diff options
| author | Andreas Klebinger <klebinger.andreas@gmx.at> | 2021-05-10 22:06:51 +0200 |
|---|---|---|
| committer | Matthew Pickering <matthewtpickering@gmail.com> | 2022-02-12 13:59:41 +0000 |
| commit | 0e93023eef174262310737004d398bc7a606939a (patch) | |
| tree | 091a34f78b7911d8b38f414ff8eab90796581c47 /compiler/GHC/Prelude.hs | |
| parent | 90a26f8b0dd99129d3fd7fe28127cb69abd46328 (diff) | |
| download | haskell-0e93023eef174262310737004d398bc7a606939a.tar.gz | |
Tag inference work.
This does three major things:
* Enforce the invariant that all strict fields must contain tagged
pointers.
* Try to predict the tag on bindings in order to omit tag checks.
* Allows functions to pass arguments unlifted (call-by-value).
The former is "simply" achieved by wrapping any constructor allocations with
a case which will evaluate the respective strict bindings.
The prediction is done by a new data flow analysis based on the STG
representation of a program. This also helps us to avoid generating
redudant cases for the above invariant.
StrictWorkers are created by W/W directly and SpecConstr indirectly.
See the Note [Strict Worker Ids]
Other minor changes:
* Add StgUtil module containing a few functions needed by, but
not specific to the tag analysis.
-------------------------
Metric Decrease:
T12545
T18698b
T18140
T18923
LargeRecord
Metric Increase:
LargeRecord
ManyAlternatives
ManyConstructors
T10421
T12425
T12707
T13035
T13056
T13253
T13253-spj
T13379
T15164
T18282
T18304
T18698a
T1969
T20049
T3294
T4801
T5321FD
T5321Fun
T783
T9233
T9675
T9961
T19695
WWRec
-------------------------
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. |