{-# 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 ----------------------------------------------------------------------------- -- -- Code generator utilities; mostly monadic -- -- (c) The University of Glasgow 2004-2006 -- ----------------------------------------------------------------------------- module CgUtils ( addIdReps, cgLit, emitDataLits, mkDataLits, emitRODataLits, mkRODataLits, emitIf, emitIfThenElse, emitRtsCall, emitRtsCallWithVols, emitRtsCallWithResult, assignTemp, newTemp, emitSimultaneously, emitSwitch, emitLitSwitch, tagToClosure, callerSaveVolatileRegs, get_GlobalReg_addr, cmmAndWord, cmmOrWord, cmmNegate, cmmEqWord, cmmNeWord, cmmUGtWord, cmmOffsetExprW, cmmOffsetExprB, cmmRegOffW, cmmRegOffB, cmmLabelOffW, cmmLabelOffB, cmmOffsetW, cmmOffsetB, cmmOffsetLitW, cmmOffsetLitB, cmmLoadIndexW, cmmConstrTag, cmmConstrTag1, tagForCon, tagCons, isSmallFamily, cmmUntag, cmmIsTagged, cmmGetTag, addToMem, addToMemE, mkWordCLit, mkStringCLit, mkByteStringCLit, packHalfWordsCLit, blankWord, getSRTInfo, clHasCafRefs ) where #include "HsVersions.h" #include "../includes/stg/MachRegs.h" import BlockId import CgMonad import TyCon import DataCon import Id import IdInfo import Constants import SMRep import PprCmm ( {- instances -} ) import Cmm import CLabel import CmmUtils import ForeignCall import ClosureInfo import StgSyn (SRT(..)) import Literal import Digraph import ListSetOps import Util import DynFlags import FastString import PackageConfig import Outputable import Data.Char import Data.Bits import Data.Word import Data.Maybe ------------------------------------------------------------------------- -- -- Random small functions -- ------------------------------------------------------------------------- addIdReps :: [Id] -> [(CgRep, Id)] addIdReps ids = [(idCgRep id, id) | id <- ids] ------------------------------------------------------------------------- -- -- Literals -- ------------------------------------------------------------------------- cgLit :: Literal -> FCode CmmLit cgLit (MachStr s) = mkByteStringCLit (bytesFS s) -- not unpackFS; we want the UTF-8 byte stream. cgLit other_lit = return (mkSimpleLit other_lit) mkSimpleLit :: Literal -> CmmLit mkSimpleLit (MachChar c) = CmmInt (fromIntegral (ord c)) wordWidth mkSimpleLit MachNullAddr = zeroCLit mkSimpleLit (MachInt i) = CmmInt i wordWidth mkSimpleLit (MachInt64 i) = CmmInt i W64 mkSimpleLit (MachWord i) = CmmInt i wordWidth mkSimpleLit (MachWord64 i) = CmmInt i W64 mkSimpleLit (MachFloat r) = CmmFloat r W32 mkSimpleLit (MachDouble r) = CmmFloat r W64 mkSimpleLit (MachLabel fs ms fod) = CmmLabel (mkForeignLabel fs ms is_dyn fod) where is_dyn = False -- ToDo: fix me mkLtOp :: Literal -> MachOp -- On signed literals we must do a signed comparison mkLtOp (MachInt _) = MO_S_Lt wordWidth mkLtOp (MachFloat _) = MO_F_Lt W32 mkLtOp (MachDouble _) = MO_F_Lt W64 mkLtOp lit = MO_U_Lt (typeWidth (cmmLitType (mkSimpleLit lit))) --------------------------------------------------- -- -- Cmm data type functions -- --------------------------------------------------- ----------------------- -- The "B" variants take byte offsets cmmRegOffB :: CmmReg -> ByteOff -> CmmExpr cmmRegOffB = cmmRegOff cmmOffsetB :: CmmExpr -> ByteOff -> CmmExpr cmmOffsetB = cmmOffset cmmOffsetExprB :: CmmExpr -> CmmExpr -> CmmExpr cmmOffsetExprB = cmmOffsetExpr cmmLabelOffB :: CLabel -> ByteOff -> CmmLit cmmLabelOffB = cmmLabelOff cmmOffsetLitB :: CmmLit -> ByteOff -> CmmLit cmmOffsetLitB = cmmOffsetLit ----------------------- -- The "W" variants take word offsets cmmOffsetExprW :: CmmExpr -> CmmExpr -> CmmExpr -- The second arg is a *word* offset; need to change it to bytes cmmOffsetExprW e (CmmLit (CmmInt n _)) = cmmOffsetW e (fromInteger n) cmmOffsetExprW e wd_off = cmmIndexExpr wordWidth e wd_off cmmOffsetW :: CmmExpr -> WordOff -> CmmExpr cmmOffsetW e n = cmmOffsetB e (wORD_SIZE * n) cmmRegOffW :: CmmReg -> WordOff -> CmmExpr cmmRegOffW reg wd_off = cmmRegOffB reg (wd_off * wORD_SIZE) cmmOffsetLitW :: CmmLit -> WordOff -> CmmLit cmmOffsetLitW lit wd_off = cmmOffsetLitB lit (wORD_SIZE * wd_off) cmmLabelOffW :: CLabel -> WordOff -> CmmLit cmmLabelOffW lbl wd_off = cmmLabelOffB lbl (wORD_SIZE * wd_off) cmmLoadIndexW :: CmmExpr -> Int -> CmmType -> CmmExpr cmmLoadIndexW base off ty = CmmLoad (cmmOffsetW base off) ty ----------------------- cmmNeWord, cmmEqWord, cmmOrWord, cmmAndWord :: CmmExpr -> CmmExpr -> CmmExpr cmmOrWord e1 e2 = CmmMachOp mo_wordOr [e1, e2] cmmAndWord e1 e2 = CmmMachOp mo_wordAnd [e1, e2] cmmNeWord e1 e2 = CmmMachOp mo_wordNe [e1, e2] cmmEqWord e1 e2 = CmmMachOp mo_wordEq [e1, e2] cmmULtWord e1 e2 = CmmMachOp mo_wordULt [e1, e2] cmmUGeWord e1 e2 = CmmMachOp mo_wordUGe [e1, e2] cmmUGtWord e1 e2 = CmmMachOp mo_wordUGt [e1, e2] --cmmShlWord e1 e2 = CmmMachOp mo_wordShl [e1, e2] --cmmUShrWord e1 e2 = CmmMachOp mo_wordUShr [e1, e2] cmmSubWord e1 e2 = CmmMachOp mo_wordSub [e1, e2] cmmNegate :: CmmExpr -> CmmExpr cmmNegate (CmmLit (CmmInt n rep)) = CmmLit (CmmInt (-n) rep) cmmNegate e = CmmMachOp (MO_S_Neg (cmmExprWidth e)) [e] blankWord :: CmmStatic blankWord = CmmUninitialised wORD_SIZE -- Tagging -- -- Tag bits mask --cmmTagBits = CmmLit (mkIntCLit tAG_BITS) cmmTagMask = CmmLit (mkIntCLit tAG_MASK) cmmPointerMask = CmmLit (mkIntCLit (complement tAG_MASK)) -- Used to untag a possibly tagged pointer -- A static label need not be untagged cmmUntag e@(CmmLit (CmmLabel _)) = e -- Default case cmmUntag e = (e `cmmAndWord` cmmPointerMask) cmmGetTag e = (e `cmmAndWord` cmmTagMask) -- Test if a closure pointer is untagged cmmIsTagged e = (e `cmmAndWord` cmmTagMask) `cmmNeWord` CmmLit zeroCLit cmmConstrTag e = (e `cmmAndWord` cmmTagMask) `cmmSubWord` (CmmLit (mkIntCLit 1)) -- Get constructor tag, but one based. cmmConstrTag1 e = e `cmmAndWord` cmmTagMask {- The family size of a data type (the number of constructors) can be either: * small, if the family size < 2**tag_bits * big, otherwise. Small families can have the constructor tag in the tag bits. Big families only use the tag value 1 to represent evaluatedness. -} isSmallFamily fam_size = fam_size <= mAX_PTR_TAG tagForCon con = tag where con_tag = dataConTagZ con fam_size = tyConFamilySize (dataConTyCon con) tag | isSmallFamily fam_size = con_tag + 1 | otherwise = 1 --Tag an expression, to do: refactor, this appears in some other module. tagCons con expr = cmmOffsetB expr (tagForCon con) -- Copied from CgInfoTbls.hs -- We keep the *zero-indexed* tag in the srt_len field of the info -- table of a data constructor. dataConTagZ :: DataCon -> ConTagZ dataConTagZ con = dataConTag con - fIRST_TAG ----------------------- -- Making literals mkWordCLit :: StgWord -> CmmLit mkWordCLit wd = CmmInt (fromIntegral wd) wordWidth packHalfWordsCLit :: (Integral a, Integral b) => a -> b -> CmmLit -- Make a single word literal in which the lower_half_word is -- at the lower address, and the upper_half_word is at the -- higher address -- ToDo: consider using half-word lits instead -- but be careful: that's vulnerable when reversed packHalfWordsCLit lower_half_word upper_half_word #ifdef WORDS_BIGENDIAN = mkWordCLit ((fromIntegral lower_half_word `shiftL` hALF_WORD_SIZE_IN_BITS) .|. fromIntegral upper_half_word) #else = mkWordCLit ((fromIntegral lower_half_word) .|. (fromIntegral upper_half_word `shiftL` hALF_WORD_SIZE_IN_BITS)) #endif -------------------------------------------------------------------------- -- -- Incrementing a memory location -- -------------------------------------------------------------------------- addToMem :: Width -- rep of the counter -> CmmExpr -- Address -> Int -- What to add (a word) -> CmmStmt addToMem width ptr n = addToMemE width ptr (CmmLit (CmmInt (toInteger n) width)) addToMemE :: Width -- rep of the counter -> CmmExpr -- Address -> CmmExpr -- What to add (a word-typed expression) -> CmmStmt addToMemE width ptr n = CmmStore ptr (CmmMachOp (MO_Add width) [CmmLoad ptr (cmmBits width), n]) ------------------------------------------------------------------------- -- -- Converting a closure tag to a closure for enumeration types -- (this is the implementation of tagToEnum#). -- ------------------------------------------------------------------------- tagToClosure :: TyCon -> CmmExpr -> CmmExpr tagToClosure tycon tag = CmmLoad (cmmOffsetExprW closure_tbl tag) gcWord where closure_tbl = CmmLit (CmmLabel lbl) lbl = mkClosureTableLabel (tyConName tycon) NoCafRefs ------------------------------------------------------------------------- -- -- Conditionals and rts calls -- ------------------------------------------------------------------------- emitIf :: CmmExpr -- Boolean -> Code -- Then part -> Code -- Emit (if e then x) -- ToDo: reverse the condition to avoid the extra branch instruction if possible -- (some conditionals aren't reversible. eg. floating point comparisons cannot -- be inverted because there exist some values for which both comparisons -- return False, such as NaN.) emitIf cond then_part = do { then_id <- newLabelC ; join_id <- newLabelC ; stmtC (CmmCondBranch cond then_id) ; stmtC (CmmBranch join_id) ; labelC then_id ; then_part ; labelC join_id } emitIfThenElse :: CmmExpr -- Boolean -> Code -- Then part -> Code -- Else part -> Code -- Emit (if e then x else y) emitIfThenElse cond then_part else_part = do { then_id <- newLabelC ; join_id <- newLabelC ; stmtC (CmmCondBranch cond then_id) ; else_part ; stmtC (CmmBranch join_id) ; labelC then_id ; then_part ; labelC join_id } emitRtsCall :: LitString -> [CmmHinted CmmExpr] -> Bool -> Code emitRtsCall fun args safe = emitRtsCall' [] fun args Nothing safe -- The 'Nothing' says "save all global registers" emitRtsCallWithVols :: LitString -> [CmmHinted CmmExpr] -> [GlobalReg] -> Bool -> Code emitRtsCallWithVols fun args vols safe = emitRtsCall' [] fun args (Just vols) safe emitRtsCallWithResult :: LocalReg -> ForeignHint -> LitString -> [CmmHinted CmmExpr] -> Bool -> Code emitRtsCallWithResult res hint fun args safe = emitRtsCall' [CmmHinted res hint] fun args Nothing safe -- Make a call to an RTS C procedure emitRtsCall' :: [CmmHinted LocalReg] -> LitString -> [CmmHinted CmmExpr] -> Maybe [GlobalReg] -> Bool -- True <=> CmmSafe call -> Code emitRtsCall' res fun args vols safe = do safety <- if safe then getSRTInfo >>= (return . CmmSafe) else return CmmUnsafe stmtsC caller_save stmtC (CmmCall target res args safety CmmMayReturn) stmtsC caller_load where (caller_save, caller_load) = callerSaveVolatileRegs vols target = CmmCallee fun_expr CCallConv fun_expr = mkLblExpr (mkRtsCodeLabel fun) ----------------------------------------------------------------------------- -- -- Caller-Save Registers -- ----------------------------------------------------------------------------- -- Here we generate the sequence of saves/restores required around a -- foreign call instruction. -- TODO: reconcile with includes/Regs.h -- * Regs.h claims that BaseReg should be saved last and loaded first -- * This might not have been tickled before since BaseReg is callee save -- * Regs.h saves SparkHd, ParkT1, SparkBase and SparkLim callerSaveVolatileRegs :: Maybe [GlobalReg] -> ([CmmStmt], [CmmStmt]) callerSaveVolatileRegs vols = (caller_save, caller_load) where caller_save = foldr ($!) [] (map callerSaveGlobalReg regs_to_save) caller_load = foldr ($!) [] (map callerRestoreGlobalReg regs_to_save) system_regs = [Sp,SpLim,Hp,HpLim,CurrentTSO,CurrentNursery, {-SparkHd,SparkTl,SparkBase,SparkLim,-}BaseReg ] regs_to_save = system_regs ++ vol_list vol_list = case vols of Nothing -> all_of_em; Just regs -> regs all_of_em = [ VanillaReg n VNonGcPtr | n <- [0..mAX_Vanilla_REG] ] -- The VNonGcPtr is a lie, but I don't think it matters ++ [ FloatReg n | n <- [0..mAX_Float_REG] ] ++ [ DoubleReg n | n <- [0..mAX_Double_REG] ] ++ [ LongReg n | n <- [0..mAX_Long_REG] ] callerSaveGlobalReg reg next | callerSaves reg = CmmStore (get_GlobalReg_addr reg) (CmmReg (CmmGlobal reg)) : next | otherwise = next callerRestoreGlobalReg reg next | callerSaves reg = CmmAssign (CmmGlobal reg) (CmmLoad (get_GlobalReg_addr reg) (globalRegType reg)) : next | otherwise = next -- ----------------------------------------------------------------------------- -- Global registers -- We map STG registers onto appropriate CmmExprs. Either they map -- to real machine registers or stored as offsets from BaseReg. Given -- a GlobalReg, get_GlobalReg_addr always produces the -- register table address for it. -- (See also get_GlobalReg_reg_or_addr in MachRegs) get_GlobalReg_addr :: GlobalReg -> CmmExpr get_GlobalReg_addr BaseReg = regTableOffset 0 get_GlobalReg_addr mid = get_Regtable_addr_from_offset (globalRegType mid) (baseRegOffset mid) -- Calculate a literal representing an offset into the register table. -- Used when we don't have an actual BaseReg to offset from. regTableOffset n = CmmLit (CmmLabelOff mkMainCapabilityLabel (oFFSET_Capability_r + n)) get_Regtable_addr_from_offset :: CmmType -> Int -> CmmExpr get_Regtable_addr_from_offset rep offset = #ifdef REG_Base CmmRegOff (CmmGlobal BaseReg) offset #else regTableOffset offset #endif -- | Returns @True@ if this global register is stored in a caller-saves -- machine register. callerSaves :: GlobalReg -> Bool #ifdef CALLER_SAVES_Base callerSaves BaseReg = True #endif #ifdef CALLER_SAVES_R1 callerSaves (VanillaReg 1 _) = True #endif #ifdef CALLER_SAVES_R2 callerSaves (VanillaReg 2 _) = True #endif #ifdef CALLER_SAVES_R3 callerSaves (VanillaReg 3 _) = True #endif #ifdef CALLER_SAVES_R4 callerSaves (VanillaReg 4 _) = True #endif #ifdef CALLER_SAVES_R5 callerSaves (VanillaReg 5 _) = True #endif #ifdef CALLER_SAVES_R6 callerSaves (VanillaReg 6 _) = True #endif #ifdef CALLER_SAVES_R7 callerSaves (VanillaReg 7 _) = True #endif #ifdef CALLER_SAVES_R8 callerSaves (VanillaReg 8 _) = True #endif #ifdef CALLER_SAVES_F1 callerSaves (FloatReg 1) = True #endif #ifdef CALLER_SAVES_F2 callerSaves (FloatReg 2) = True #endif #ifdef CALLER_SAVES_F3 callerSaves (FloatReg 3) = True #endif #ifdef CALLER_SAVES_F4 callerSaves (FloatReg 4) = True #endif #ifdef CALLER_SAVES_D1 callerSaves (DoubleReg 1) = True #endif #ifdef CALLER_SAVES_D2 callerSaves (DoubleReg 2) = True #endif #ifdef CALLER_SAVES_L1 callerSaves (LongReg 1) = True #endif #ifdef CALLER_SAVES_Sp callerSaves Sp = True #endif #ifdef CALLER_SAVES_SpLim callerSaves SpLim = True #endif #ifdef CALLER_SAVES_Hp callerSaves Hp = True #endif #ifdef CALLER_SAVES_HpLim callerSaves HpLim = True #endif #ifdef CALLER_SAVES_CurrentTSO callerSaves CurrentTSO = True #endif #ifdef CALLER_SAVES_CurrentNursery callerSaves CurrentNursery = True #endif callerSaves _ = False -- ----------------------------------------------------------------------------- -- Information about global registers baseRegOffset :: GlobalReg -> Int baseRegOffset (VanillaReg 1 _) = oFFSET_StgRegTable_rR1 baseRegOffset (VanillaReg 2 _) = oFFSET_StgRegTable_rR2 baseRegOffset (VanillaReg 3 _) = oFFSET_StgRegTable_rR3 baseRegOffset (VanillaReg 4 _) = oFFSET_StgRegTable_rR4 baseRegOffset (VanillaReg 5 _) = oFFSET_StgRegTable_rR5 baseRegOffset (VanillaReg 6 _) = oFFSET_StgRegTable_rR6 baseRegOffset (VanillaReg 7 _) = oFFSET_StgRegTable_rR7 baseRegOffset (VanillaReg 8 _) = oFFSET_StgRegTable_rR8 baseRegOffset (VanillaReg 9 _) = oFFSET_StgRegTable_rR9 baseRegOffset (VanillaReg 10 _) = oFFSET_StgRegTable_rR10 baseRegOffset (FloatReg 1) = oFFSET_StgRegTable_rF1 baseRegOffset (FloatReg 2) = oFFSET_StgRegTable_rF2 baseRegOffset (FloatReg 3) = oFFSET_StgRegTable_rF3 baseRegOffset (FloatReg 4) = oFFSET_StgRegTable_rF4 baseRegOffset (DoubleReg 1) = oFFSET_StgRegTable_rD1 baseRegOffset (DoubleReg 2) = oFFSET_StgRegTable_rD2 baseRegOffset Sp = oFFSET_StgRegTable_rSp baseRegOffset SpLim = oFFSET_StgRegTable_rSpLim baseRegOffset (LongReg 1) = oFFSET_StgRegTable_rL1 baseRegOffset Hp = oFFSET_StgRegTable_rHp baseRegOffset HpLim = oFFSET_StgRegTable_rHpLim baseRegOffset CurrentTSO = oFFSET_StgRegTable_rCurrentTSO baseRegOffset CurrentNursery = oFFSET_StgRegTable_rCurrentNursery baseRegOffset HpAlloc = oFFSET_StgRegTable_rHpAlloc baseRegOffset EagerBlackholeInfo = oFFSET_stgEagerBlackholeInfo baseRegOffset GCEnter1 = oFFSET_stgGCEnter1 baseRegOffset GCFun = oFFSET_stgGCFun baseRegOffset BaseReg = panic "baseRegOffset:BaseReg" baseRegOffset _ = panic "baseRegOffset:other" ------------------------------------------------------------------------- -- -- Strings generate a top-level data block -- ------------------------------------------------------------------------- emitDataLits :: CLabel -> [CmmLit] -> Code -- Emit a data-segment data block emitDataLits lbl lits = emitData Data (CmmDataLabel lbl : map CmmStaticLit lits) mkDataLits :: CLabel -> [CmmLit] -> GenCmmTop CmmStatic info graph -- Emit a data-segment data block mkDataLits lbl lits = CmmData Data (CmmDataLabel lbl : map CmmStaticLit lits) emitRODataLits :: String -> CLabel -> [CmmLit] -> Code -- Emit a read-only data block emitRODataLits caller lbl lits = emitData section (CmmDataLabel lbl : map CmmStaticLit lits) where section | any needsRelocation lits = RelocatableReadOnlyData | otherwise = ReadOnlyData needsRelocation (CmmLabel _) = True needsRelocation (CmmLabelOff _ _) = True needsRelocation _ = False mkRODataLits :: CLabel -> [CmmLit] -> GenCmmTop CmmStatic info graph mkRODataLits lbl lits = CmmData section (CmmDataLabel lbl : map CmmStaticLit lits) where section | any needsRelocation lits = RelocatableReadOnlyData | otherwise = ReadOnlyData needsRelocation (CmmLabel _) = True needsRelocation (CmmLabelOff _ _) = True needsRelocation _ = False mkStringCLit :: String -> FCode CmmLit -- Make a global definition for the string, -- and return its label mkStringCLit str = mkByteStringCLit (map (fromIntegral.ord) str) mkByteStringCLit :: [Word8] -> FCode CmmLit mkByteStringCLit bytes = do { uniq <- newUnique ; let lbl = mkStringLitLabel uniq ; emitData ReadOnlyData [CmmDataLabel lbl, CmmString bytes] ; return (CmmLabel lbl) } ------------------------------------------------------------------------- -- -- Assigning expressions to temporaries -- ------------------------------------------------------------------------- assignTemp :: CmmExpr -> FCode CmmExpr -- For a non-trivial expression, e, create a local -- variable and assign the expression to it assignTemp e | isTrivialCmmExpr e = return e | otherwise = do { reg <- newTemp (cmmExprType e) ; stmtC (CmmAssign (CmmLocal reg) e) ; return (CmmReg (CmmLocal reg)) } newTemp :: CmmType -> FCode LocalReg newTemp rep = do { uniq <- newUnique; return (LocalReg uniq rep) } ------------------------------------------------------------------------- -- -- Building case analysis -- ------------------------------------------------------------------------- emitSwitch :: CmmExpr -- Tag to switch on -> [(ConTagZ, CgStmts)] -- Tagged branches -> Maybe CgStmts -- Default branch (if any) -> ConTagZ -> ConTagZ -- Min and Max possible values; behaviour -- outside this range is undefined -> Code -- ONLY A DEFAULT BRANCH: no case analysis to do emitSwitch tag_expr [] (Just stmts) _ _ = emitCgStmts stmts -- Right, off we go emitSwitch tag_expr branches mb_deflt lo_tag hi_tag = -- Just sort the branches before calling mk_sritch do { mb_deflt_id <- case mb_deflt of Nothing -> return Nothing Just stmts -> do id <- forkCgStmts stmts; return (Just id) ; dflags <- getDynFlags ; let via_C | HscC <- hscTarget dflags = True | otherwise = False ; stmts <- mk_switch tag_expr (sortLe le branches) mb_deflt_id lo_tag hi_tag via_C ; emitCgStmts stmts } where (t1,_) `le` (t2,_) = t1 <= t2 mk_switch :: CmmExpr -> [(ConTagZ, CgStmts)] -> Maybe BlockId -> ConTagZ -> ConTagZ -> Bool -> FCode CgStmts -- SINGLETON TAG RANGE: no case analysis to do mk_switch tag_expr [(tag,stmts)] _ lo_tag hi_tag via_C | lo_tag == hi_tag = ASSERT( tag == lo_tag ) return stmts -- SINGLETON BRANCH, NO DEFUALT: no case analysis to do mk_switch tag_expr [(tag,stmts)] Nothing lo_tag hi_tag via_C = return stmts -- The simplifier might have eliminated a case -- so we may have e.g. case xs of -- [] -> e -- In that situation we can be sure the (:) case -- can't happen, so no need to test -- SINGLETON BRANCH: one equality check to do mk_switch tag_expr [(tag,stmts)] (Just deflt) lo_tag hi_tag via_C = return (CmmCondBranch cond deflt `consCgStmt` stmts) where cond = cmmNeWord tag_expr (CmmLit (mkIntCLit tag)) -- We have lo_tag < hi_tag, but there's only one branch, -- so there must be a default -- ToDo: we might want to check for the two branch case, where one of -- the branches is the tag 0, because comparing '== 0' is likely to be -- more efficient than other kinds of comparison. -- DENSE TAG RANGE: use a switch statment. -- -- We also use a switch uncoditionally when compiling via C, because -- this will get emitted as a C switch statement and the C compiler -- should do a good job of optimising it. Also, older GCC versions -- (2.95 in particular) have problems compiling the complicated -- if-trees generated by this code, so compiling to a switch every -- time works around that problem. -- mk_switch tag_expr branches mb_deflt lo_tag hi_tag via_C | use_switch -- Use a switch = do { branch_ids <- mapM forkCgStmts (map snd branches) ; let tagged_blk_ids = zip (map fst branches) (map Just branch_ids) find_branch :: ConTagZ -> Maybe BlockId find_branch i = assocDefault mb_deflt tagged_blk_ids i -- NB. we have eliminated impossible branches at -- either end of the range (see below), so the first -- tag of a real branch is real_lo_tag (not lo_tag). arms = [ find_branch i | i <- [real_lo_tag..real_hi_tag]] switch_stmt = CmmSwitch (cmmOffset tag_expr (- real_lo_tag)) arms ; ASSERT(not (all isNothing arms)) return (oneCgStmt switch_stmt) } -- if we can knock off a bunch of default cases with one if, then do so | Just deflt <- mb_deflt, (lowest_branch - lo_tag) >= n_branches = do { (assign_tag, tag_expr') <- assignTemp' tag_expr ; let cond = cmmULtWord tag_expr' (CmmLit (mkIntCLit lowest_branch)) branch = CmmCondBranch cond deflt ; stmts <- mk_switch tag_expr' branches mb_deflt lowest_branch hi_tag via_C ; return (assign_tag `consCgStmt` (branch `consCgStmt` stmts)) } | Just deflt <- mb_deflt, (hi_tag - highest_branch) >= n_branches = do { (assign_tag, tag_expr') <- assignTemp' tag_expr ; let cond = cmmUGtWord tag_expr' (CmmLit (mkIntCLit highest_branch)) branch = CmmCondBranch cond deflt ; stmts <- mk_switch tag_expr' branches mb_deflt lo_tag highest_branch via_C ; return (assign_tag `consCgStmt` (branch `consCgStmt` stmts)) } | otherwise -- Use an if-tree = do { (assign_tag, tag_expr') <- assignTemp' tag_expr -- To avoid duplication ; lo_stmts <- mk_switch tag_expr' lo_branches mb_deflt lo_tag (mid_tag-1) via_C ; hi_stmts <- mk_switch tag_expr' hi_branches mb_deflt mid_tag hi_tag via_C ; hi_id <- forkCgStmts hi_stmts ; let cond = cmmUGeWord tag_expr' (CmmLit (mkIntCLit mid_tag)) branch_stmt = CmmCondBranch cond hi_id ; return (assign_tag `consCgStmt` (branch_stmt `consCgStmt` lo_stmts)) } -- we test (e >= mid_tag) rather than (e < mid_tag), because -- the former works better when e is a comparison, and there -- are two tags 0 & 1 (mid_tag == 1). In this case, the code -- generator can reduce the condition to e itself without -- having to reverse the sense of the comparison: comparisons -- can't always be easily reversed (eg. floating -- pt. comparisons). where use_switch = {- pprTrace "mk_switch" ( ppr tag_expr <+> text "n_tags:" <+> int n_tags <+> text "branches:" <+> ppr (map fst branches) <+> text "n_branches:" <+> int n_branches <+> text "lo_tag:" <+> int lo_tag <+> text "hi_tag:" <+> int hi_tag <+> text "real_lo_tag:" <+> int real_lo_tag <+> text "real_hi_tag:" <+> int real_hi_tag) $ -} ASSERT( n_branches > 1 && n_tags > 1 ) n_tags > 2 && (via_C || (dense && big_enough)) -- up to 4 branches we use a decision tree, otherwise -- a switch (== jump table in the NCG). This seems to be -- optimal, and corresponds with what gcc does. big_enough = n_branches > 4 dense = n_branches > (n_tags `div` 2) n_branches = length branches -- ignore default slots at each end of the range if there's -- no default branch defined. lowest_branch = fst (head branches) highest_branch = fst (last branches) real_lo_tag | isNothing mb_deflt = lowest_branch | otherwise = lo_tag real_hi_tag | isNothing mb_deflt = highest_branch | otherwise = hi_tag n_tags = real_hi_tag - real_lo_tag + 1 -- INVARIANT: Provided hi_tag > lo_tag (which is true) -- lo_tag <= mid_tag < hi_tag -- lo_branches have tags < mid_tag -- hi_branches have tags >= mid_tag (mid_tag,_) = branches !! (n_branches `div` 2) -- 2 branches => n_branches `div` 2 = 1 -- => branches !! 1 give the *second* tag -- There are always at least 2 branches here (lo_branches, hi_branches) = span is_lo branches is_lo (t,_) = t < mid_tag assignTemp' e | isTrivialCmmExpr e = return (CmmNop, e) | otherwise = do { reg <- newTemp (cmmExprType e) ; return (CmmAssign (CmmLocal reg) e, CmmReg (CmmLocal reg)) } emitLitSwitch :: CmmExpr -- Tag to switch on -> [(Literal, CgStmts)] -- Tagged branches -> CgStmts -- Default branch (always) -> Code -- Emit the code -- Used for general literals, whose size might not be a word, -- where there is always a default case, and where we don't know -- the range of values for certain. For simplicity we always generate a tree. -- -- ToDo: for integers we could do better here, perhaps by generalising -- mk_switch and using that. --SDM 15/09/2004 emitLitSwitch scrut [] deflt = emitCgStmts deflt emitLitSwitch scrut branches deflt_blk = do { scrut' <- assignTemp scrut ; deflt_blk_id <- forkCgStmts deflt_blk ; blk <- mk_lit_switch scrut' deflt_blk_id (sortLe le branches) ; emitCgStmts blk } where le (t1,_) (t2,_) = t1 <= t2 mk_lit_switch :: CmmExpr -> BlockId -> [(Literal,CgStmts)] -> FCode CgStmts mk_lit_switch scrut deflt_blk_id [(lit,blk)] = return (consCgStmt if_stmt blk) where cmm_lit = mkSimpleLit lit rep = cmmLitType cmm_lit ne = if isFloatType rep then MO_F_Ne else MO_Ne cond = CmmMachOp (ne (typeWidth rep)) [scrut, CmmLit cmm_lit] if_stmt = CmmCondBranch cond deflt_blk_id mk_lit_switch scrut deflt_blk_id branches = do { hi_blk <- mk_lit_switch scrut deflt_blk_id hi_branches ; lo_blk <- mk_lit_switch scrut deflt_blk_id lo_branches ; lo_blk_id <- forkCgStmts lo_blk ; let if_stmt = CmmCondBranch cond lo_blk_id ; return (if_stmt `consCgStmt` hi_blk) } where n_branches = length branches (mid_lit,_) = branches !! (n_branches `div` 2) -- See notes above re mid_tag (lo_branches, hi_branches) = span is_lo branches is_lo (t,_) = t < mid_lit cond = CmmMachOp (mkLtOp mid_lit) [scrut, CmmLit (mkSimpleLit mid_lit)] ------------------------------------------------------------------------- -- -- Simultaneous assignment -- ------------------------------------------------------------------------- emitSimultaneously :: CmmStmts -> Code -- Emit code to perform the assignments in the -- input simultaneously, using temporary variables when necessary. -- -- The Stmts must be: -- CmmNop, CmmComment, CmmAssign, CmmStore -- and nothing else -- We use the strongly-connected component algorithm, in which -- * the vertices are the statements -- * an edge goes from s1 to s2 iff -- s1 assigns to something s2 uses -- that is, if s1 should *follow* s2 in the final order type CVertex = (Int, CmmStmt) -- Give each vertex a unique number, -- for fast comparison emitSimultaneously stmts = codeOnly $ case filterOut isNopStmt (stmtList stmts) of -- Remove no-ops [] -> nopC [stmt] -> stmtC stmt -- It's often just one stmt stmt_list -> doSimultaneously1 (zip [(1::Int)..] stmt_list) doSimultaneously1 :: [CVertex] -> Code doSimultaneously1 vertices = let edges = [ (vertex, key1, edges_from stmt1) | vertex@(key1, stmt1) <- vertices ] edges_from stmt1 = [ key2 | (key2, stmt2) <- vertices, stmt1 `mustFollow` stmt2 ] components = stronglyConnCompFromEdgedVertices edges -- do_components deal with one strongly-connected component -- Not cyclic, or singleton? Just do it do_component (AcyclicSCC (n,stmt)) = stmtC stmt do_component (CyclicSCC [(n,stmt)]) = stmtC stmt -- Cyclic? Then go via temporaries. Pick one to -- break the loop and try again with the rest. do_component (CyclicSCC ((n,first_stmt) : rest)) = do { from_temp <- go_via_temp first_stmt ; doSimultaneously1 rest ; stmtC from_temp } go_via_temp (CmmAssign dest src) = do { tmp <- newTemp (cmmRegType dest) -- TODO FIXME NOW if the pair of assignments move across a call this will be wrong ; stmtC (CmmAssign (CmmLocal tmp) src) ; return (CmmAssign dest (CmmReg (CmmLocal tmp))) } go_via_temp (CmmStore dest src) = do { tmp <- newTemp (cmmExprType src) -- TODO FIXME NOW if the pair of assignemnts move across a call this will be wrong ; stmtC (CmmAssign (CmmLocal tmp) src) ; return (CmmStore dest (CmmReg (CmmLocal tmp))) } in mapCs do_component components mustFollow :: CmmStmt -> CmmStmt -> Bool CmmAssign reg _ `mustFollow` stmt = anySrc (reg `regUsedIn`) stmt CmmStore loc e `mustFollow` stmt = anySrc (locUsedIn loc (cmmExprType e)) stmt CmmNop `mustFollow` stmt = False CmmComment _ `mustFollow` stmt = False anySrc :: (CmmExpr -> Bool) -> CmmStmt -> Bool -- True if the fn is true of any input of the stmt anySrc p (CmmAssign _ e) = p e anySrc p (CmmStore e1 e2) = p e1 || p e2 -- Might be used in either side anySrc p (CmmComment _) = False anySrc p CmmNop = False anySrc p other = True -- Conservative regUsedIn :: CmmReg -> CmmExpr -> Bool reg `regUsedIn` CmmLit _ = False reg `regUsedIn` CmmLoad e _ = reg `regUsedIn` e reg `regUsedIn` CmmReg reg' = reg == reg' reg `regUsedIn` CmmRegOff reg' _ = reg == reg' reg `regUsedIn` CmmMachOp _ es = any (reg `regUsedIn`) es locUsedIn :: CmmExpr -> CmmType -> CmmExpr -> Bool -- (locUsedIn a r e) checks whether writing to r[a] could affect the value of -- 'e'. Returns True if it's not sure. locUsedIn loc rep (CmmLit _) = False locUsedIn loc rep (CmmLoad e ld_rep) = possiblySameLoc loc rep e ld_rep locUsedIn loc rep (CmmReg reg') = False locUsedIn loc rep (CmmRegOff reg' _) = False locUsedIn loc rep (CmmMachOp _ es) = any (locUsedIn loc rep) es possiblySameLoc :: CmmExpr -> CmmType -> CmmExpr -> CmmType -> Bool -- Assumes that distinct registers (eg Hp, Sp) do not -- point to the same location, nor any offset thereof. possiblySameLoc (CmmReg r1) rep1 (CmmReg r2) rep2 = r1==r2 possiblySameLoc (CmmReg r1) rep1 (CmmRegOff r2 0) rep2 = r1==r2 possiblySameLoc (CmmRegOff r1 0) rep1 (CmmReg r2) rep2 = r1==r2 possiblySameLoc (CmmRegOff r1 start1) rep1 (CmmRegOff r2 start2) rep2 = r1==r2 && end1 > start2 && end2 > start1 where end1 = start1 + widthInBytes (typeWidth rep1) end2 = start2 + widthInBytes (typeWidth rep2) possiblySameLoc l1 rep1 (CmmLit _) rep2 = False possiblySameLoc l1 rep1 l2 rep2 = True -- Conservative ------------------------------------------------------------------------- -- -- Static Reference Tables -- ------------------------------------------------------------------------- -- There is just one SRT for each top level binding; all the nested -- bindings use sub-sections of this SRT. The label is passed down to -- the nested bindings via the monad. getSRTInfo :: FCode C_SRT getSRTInfo = do srt_lbl <- getSRTLabel srt <- getSRT case srt of -- TODO: Should we panic in this case? -- Someone obviously thinks there should be an SRT NoSRT -> return NoC_SRT SRTEntries {} -> panic "getSRTInfo: SRTEntries. Perhaps you forgot to run SimplStg?" SRT off len bmp | len > hALF_WORD_SIZE_IN_BITS || bmp == [fromIntegral srt_escape] -> do id <- newUnique let srt_desc_lbl = mkLargeSRTLabel id emitRODataLits "getSRTInfo" srt_desc_lbl ( cmmLabelOffW srt_lbl off : mkWordCLit (fromIntegral len) : map mkWordCLit bmp) return (C_SRT srt_desc_lbl 0 srt_escape) SRT off len bmp | otherwise -> return (C_SRT srt_lbl off (fromIntegral (head bmp))) -- The fromIntegral converts to StgHalfWord srt_escape = (-1) :: StgHalfWord clHasCafRefs :: ClosureInfo -> CafInfo clHasCafRefs (ClosureInfo {closureSRT = srt}) = case srt of NoC_SRT -> NoCafRefs _ -> MayHaveCafRefs clHasCafRefs (ConInfo {}) = NoCafRefs