[GHC] #5302: Unused arguments in join points
GHC
ghc-devs at haskell.org
Thu Feb 15 07:30:39 UTC 2018
#5302: Unused arguments in join points
-------------------------------------+-------------------------------------
Reporter: reinerp | Owner: simonpj
Type: bug | Status: new
Priority: low | Milestone:
Component: Compiler | Version: 7.0.3
Resolution: | Keywords: JoinPoints
Operating System: Unknown/Multiple | Architecture:
Type of failure: Runtime | Unknown/Multiple
performance bug | Test Case:
Blocked By: | Blocking:
Related Tickets: | Differential Rev(s):
Wiki Page: |
-------------------------------------+-------------------------------------
Comment (by osa1):
Just tried with GHC HEAD. Late demand analysis removes unused join point
argument.
{{{
let-no-escape {
$j_s4wc [Occ=Once*!T[2], Dmd=<C(C(S)),1*C1(C1(U(U,U)))>]
:: GHC.Prim.Int#
-> GHC.Types.Int
-> (# Unboxed.FingerTree
Unboxed.Size (Unboxed.Node Unboxed.Size c_s44z),
Unboxed.FingerTree
Unboxed.Size (Unboxed.Node Unboxed.Size c_s44z) #)
[LclId[JoinId(2)], Arity=2, Str=<S,U><L,A>, Unf=OtherCon []] = ...
}}}
After:
{{{
let-no-escape {
$w$j_s4BK [InlPrag=NOUSERINLINE[0],
Occ=Once*!T[1],
Dmd=<C(S),1*C1(U(U,U))>]
:: GHC.Prim.Int#
-> (# Unboxed.FingerTree
Unboxed.Size (Unboxed.Node Unboxed.Size c_s45o),
Unboxed.FingerTree
Unboxed.Size (Unboxed.Node Unboxed.Size c_s45o) #)
[LclId[JoinId(1)], Arity=1, Str=<S,U>, Unf=OtherCon []] = ...
}}}
--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5302#comment:17>
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