Re: [GHC] #2270: gcd is specialised only for Int
#2270: gcd is specialised only for Int +--- Reporter: dons |Owner: d...@galois.com Type: bug | Status: closed Priority: normal |Milestone: 6.12.1 Component: libraries/base | Version: 6.8.2 Severity: normal | Resolution: duplicate Keywords: rules, performance, double, gcd | Difficulty: Unknown Testcase: | Os: Unknown/Multiple Architecture: Unknown/Multiple | +--- Changes (by igloo): * status: new = closed * resolution: = duplicate Comment: Closing, as this ticket is subsumed by #3055. -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/2270#comment:8 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Re: [GHC] #2270: gcd is specialised only for Int
#2270: gcd is specialised only for Int +--- Reporter: dons |Owner: d...@galois.com Type: bug | Status: new Priority: normal |Milestone: 6.12.1 Component: libraries/base | Version: 6.8.2 Severity: normal | Resolution: Keywords: rules, performance, double, gcd | Difficulty: Unknown Testcase: | Os: Unknown/Multiple Architecture: Unknown/Multiple | +--- Changes (by igloo): * milestone: 6.10.2 = 6.12.1 -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/2270#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Re: [GHC] #2270: gcd is specialised only for Int
#2270: gcd is specialised only for Int -+-- Reporter: dons | Owner: [EMAIL PROTECTED] Type: bug | Status: new Priority: normal | Milestone: 6.10.2 Component: libraries/base |Version: 6.8.2 Severity: normal | Resolution: Keywords: rules, performance, double, gcd | Difficulty: Unknown Testcase: | Architecture: Unknown/Multiple Os: Unknown/Multiple | -+-- Changes (by igloo): * milestone: 6.10.1 = 6.10.2 -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/2270#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Re: [GHC] #2270: gcd is specialised only for Int
#2270: gcd is specialised only for Int -+-- Reporter: dons | Owner: [EMAIL PROTECTED] Type: bug | Status: new Priority: normal | Milestone: 6.10.1 Component: libraries/base |Version: 6.8.2 Severity: normal | Resolution: Keywords: rules, performance, double, gcd | Difficulty: Unknown Testcase: | Architecture: Unknown Os: Unknown | -+-- Changes (by guest): * keywords: = rules, performance, double, gcd * cc: rules, performance, double, gcd (removed) * cc: [EMAIL PROTECTED] (added) -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/2270#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Re: [GHC] #2270: gcd is specialised only for Int
#2270: gcd is specialised only for Int +--- Reporter: dons| Owner: [EMAIL PROTECTED] Type: bug | Status: new Priority: normal | Milestone: 6.10.1 Component: libraries/base |Version: 6.8.2 Severity: normal | Resolution: Keywords: | Difficulty: Unknown Testcase: | Architecture: Unknown Os: Unknown | +--- Changes (by igloo): * component: Compiler = libraries/base -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/2270#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Re: [GHC] #2270: gcd is specialised only for Int
#2270: gcd is specialised only for Int --+- Reporter: dons | Owner: [EMAIL PROTECTED] Type: bug | Status: new Priority: normal| Milestone: 6.10.1 Component: Compiler |Version: 6.8.2 Severity: normal| Resolution: Keywords:| Difficulty: Unknown Testcase:| Architecture: Unknown Os: Unknown | --+- Changes (by igloo): * difficulty: = Unknown * milestone: = 6.10.1 -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/2270#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
[GHC] #2270: gcd is specialised only for Int
#2270: gcd is specialised only for Int
+---
Reporter: dons | Owner: [EMAIL PROTECTED]
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 6.8.2|Severity: normal
Keywords: |Testcase:
Architecture: Unknown | Os: Unknown
+---
We have the general:
{{{
gcd :: (Integral a) = a - a - a
gcd 0 0 = error Prelude.gcd: gcd 0 0 is undefined
gcd x y = gcd' (abs x) (abs y)
where gcd' a 0 = a
gcd' a b = gcd' b (a `rem` b)
}}}
And a specialisation for Int only:
{{{
{-# RULES
gcd/Int-Int-Int gcd = gcdInt
#-}
gcdInt (I# a) (I# b) = g a b
where g 0# 0# = error GHC.Base.gcdInt: gcd 0 0 is undefined
g 0# _ = I# absB
g _ 0# = I# absA
g _ _ = I# (gcdInt# absA absB
}}}
Thanks to the gcdInt# primop.
If we use Word here, or other Int types, we get the slow version (which is
only 10x slower, surprisingly):
{{{
main = print . sumU
. mapU (gcd 2)
$ enumFromToU 0 (1 :: Word)
}}}
Comes out as:
{{{
time ./henning
15002
./henning 25.73s user 0.05s system 99% cpu 25.936 total
}}}
Versus:
{{{
$ time ./henning
15002
./henning 2.33s user 0.00s system 99% cpu 2.334 tota
}}}
So there are two things we can do here to improve the situation:
== Step 1: Add rules for getting from the other Int* types to gcdInt# ==
{{{
{-# RULES
gcd/Int32-Int32-Int32 gcd = gcdInt32
#-}
gcdInt32 :: Int32 - Int32 - Int32
gcdInt32 x y = fromIntegral ((gcd :: Int - Int - Int) (fromIntegral x)
(fromIntegral y))
}}}
For example, takes the running time from 28 seconds to 2.4seconds, for:
{{{
main = print . sumU
. mapU (gcd 2)
$ enumFromToU 0 (1 :: Int32)
}}}
== Step 2: optionally add a gcdWord# ==
We could then also add a gcdWord# primop,or perhaps just following
fromIntegral, and test
for negative first, then conditionally dispatch to gcdInt.
What do people think?
--
Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/2270
GHC http://www.haskell.org/ghc/
The Glasgow Haskell Compiler___
Glasgow-haskell-bugs mailing list
Glasgow-haskell-bugs@haskell.org
http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
