{-# LANGUAGE BangPatterns #-}{-# LANGUAGE CPP #-}{-# LANGUAGE ExplicitForAll #-}{-# LANGUAGE FlexibleContexts #-}{-# LANGUAGE FlexibleInstances #-}{-# LANGUAGE GADTs #-}{-# LANGUAGE MultiParamTypeClasses #-}{-# LANGUAGE StandaloneDeriving #-}{-# LANGUAGE UndecidableInstances #-}{-# LANGUAGE ScopedTypeVariables #-}-- CmmNode type for representation using Hoopl graphs.moduleCmmNode(CmmNode (..),CmmFormal ,CmmActual ,CmmTickish ,UpdFrameOffset ,Convention (..),ForeignConvention (..),ForeignTarget (..),foreignTargetHints ,CmmReturnInfo (..),mapExp ,mapExpDeep ,wrapRecExp ,foldExp ,foldExpDeep ,wrapRecExpf ,mapExpM ,mapExpDeepM ,wrapRecExpM ,mapSuccessors ,mapCollectSuccessors ,-- * Tick scopesCmmTickScope (..),isTickSubScope ,combineTickScopes ,)whereimportGhcPrelude hiding(succ)importCodeGen.Platform importCmmExpr importCmmSwitch importDynFlags importFastString importForeignCall importOutputable importSMRep importCoreSyn (Tickish )importqualifiedUnique asUimportHoopl.Block importHoopl.Graph importHoopl.Collections importHoopl.Label importData.MaybeimportData.List(tails,sortBy)importUnique (nonDetCmpUnique )importUtil -------------------------- CmmNode#define ULabel {-# UNPACK #-} !Label
dataCmmNode e x whereCmmEntry ::ULabel->CmmTickScope->CmmNode C O CmmComment ::FastString ->CmmNode O O -- Tick annotation, covering Cmm code in our tick scope. We only-- expect non-code @Tickish@ at this point (e.g. @SourceNote@).-- See Note [CmmTick scoping details]CmmTick ::!CmmTickish ->CmmNode O O -- Unwind pseudo-instruction, encoding stack unwinding-- instructions for a debugger. This describes how to reconstruct-- the "old" value of a register if we want to navigate the stack-- up one frame. Having unwind information for @Sp@ will allow the-- debugger to "walk" the stack.---- See Note [What is this unwinding business?] in DebugCmmUnwind ::[(GlobalReg ,MaybeCmmExpr )]->CmmNode O O CmmAssign ::!CmmReg ->!CmmExpr ->CmmNode O O -- Assign to registerCmmStore ::!CmmExpr ->!CmmExpr ->CmmNode O O -- Assign to memory location. Size is-- given by cmmExprType of the rhs.CmmUnsafeForeignCall ::-- An unsafe foreign call;-- see Note [Foreign calls]-- Like a "fat machine instruction"; can occur-- in the middle of a blockForeignTarget ->-- call target[CmmFormal ]->-- zero or more results[CmmActual ]->-- zero or more argumentsCmmNode O O -- Semantics: clobbers any GlobalRegs for which callerSaves r == True-- See Note [Unsafe foreign calls clobber caller-save registers]---- Invariant: the arguments and the ForeignTarget must not-- mention any registers for which CodeGen.Platform.callerSaves-- is True. See Note [Register Parameter Passing].CmmBranch ::ULabel->CmmNodeO C -- Goto another block in the same procedureCmmCondBranch ::{-- conditional branchcml_pred ::CmmExpr ,cml_true ,cml_false ::ULabel,cml_likely ::MaybeBool-- likely result of the conditional,-- if known}->CmmNode O C CmmSwitch ::CmmExpr -- Scrutinee, of some integral type->SwitchTargets -- Cases. See [Note SwitchTargets]->CmmNode O C CmmCall ::{-- A native call or tail callcml_target ::CmmExpr ,-- never a CmmPrim to a CallishMachOp!cml_cont ::MaybeLabel ,-- Label of continuation (Nothing for return or tail call)---- Note [Continuation BlockId]: these BlockIds are called-- Continuation BlockIds, and are the only BlockIds that can-- occur in CmmExprs, namely as (CmmLit (CmmBlock b)) or-- (CmmStackSlot (Young b) _).cml_args_regs ::[GlobalReg ],-- The argument GlobalRegs (Rx, Fx, Dx, Lx) that are passed-- to the call. This is essential information for the-- native code generator's register allocator; without-- knowing which GlobalRegs are live it has to assume that-- they are all live. This list should only include-- GlobalRegs that are mapped to real machine registers on-- the target platform.cml_args ::ByteOff ,-- Byte offset, from the *old* end of the Area associated with-- the Label (if cml_cont = Nothing, then Old area), of-- youngest outgoing arg. Set the stack pointer to this before-- transferring control.-- (NB: an update frame might also have been stored in the Old-- area, but it'll be in an older part than the args.)cml_ret_args ::ByteOff ,-- For calls *only*, the byte offset for youngest returned value-- This is really needed at the *return* point rather than here-- at the call, but in practice it's convenient to record it here.cml_ret_off ::ByteOff -- For calls *only*, the byte offset of the base of the frame that-- must be described by the info table for the return point.-- The older words are an update frames, which have their own-- info-table and layout information-- From a liveness point of view, the stack words older than-- cml_ret_off are treated as live, even if the sequel of-- the call goes into a loop.}->CmmNode O C CmmForeignCall ::{-- A safe foreign call; see Note [Foreign calls]-- Always the last node of a blocktgt ::ForeignTarget ,-- call target and conventionres ::[CmmFormal ],-- zero or more resultsargs ::[CmmActual ],-- zero or more arguments; see Note [Register parameter passing]succ ::ULabel,-- Label of continuationret_args ::ByteOff ,-- same as cml_ret_argsret_off ::ByteOff ,-- same as cml_ret_offintrbl ::Bool-- whether or not the call is interruptible}->CmmNode O C {- Note [Foreign calls]
~~~~~~~~~~~~~~~~~~~~~~~
A CmmUnsafeForeignCall is used for *unsafe* foreign calls;
a CmmForeignCall call is used for *safe* foreign calls.
Unsafe ones are mostly easy: think of them as a "fat machine
instruction". In particular, they do *not* kill all live registers,
just the registers they return to (there was a bit of code in GHC that
conservatively assumed otherwise.) However, see [Register parameter passing].
Safe ones are trickier. A safe foreign call
 r = f(x)
ultimately expands to
 push "return address" -- Never used to return to;
 -- just points an info table
 save registers into TSO
 call suspendThread
 r = f(x) -- Make the call
 call resumeThread
 restore registers
 pop "return address"
We cannot "lower" a safe foreign call to this sequence of Cmms, because
after we've saved Sp all the Cmm optimiser's assumptions are broken.
Note that a safe foreign call needs an info table.
So Safe Foreign Calls must remain as last nodes until the stack is
made manifest in CmmLayoutStack, where they are lowered into the above
sequence.
-}{- Note [Unsafe foreign calls clobber caller-save registers]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A foreign call is defined to clobber any GlobalRegs that are mapped to
caller-saves machine registers (according to the prevailing C ABI).
StgCmmUtils.callerSaves tells you which GlobalRegs are caller-saves.
This is a design choice that makes it easier to generate code later.
We could instead choose to say that foreign calls do *not* clobber
caller-saves regs, but then we would have to figure out which regs
were live across the call later and insert some saves/restores.
Furthermore when we generate code we never have any GlobalRegs live
across a call, because they are always copied-in to LocalRegs and
copied-out again before making a call/jump. So all we have to do is
avoid any code motion that would make a caller-saves GlobalReg live
across a foreign call during subsequent optimisations.
-}{- Note [Register parameter passing]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
On certain architectures, some registers are utilized for parameter
passing in the C calling convention. For example, in x86-64 Linux
convention, rdi, rsi, rdx and rcx (as well as r8 and r9) may be used for
argument passing. These are registers R3-R6, which our generated
code may also be using; as a result, it's necessary to save these
values before doing a foreign call. This is done during initial
code generation in callerSaveVolatileRegs in StgCmmUtils.hs. However,
one result of doing this is that the contents of these registers
may mysteriously change if referenced inside the arguments. This
is dangerous, so you'll need to disable inlining much in the same
way is done in cmm/CmmOpt.hs currently. We should fix this!
-}----------------------------------------------- Eq instance of CmmNodederivinginstanceEq(CmmNode e x )------------------------------------------------ Hoopl instances of CmmNodeinstanceNonLocal CmmNode whereentryLabel (CmmEntry l _)=l successors (CmmBranch l )=[l ]successors(CmmCondBranch {cml_true=t ,cml_false=f })=[f ,t ]-- meets layout constraintsuccessors(CmmSwitch _ids )=switchTargetsToList ids successors(CmmCall {cml_cont=l })=maybeToListl successors(CmmForeignCall {succ=l })=[l ]---------------------------------------------------- Various helper typestypeCmmActual =CmmExpr typeCmmFormal =LocalReg typeUpdFrameOffset =ByteOff -- | A convention maps a list of values (function arguments or return-- values) to registers or stack locations.dataConvention =NativeDirectCall -- ^ top-level Haskell functions use @NativeDirectCall@, which-- maps arguments to registers starting with R2, according to-- how many registers are available on the platform. This-- convention ignores R1, because for a top-level function call-- the function closure is implicit, and doesn't need to be passed.|NativeNodeCall -- ^ non-top-level Haskell functions, which pass the address of-- the function closure in R1 (regardless of whether R1 is a-- real register or not), and the rest of the arguments in-- registers or on the stack.|NativeReturn -- ^ a native return. The convention for returns depends on-- how many values are returned: for just one value returned,-- the appropriate register is used (R1, F1, etc.). regardless-- of whether it is a real register or not. For multiple-- values returned, they are mapped to registers or the stack.|Slow -- ^ Slow entry points: all args pushed on the stack|GC -- ^ Entry to the garbage collector: uses the node reg!-- (TODO: I don't think we need this --SDM)deriving(Eq)dataForeignConvention =ForeignConvention CCallConv -- Which foreign-call convention[ForeignHint ]-- Extra info about the args[ForeignHint ]-- Extra info about the resultCmmReturnInfo derivingEqdataCmmReturnInfo =CmmMayReturn |CmmNeverReturns deriving(Eq)dataForeignTarget -- The target of a foreign call=ForeignTarget -- A foreign procedureCmmExpr -- Its addressForeignConvention -- Its calling convention|PrimTarget -- A possibly-side-effecting machine operationCallishMachOp -- Which onederivingEqforeignTargetHints::ForeignTarget ->([ForeignHint ],[ForeignHint ])foreignTargetHints target =(res_hints ++repeatNoHint ,arg_hints ++repeatNoHint )where(res_hints ,arg_hints )=casetarget ofPrimTarget op ->callishMachOpHints op ForeignTarget _(ForeignConvention _arg_hints res_hints _)->(res_hints ,arg_hints )---------------------------------------------------- Instances of register and slot users / definersinstanceUserOfRegs LocalReg (CmmNode e x )wherefoldRegsUsed dflags f !z n =casen ofCmmAssign _expr ->fold f z expr CmmStore addr rval ->fold f (fold f z addr )rval CmmUnsafeForeignCall t _args ->fold f (fold f z t )args CmmCondBranch expr ___->fold f z expr CmmSwitch expr _->fold f z expr CmmCall {cml_target=tgt }->fold f z tgt CmmForeignCall {tgt=tgt ,args=args }->fold f (fold f z tgt )args _->z wherefold::foralla b .UserOfRegs LocalReg a =>(b ->LocalReg ->b )->b ->a ->b fold f z n =foldRegsUsed dflags f z n instanceUserOfRegs GlobalReg (CmmNode e x )wherefoldRegsUsed dflags f !z n =casen ofCmmAssign _expr ->fold f z expr CmmStore addr rval ->fold f (fold f z addr )rval CmmUnsafeForeignCall t _args ->fold f (fold f z t )args CmmCondBranch expr ___->fold f z expr CmmSwitch expr _->fold f z expr CmmCall {cml_target=tgt ,cml_args_regs=args }->fold f (fold f z args )tgt CmmForeignCall {tgt=tgt ,args=args }->fold f (fold f z tgt )args _->z wherefold::foralla b .UserOfRegs GlobalReg a =>(b ->GlobalReg ->b )->b ->a ->b fold f z n =foldRegsUsed dflags f z n instance(Ordr ,UserOfRegs r CmmReg )=>UserOfRegs r ForeignTarget where-- The (Ord r) in the context is necessary here-- See Note [Recursive superclasses] in TcInstDclsfoldRegsUsed __!z (PrimTarget _)=z foldRegsUseddflags f !z (ForeignTarget e _)=foldRegsUsed dflags f z e instanceDefinerOfRegs LocalReg (CmmNode e x )wherefoldRegsDefd dflags f !z n =casen ofCmmAssign lhs _->fold f z lhs CmmUnsafeForeignCall _fs _->fold f z fs CmmForeignCall {res=res }->fold f z res _->z wherefold::foralla b .DefinerOfRegs LocalReg a =>(b ->LocalReg ->b )->b ->a ->b fold f z n =foldRegsDefd dflags f z n instanceDefinerOfRegs GlobalReg (CmmNode e x )wherefoldRegsDefd dflags f !z n =casen ofCmmAssign lhs _->fold f z lhs CmmUnsafeForeignCall tgt __->fold f z (foreignTargetRegs tgt )CmmCall {}->fold f z activeRegs CmmForeignCall {}->fold f z activeRegs -- See Note [Safe foreign calls clobber STG registers]_->z wherefold::foralla b .DefinerOfRegs GlobalReg a =>(b ->GlobalReg ->b )->b ->a ->b fold f z n =foldRegsDefd dflags f z n platform =targetPlatform dflags activeRegs =activeStgRegs platform activeCallerSavesRegs =filter(callerSaves platform )activeRegs foreignTargetRegs (ForeignTarget _(ForeignConvention ___CmmNeverReturns ))=[]foreignTargetRegs_=activeCallerSavesRegs -- Note [Safe foreign calls clobber STG registers]-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~---- During stack layout phase every safe foreign call is expanded into a block-- that contains unsafe foreign call (instead of safe foreign call) and ends-- with a normal call (See Note [Foreign calls]). This means that we must-- treat safe foreign call as if it was a normal call (because eventually it-- will be). This is important if we try to run sinking pass before stack-- layout phase. Consider this example of what might go wrong (this is cmm-- code from stablename001 test). Here is code after common block elimination-- (before stack layout):---- c1q6:-- _s1pf::P64 = R1;-- _c1q8::I64 = performMajorGC;-- I64[(young<c1q9> + 8)] = c1q9;-- foreign call "ccall" arg hints: [] result hints: [] (_c1q8::I64)(...)-- returns to c1q9 args: ([]) ress: ([])ret_args: 8ret_off: 8;-- c1q9:-- I64[(young<c1qb> + 8)] = c1qb;-- R1 = _s1pc::P64;-- call stg_makeStableName#(R1) returns to c1qb, args: 8, res: 8, upd: 8;---- If we run sinking pass now (still before stack layout) we will get this:---- c1q6:-- I64[(young<c1q9> + 8)] = c1q9;-- foreign call "ccall" arg hints: [] result hints: [] performMajorGC(...)-- returns to c1q9 args: ([]) ress: ([])ret_args: 8ret_off: 8;-- c1q9:-- I64[(young<c1qb> + 8)] = c1qb;-- _s1pf::P64 = R1; <------ _s1pf sunk past safe foreign call-- R1 = _s1pc::P64;-- call stg_makeStableName#(R1) returns to c1qb, args: 8, res: 8, upd: 8;---- Notice that _s1pf was sunk past a foreign call. When we run stack layout-- safe call to performMajorGC will be turned into:---- c1q6:-- _s1pc::P64 = P64[Sp + 8];-- I64[Sp - 8] = c1q9;-- Sp = Sp - 8;-- I64[I64[CurrentTSO + 24] + 16] = Sp;-- P64[CurrentNursery + 8] = Hp + 8;-- (_u1qI::I64) = call "ccall" arg hints: [PtrHint,]-- result hints: [PtrHint] suspendThread(BaseReg, 0);-- call "ccall" arg hints: [] result hints: [] performMajorGC();-- (_u1qJ::I64) = call "ccall" arg hints: [PtrHint]-- result hints: [PtrHint] resumeThread(_u1qI::I64);-- BaseReg = _u1qJ::I64;-- _u1qK::P64 = CurrentTSO;-- _u1qL::P64 = I64[_u1qK::P64 + 24];-- Sp = I64[_u1qL::P64 + 16];-- SpLim = _u1qL::P64 + 192;-- HpAlloc = 0;-- Hp = I64[CurrentNursery + 8] - 8;-- HpLim = I64[CurrentNursery] + (%MO_SS_Conv_W32_W64(I32[CurrentNursery + 48]) * 4096 - 1);-- call (I64[Sp])() returns to c1q9, args: 8, res: 8, upd: 8;-- c1q9:-- I64[(young<c1qb> + 8)] = c1qb;-- _s1pf::P64 = R1; <------ INCORRECT!-- R1 = _s1pc::P64;-- call stg_makeStableName#(R1) returns to c1qb, args: 8, res: 8, upd: 8;---- Notice that c1q6 now ends with a call. Sinking _s1pf::P64 = R1 past that-- call is clearly incorrect. This is what would happen if we assumed that-- safe foreign call has the same semantics as unsafe foreign call. To prevent-- this we need to treat safe foreign call as if was normal call.------------------------------------- mapping Expr in CmmNodemapForeignTarget::(CmmExpr ->CmmExpr )->ForeignTarget ->ForeignTarget mapForeignTarget exp (ForeignTarget e c )=ForeignTarget (exp e )c mapForeignTarget_m @(PrimTarget _)=m wrapRecExp::(CmmExpr ->CmmExpr )->CmmExpr ->CmmExpr -- Take a transformer on expressions and apply it recursively.-- (wrapRecExp f e) first recursively applies itself to sub-expressions of e-- then uses f to rewrite the resulting expressionwrapRecExp f (CmmMachOp op es )=f (CmmMachOp op $map(wrapRecExp f )es )wrapRecExpf (CmmLoad addr ty )=f (CmmLoad (wrapRecExp f addr )ty )wrapRecExpf e =f e mapExp::(CmmExpr ->CmmExpr )->CmmNode e x ->CmmNode e x mapExp _f @(CmmEntry {})=f mapExp_m @(CmmComment _)=m mapExp_m @(CmmTick _)=m mapExpf (CmmUnwind regs )=CmmUnwind (map(fmap(fmapf ))regs )mapExpf (CmmAssign r e )=CmmAssign r (f e )mapExpf (CmmStore addr e )=CmmStore (f addr )(f e )mapExpf (CmmUnsafeForeignCall tgt fs as)=CmmUnsafeForeignCall (mapForeignTarget f tgt )fs (mapf as)mapExp_l @(CmmBranch _)=l mapExpf (CmmCondBranch e ti fi l )=CmmCondBranch (f e )ti fi l mapExpf (CmmSwitch e ids )=CmmSwitch (f e )ids mapExpf n @CmmCall {cml_target=tgt }=n {cml_target=f tgt }mapExpf (CmmForeignCall tgt fs assucc ret_args updfr intrbl )=CmmForeignCall (mapForeignTarget f tgt )fs (mapf as)succ ret_args updfr intrbl mapExpDeep::(CmmExpr ->CmmExpr )->CmmNode e x ->CmmNode e x mapExpDeep f =mapExp $wrapRecExp f -------------------------------------------------------------------------- mapping Expr in CmmNode, but not performing allocation if no changesmapForeignTargetM::(CmmExpr ->MaybeCmmExpr )->ForeignTarget ->MaybeForeignTarget mapForeignTargetM f (ForeignTarget e c )=(\x ->ForeignTarget x c )`fmap`f e mapForeignTargetM_(PrimTarget _)=NothingwrapRecExpM::(CmmExpr ->MaybeCmmExpr )->(CmmExpr ->MaybeCmmExpr )-- (wrapRecExpM f e) first recursively applies itself to sub-expressions of e-- then gives f a chance to rewrite the resulting expressionwrapRecExpM f n @(CmmMachOp op es )=maybe(f n )(f .CmmMachOp op )(mapListM (wrapRecExpM f )es )wrapRecExpMf n @(CmmLoad addr ty )=maybe(f n )(f .flipCmmLoad ty )(wrapRecExpM f addr )wrapRecExpMf e =f e mapExpM::(CmmExpr ->MaybeCmmExpr )->CmmNode e x ->Maybe(CmmNode e x )mapExpM _(CmmEntry {})=NothingmapExpM_(CmmComment _)=NothingmapExpM_(CmmTick _)=NothingmapExpMf (CmmUnwind regs )=CmmUnwind `fmap`mapM(\(r ,e )->mapMf e >>=\e' ->pure(r ,e' ))regs mapExpMf (CmmAssign r e )=CmmAssign r `fmap`f e mapExpMf (CmmStore addr e )=(\[addr' ,e' ]->CmmStore addr' e' )`fmap`mapListM f [addr ,e ]mapExpM_(CmmBranch _)=NothingmapExpMf (CmmCondBranch e ti fi l )=(\x ->CmmCondBranch x ti fi l )`fmap`f e mapExpMf (CmmSwitch e tbl )=(\x ->CmmSwitch x tbl )`fmap`f e mapExpMf (CmmCall tgt mb_id r o i s )=(\x ->CmmCall x mb_id r o i s )`fmap`f tgt mapExpMf (CmmUnsafeForeignCall tgt fs as)=casemapForeignTargetM f tgt ofJusttgt' ->Just(CmmUnsafeForeignCall tgt' fs (mapListJ f as))Nothing->(\xs ->CmmUnsafeForeignCall tgt fs xs )`fmap`mapListM f asmapExpMf (CmmForeignCall tgt fs assucc ret_args updfr intrbl )=casemapForeignTargetM f tgt ofJusttgt' ->Just(CmmForeignCall tgt' fs (mapListJ f as)succ ret_args updfr intrbl )Nothing->(\xs ->CmmForeignCall tgt fs xs succ ret_args updfr intrbl )`fmap`mapListM f as-- share as much as possiblemapListM::(a ->Maybea )->[a ]->Maybe[a ]mapListM f xs =let(b ,r )=mapListT f xs inifb thenJustr elseNothingmapListJ::(a ->Maybea )->[a ]->[a ]mapListJ f xs =snd(mapListT f xs )mapListT::(a ->Maybea )->[a ]->(Bool,[a ])mapListT f xs =foldrg (False,[])(zip3(tailsxs )xs (mapf xs ))whereg (_,y ,Nothing)(True,ys )=(True,y :ys )g(_,_,Justy )(True,ys )=(True,y :ys )g(ys' ,_,Nothing)(False,_)=(False,ys' )g(_,_,Justy )(False,ys )=(True,y :ys )mapExpDeepM::(CmmExpr ->MaybeCmmExpr )->CmmNode e x ->Maybe(CmmNode e x )mapExpDeepM f =mapExpM $wrapRecExpM f ------------------------------------- folding Expr in CmmNodefoldExpForeignTarget::(CmmExpr ->z ->z )->ForeignTarget ->z ->z foldExpForeignTarget exp (ForeignTarget e _)z =exp e z foldExpForeignTarget_(PrimTarget _)z =z -- Take a folder on expressions and apply it recursively.-- Specifically (wrapRecExpf f e z) deals with CmmMachOp and CmmLoad-- itself, delegating all the other CmmExpr forms to 'f'.wrapRecExpf::(CmmExpr ->z ->z )->CmmExpr ->z ->z wrapRecExpf f e @(CmmMachOp _es )z =foldr(wrapRecExpf f )(f e z )es wrapRecExpff e @(CmmLoad addr _)z =wrapRecExpf f addr (f e z )wrapRecExpff e z =f e z foldExp::(CmmExpr ->z ->z )->CmmNode e x ->z ->z foldExp _(CmmEntry {})z =z foldExp_(CmmComment {})z =z foldExp_(CmmTick {})z =z foldExpf (CmmUnwind xs )z =foldr(maybeidf )z (mapsndxs )foldExpf (CmmAssign _e )z =f e z foldExpf (CmmStore addr e )z =f addr $f e z foldExpf (CmmUnsafeForeignCall t _as)z =foldrf (foldExpForeignTarget f t z )asfoldExp_(CmmBranch _)z =z foldExpf (CmmCondBranch e ___)z =f e z foldExpf (CmmSwitch e _)z =f e z foldExpf (CmmCall {cml_target=tgt })z =f tgt z foldExpf (CmmForeignCall {tgt=tgt ,args=args })z =foldrf (foldExpForeignTarget f tgt z )args foldExpDeep::(CmmExpr ->z ->z )->CmmNode e x ->z ->z foldExpDeep f =foldExp (wrapRecExpf f )-- -----------------------------------------------------------------------------mapSuccessors::(Label ->Label )->CmmNode O C ->CmmNode O C mapSuccessors f (CmmBranch bid )=CmmBranch (f bid )mapSuccessorsf (CmmCondBranch p y n l )=CmmCondBranch p (f y )(f n )l mapSuccessorsf (CmmSwitch e ids )=CmmSwitch e (mapSwitchTargets f ids )mapSuccessors_n =n mapCollectSuccessors::foralla .(Label ->(Label ,a ))->CmmNode O C ->(CmmNode O C ,[a ])mapCollectSuccessors f (CmmBranch bid )=let(bid' ,acc )=f bid in(CmmBranch bid' ,[acc ])mapCollectSuccessorsf (CmmCondBranch p y n l )=let(bidt ,acct )=f y (bidf ,accf )=f n in(CmmCondBranch p bidt bidf l ,[accf ,acct ])mapCollectSuccessorsf (CmmSwitch e ids )=letlbls =switchTargetsToList ids ::[Label ]lblMap =mapFromList $ziplbls (mapf lbls )::LabelMap (Label ,a )in(CmmSwitch e (mapSwitchTargets (\l ->fst$mapFindWithDefault (error"impossible")l lblMap )ids ),mapsnd(mapElems lblMap ))mapCollectSuccessors_n =(n ,[])-- ------------------------------------------------------------------------------- | Tickish in Cmm context (annotations only)typeCmmTickish =Tickish ()-- | Tick scope identifier, allowing us to reason about what-- annotations in a Cmm block should scope over. We especially take-- care to allow optimisations to reorganise blocks without losing-- tick association in the process.dataCmmTickScope =GlobalScope -- ^ The global scope is the "root" of the scope graph. Every-- scope is a sub-scope of the global scope. It doesn't make sense-- to add ticks to this scope. On the other hand, this means that-- setting this scope on a block means no ticks apply to it.|SubScope !U.Unique CmmTickScope -- ^ Constructs a new sub-scope to an existing scope. This allows-- us to translate Core-style scoping rules (see @tickishScoped@)-- into the Cmm world. Suppose the following code:---- tick<1> case ... of-- A -> tick<2> ...-- B -> tick<3> ...---- We want the top-level tick annotation to apply to blocks-- generated for the A and B alternatives. We can achieve that by-- generating tick<1> into a block with scope a, while the code-- for alternatives A and B gets generated into sub-scopes a/b and-- a/c respectively.|CombinedScope CmmTickScope CmmTickScope -- ^ A combined scope scopes over everything that the two given-- scopes cover. It is therefore a sub-scope of either scope. This-- is required for optimisations. Consider common block elimination:---- A -> tick<2> case ... of-- C -> [common]-- B -> tick<3> case ... of-- D -> [common]---- We will generate code for the C and D alternatives, and figure-- out afterwards that it's actually common code. Scoping rules-- dictate that the resulting common block needs to be covered by-- both tick<2> and tick<3>, therefore we need to construct a-- scope that is a child to *both* scope. Now we can do that - if-- we assign the scopes a/c and b/d to the common-ed up blocks,-- the new block could have a combined tick scope a/c+b/d, which-- both tick<2> and tick<3> apply to.-- Note [CmmTick scoping details]:---- The scope of a @CmmTick@ is given by the @CmmEntry@ node of the-- same block. Note that as a result of this, optimisations making-- tick scopes more specific can *reduce* the amount of code a tick-- scopes over. Fixing this would require a separate @CmmTickScope@-- field for @CmmTick@. Right now we do not do this simply because I-- couldn't find an example where it actually mattered -- multiple-- blocks within the same scope generally jump to each other, which-- prevents common block elimination from happening in the first-- place. But this is no strong reason, so if Cmm optimisations become-- more involved in future this might have to be revisited.-- | Output all scope paths.scopeToPaths::CmmTickScope ->[[U.Unique ]]scopeToPaths GlobalScope =[[]]scopeToPaths(SubScope u s )=map(u :)(scopeToPaths s )scopeToPaths(CombinedScope s1 s2 )=scopeToPaths s1 ++scopeToPaths s2 -- | Returns the head uniques of the scopes. This is based on the-- assumption that the @Unique@ of @SubScope@ identifies the-- underlying super-scope. Used for efficient equality and comparison,-- see below.scopeUniques::CmmTickScope ->[U.Unique ]scopeUniques GlobalScope =[]scopeUniques(SubScope u _)=[u ]scopeUniques(CombinedScope s1 s2 )=scopeUniques s1 ++scopeUniques s2 -- Equality and order is based on the head uniques defined above. We-- take care to short-cut the (extremly) common cases.instanceEqCmmTickScope whereGlobalScope == GlobalScope =TrueGlobalScope ==_=False_==GlobalScope =False(SubScope u _)==(SubScope u' _)=u ==u' (SubScope __)==_=False_==(SubScope __)=Falsescope ==scope' =sortBynonDetCmpUnique (scopeUniques scope )==sortBynonDetCmpUnique (scopeUniques scope' )-- This is still deterministic because-- the order is the same for equal lists-- This is non-deterministic but we do not currently support deterministic-- code-generation. See Note [Unique Determinism and code generation]-- See Note [No Ord for Unique]instanceOrdCmmTickScope wherecompare GlobalScope GlobalScope =EQcompareGlobalScope _=LTcompare_GlobalScope =GTcompare(SubScope u _)(SubScope u' _)=nonDetCmpUnique u u' comparescope scope' =cmpList nonDetCmpUnique (sortBynonDetCmpUnique $scopeUniques scope )(sortBynonDetCmpUnique $scopeUniques scope' )instanceOutputable CmmTickScope whereppr GlobalScope =text "global"ppr(SubScope us GlobalScope )=ppr us ppr(SubScope us s )=ppr s <> char '/'<> ppr us pprcombined =parens $hcat $punctuate (char '+')$map(hcat .punctuate (char '/').mapppr .reverse)$scopeToPaths combined -- | Checks whether two tick scopes are sub-scopes of each other. True-- if the two scopes are equal.isTickSubScope::CmmTickScope ->CmmTickScope ->BoolisTickSubScope =cmp wherecmp _GlobalScope =TruecmpGlobalScope _=Falsecmp(CombinedScope s1 s2 )s' =cmp s1 s' &&cmp s2 s' cmps (CombinedScope s1' s2' )=cmp s s1' ||cmp s s2' cmp(SubScope u s )s' @(SubScope u' _)=u ==u' ||cmp s s' -- | Combine two tick scopes. The new scope should be sub-scope of-- both parameters. We simplfy automatically if one tick scope is a-- sub-scope of the other already.combineTickScopes::CmmTickScope ->CmmTickScope ->CmmTickScope combineTickScopes s1 s2 |s1 `isTickSubScope `s2 =s1 |s2 `isTickSubScope `s1 =s2 |otherwise=CombinedScope s1 s2