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| author | Herbert Valerio Riedel <hvr@gnu.org> | 2014-08-11 18:56:57 +0200 |
|---|---|---|
| committer | Herbert Valerio Riedel <hvr@gnu.org> | 2014-08-14 11:34:23 +0200 |
| commit | e0c1767d0ea8d12e0a4badf43682a08784e379c6 (patch) | |
| tree | 6662fe33cd7e803253458f91307b1b5826e30b0f /includes | |
| parent | 6b5ea617dcd162e682886d5843df51a2866218d3 (diff) | |
| download | haskell-e0c1767d0ea8d12e0a4badf43682a08784e379c6.tar.gz | |
Implement new CLZ and CTZ primops (re #9340)
This implements the new primops
clz#, clz32#, clz64#,
ctz#, ctz32#, ctz64#
which provide efficient implementations of the popular
count-leading-zero and count-trailing-zero respectively
(see testcase for a pure Haskell reference implementation).
On x86, NCG as well as LLVM generates code based on the BSF/BSR
instructions (which need extra logic to make the 0-case well-defined).
Test Plan: validate and succesful tests on i686 and amd64
Reviewers: rwbarton, simonmar, ezyang, austin
Subscribers: simonmar, relrod, ezyang, carter
Differential Revision: https://phabricator.haskell.org/D144
GHC Trac Issues: #9340
Diffstat (limited to 'includes')
| -rw-r--r-- | includes/stg/Prim.h | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/includes/stg/Prim.h b/includes/stg/Prim.h index 9fdfd3ceaa..48bbddb09c 100644 --- a/includes/stg/Prim.h +++ b/includes/stg/Prim.h @@ -32,4 +32,16 @@ StgWord hs_popcnt(StgWord x); StgFloat hs_word2float32(StgWord x); StgDouble hs_word2float64(StgWord x); +/* libraries/ghc-prim/cbits/clz.c */ +StgWord hs_clz8(StgWord x); +StgWord hs_clz16(StgWord x); +StgWord hs_clz32(StgWord x); +StgWord hs_clz64(StgWord64 x); + +/* libraries/ghc-prim/cbits/ctz.c */ +StgWord hs_ctz8(StgWord x); +StgWord hs_ctz16(StgWord x); +StgWord hs_ctz32(StgWord x); +StgWord hs_ctz64(StgWord64 x); + #endif /* PRIM_H */ |