X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Fcmm%2FCmmOpt.hs;h=9873e29cfd597a0a96fc56560a71544b709feefb;hb=a385f0af5ea320a18d580f6a36c59c55b3516efd;hp=9664b9bece3c00fd91427e84b8084f7fbb130f71;hpb=bb66ce578f2ef5cbeb35de9719f0839a32fbeb35;p=ghc-hetmet.git diff --git a/compiler/cmm/CmmOpt.hs b/compiler/cmm/CmmOpt.hs index 9664b9b..9873e29 100644 --- a/compiler/cmm/CmmOpt.hs +++ b/compiler/cmm/CmmOpt.hs @@ -1,3 +1,10 @@ +{-# OPTIONS -w #-} +-- The above warning supression flag is a temporary kludge. +-- While working on this module you are encouraged to remove it and fix +-- any warnings in the module. See +-- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings +-- for details + ----------------------------------------------------------------------------- -- -- Cmm optimisation @@ -15,6 +22,7 @@ module CmmOpt ( #include "HsVersions.h" import Cmm +import CmmExpr import CmmUtils import CLabel import MachOp @@ -22,13 +30,12 @@ import StaticFlags import UniqFM import Unique - +import FastTypes import Outputable import Data.Bits import Data.Word import Data.Int -import GHC.Exts -- ----------------------------------------------------------------------------- -- The mini-inliner @@ -45,6 +52,10 @@ once. It works as follows: - if we reach the statement that uses it, inline the rhs and delete the original assignment. +[N.B. In the Quick C-- compiler, this optimization is achieved by a + combination of two dataflow passes: forward substitution (peephole + optimization) and dead-assignment elimination. ---NR] + Possible generalisations: here is an example from factorial Fac_zdwfac_entry: @@ -78,21 +89,23 @@ To inline _smi: its occurrences. -} +countUses :: UserOfLocalRegs a => a -> UniqFM Int +countUses a = foldRegsUsed (\m r -> addToUFM m r (count m r + 1)) emptyUFM a + where count m r = lookupWithDefaultUFM m (0::Int) r + cmmMiniInline :: [CmmBasicBlock] -> [CmmBasicBlock] cmmMiniInline blocks = map do_inline blocks - where - blockUses (BasicBlock _ stmts) - = foldr (plusUFM_C (+)) emptyUFM (map getStmtUses stmts) - - uses = foldr (plusUFM_C (+)) emptyUFM (map blockUses blocks) - - do_inline (BasicBlock id stmts) - = BasicBlock id (cmmMiniInlineStmts uses stmts) - + where do_inline (BasicBlock id stmts) + = BasicBlock id (cmmMiniInlineStmts (countUses blocks) stmts) cmmMiniInlineStmts :: UniqFM Int -> [CmmStmt] -> [CmmStmt] cmmMiniInlineStmts uses [] = [] cmmMiniInlineStmts uses (stmt@(CmmAssign (CmmLocal (LocalReg u _ _)) expr) : stmts) + -- not used at all: just discard this assignment + | Nothing <- lookupUFM uses u + = cmmMiniInlineStmts uses stmts + + -- used once: try to inline at the use site | Just 1 <- lookupUFM uses u, Just stmts' <- lookForInline u expr stmts = @@ -110,7 +123,7 @@ cmmMiniInlineStmts uses (stmt:stmts) -- and temporaries are single-assignment. lookForInline u expr (stmt@(CmmAssign (CmmLocal (LocalReg u' _ _)) rhs) : rest) | u /= u' - = case lookupUFM (getExprUses rhs) u of + = case lookupUFM (countUses rhs) u of Just 1 -> Just (inlineStmt u expr stmt : rest) _other -> case lookForInline u expr rest of Nothing -> Nothing @@ -119,8 +132,10 @@ lookForInline u expr (stmt@(CmmAssign (CmmLocal (LocalReg u' _ _)) rhs) : rest) lookForInline u expr (CmmNop : rest) = lookForInline u expr rest +lookForInline _ _ [] = Nothing + lookForInline u expr (stmt:stmts) - = case lookupUFM (getStmtUses stmt) u of + = case lookupUFM (countUses stmt) u of Just 1 | ok_to_inline -> Just (inlineStmt u expr stmt : stmts) _other -> Nothing where @@ -133,30 +148,6 @@ lookForInline u expr (stmt:stmts) CmmCall{} -> hasNoGlobalRegs expr _ -> True --- ----------------------------------------------------------------------------- --- Boring Cmm traversals for collecting usage info and substitutions. - -getStmtUses :: CmmStmt -> UniqFM Int -getStmtUses (CmmAssign _ e) = getExprUses e -getStmtUses (CmmStore e1 e2) = plusUFM_C (+) (getExprUses e1) (getExprUses e2) -getStmtUses (CmmCall target _ es _ _) - = plusUFM_C (+) (uses target) (getExprsUses (map fst es)) - where uses (CmmCallee e _) = getExprUses e - uses _ = emptyUFM -getStmtUses (CmmCondBranch e _) = getExprUses e -getStmtUses (CmmSwitch e _) = getExprUses e -getStmtUses (CmmJump e _) = getExprUses e -getStmtUses _ = emptyUFM - -getExprUses :: CmmExpr -> UniqFM Int -getExprUses (CmmReg (CmmLocal (LocalReg u _ _))) = unitUFM u 1 -getExprUses (CmmRegOff (CmmLocal (LocalReg u _ _)) _) = unitUFM u 1 -getExprUses (CmmLoad e _) = getExprUses e -getExprUses (CmmMachOp _ es) = getExprsUses es -getExprUses _other = emptyUFM - -getExprsUses es = foldr (plusUFM_C (+)) emptyUFM (map getExprUses es) - inlineStmt :: Unique -> CmmExpr -> CmmStmt -> CmmStmt inlineStmt u a (CmmAssign r e) = CmmAssign r (inlineExpr u a e) inlineStmt u a (CmmStore e1 e2) = CmmStore (inlineExpr u a e1) (inlineExpr u a e2) @@ -164,7 +155,7 @@ inlineStmt u a (CmmCall target regs es srt ret) = CmmCall (infn target) regs es' srt ret where infn (CmmCallee fn cconv) = CmmCallee fn cconv infn (CmmPrim p) = CmmPrim p - es' = [ (inlineExpr u a e, hint) | (e,hint) <- es ] + es' = [ (CmmKinded (inlineExpr u a e) hint) | (CmmKinded e hint) <- es ] inlineStmt u a (CmmCondBranch e d) = CmmCondBranch (inlineExpr u a e) d inlineStmt u a (CmmSwitch e d) = CmmSwitch (inlineExpr u a e) d inlineStmt u a (CmmJump e d) = CmmJump (inlineExpr u a e) d @@ -339,34 +330,53 @@ cmmMachOpFold (MO_Sub _) [CmmLit (CmmLabel lbl), CmmLit (CmmInt i rep)] = CmmLit (CmmLabelOff lbl (fromIntegral (negate (narrowU rep i)))) --- Comparison of literal with narrowed/widened operand: perform --- the comparison at a different width, as long as the literal is --- within range. +-- Comparison of literal with widened operand: perform the comparison +-- at the smaller width, as long as the literal is within range. + +-- We can't do the reverse trick, when the operand is narrowed: +-- narrowing throws away bits from the operand, there's no way to do +-- the same comparison at the larger size. #if i386_TARGET_ARCH || x86_64_TARGET_ARCH -- powerPC NCG has a TODO for I8/I16 comparisons, so don't try cmmMachOpFold cmp [CmmMachOp conv [x], CmmLit (CmmInt i _)] - | Just (rep, narrow) <- maybe_conversion conv, - Just narrow_cmp <- maybe_comparison cmp rep, - let narrow_i = narrow rep i, - narrow_i == i - = cmmMachOpFold narrow_cmp [x, CmmLit (CmmInt narrow_i rep)] + | -- if the operand is widened: + Just (rep, signed, narrow_fn) <- maybe_conversion conv, + -- and this is a comparison operation: + Just narrow_cmp <- maybe_comparison cmp rep signed, + -- and the literal fits in the smaller size: + i == narrow_fn rep i + -- then we can do the comparison at the smaller size + = cmmMachOpFold narrow_cmp [x, CmmLit (CmmInt i rep)] where - maybe_conversion (MO_U_Conv from _) = Just (from, narrowU) - maybe_conversion (MO_S_Conv from _) = Just (from, narrowS) + maybe_conversion (MO_U_Conv from to) + | to > from + = Just (from, False, narrowU) + maybe_conversion (MO_S_Conv from to) + | to > from, not (isFloatingRep from) + = Just (from, True, narrowS) + -- don't attempt to apply this optimisation when the source + -- is a float; see #1916 maybe_conversion _ = Nothing - maybe_comparison (MO_U_Gt _) rep = Just (MO_U_Gt rep) - maybe_comparison (MO_U_Ge _) rep = Just (MO_U_Ge rep) - maybe_comparison (MO_U_Lt _) rep = Just (MO_U_Lt rep) - maybe_comparison (MO_U_Le _) rep = Just (MO_U_Le rep) - maybe_comparison (MO_S_Gt _) rep = Just (MO_S_Gt rep) - maybe_comparison (MO_S_Ge _) rep = Just (MO_S_Ge rep) - maybe_comparison (MO_S_Lt _) rep = Just (MO_S_Lt rep) - maybe_comparison (MO_S_Le _) rep = Just (MO_S_Le rep) - maybe_comparison (MO_Eq _) rep = Just (MO_Eq rep) - maybe_comparison _ _ = Nothing + -- careful (#2080): if the original comparison was signed, but + -- we were doing an unsigned widen, then we must do an + -- unsigned comparison at the smaller size. + maybe_comparison (MO_U_Gt _) rep _ = Just (MO_U_Gt rep) + maybe_comparison (MO_U_Ge _) rep _ = Just (MO_U_Ge rep) + maybe_comparison (MO_U_Lt _) rep _ = Just (MO_U_Lt rep) + maybe_comparison (MO_U_Le _) rep _ = Just (MO_U_Le rep) + maybe_comparison (MO_Eq _) rep _ = Just (MO_Eq rep) + maybe_comparison (MO_S_Gt _) rep True = Just (MO_S_Gt rep) + maybe_comparison (MO_S_Ge _) rep True = Just (MO_S_Ge rep) + maybe_comparison (MO_S_Lt _) rep True = Just (MO_S_Lt rep) + maybe_comparison (MO_S_Le _) rep True = Just (MO_S_Le rep) + maybe_comparison (MO_S_Gt _) rep False = Just (MO_U_Gt rep) + maybe_comparison (MO_S_Ge _) rep False = Just (MO_U_Ge rep) + maybe_comparison (MO_S_Lt _) rep False = Just (MO_U_Lt rep) + maybe_comparison (MO_S_Le _) rep False = Just (MO_U_Le rep) + maybe_comparison _ _ _ = Nothing #endif @@ -384,15 +394,15 @@ cmmMachOpFold mop args@[x, y@(CmmLit (CmmInt 0 _))] MO_S_Shr r -> x MO_U_Shr r -> x MO_Ne r | isComparisonExpr x -> x - MO_Eq r | Just x' <- maybeInvertConditionalExpr x -> x' + MO_Eq r | Just x' <- maybeInvertCmmExpr x -> x' MO_U_Gt r | isComparisonExpr x -> x MO_S_Gt r | isComparisonExpr x -> x MO_U_Lt r | isComparisonExpr x -> CmmLit (CmmInt 0 wordRep) MO_S_Lt r | isComparisonExpr x -> CmmLit (CmmInt 0 wordRep) MO_U_Ge r | isComparisonExpr x -> CmmLit (CmmInt 1 wordRep) MO_S_Ge r | isComparisonExpr x -> CmmLit (CmmInt 1 wordRep) - MO_U_Le r | Just x' <- maybeInvertConditionalExpr x -> x' - MO_S_Le r | Just x' <- maybeInvertConditionalExpr x -> x' + MO_U_Le r | Just x' <- maybeInvertCmmExpr x -> x' + MO_S_Le r | Just x' <- maybeInvertCmmExpr x -> x' other -> CmmMachOp mop args cmmMachOpFold mop args@[x, y@(CmmLit (CmmInt 1 rep))] @@ -402,10 +412,10 @@ cmmMachOpFold mop args@[x, y@(CmmLit (CmmInt 1 rep))] MO_U_Quot r -> x MO_S_Rem r -> CmmLit (CmmInt 0 rep) MO_U_Rem r -> CmmLit (CmmInt 0 rep) - MO_Ne r | Just x' <- maybeInvertConditionalExpr x -> x' + MO_Ne r | Just x' <- maybeInvertCmmExpr x -> x' MO_Eq r | isComparisonExpr x -> x - MO_U_Lt r | Just x' <- maybeInvertConditionalExpr x -> x' - MO_S_Lt r | Just x' <- maybeInvertConditionalExpr x -> x' + MO_U_Lt r | Just x' <- maybeInvertCmmExpr x -> x' + MO_S_Lt r | Just x' <- maybeInvertCmmExpr x -> x' MO_U_Gt r | isComparisonExpr x -> CmmLit (CmmInt 0 wordRep) MO_S_Gt r | isComparisonExpr x -> CmmLit (CmmInt 0 wordRep) MO_U_Le r | isComparisonExpr x -> CmmLit (CmmInt 1 wordRep) @@ -468,23 +478,26 @@ cmmMachOpFold mop args = CmmMachOp mop args -- Used to be in MachInstrs --SDM. -- ToDo: remove use of unboxery --SDM. -w2i x = word2Int# x -i2w x = int2Word# x +-- Unboxery removed in favor of FastInt; but is the function supposed to fail +-- on inputs >= 2147483648, or was that just an implementation artifact? +-- And is this speed-critical, or can we just use Integer operations +-- (including Data.Bits)? +-- --Isaac Dupree exactLog2 :: Integer -> Maybe Integer -exactLog2 x - = if (x <= 0 || x >= 2147483648) then +exactLog2 x_ + = if (x_ <= 0 || x_ >= 2147483648) then Nothing else - case fromInteger x of { I# x# -> - if (w2i ((i2w x#) `and#` (i2w (0# -# x#))) /=# x#) then + case iUnbox (fromInteger x_) of { x -> + if (x `bitAndFastInt` negateFastInt x) /=# x then Nothing else - Just (toInteger (I# (pow2 x#))) + Just (toInteger (iBox (pow2 x))) } where - pow2 x# | x# ==# 1# = 0# - | otherwise = 1# +# pow2 (w2i (i2w x# `shiftRL#` 1#)) + pow2 x | x ==# _ILIT(1) = _ILIT(0) + | otherwise = _ILIT(1) +# pow2 (x `shiftR_FastInt` _ILIT(1)) -- ----------------------------------------------------------------------------- @@ -531,11 +544,11 @@ narrowS _ _ = panic "narrowTo" -} cmmLoopifyForC :: RawCmmTop -> RawCmmTop -cmmLoopifyForC p@(CmmProc info entry_lbl [] blocks@(BasicBlock top_id _ : _)) +cmmLoopifyForC p@(CmmProc info entry_lbl [] (ListGraph blocks@(BasicBlock top_id _ : _))) | null info = p -- only if there's an info table, ignore case alts | otherwise = -- pprTrace "jump_lbl" (ppr jump_lbl <+> ppr entry_lbl) $ - CmmProc info entry_lbl [] blocks' + CmmProc info entry_lbl [] (ListGraph blocks') where blocks' = [ BasicBlock id (map do_stmt stmts) | BasicBlock id stmts <- blocks ] @@ -558,10 +571,6 @@ isComparisonExpr :: CmmExpr -> Bool isComparisonExpr (CmmMachOp op _) = isComparisonMachOp op isComparisonExpr _other = False -maybeInvertConditionalExpr :: CmmExpr -> Maybe CmmExpr -maybeInvertConditionalExpr (CmmMachOp op args) - | Just op' <- maybeInvertComparison op = Just (CmmMachOp op' args) -maybeInvertConditionalExpr _ = Nothing - isPicReg (CmmReg (CmmGlobal PicBaseReg)) = True isPicReg _ = False +