[Git][ghc/ghc][wip/mod-rem-strict] Make `Int`'s `mod` and `rem` strict in their first arguments

[Sebastian Graf]

Sebastian Graf pushed to branch wip/mod-rem-strict at Glasgow Haskell Compiler / GHC


Commits:
748cf6be by Sebastian Graf at 2020-05-14T18:37:21+02:00
Make `Int`'s `mod` and `rem` strict in their first arguments

They used to be strict until 4d2ac2d (9 years ago).

It's obviously better to be strict for performance reasons.
It also blocks #18067.

NoFib results:

```
--------------------------------------------------------------------------------
        Program         Allocs    Instrs
--------------------------------------------------------------------------------
        integer          -1.1%     +0.4%
   wheel-sieve2         +21.2%    +20.7%
--------------------------------------------------------------------------------
            Min          -1.1%     -0.0%
            Max         +21.2%    +20.7%
 Geometric Mean          +0.2%     +0.2%
```

The regression in `wheel-sieve2` is due to reboxing that likely will go
away with the resolution of #18067. See !3282 for details.

Fixes #18187.

- - - - -


1 changed file:

- libraries/base/GHC/Real.hs


Changes:

=====================================
libraries/base/GHC/Real.hs
=====================================
@@ -334,7 +334,7 @@ instance  Integral Int  where
                                                   -- in GHC.Int
      | otherwise                  =  a `quotInt` b
 
-    a `rem` b
+    !a `rem` b
      | b == 0                     = divZeroError
        -- The quotRem CPU instruction fails for minBound `quotRem` -1,
        -- but minBound `rem` -1 is well-defined (0). We therefore
@@ -348,7 +348,7 @@ instance  Integral Int  where
                                                   -- in GHC.Int
      | otherwise                  =  a `divInt` b
 
-    a `mod` b
+    !a `mod` b
      | b == 0                     = divZeroError
        -- The divMod CPU instruction fails for minBound `divMod` -1,
        -- but minBound `mod` -1 is well-defined (0). We therefore



View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/748cf6be65805844ce0c5a978b457feefd6d06bd

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/748cf6be65805844ce0c5a978b457feefd6d06bd
You're receiving this email because of your account on gitlab.haskell.org.


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/ghc-commits/attachments/20200514/8e575573/attachment.html>