[Issue 7546] 64-bit floating-point issue with negative zero: -0.0 == 0.0 is false.

2012-05-11 Thread d-bugmail
http://d.puremagic.com/issues/show_bug.cgi?id=7546



--- Comment #3 from github-bugzi...@puremagic.com 2012-05-11 19:02:54 PDT ---
Commit pushed to master at https://github.com/D-Programming-Language/dmd

https://github.com/D-Programming-Language/dmd/commit/a8ffc8ab60aa3e1ae965e5764f0900e14a0881c1
Fix issue 7546 64-bit floating-point issue with negative zero: -0.0 == 0.0 is
false

Just duplicate the code for float == float.

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[Issue 7546] 64-bit floating-point issue with negative zero: -0.0 == 0.0 is false.

2012-02-19 Thread d-bugmail
http://d.puremagic.com/issues/show_bug.cgi?id=7546



--- Comment #1 from kenn...@gmail.com 2012-02-19 11:38:41 PST ---
The problem is that, when comparing with 0.0 or -0.0, the backend will generate
an integer 'cmp' instruction, but -0.0 has a different bit pattern than 0.0, so
the equality will fail.

 cmpQWORD PTR [rbp-0x8],0x0
 je ...

The code works if the type is 'float' because it uses an 'add eax, eax' trick
make both 0.0f and -0.0f set the ZF flag.

This code also work if the type if 'real' because it uses x87.

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[Issue 7546] 64-bit floating-point issue with negative zero: -0.0 == 0.0 is false.

2012-02-19 Thread d-bugmail
http://d.puremagic.com/issues/show_bug.cgi?id=7546


bearophile_h...@eml.cc changed:

   What|Removed |Added

 CC||bearophile_h...@eml.cc


--- Comment #2 from bearophile_h...@eml.cc 2012-02-19 12:05:22 PST ---
I think 0.0 == -0.0, but 0.0 !is -0.0.

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