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Diffstat (limited to 'compiler/GHC/Prelude.hs')
| -rw-r--r-- | compiler/GHC/Prelude.hs | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/compiler/GHC/Prelude.hs b/compiler/GHC/Prelude.hs index f61dad9517..6a810ac200 100644 --- a/compiler/GHC/Prelude.hs +++ b/compiler/GHC/Prelude.hs @@ -1,5 +1,6 @@ {-# LANGUAGE CPP #-} {-# OPTIONS_HADDOCK not-home #-} +{-# OPTIONS_GHC -O2 #-} -- See Note [-O2 Prelude] -- | Custom GHC "Prelude" -- @@ -18,6 +19,17 @@ module GHC.Prelude ) where +{- Note [-O2 Prelude] +~~~~~~~~~~~~~~~~~~~~~ +There is some code in GHC that is *always* compiled with -O[2] because +of it's impact on compile time performance. Some of this code might depend +on the definitions like shiftL being defined here being performant. + +So we always compile this module with -O2. It's (currently) tiny so I +have little reason to suspect this impacts overall GHC compile times +negatively. + +-} -- We export the 'Semigroup' class but w/o the (<>) operator to avoid -- clashing with the (Outputable.<>) operator which is heavily used -- through GHC's code-base. |