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| author | Sebastian Graf <sebastian.graf@kit.edu> | 2020-10-30 17:20:37 +0100 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2020-11-20 02:09:51 -0500 |
| commit | 0aec78b6c97cee58ba20bfcb959f1369b80c4e4c (patch) | |
| tree | 3e48861640dbeb7a9d7784f0f02c2bc564af50ec /testsuite/tests/stranal/sigs/DmdAnalGADTs.stderr | |
| parent | 321d1bd8a79ab39c3c9e8697fffb0107c43f83cf (diff) | |
| download | haskell-0aec78b6c97cee58ba20bfcb959f1369b80c4e4c.tar.gz | |
Demand: Interleave usage and strictness demands (#18903)
As outlined in #18903, interleaving usage and strictness demands not
only means a more compact demand representation, but also allows us to
express demands that we weren't easily able to express before.
Call demands are *relative* in the sense that a call demand `Cn(cd)`
on `g` says "`g` is called `n` times. *Whenever `g` is called*, the
result is used according to `cd`". Example from #18903:
```hs
h :: Int -> Int
h m =
let g :: Int -> (Int,Int)
g 1 = (m, 0)
g n = (2 * n, 2 `div` n)
{-# NOINLINE g #-}
in case m of
1 -> 0
2 -> snd (g m)
_ -> uncurry (+) (g m)
```
Without the interleaved representation, we would just get `L` for the
strictness demand on `g`. Now we are able to express that whenever
`g` is called, its second component is used strictly in denoting `g`
by `1C1(P(1P(U),SP(U)))`. This would allow Nested CPR to unbox the
division, for example.
Fixes #18903.
While fixing regressions, I also discovered and fixed #18957.
Metric Decrease:
T13253-spj
Diffstat (limited to 'testsuite/tests/stranal/sigs/DmdAnalGADTs.stderr')
| -rw-r--r-- | testsuite/tests/stranal/sigs/DmdAnalGADTs.stderr | 16 |
1 files changed, 8 insertions, 8 deletions
diff --git a/testsuite/tests/stranal/sigs/DmdAnalGADTs.stderr b/testsuite/tests/stranal/sigs/DmdAnalGADTs.stderr index 6dd5576da4..41fae8f5ce 100644 --- a/testsuite/tests/stranal/sigs/DmdAnalGADTs.stderr +++ b/testsuite/tests/stranal/sigs/DmdAnalGADTs.stderr @@ -5,11 +5,11 @@ DmdAnalGADTs.$tc'B: DmdAnalGADTs.$tcD: DmdAnalGADTs.$trModule: DmdAnalGADTs.diverges: b -DmdAnalGADTs.f: <S,1*U> -DmdAnalGADTs.f': <S,1*U> -DmdAnalGADTs.g: <S,1*U> +DmdAnalGADTs.f: <SU> +DmdAnalGADTs.f': <SU> +DmdAnalGADTs.g: <SU> DmdAnalGADTs.hasCPR: -DmdAnalGADTs.hasStrSig: <S,1*U(U)> +DmdAnalGADTs.hasStrSig: <SP(U)> @@ -33,10 +33,10 @@ DmdAnalGADTs.$tc'B: DmdAnalGADTs.$tcD: DmdAnalGADTs.$trModule: DmdAnalGADTs.diverges: b -DmdAnalGADTs.f: <S,1*U> -DmdAnalGADTs.f': <S,1*U> -DmdAnalGADTs.g: <S,1*U> +DmdAnalGADTs.f: <SU> +DmdAnalGADTs.f': <SU> +DmdAnalGADTs.g: <SU> DmdAnalGADTs.hasCPR: -DmdAnalGADTs.hasStrSig: <S,1*U(U)> +DmdAnalGADTs.hasStrSig: <SP(U)> |