[Git][ghc/ghc][master] nonmoving: Optimise log2_ceil

[Marge Bot]

 Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC


Commits:
f945eea5 by Ben Gamari at 2020-06-01T06:34:58-04:00
nonmoving: Optimise log2_ceil

- - - - -


1 changed file:

- rts/sm/NonMoving.c


Changes:

=====================================
rts/sm/NonMoving.c
=====================================
@@ -586,15 +586,9 @@ static struct NonmovingSegment *nonmovingAllocSegment(uint32_t node)
     return ret;
 }
 
-static inline unsigned long log2_floor(unsigned long x)
-{
-    return sizeof(unsigned long)*8 - 1 - __builtin_clzl(x);
-}
-
 static inline unsigned long log2_ceil(unsigned long x)
 {
-    unsigned long log = log2_floor(x);
-    return (x - (1 << log)) ? log + 1 : log;
+    return (sizeof(unsigned long)*8) - __builtin_clzl(x-1);
 }
 
 // Advance a segment's next_free pointer. Returns true if segment if full.



View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/f945eea569993a4e5ed953f4573e6eab785f309f

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/f945eea569993a4e5ed953f4573e6eab785f309f
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