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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 /compiler/codeGen/StgCmmPrim.hs | |
| 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 'compiler/codeGen/StgCmmPrim.hs')
| -rw-r--r-- | compiler/codeGen/StgCmmPrim.hs | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/compiler/codeGen/StgCmmPrim.hs b/compiler/codeGen/StgCmmPrim.hs index 77739fe0fb..9e12427355 100644 --- a/compiler/codeGen/StgCmmPrim.hs +++ b/compiler/codeGen/StgCmmPrim.hs @@ -563,6 +563,20 @@ emitPrimOp _ [res] PopCnt32Op [w] = emitPopCntCall res w W32 emitPrimOp _ [res] PopCnt64Op [w] = emitPopCntCall res w W64 emitPrimOp dflags [res] PopCntOp [w] = emitPopCntCall res w (wordWidth dflags) +-- count leading zeros +emitPrimOp _ [res] Clz8Op [w] = emitClzCall res w W8 +emitPrimOp _ [res] Clz16Op [w] = emitClzCall res w W16 +emitPrimOp _ [res] Clz32Op [w] = emitClzCall res w W32 +emitPrimOp _ [res] Clz64Op [w] = emitClzCall res w W64 +emitPrimOp dflags [res] ClzOp [w] = emitClzCall res w (wordWidth dflags) + +-- count trailing zeros +emitPrimOp _ [res] Ctz8Op [w] = emitCtzCall res w W8 +emitPrimOp _ [res] Ctz16Op [w] = emitCtzCall res w W16 +emitPrimOp _ [res] Ctz32Op [w] = emitCtzCall res w W32 +emitPrimOp _ [res] Ctz64Op [w] = emitCtzCall res w W64 +emitPrimOp dflags [res] CtzOp [w] = emitCtzCall res w (wordWidth dflags) + -- Unsigned int to floating point conversions emitPrimOp _ [res] Word2FloatOp [w] = emitPrimCall [res] (MO_UF_Conv W32) [w] @@ -2096,3 +2110,17 @@ emitPopCntCall res x width = do [ res ] (MO_PopCnt width) [ x ] + +emitClzCall :: LocalReg -> CmmExpr -> Width -> FCode () +emitClzCall res x width = do + emitPrimCall + [ res ] + (MO_Clz width) + [ x ] + +emitCtzCall :: LocalReg -> CmmExpr -> Width -> FCode () +emitCtzCall res x width = do + emitPrimCall + [ res ] + (MO_Ctz width) + [ x ] |