On Thursday, 2 March 2017 at 21:34:56 UTC, ag0aep6g wrote:
On 03/02/2017 10:10 PM, Guillaume Chatelet wrote:
On Thursday, 2 March 2017 at 20:30:47 UTC, Guillaume Chatelet
wrote:
Here is the same code in D:
void main(string[] args)
{
import std.math;
FloatingPointControl fpctrl;
fpctrl.rounding = FloatingPointControl.roundUp;
writefln("%.32g", float.min_normal + 1.0f);
}
Execution on my machine yields:
dmd -run test_denormal.d
1
Did I miss something?
This example is closer to the C++ one:
void main(string[] args)
{
import core.stdc.fenv;
fesetround(FE_UPWARD);
writefln("%.32g", float.min_normal + 1.0f);
}
It still yields "1"
This prints the same as the C++ version:
----
void main(string[] args)
{
import std.stdio;
import core.stdc.fenv;
fesetround(FE_UPWARD);
float x = 1.0f;
x += float.min_normal;
writefln("%.32g", x);
}
----
Soo, a bug/limitation of constant folding?
With FloatingPointControl it still prints "1". Does
FloatingPointControl.rounding do something different than
fesetround? The example in the docs [1] only shows how it
changes rint's behavior.
[1] http://dlang.org/phobos/std_math.html#.FloatingPointControl
Thx for the investigation!
Here is the code for FloatingPointControl
https://github.com/dlang/phobos/blob/master/std/math.d#L4809
Other code (enableExceptions / disableExceptions) seems to have
two code path depending on "version(X86_Any)", rounding doesn't.
Maybe that's the bug?
