real operations imprecise?

[WebFreak001]

I was dumping the full PI value on my machine with the highest 
precision it could get and got:

$ rdmd --eval='printf("%.70llf\n", PI)'
3.1415926535897932385128089594061862044327426701784133911132812500000000

now this all looks good, but when I tried to print PI_2 I got

$ rdmd --eval='printf("%.70llf\n", PI_2)'
1.5707963267948965579989817342720925807952880859375000000000000000000000

note how many more 0's there are.

When manually writing down the identifier as it is defined for PI 
but with the exponent reduced by one it looks good again:
$ rdmd --eval='printf("%.70llf\n", 
cast(real)0x1.921fb54442d18469898cc51701b84p+0L)'
1.5707963267948966192564044797030931022163713350892066955566406250000000

I would expect that the manifest constant PI_2 being defined as 
PI/2 would simply modify the exponent and not the actual value in 
such a drastic manner.

While I don't need it myself right now, is there some compiler 
switch to make real operations like this division more precise to 
not lose all these bits of information? (LDC 1.20.1)

Sure, 1^-50 precision might not be everyones typical use-case but 
I think there is potential improvement either in the compiler or 
std.math to be done here :p