
1.5
calculate3:
1.5
1.5

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next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=7376


Walter Bright <bugzilla digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bugzilla digitalmars.com



01:40:06 PST ---
I tried this on Ubuntu Linux with the latest build:

dmd foo -O
dmd foo
dmd foo -O -inline

and could not reproduce an error. The generated code looks fine, too.

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Jonathan M Davis <jmdavisProg gmx.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jmdavisProg gmx.com



PST ---
I see it on 2.057 without -inline or -O (the problem seems to go away with
either of those flags), but I don't see it at all on the latest from github.
This using using 64-bit Arch Linux.

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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
         Resolution|                            |WORKSFORME



09:23:42 PST ---
Ok, so without further evidence it is not working in the latest build, I'm
going to resolve this.

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