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| author | Sebastian Graf <sebastian.graf@kit.edu> | 2018-05-05 13:30:32 -0400 |
|---|---|---|
| committer | Ben Gamari <ben@smart-cactus.org> | 2018-05-05 17:06:35 -0400 |
| commit | 6243bba73d14cbee4219a16d45f57d1b254a6456 (patch) | |
| tree | 56c4528dd27b7c0634ef3707adb0a47771f62011 /compiler/codeGen/StgCmmPrim.hs | |
| parent | 418881f7181cbfa31c44f0794db65bf00916bde2 (diff) | |
| download | haskell-6243bba73d14cbee4219a16d45f57d1b254a6456.tar.gz | |
Add 'addWordC#' PrimOp
This is mostly for congruence with 'subWordC#' and '{add,sub}IntC#'.
I found 'plusWord2#' while implementing this, which both lacks
documentation and has a slightly different specification than
'addWordC#', which means the generic implementation is unnecessarily
complex.
While I was at it, I also added lacking meta-information on PrimOps
and refactored 'subWordC#'s generic implementation to be branchless.
Reviewers: bgamari, simonmar, jrtc27, dfeuer
Reviewed By: bgamari, dfeuer
Subscribers: dfeuer, thomie, carter
Differential Revision: https://phabricator.haskell.org/D4592
Diffstat (limited to 'compiler/codeGen/StgCmmPrim.hs')
| -rw-r--r-- | compiler/codeGen/StgCmmPrim.hs | 72 |
1 files changed, 62 insertions, 10 deletions
diff --git a/compiler/codeGen/StgCmmPrim.hs b/compiler/codeGen/StgCmmPrim.hs index 809dc55a58..fe89955285 100644 --- a/compiler/codeGen/StgCmmPrim.hs +++ b/compiler/codeGen/StgCmmPrim.hs @@ -907,6 +907,11 @@ callishPrimOpSupported dflags op || llvm -> Left (MO_Add2 (wordWidth dflags)) | otherwise -> Right genericWordAdd2Op + WordAddCOp | (ncg && (x86ish + || ppc)) + || llvm -> Left (MO_AddWordC (wordWidth dflags)) + | otherwise -> Right genericWordAddCOp + WordSubCOp | (ncg && (x86ish || ppc)) || llvm -> Left (MO_SubWordC (wordWidth dflags)) @@ -1043,17 +1048,64 @@ genericWordAdd2Op [res_h, res_l] [arg_x, arg_y] (bottomHalf (CmmReg (CmmLocal r1))))] genericWordAdd2Op _ _ = panic "genericWordAdd2Op" +-- | Implements branchless recovery of the carry flag @c@ by checking the +-- leftmost bits of both inputs @a@ and @b@ and result @r = a + b@: +-- +-- @ +-- c = a&b | (a|b)&~r +-- @ +-- +-- https://brodowsky.it-sky.net/2015/04/02/how-to-recover-the-carry-bit/ +genericWordAddCOp :: GenericOp +genericWordAddCOp [res_r, res_c] [aa, bb] + = do dflags <- getDynFlags + emit $ catAGraphs [ + mkAssign (CmmLocal res_r) (CmmMachOp (mo_wordAdd dflags) [aa,bb]), + mkAssign (CmmLocal res_c) $ + CmmMachOp (mo_wordUShr dflags) [ + CmmMachOp (mo_wordOr dflags) [ + CmmMachOp (mo_wordAnd dflags) [aa,bb], + CmmMachOp (mo_wordAnd dflags) [ + CmmMachOp (mo_wordOr dflags) [aa,bb], + CmmMachOp (mo_wordNot dflags) [CmmReg (CmmLocal res_r)] + ] + ], + mkIntExpr dflags (wORD_SIZE_IN_BITS dflags - 1) + ] + ] +genericWordAddCOp _ _ = panic "genericWordAddCOp" + +-- | Implements branchless recovery of the carry flag @c@ by checking the +-- leftmost bits of both inputs @a@ and @b@ and result @r = a - b@: +-- +-- @ +-- c = ~a&b | (~a|b)&r +-- @ +-- +-- https://brodowsky.it-sky.net/2015/04/02/how-to-recover-the-carry-bit/ genericWordSubCOp :: GenericOp -genericWordSubCOp [res_r, res_c] [aa, bb] = do - dflags <- getDynFlags - emit $ catAGraphs - [ -- Put the result into 'res_r'. - mkAssign (CmmLocal res_r) $ - CmmMachOp (mo_wordSub dflags) [aa, bb] - -- Set 'res_c' to 1 if 'bb > aa' and to 0 otherwise. - , mkAssign (CmmLocal res_c) $ - CmmMachOp (mo_wordUGt dflags) [bb, aa] - ] +genericWordSubCOp [res_r, res_c] [aa, bb] + = do dflags <- getDynFlags + emit $ catAGraphs [ + mkAssign (CmmLocal res_r) (CmmMachOp (mo_wordSub dflags) [aa,bb]), + mkAssign (CmmLocal res_c) $ + CmmMachOp (mo_wordUShr dflags) [ + CmmMachOp (mo_wordOr dflags) [ + CmmMachOp (mo_wordAnd dflags) [ + CmmMachOp (mo_wordNot dflags) [aa], + bb + ], + CmmMachOp (mo_wordAnd dflags) [ + CmmMachOp (mo_wordOr dflags) [ + CmmMachOp (mo_wordNot dflags) [aa], + bb + ], + CmmReg (CmmLocal res_r) + ] + ], + mkIntExpr dflags (wORD_SIZE_IN_BITS dflags - 1) + ] + ] genericWordSubCOp _ _ = panic "genericWordSubCOp" genericIntAddCOp :: GenericOp |