2015-04-19 9:44 GMT+02:00 Joachim Breitner m...@joachim-breitner.de:
[...] So my question to the general audience: Is such branchless code really
better than the current, branching code? Can someone provide us with an
example that shows that it is better? Do I need to produce different
Hi,
Am Montag, den 20.04.2015, 16:29 +0200 schrieb Sven Panne:
2015-04-19 9:44 GMT+02:00 Joachim Breitner m...@joachim-breitner.de:
[...] So my question to the general audience: Is such branchless code really
better than the current, branching code? Can someone provide us with an
example
Sorry, I forgot to answer to the list.
If the code is already there and some architectures can profit of it,
especially in inner loops - why not just make it an optimisation flag?
Nicu
Am 20.04.2015 um 16:41 schrieb Joachim Breitner:
Hi,
Am Montag, den 20.04.2015, 16:29 +0200 schrieb Sven
Hi,
Am Montag, den 20.04.2015, 19:45 +0200 schrieb Niculae Ionita:
Sorry, I forgot to answer to the list.
ah, and sorry for telling you so before looking on the list.
If the code is already there and some architectures can profit of it,
especially in inner loops - why not just make it an
I've gotten substantial speedups (30%) in the past (e.g. in the hashtables
package) by replacing search loops with branchless code, but the technique
works best in situations where you have a long run of straight-line integer
code for the CPU to chew on; for branchless to be a win you need to feed
2015-04-20 16:41 GMT+02:00 Joachim Breitner m...@joachim-breitner.de:
The conclusion I draw from your mail, at last for our case, is:
Don’t bother (and keep the compiler code simple). Is that a correct
reading?
Yes, I think that's the right approach. Do simple things like e.g. a
distinction
On Mon, Apr 20, 2015 at 10:29 AM, Sven Panne svenpa...@gmail.com wrote:
* On more powerful cores with heavy out-of-order execution, it's
hard to beat a well-predicted branch.
With regard to this, I was wondering if we have a way of arranging for
good branch prediction in GHC.
For
On Apr 19, 2015 09:44, Joachim Breitner m...@joachim-breitner.de wrote:
Dear devs,
in https://ghc.haskell.org/trac/ghc/ticket/10124 bgamari suggested that
code like
f :: Int - Bool
f a = case a of
1 - True
5 - True
8 -
Joachim Breitner m...@joachim-breitner.de writes:
Dear devs,
in https://ghc.haskell.org/trac/ghc/ticket/10124 bgamari suggested that
code like
f :: Int - Bool
f a = case a of
1 - True
5 - True
8 - True
the optimization manual ben mentions is
http://www.intel.com/content/www/us/en/architecture-and-technology/64-ia-32-architectures-optimization-manual.html
it does a very good job laying out the scope of both *generality* and
*impact* for a huge range of systemsy tricks.
there are certain
Em domingo, 19 de abril de 2015, Joachim Breitner m...@joachim-breitner.de
escreveu:
Dear devs,
in https://ghc.haskell.org/trac/ghc/ticket/10124 bgamari suggested that
code like
f :: Int - Bool
f a = case a of
1 - True
5 - True
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