Inlining magicHEADmaster

1 files changed, 5 insertions, 3 deletions

diff --git a/src/Data/Array/Nested/Mixed/Shape/Internal.hs b/src/Data/Array/Nested/Mixed/Shape/Internal.hs
index 9997b0f..2a86ac1 100644
--- a/src/Data/Array/Nested/Mixed/Shape/Internal.hs
+++ b/src/Data/Array/Nested/Mixed/Shape/Internal.hs
@@ -20,9 +20,11 @@ ixFromLinearStub fname' ishty ixty zshC consshC ixz ixcons shtolist = do
 
   locals <- [d|
     -- Unfold first iteration of fromLin to do the range check.
-    -- Don't inline because if this is inlined, GHC seems to stop sharing
-    -- 'suffixes' over multiple calls, which breaks performance in sh*Enum.
-    {-# NOINLINE fromLin0 #-}
+    -- Don't inline this function at first to allow GHC to inline the outer
+    -- function and realise that 'suffixes' is shared. But then later inline it
+    -- anyway, to avoid the function call. Removing the pragma makes GHC
+    -- somehow unable to recognise that 'suffixes' can be shared in a loop.
+    {-# NOINLINE [0] fromLin0 #-}
     fromLin0 :: Num i => $ishty sh -> [Int] -> Int -> $ixty sh i
     fromLin0 sh suffixes i =
         if i < 0 then outrange sh i else