From 0e93023eef174262310737004d398bc7a606939a Mon Sep 17 00:00:00 2001
From: Andreas Klebinger <klebinger.andreas@gmx.at>
Date: Mon, 10 May 2021 22:06:51 +0200
Subject: 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
-------------------------
---
 compiler/GHC/Unit/Module/ModGuts.hs | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'compiler/GHC/Unit/Module/ModGuts.hs')

diff --git a/compiler/GHC/Unit/Module/ModGuts.hs b/compiler/GHC/Unit/Module/ModGuts.hs
index 1558e5944a..4fc683d844 100644
--- a/compiler/GHC/Unit/Module/ModGuts.hs
+++ b/compiler/GHC/Unit/Module/ModGuts.hs
@@ -31,6 +31,7 @@ import GHC.Types.Fixity.Env
 import GHC.Types.ForeignStubs
 import GHC.Types.HpcInfo
 import GHC.Types.Name.Reader
+import GHC.Types.Name.Set (NameSet)
 import GHC.Types.SafeHaskell
 import GHC.Types.SourceFile ( HscSource(..), hscSourceToIsBoot )
 import GHC.Types.SrcLoc
@@ -88,6 +89,7 @@ data ModGuts
         mg_fam_inst_env :: FamInstEnv,          -- ^ Type-family instance environment for
                                                 -- /home-package/ modules (including this
                                                 -- one); c.f. 'tcg_fam_inst_env'
+        mg_boot_exports :: !NameSet,             -- Things that are also export via hs-boot file
 
         mg_safe_haskell :: SafeHaskellMode,     -- ^ Safe Haskell mode
         mg_trust_pkg    :: Bool,                -- ^ Do we need to trust our
-- 
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