id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	os	architecture	failure	difficulty	testcase	blockedby	blocking	related
2070	Record field selectors are not optimized	twanvl		"It seems that record field selectors are not optimized. Usually this doesn't matter, but when there are unpacked fields this leaves suboptimal code. The equivalent code using the data type constructor ''is'' optimized.

For example:
{{{
module Test where

data Test = Test { getR :: {-# UNPACK #-} !Int }
getC (Test a) = a
}}}

Generates the following core (with -O2 -ddump-simpl):

{{{
Test.getR :: Test.Test -> GHC.Base.Int
[RecSel]
[Arity 1
 NoCafRefs
 Str: DmdType U(L)m]
Test.getR =
  \ (tpl_B1 :: Test.Test) ->
    case tpl_B1 of tpl1_B2 { Test.Test rb_B4 ->
    let {
      ipv_B3 [Just S] :: GHC.Base.Int
      [Str: DmdType m]
      ipv_B3 = GHC.Base.I# rb_B4
    } in  ipv_B3
    }

Test.getC :: Test.Test -> GHC.Base.Int
[GlobalId]
[Arity 1
 NoCafRefs
 Str: DmdType U(L)m]
Test.getC =
  \ (ds_d5Q :: Test.Test) ->
    case ds_d5Q of wild_B1 { Test.Test rb_d5S -> GHC.Base.I# rb_d5S }
}}}

After further investigation, it seems that `getR` is not passed through the optimizer at all, earlier simplifier passes (-ddump-simpl-iterations, -ddump-cse, -ddump-occur-anal) do not include the function."	bug	closed	normal		Compiler	6.9	fixed			Unknown/Multiple	Unknown/Multiple		Unknown