On Thursday, 6 October 2016 at 20:45:24 UTC, Iain Buclaw wrote:
On 6 October 2016 at 22:31, Ilya Yaroshenko via Digitalmars-d
<digitalmars-d@puremagic.com> wrote:
On Thursday, 6 October 2016 at 20:07:19 UTC, Iain Buclaw wrote:
On 6 October 2016 at 18:53, Ilya Yaroshenko via Digitalmars-d
<digitalmars-d@puremagic.com> wrote:
[...]
If you can prove that llvm intrinsics are pure (gcc math
intrinsics are not) and that llvm intrinsics pass the
unittest (gcc math intrinsics aren't guaranteed to due to the
vagary of libm implementations and quirky cpu support that
trades correctness for efficiency).
[...]
LLVM math functions are pure :P
http://llvm.org/docs/LangRef.html
I picked a random example.
http://llvm.org/docs/LangRef.html#llvm-sin-intrinsic
"""
Semantics:
This function returns the sine of the specified operand,
returning the same values as the libm sin functions would, and
handles error conditions in the same way.
"""
This would have me believe that they are infact not pure. ;-)
But, I've never looked under the hood of LLVM, so I can only
believe those who have. In any case, IMO, you should focus on
getting this into core.math. That's where compiler intrinsics
should go. The intrinsics of std.math are historical baggage
and are probably due a deprecation - that is, in the sense that
their symbols be converted into aliases.
Iain.
Current code is (please look in LDC's fork):
version(LDC)
{
real cos(real x) @safe pure nothrow @nogc { return
llvm_cos(x); }
///ditto
double cos(double x) @safe pure nothrow @nogc { return
llvm_cos(x); }
///ditto
float cos(float x) @safe pure nothrow @nogc { return
llvm_cos(x); }
}
else
{
real cos(real x) @safe pure nothrow @nogc { pragma(inline, true);
return core.math.cos(x); }
//FIXME
///ditto
double cos(double x) @safe pure nothrow @nogc { return
cos(cast(real)x); }
//FIXME
///ditto
float cos(float x) @safe pure nothrow @nogc { return
cos(cast(real)x); }
}
So, I don't see a reason why this change break something, hehe
