CprAnal: Don't attach CPR sigs to expandable bindings (#18154)

Instead, look through expandable unfoldings in `cprTransform`.
See the new Note [CPR for expandable unfoldings]:

```
Long static data structures (whether top-level or not) like

  xs = x1 : xs1
  xs1 = x2 : xs2
  xs2 = x3 : xs3

should not get CPR signatures, because they

  * Never get WW'd, so their CPR signature should be irrelevant after analysis
    (in fact the signature might even be harmful for that reason)
  * Would need to be inlined/expanded to see their constructed product
  * Recording CPR on them blows up interface file sizes and is redundant with
    their unfolding. In case of Nested CPR, this blow-up can be quadratic!

But we can't just stop giving DataCon application bindings the CPR property,
for example

  fac 0 = 1
  fac n = n * fac (n-1)

fac certainly has the CPR property and should be WW'd! But FloatOut will
transform the first clause to

  lvl = 1
  fac 0 = lvl

If lvl doesn't have the CPR property, fac won't either. But lvl doesn't have a
CPR signature to extrapolate into a CPR transformer ('cprTransform'). So
instead we keep on cprAnal'ing through *expandable* unfoldings for these arity
0 bindings via 'cprExpandUnfolding_maybe'.

In practice, GHC generates a lot of (nested) TyCon and KindRep bindings, one
for each data declaration. It's wasteful to attach CPR signatures to each of
them (and intractable in case of Nested CPR).
```

Fixes #18154.

3 files changed, 0 insertions, 9 deletions

diff --git a/testsuite/tests/numeric/should_compile/T14170.stdout b/testsuite/tests/numeric/should_compile/T14170.stdout
index 700e8d8848..37868a239b 100644
--- a/testsuite/tests/numeric/should_compile/T14170.stdout
+++ b/testsuite/tests/numeric/should_compile/T14170.stdout
@@ -13,7 +13,6 @@ NatVal.$trModule4 = "main"#
 -- RHS size: {terms: 2, types: 0, coercions: 0, joins: 0/0}
 NatVal.$trModule3 :: GHC.Types.TrName
 [GblId,
- Cpr=m1,
  Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True,
          WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 10 20}]
 NatVal.$trModule3 = GHC.Types.TrNameS NatVal.$trModule4
@@ -28,7 +27,6 @@ NatVal.$trModule2 = "NatVal"#
 -- RHS size: {terms: 2, types: 0, coercions: 0, joins: 0/0}
 NatVal.$trModule1 :: GHC.Types.TrName
 [GblId,
- Cpr=m1,
  Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True,
          WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 10 20}]
 NatVal.$trModule1 = GHC.Types.TrNameS NatVal.$trModule2
@@ -36,7 +34,6 @@ NatVal.$trModule1 = GHC.Types.TrNameS NatVal.$trModule2
 -- RHS size: {terms: 3, types: 0, coercions: 0, joins: 0/0}
 NatVal.$trModule :: GHC.Types.Module
 [GblId,
- Cpr=m1,
  Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True,
          WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 10 30}]
 NatVal.$trModule
diff --git a/testsuite/tests/numeric/should_compile/T14465.stdout b/testsuite/tests/numeric/should_compile/T14465.stdout
index 7a5f49177b..1eb5182a6c 100644
--- a/testsuite/tests/numeric/should_compile/T14465.stdout
+++ b/testsuite/tests/numeric/should_compile/T14465.stdout
@@ -20,7 +20,6 @@ M.$trModule4 = "main"#
 -- RHS size: {terms: 2, types: 0, coercions: 0, joins: 0/0}
 M.$trModule3 :: GHC.Types.TrName
 [GblId,
- Cpr=m1,
  Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True,
          WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 10 20}]
 M.$trModule3 = GHC.Types.TrNameS M.$trModule4
@@ -35,7 +34,6 @@ M.$trModule2 = "M"#
 -- RHS size: {terms: 2, types: 0, coercions: 0, joins: 0/0}
 M.$trModule1 :: GHC.Types.TrName
 [GblId,
- Cpr=m1,
  Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True,
          WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 10 20}]
 M.$trModule1 = GHC.Types.TrNameS M.$trModule2
@@ -43,7 +41,6 @@ M.$trModule1 = GHC.Types.TrNameS M.$trModule2
 -- RHS size: {terms: 3, types: 0, coercions: 0, joins: 0/0}
 M.$trModule :: GHC.Types.Module
 [GblId,
- Cpr=m1,
  Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True,
          WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 10 30}]
 M.$trModule = GHC.Types.Module M.$trModule3 M.$trModule1
diff --git a/testsuite/tests/numeric/should_compile/T7116.stdout b/testsuite/tests/numeric/should_compile/T7116.stdout
index e9adc6b988..364ab5d7ee 100644
--- a/testsuite/tests/numeric/should_compile/T7116.stdout
+++ b/testsuite/tests/numeric/should_compile/T7116.stdout
@@ -13,7 +13,6 @@ T7116.$trModule4 = "main"#
 -- RHS size: {terms: 2, types: 0, coercions: 0, joins: 0/0}
 T7116.$trModule3 :: GHC.Types.TrName
 [GblId,
- Cpr=m1,
  Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True,
          WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 10 20}]
 T7116.$trModule3 = GHC.Types.TrNameS T7116.$trModule4
@@ -28,7 +27,6 @@ T7116.$trModule2 = "T7116"#
 -- RHS size: {terms: 2, types: 0, coercions: 0, joins: 0/0}
 T7116.$trModule1 :: GHC.Types.TrName
 [GblId,
- Cpr=m1,
  Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True,
          WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 10 20}]
 T7116.$trModule1 = GHC.Types.TrNameS T7116.$trModule2
@@ -36,7 +34,6 @@ T7116.$trModule1 = GHC.Types.TrNameS T7116.$trModule2
 -- RHS size: {terms: 3, types: 0, coercions: 0, joins: 0/0}
 T7116.$trModule :: GHC.Types.Module
 [GblId,
- Cpr=m1,
  Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True,
          WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 10 30}]
 T7116.$trModule