Re: GNAT Optimization of Constant Expressions

[Duncan Sands <baldrick@free.fr>]

> while what you say is very logical, unfortunately it seems to be wrong: I
> checked and these functions are not being marked pure.  So how come declaring
> a constant helps?  I don't know - I didn't look into it yet.

I took a quick look.  At -O2 defining constants makes no difference (in the
C case "const" functions are hoisted out of the loop at -O2) but with -O3
the calls are hoisted.  This is presumably because gcc inlines the bodies
for sin etc at -O3 and sees that in fact they have no side-effects, but
for some reason doesn't hoist them unless the constants have been defined.

Ciao,

Duncan.