Annoying std.math issue
monarch_dodra
monarchdodra at gmail.com
Thu Mar 27 11:32:03 PDT 2014
On Thursday, 27 March 2014 at 18:18:25 UTC, H. S. Teoh wrote:
> Some time ago, Iain Buclaw kindly added non-asm implementations
> of math
> functions in std.math. However, CTFE still seems unable to
> correctly
> evaluate certain functions like atan2:
>
> import std.math;
> enum x = atan2(1.0, 2.0);
>
> Compiler output:
>
> /usr/src/d/phobos/std/math.d(856): Error: asm statements
> cannot be interpreted at compile time
> /usr/src/d/phobos/std/math.d(917): called from here:
> atan2(cast(real)y, cast(real)x)
> test.d(2): called from here: atan2(1.00000, 2.00000)
>
> Looking at std/math.d, it appears that
> version=InlineAsm_X86_Any is
> defined, which leads to the asm implementation of atan2, which
> CTFE
> can't interpret.
>
> However, right below that block is an else block containing a D
> implementation of atan2 that AFAICT *can* be interpreted in
> CTFE.
>
> So it would appear that version=InlineAsm_X86_Any should be
> suppressed
> during CTFE? But I'm not sure how this could be done in the
> compiler.
>
> In any case, it's an annoying limitation. :-(
>
>
> T
//----
auto atan(double x)
{
version(InlineAsm_X86_Any)
if (!__ctfe)
{
asm
{
...
}
return;
}
Fall back non-InlineAsm_X86_Any and ctfe
}
//----
?
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