Don't mark lambda binders as OtherCon

We used to put OtherCon unfoldings on lambda binders of workers
and sometimes also join points/specializations with with the
assumption that since the wrapper would force these arguments
once we execute the RHS they would indeed be in WHNF.

This was wrong for reasons detailed in #21472. So now we purge
evaluated unfoldings from *all* lambda binders.

This fixes #21472, but at the cost of sometimes not using as efficient a
calling convention. It can also change inlining behaviour as some
occurances will no longer look like value arguments when they did
before.

As consequence we also change how we compute CBV information for
arguments slightly. We now *always* determine the CBV convention
for arguments during tidy. Earlier in the pipeline we merely mark
functions as candidates for having their arguments treated as CBV.

As before the process is described in the relevant notes:
Note [CBV Function Ids]
Note [Attaching CBV Marks to ids]
Note [Never put `OtherCon` unfoldigns on lambda binders]

-------------------------
Metric Decrease:
    T12425
    T13035
    T18223
    T18223
    T18923
    MultiLayerModulesTH_OneShot
Metric Increase:
    WWRec
-------------------------

5 files changed, 29 insertions, 12 deletions

diff --git a/testsuite/tests/stranal/should_compile/T20817.stderr b/testsuite/tests/stranal/should_compile/T20817.stderr
index ba364234db..c113c3c2d1 100644
--- a/testsuite/tests/stranal/should_compile/T20817.stderr
+++ b/testsuite/tests/stranal/should_compile/T20817.stderr
@@ -234,10 +234,10 @@ Rec {
 -- RHS size: {terms: 34, types: 36, coercions: 0, joins: 0/0}
 $wg [InlPrag=[2],
      Occ=LoopBreaker,
-     Dmd=LCL(C1(C1(C1(C1(C1(C1(!L)))))))]
+     Dmd=LCS(C1(C1(C1(C1(C1(C1(L)))))))]
   :: forall {a} {b} {c} {d} {e} {t} {t} {t}.
      Bool -> a -> b -> c -> t -> t -> t -> (# a, b, c, t, t, t #)
-[LclId[StrictWorker([!, ~, ~, ~, ~, ~, ~])],
+[LclId[StrictWorker([])],
  Arity=7,
  Str=<1L><L><L><L><L><L><L>,
  Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True,
@@ -252,9 +252,7 @@ $wg
       (@t)
       (@t)
       (@t)
-      (ds [Dmd=1L]
-         :: Bool
-         Unf=OtherCon [])
+      (ds [Dmd=1L] :: Bool)
       (ww :: a)
       (ww :: b)
       (ww :: c)
diff --git a/testsuite/tests/stranal/sigs/T16197b.hs b/testsuite/tests/stranal/sigs/T16197b.hs
index 4ce440d3bf..dda6670c64 100644
--- a/testsuite/tests/stranal/sigs/T16197b.hs
+++ b/testsuite/tests/stranal/sigs/T16197b.hs
@@ -2,6 +2,11 @@
 -- Important takeaway: The signature of `f` may not say "strict in the Bool
 -- field of T", otherwise the Simplifier will drop the `seq` on the `Bool` at
 -- call sites after unboxing the `T`.
+--
+-- Now (with #21497) this has  a twist. When we do w/w we insert seqs to make the worker strict in
+-- strict fields. This means the simplifier might drop the seq at the call site
+-- but we will seq inside the worker so things still work.
+-- So instead of checking the strictness sig we now check if there is a seq in the worker.
 module T16197b where
 
 data T = T !Bool
diff --git a/testsuite/tests/stranal/sigs/T16197b.stderr b/testsuite/tests/stranal/sigs/T16197b.stderr
index d4c250b44a..88988c266b 100644
--- a/testsuite/tests/stranal/sigs/T16197b.stderr
+++ b/testsuite/tests/stranal/sigs/T16197b.stderr
@@ -1,15 +1,29 @@
 
 ==================== Strictness signatures ====================
-T16197b.f: <1!P(L)>
+f: <1!P(L)>
 
 
 
 ==================== Cpr signatures ====================
-T16197b.f: 1
+f: 1
 
 
 
 ==================== Strictness signatures ====================
-T16197b.f: <1!P(L)>
+f: <1!P(1L)>
+
+
+
+==================== Tidy Core ====================
+Result size of Tidy Core
+  = {terms: 25, types: 23, coercions: 0, joins: 0/0}
+
+$WT = \ conrep -> case conrep of conrep { __DEFAULT -> T conrep }
+
+$wf = \ ww -> case ww of ww1 { __DEFAULT -> (# ww1 #) }
+
+f = \ ds ->
+      case ds of { T ww -> case $wf ww of { (# ww1 #) -> Box ww1 } }
+
 
 
diff --git a/testsuite/tests/stranal/sigs/T16859.stderr b/testsuite/tests/stranal/sigs/T16859.stderr
index 6dd199c07c..afd96a8000 100644
--- a/testsuite/tests/stranal/sigs/T16859.stderr
+++ b/testsuite/tests/stranal/sigs/T16859.stderr
@@ -27,10 +27,10 @@ T16859.n_uniq: 1
 
 ==================== Strictness signatures ====================
 T16859.bar: <1!A><L>
-T16859.baz: <L><1!P(L)><1C1(L)>
+T16859.baz: <1L><1!P(L)><1C1(L)>
 T16859.buz: <1!P(L,L)>
-T16859.foo: <L><L>
-T16859.mkInternalName: <1!P(L)><L><L>
+T16859.foo: <1L><L>
+T16859.mkInternalName: <1!P(L)><1L><1L>
 T16859.n_loc: <1!P(A,A,A,1L)>
 T16859.n_occ: <1!P(A,1!P(L,L),A,A)>
 T16859.n_sort: <1!P(1L,A,A,A)>
diff --git a/testsuite/tests/stranal/sigs/all.T b/testsuite/tests/stranal/sigs/all.T
index 3782fa97a6..3ebfe287ec 100644
--- a/testsuite/tests/stranal/sigs/all.T
+++ b/testsuite/tests/stranal/sigs/all.T
@@ -23,7 +23,7 @@ test('T13380c', expect_broken('!3014'), compile, [''])
 test('T13380f', normal, compile, [''])
 test('T18086', normal, compile, ['-package ghc'])
 test('T18957', normal, compile, [''])
-test('T16197b', normal, compile, [''])
+test('T16197b', [grep_errmsg('\$wf')], compile, ['-ddump-simpl -dsuppress-uniques -dsuppress-all'])
 test('T19407', normal, compile, [''])
 test('T19871', normal, compile, [''])
 test('T16859', normal, compile, ['-package ghc'])