• bearophile (5/5) Jun 22 2014 If someone here has followed this thread, ldc2 has big
• Orvid King (9/14) Jun 22 2014 Well, unless LDC is doing something somewhere that I can't find, Clang
• David Nadlinger via digitalmars-d-ldc (8/12) Jun 22 2014 The problem is that we somehow ended up with Iain's pure, multi-bitwidth...

"bearophile" <bearophileHUGS lycos.com> writes:

If someone here has followed this thread, ldc2 has big 
performance problems with the function "floor":

http://forum.dlang.org/thread/lo19l7$n2a$1 digitalmars.com

Bye,
bearophile

Orvid King <blah38621 gmail.com> writes:

On 6/22/2014 1:49 PM, bearophile wrote:
 If someone here has followed this thread, ldc2 has big performance
 problems with the function "floor":

 http://forum.dlang.org/thread/lo19l7$n2a$1 digitalmars.com

 Bye,
 bearophile

Well, unless LDC is doing something somewhere that I can't find, Clang
is using llvm's floor intrinsic, while LDC is using the non-inline asm
version of floor in phobos. There is however a declaration for llvm's
floor intrinsic in ldc.intrinsics : llvm_floor, but, with my limited
knowledge of LDC's inner workings, I don't believe that is what is being
used when you call std.math : floor. core.stdc.math would be using the
standard C library's floor function, which would be using an intrinsic
for floor.

David Nadlinger via digitalmars-d-ldc <digitalmars-d-ldc puremagic.com> writes:

On 22 Jun 2014, at 21:33, Orvid King via digitalmars-d-ldc wrote:
 On 6/22/2014 1:49 PM, bearophile wrote:
 If someone here has followed this thread, ldc2 has big performance
 problems with the function "floor":

 Well, unless LDC is doing something somewhere that I can't find, […]

The problem is that we somehow ended up with Iain's pure, multi-bitwidth 
D implementation being the default.

We should make our std.math call llvm.floor.*, or at least the C 
standard library one by default. Anybody wants to cook up a pull request 
for ldc-developers/phobos?

Thanks,
David