[GHC] #13570: CoreFVs patch makes n-body slower
GHC
ghc-devs at haskell.org
Fri Apr 28 03:30:19 UTC 2017
#13570: CoreFVs patch makes n-body slower
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Reporter: simonpj | Owner: (none)
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 8.0.1
Resolution: | Keywords:
Operating System: Unknown/Multiple | Architecture:
| Unknown/Multiple
Type of failure: None/Unknown | Test Case:
Blocked By: | Blocking:
Related Tickets: | Differential Rev(s):
Wiki Page: |
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Comment (by hsyl20):
With the floating-in of the array-indexing primop, instead of having the
following order:
{{{
1) A <- load from address @XXX
2) compute several things (sqrt,mul,div,sub,add) independent of A
3) store (A - ..) at address @XXX
}}}
We have this order: 2, 1, 3.
As this is n-body, could it be a prefetching issue?
--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13570#comment:3>
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