[External] : Re: Classfile API tracking RFEs

[Adam Sotona]

On 08.03.2023 8:23, "Michael van Acken" <michael.van.acken at gmail.com> wrote:

Am Mi., 8. März 2023 um 08:05 Uhr schrieb Adam Sotona <adam.sotona at oracle.com<mailto:adam.sotona at oracle.com>>:

Oh, and constantInstruction() properly handling -0.0d and -0.0f would be nice.  This is the
one patch I have been carrying around since the very beginning that has not been resolved.

-- mva

Hi Michael,
Do you know some cases of -0.0d and -0.0f wrong handling?

I don't quite understand the question.

Negative zero compares as ==-equal to positive zero under IEEE-754, but
the two are distinct bit patterns.  Both javac and jshell treat them as distinct,
as do equals() and compareTo().

jshell> 0.0f == -0.0f
$3 ==> true

jshell> Float.floatToRawIntBits(0.0f)
$4 ==> 0

jshell> Float.floatToRawIntBits(-0.0f)
$5 ==> -2147483648

The current constantInstruction would lead to a different output for the last line,
by squashing the value to 0.0f.

-- mva


Thanks for pointing it out, I’ve added test and fixed it, see:
https://github.com/openjdk/jdk/pull/10982/commits/65a69135f6623e0f78aeaf8cd7b2ebdc8e1bbb27


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