-- -fglagow-exts for kind signatures
module ZipDataflow
- ( zdfSolveFrom, zdfRewriteFrom
+ ( DebugNodes(), RewritingDepth(..), LastOutFacts(..)
+ , zdfSolveFrom, zdfRewriteFrom
, ForwardTransfers(..), BackwardTransfers(..)
, ForwardRewrites(..), BackwardRewrites(..)
, ForwardFixedPoint, BackwardFixedPoint
)
where
+import BlockId
import CmmTx
import DFMonad
import MkZipCfg
import Outputable
import Panic
import UniqFM
-import UniqSupply
import Control.Monad
import Maybe
+{-
+
+This module implements two useful tools:
+
+ 1. An iterative solver for dataflow problems
+
+ 2. The combined dataflow-analysis-and-transformation framework
+ described by Lerner, Grove, and Chambers in their excellent
+ 2002 POPL paper (http://tinyurl.com/3zycbr or
+ http://tinyurl.com/3pnscd).
+
+Each tool comes in two flavors: one for forward dataflow problems
+and one for backward dataflow problems.
+
+We quote the paper above:
+
+ Dataflow analyses can have mutually beneficial interactions.
+ Previous efforts to exploit these interactions have either
+ (1) iteratively performed each individual analysis until no
+ further improvements are discovered or (2) developed "super-
+ analyses" that manually combine conceptually separate anal-
+ yses. We have devised a new approach that allows anal-
+ yses to be defined independently while still enabling them
+ to be combined automatically and profitably. Our approach
+ avoids the loss of precision associated with iterating indi-
+ vidual analyses and the implementation difficulties of man-
+ ually writing a super-analysis.
+
+The key idea is to provide at each CFG node not only a dataflow
+transfer function but also a rewriting function that has the option to
+replace the node with a new (possibly empty) graph. The rewriting
+function takes a dataflow fact as input, and the fact is used to
+justify any rewriting. For example, in a backward problem, the fact
+that variable x is dead can be used to justify rewriting node
+ x := e
+to the empty graph. In a forward problem, the fact that x == 7 can
+be used to justify rewriting node
+ y := x + 1
+to
+ y := 8
+which in turn will be analyzed and produce a new fact:
+x == 7 and y == 8.
+
+In its most general form, this module takes as input graph, transfer
+equations, rewrites, and an initial set of dataflow facts, and
+iteratively computes a new graph and a new set of dataflow facts such
+that
+ * The set of facts is a fixed point of the transfer equations
+ * The graph has been rewritten as much as is consistent with
+ the given facts and requested rewriting depth (see below)
+N.B. 'A set of facts' is shorthand for 'A finite map from CFG label to fact'.
+
+The types of transfer equations, rewrites, and fixed points are
+different for forward and backward problems. To avoid cluttering the
+name space with two versions of every names, other names such as
+zdfSolveFrom are overloaded to work in both forward or backward
+directions. This design decision is based on experience with the
+predecessor module, now called ZipDataflow0 and destined for the bit bucket.
+
+
+This module is deliberately very abstract. It is a completely general
+framework and well-nigh impossible to understand in isolation. The
+cautious reader will begin with some concrete examples in the form of
+clients. NR recommends
+
+ CmmLiveZ A simple liveness analysis
+
+ CmmSpillReload.removeDeadAssignmentsAndReloads
+ A piece of spaghetti to pull on, which leads to
+ - a two-part liveness analysis that tracks
+ variables live in registers and live on the stack
+ - elimination of assignments to dead variables
+ - elimination of redundant reloads
+
+Even hearty souls should avoid the CmmProcPointZ client, at least for
+the time being.
+
+-}
+
+
+{- ============ TRANSFER FUNCTIONS AND REWRITES =========== -}
+
+-- | For a backward transfer, you're given the fact on a node's
+-- outedge and you compute the fact on the inedge. Facts have type 'a'.
+-- A last node may have multiple outedges, each pointing to a labelled
+-- block, so instead of a fact it is given a mapping from BlockId to fact.
-type PassName = String
-type Fuel = OptimizationFuel
-
-data RewritingDepth = RewriteShallow | RewriteDeep
--- When a transformation proposes to rewrite a node,
--- you can either ask the system to
--- * "shallow": accept the new graph, analyse it without further rewriting
--- * "deep": recursively analyse-and-rewrite the new graph
-
------------------------------
--- zdfSolveFrom is a pure analysis with no rewriting
-
-class DataflowSolverDirection transfers fixedpt where
- zdfSolveFrom :: (DebugNodes m l, Outputable a)
- => BlockEnv a -- Initial facts (unbound == bottom)
- -> PassName
- -> DataflowLattice a -- Lattice
- -> transfers m l a -- Dataflow transfer functions
- -> a -- Fact flowing in (at entry or exit)
- -> Graph m l -- Graph to be analyzed
- -> fixedpt m l a () -- Answers
+data BackwardTransfers middle last a = BackwardTransfers
+ { bt_first_in :: a -> BlockId -> a
+ , bt_middle_in :: a -> middle -> a
+ , bt_last_in :: (BlockId -> a) -> last -> a
+ }
--- There are exactly two instances: forward and backward
-instance DataflowSolverDirection ForwardTransfers ForwardFixedPoint
- where zdfSolveFrom = solve_f
-
-instance DataflowSolverDirection BackwardTransfers BackwardFixedPoint
- where zdfSolveFrom = solve_b
+-- | For a forward transfer, you're given the fact on a node's
+-- inedge and you compute the fact on the outedge. Because a last node
+-- may have multiple outedges, each pointing to a labelled
+-- block, so instead of a fact it produces a list of (BlockId, fact) pairs.
data ForwardTransfers middle last a = ForwardTransfers
{ ft_first_out :: a -> BlockId -> a
-- They are either to be set (if they pertain to the graph currently
-- under analysis) or propagated out of a sub-analysis
-data BackwardTransfers middle last a = BackwardTransfers
- { bt_first_in :: a -> BlockId -> a
- , bt_middle_in :: a -> middle -> a
- , bt_last_in :: (BlockId -> a) -> last -> a
+
+-- | A backward rewrite takes the same inputs as a backward transfer,
+-- but instead of producing a fact, it produces a replacement graph or Nothing.
+-- The type of the replacement graph is given as a type parameter 'g'
+-- of kind * -> * -> *. This design offers great flexibility to clients,
+-- but it might be worth simplifying this module by replacing this type
+-- parameter with AGraph everywhere (SLPJ 19 May 2008).
+
+data BackwardRewrites middle last a = BackwardRewrites
+ { br_first :: a -> BlockId -> Maybe (AGraph middle last)
+ , br_middle :: a -> middle -> Maybe (AGraph middle last)
+ , br_last :: (BlockId -> a) -> last -> Maybe (AGraph middle last)
+ , br_exit :: Maybe (AGraph middle last)
}
+-- | A forward rewrite takes the same inputs as a forward transfer,
+-- but instead of producing a fact, it produces a replacement graph or Nothing.
+
+data ForwardRewrites middle last a = ForwardRewrites
+ { fr_first :: a -> BlockId -> Maybe (AGraph middle last)
+ , fr_middle :: a -> middle -> Maybe (AGraph middle last)
+ , fr_last :: a -> last -> Maybe (AGraph middle last)
+ , fr_exit :: a -> Maybe (AGraph middle last)
+ }
+
+{- ===================== FIXED POINTS =================== -}
+
+-- | The result of combined analysis and transformation is a
+-- solution to the set of dataflow equations together with a 'contained value'.
+-- This solution is a member of type class 'FixedPoint', which is parameterized by
+-- * middle and last nodes 'm' and 'l'
+-- * data flow fact 'fact'
+-- * the type 'a' of the contained value
+--
+-- In practice, the contained value 'zdfFpContents' is either a
+-- rewritten graph, when rewriting, or (), when solving without
+-- rewriting. A function 'zdfFpMap' allows a client to change
+-- the contents without changing other values.
+--
+-- To save space, we provide the solution 'zdfFpFacts' as a mapping
+-- from BlockId to fact; if necessary, facts on edges can be
+-- reconstructed using the transfer functions; this functionality is
+-- intended to be included as the 'zdfDecoratedGraph', but the code
+-- has not yet been implemented.
+--
+-- The solution may also includes a fact 'zdfFpOuputFact', which is
+-- not associated with any label:
+-- * for a backward problem, this is the fact at entry
+-- * for a forward problem, this is the fact at the distinguished exit node,
+-- if such a node is present
+--
+-- For a forward problem only, the solution includes 'zdfFpLastOuts',
+-- which is the set of facts on edges leaving the graph.
+--
+-- The flag 'zdfGraphChanged' tells whether the engine did any rewriting.
+
+class FixedPoint fp where
+ zdfFpContents :: fp m l fact a -> a
+ zdfFpFacts :: fp m l fact a -> BlockEnv fact
+ zdfFpOutputFact :: fp m l fact a -> fact -- entry for backward; exit for forward
+ zdfDecoratedGraph :: fp m l fact a -> Graph (fact, m) (fact, l)
+ zdfGraphChanged :: fp m l fact a -> ChangeFlag
+ zdfFpMap :: (a -> b) -> (fp m l fact a -> fp m l fact b)
+
+-- | The class 'FixedPoint' has two instances: one for forward problems and
+-- one for backward problems. The 'CommonFixedPoint' defines all fields
+-- common to both. (The instance declarations are uninteresting and appear below.)
+
data CommonFixedPoint m l fact a = FP
{ fp_facts :: BlockEnv fact
, fp_out :: fact -- entry for backward; exit for forward
, fp_contents :: a
}
+-- | The common fixed point is sufficient for a backward problem.
type BackwardFixedPoint = CommonFixedPoint
+-- | A forward problem needs the common fields, plus the facts on the outedges.
data ForwardFixedPoint m l fact a = FFP
{ ffp_common :: CommonFixedPoint m l fact a
, zdfFpLastOuts :: LastOutFacts fact
}
------------------------------
--- zdfRewriteFrom is an interleaved analysis and transformation
+
+{- ============== SOLVING AND REWRITING ============== -}
+
+type PassName = String
+
+-- | zdfSolveFrom is an overloaded name that resolves to a pure
+-- analysis with no rewriting. It has only two instances: forward and
+-- backward. Since it needs no rewrites, the type parameters of the
+-- class are transfer functions and the fixed point.
+--
+--
+-- An iterative solver normally starts with the bottom fact at every
+-- node, but it can be useful in other contexts as well. For this
+-- reason the initial set of facts (at labelled blocks only) is a
+-- parameter to the solver.
+--
+-- The constraints on the type signature exist purely for debugging;
+-- they make it possible to prettyprint nodes and facts. The parameter of
+-- type 'PassName' is also used just for debugging.
+--
+-- Note that the result is a fixed point with no contents, that is,
+-- the contents have type ().
+--
+-- The intent of the rest of the type signature should be obvious.
+-- If not, place a skype call to norman-ramsey or complain bitterly
+-- to norman-ramsey@acm.org.
+
+class DataflowSolverDirection transfers fixedpt where
+ zdfSolveFrom :: (DebugNodes m l, Outputable a)
+ => BlockEnv a -- Initial facts (unbound == bottom)
+ -> PassName
+ -> DataflowLattice a -- Lattice
+ -> transfers m l a -- Dataflow transfer functions
+ -> a -- Fact flowing in (at entry or exit)
+ -> Graph m l -- Graph to be analyzed
+ -> FuelMonad (fixedpt m l a ()) -- Answers
+
+-- There are exactly two instances: forward and backward
+instance DataflowSolverDirection ForwardTransfers ForwardFixedPoint
+ where zdfSolveFrom = solve_f
+
+instance DataflowSolverDirection BackwardTransfers BackwardFixedPoint
+ where zdfSolveFrom = solve_b
+
+
+-- | zdfRewriteFrom is an overloaded name that resolves to an
+-- interleaved analysis and transformation. It too is instantiated in
+-- forward and backward directions.
+--
+-- The type parameters of the class include not only transfer
+-- functions and the fixed point but also rewrites and the type
+-- constructor (here called 'graph') for making rewritten graphs. As
+-- above, in the definitoins of the rewrites, it might simplify
+-- matters if 'graph' were replaced with 'AGraph'.
+--
+-- The type signature of 'zdfRewriteFrom' is that of 'zdfSolveFrom'
+-- with additional parameters and a different result. Of course the
+-- rewrites are an additional parameter, but there are further
+-- parameters which reflect the fact that rewriting consumes both
+-- OptimizationFuel and Uniqs.
+--
+-- The result type is changed to reflect fuel consumption, and also
+-- the resulting fixed point containts a rewritten graph.
+--
+-- John Dias is going to improve the management of Uniqs and Fuel so
+-- that it doesn't make us sick to look at the types.
class DataflowSolverDirection transfers fixedpt =>
- DataflowDirection transfers fixedpt rewrites
- (graph :: * -> * -> *) where
+ DataflowDirection transfers fixedpt rewrites where
zdfRewriteFrom :: (DebugNodes m l, Outputable a)
- => RewritingDepth
- -> BlockEnv a
+ => RewritingDepth -- whether to rewrite a rewritten graph
+ -> BlockEnv a -- initial facts (unbound == botton)
-> PassName
-> DataflowLattice a
-> transfers m l a
- -> rewrites m l a graph
- -> a -- fact flowing in (at entry or exit)
+ -> rewrites m l a
+ -> a -- fact flowing in (at entry or exit)
-> Graph m l
- -> UniqSupply
-> FuelMonad (fixedpt m l a (Graph m l))
+data RewritingDepth = RewriteShallow | RewriteDeep
+-- When a transformation proposes to rewrite a node,
+-- you can either ask the system to
+-- * "shallow": accept the new graph, analyse it without further rewriting
+-- * "deep": recursively analyse-and-rewrite the new graph
+
+
-- There are currently four instances, but there could be more
-- forward, backward (instantiates transfers, fixedpt, rewrites)
-- Graph, AGraph (instantiates graph)
-instance DataflowDirection ForwardTransfers ForwardFixedPoint ForwardRewrites Graph
- where zdfRewriteFrom = rewrite_f_graph
-
-instance DataflowDirection ForwardTransfers ForwardFixedPoint ForwardRewrites AGraph
+instance DataflowDirection ForwardTransfers ForwardFixedPoint ForwardRewrites
where zdfRewriteFrom = rewrite_f_agraph
-instance DataflowDirection BackwardTransfers BackwardFixedPoint BackwardRewrites Graph
- where zdfRewriteFrom = rewrite_b_graph
-
-instance DataflowDirection BackwardTransfers BackwardFixedPoint BackwardRewrites AGraph
+instance DataflowDirection BackwardTransfers BackwardFixedPoint BackwardRewrites
where zdfRewriteFrom = rewrite_b_agraph
-data ForwardRewrites middle last a g = ForwardRewrites
- { fr_first :: a -> BlockId -> Maybe (g middle last)
- , fr_middle :: a -> middle -> Maybe (g middle last)
- , fr_last :: a -> last -> Maybe (g middle last)
- , fr_exit :: a -> Maybe (g middle last)
- }
-
-data BackwardRewrites middle last a g = BackwardRewrites
- { br_first :: a -> BlockId -> Maybe (g middle last)
- , br_middle :: a -> middle -> Maybe (g middle last)
- , br_last :: (BlockId -> a) -> last -> Maybe (g middle last)
- , br_exit :: Maybe (g middle last)
- }
-
-class FixedPoint fp where
- zdfFpFacts :: fp m l fact a -> BlockEnv fact
- zdfFpOutputFact :: fp m l fact a -> fact -- entry for backward; exit for forward
- zdfGraphChanged :: fp m l fact a -> ChangeFlag
- zdfDecoratedGraph :: fp m l fact a -> Graph (fact, m) (fact, l)
- zdfFpContents :: fp m l fact a -> a
- zdfFpMap :: (a -> b) -> (fp m l fact a -> fp m l fact b)
+{- =================== IMPLEMENTATIONS ===================== -}
-----------------------------------------------------------
-> ForwardTransfers m l a -- dataflow transfer functions
-> a
-> Graph m l -- graph to be analyzed
- -> ForwardFixedPoint m l a () -- answers
+ -> FuelMonad (ForwardFixedPoint m l a ()) -- answers
solve_f env name lattice transfers in_fact g =
- runWithInfiniteFuel $ runDFM panic_us lattice $
- fwd_pure_anal name env transfers in_fact g
- where panic_us = panic "pure analysis pulled on a UniqSupply"
+ runDFM lattice $ fwd_pure_anal name env transfers in_fact g
-rewrite_f_graph :: (DebugNodes m l, Outputable a)
- => RewritingDepth
- -> BlockEnv a
- -> PassName
- -> DataflowLattice a
- -> ForwardTransfers m l a
- -> ForwardRewrites m l a Graph
- -> a -- fact flowing in (at entry or exit)
- -> Graph m l
- -> UniqSupply
- -> FuelMonad (ForwardFixedPoint m l a (Graph m l))
-rewrite_f_graph depth start_facts name lattice transfers rewrites in_fact g u =
- runDFM u lattice $
- do fuel <- fuelRemaining
- (fp, fuel') <- forward_rew maybeRewriteWithFuel return depth start_facts name
- transfers rewrites in_fact g fuel
- fuelDecrement name fuel fuel'
- return fp
-
rewrite_f_agraph :: (DebugNodes m l, Outputable a)
=> RewritingDepth
-> BlockEnv a
-> PassName
-> DataflowLattice a
-> ForwardTransfers m l a
- -> ForwardRewrites m l a AGraph
+ -> ForwardRewrites m l a
-> a -- fact flowing in (at entry or exit)
-> Graph m l
- -> UniqSupply
-> FuelMonad (ForwardFixedPoint m l a (Graph m l))
-rewrite_f_agraph depth start_facts name lattice transfers rewrites in_fact g u =
- runDFM u lattice $
+rewrite_f_agraph depth start_facts name lattice transfers rewrites in_fact g =
+ runDFM lattice $
do fuel <- fuelRemaining
- (fp, fuel') <- forward_rew maybeRewriteWithFuel areturn depth start_facts name
+ (fp, fuel') <- forward_rew maybeRewriteWithFuel depth start_facts name
transfers rewrites in_fact g fuel
fuelDecrement name fuel fuel'
return fp
areturn :: AGraph m l -> DFM a (Graph m l)
-areturn g = liftUSM $ graphOfAGraph g
+areturn g = liftToDFM $ liftUniq $ graphOfAGraph g
{-
class (Outputable m, Outputable l, LastNode l, Outputable (LGraph m l)) => DebugNodes m l
-fwd_pure_anal :: (DebugNodes m l, Outputable a)
+fwd_pure_anal :: (DebugNodes m l, LastNode l, Outputable a)
=> PassName
-> BlockEnv a
-> ForwardTransfers m l a
do (fp, _) <- anal_f name env transfers panic_rewrites in_fact g panic_fuel
return fp
where -- definitiely a case of "I love lazy evaluation"
- anal_f = forward_sol (\_ _ -> Nothing) panic_return panic_depth
+ anal_f = forward_sol (\_ _ -> Nothing) panic_depth
panic_rewrites = panic "pure analysis asked for a rewrite function"
panic_fuel = panic "pure analysis asked for fuel"
- panic_return = panic "pure analysis tried to return a rewritten graph"
panic_depth = panic "pure analysis asked for a rewrite depth"
-----------------------------------------------------------------------
-----------------------------------------------------------------------
+type Fuel = OptimizationFuel
{-# INLINE forward_sol #-}
forward_sol
- :: forall m l g a .
+ :: forall m l a .
(DebugNodes m l, LastNode l, Outputable a)
=> (forall a . Fuel -> Maybe a -> Maybe a)
-- Squashes proposed rewrites if there is
-- no more fuel; OR if we are doing a pure
-- analysis, so totally ignore the rewrite
-- ie. For pure-analysis the fn is (\_ _ -> Nothing)
- -> (g m l -> DFM a (Graph m l))
- -- Transforms the kind of graph 'g' wanted by the
- -- client (in ForwardRewrites) to the kind forward_sol likes
-> RewritingDepth -- Shallow/deep
-> PassName
-> BlockEnv a -- Initial set of facts
-> ForwardTransfers m l a
- -> ForwardRewrites m l a g
+ -> ForwardRewrites m l a
-> a -- Entry fact
-> Graph m l
-> Fuel
-> DFM a (ForwardFixedPoint m l a (), Fuel)
-forward_sol check_maybe return_graph = forw
+forward_sol check_maybe = forw
where
forw :: RewritingDepth
-> PassName
-> BlockEnv a
-> ForwardTransfers m l a
- -> ForwardRewrites m l a g
+ -> ForwardRewrites m l a
-> a
-> Graph m l
-> Fuel
do { idfact <- getFact id
; (last_outs, fuel) <-
case check_maybe fuel $ fr_first rewrites idfact id of
- Nothing -> solve_tail idfact tail fuel
+ Nothing -> solve_tail (ft_first_out transfers idfact id) tail fuel
Just g ->
- do g <- return_graph g
+ do g <- areturn g
(a, fuel) <- subAnalysis' $
case rewrite of
RewriteDeep -> solve getExitFact idfact g (oneLessFuel fuel)
case check_maybe fuel $ fr_middle rewrites in' m of
Nothing -> solve_tail (ft_middle_out transfers in' m) t fuel
Just g ->
- do { g <- return_graph g
+ do { g <- areturn g
; (a, fuel) <- subAnalysis' $
case rewrite of
RewriteDeep -> solve getExitFact in' g (oneLessFuel fuel)
LastExit -> do { setExitFact (ft_exit_out transfers in')
; return (LastOutFacts [], fuel) }
Just g ->
- do { g <- return_graph g
+ do { g <- areturn g
; (last_outs :: LastOutFacts a, fuel) <- subAnalysis' $
case rewrite of
RewriteDeep -> solve lastOutFacts in' g (oneLessFuel fuel)
{-# INLINE forward_rew #-}
forward_rew
- :: forall m l g a .
+ :: forall m l a .
(DebugNodes m l, LastNode l, Outputable a)
=> (forall a . Fuel -> Maybe a -> Maybe a)
- -> (g m l -> DFM a (Graph m l)) -- option on what to rewrite
-> RewritingDepth
-> BlockEnv a
-> PassName
-> ForwardTransfers m l a
- -> ForwardRewrites m l a g
+ -> ForwardRewrites m l a
-> a
-> Graph m l
-> Fuel
-> DFM a (ForwardFixedPoint m l a (Graph m l), Fuel)
-forward_rew check_maybe return_graph = forw
+forward_rew check_maybe = forw
where
- solve = forward_sol check_maybe return_graph
+ solve = forward_sol check_maybe
forw :: RewritingDepth
-> BlockEnv a
-> PassName
-> ForwardTransfers m l a
- -> ForwardRewrites m l a g
+ -> ForwardRewrites m l a
-> a
-> Graph m l
-> Fuel
; a <- finish
; return (a, lgraphToGraph (LGraph eid rewritten), fuel)
}
- don't_rewrite finish in_fact g fuel =
- do { solve depth name emptyBlockEnv transfers rewrites in_fact g fuel
+ don't_rewrite facts finish in_fact g fuel =
+ do { solve depth name facts transfers rewrites in_fact g fuel
; a <- finish
; return (a, g, fuel)
}
- inner_rew = case depth of RewriteShallow -> don't_rewrite
- RewriteDeep -> rewrite emptyBlockEnv
+ inner_rew :: DFM a f -> a -> Graph m l -> Fuel -> DFM a (f, Graph m l, Fuel)
+ inner_rew f i g fu = getAllFacts >>= \facts -> inner_rew' facts f i g fu
+ where inner_rew' = case depth of RewriteShallow -> don't_rewrite
+ RewriteDeep -> rewrite
fixed_pt_and_fuel =
do { (a, g, fuel) <- rewrite xstart_facts getExitFact in_factx gx fuelx
; facts <- getAllFacts
do let h = ZFirst id
a <- getFact id
case check_maybe fuel $ fr_first rewrites a id of
- Nothing -> do { (rewritten, fuel) <- rew_tail h a t rewritten fuel
+ Nothing -> do { (rewritten, fuel) <-
+ rew_tail h (ft_first_out transfers a id)
+ t rewritten fuel
; rewrite_blocks bs rewritten fuel }
Just g -> do { markGraphRewritten
- ; g <- return_graph g
+ ; g <- areturn g
; (outfact, g, fuel) <- inner_rew getExitFact a g fuel
; let (blocks, h) = splice_head' (ZFirst id) g
; (rewritten, fuel) <-
Nothing -> rew_tail (G.ZHead head m) (ft_middle_out transfers in' m) t
rewritten fuel
Just g -> do { markGraphRewritten
- ; g <- return_graph g
+ ; g <- areturn g
; (a, g, fuel) <- inner_rew getExitFact in' g fuel
; let (blocks, h) = G.splice_head' head g
; rew_tail h a t (blocks `plusUFM` rewritten) fuel
rew_tail h in' (G.ZLast l) rewritten fuel =
my_trace "Rewriting last node" (ppr l) $
case check_maybe fuel $ either_last rewrites in' l of
- Nothing -> -- can throw away facts because this is the rewriting phase
- return (insertBlock (zipht h (G.ZLast l)) rewritten, fuel)
+ Nothing -> do check_facts in' l
+ return (insertBlock (zipht h (G.ZLast l)) rewritten, fuel)
Just g -> do { markGraphRewritten
- ; g <- return_graph g
+ ; g <- areturn g
; ((), g, fuel) <- inner_rew (return ()) in' g fuel
; let g' = G.splice_head_only' h g
; return (G.lg_blocks g' `plusUFM` rewritten, fuel)
}
either_last rewrites in' (LastExit) = fr_exit rewrites in'
either_last rewrites in' (LastOther l) = fr_last rewrites in' l
+ check_facts in' (LastOther l) =
+ let LastOutFacts last_outs = ft_last_outs transfers in' l
+ in mapM (uncurry checkFactMatch) last_outs
+ check_facts _ LastExit = return []
in fixed_pt_and_fuel
---lastOutFacts :: (DataflowAnalysis m, Monad (m f)) => m f (LastOutFacts f)
lastOutFacts :: DFM f (LastOutFacts f)
lastOutFacts = bareLastOutFacts >>= return . LastOutFacts
-> BackwardTransfers m l a -- dataflow transfer functions
-> a -- exit fact
-> Graph m l -- graph to be analyzed
- -> BackwardFixedPoint m l a () -- answers
+ -> FuelMonad (BackwardFixedPoint m l a ()) -- answers
solve_b env name lattice transfers exit_fact g =
- runWithInfiniteFuel $ runDFM panic_us lattice $
- bwd_pure_anal name env transfers g exit_fact
- where panic_us = panic "pure analysis pulled on a UniqSupply"
+ runDFM lattice $ bwd_pure_anal name env transfers g exit_fact
-rewrite_b_graph :: (DebugNodes m l, Outputable a)
- => RewritingDepth
- -> BlockEnv a
- -> PassName
- -> DataflowLattice a
- -> BackwardTransfers m l a
- -> BackwardRewrites m l a Graph
- -> a -- fact flowing in at exit
- -> Graph m l
- -> UniqSupply
- -> FuelMonad (BackwardFixedPoint m l a (Graph m l))
-rewrite_b_graph depth start_facts name lattice transfers rewrites exit_fact g u =
- runDFM u lattice $
- do fuel <- fuelRemaining
- (fp, fuel') <- backward_rew maybeRewriteWithFuel return depth start_facts name
- transfers rewrites g exit_fact fuel
- fuelDecrement name fuel fuel'
- return fp
-
rewrite_b_agraph :: (DebugNodes m l, Outputable a)
=> RewritingDepth
-> BlockEnv a
-> PassName
-> DataflowLattice a
-> BackwardTransfers m l a
- -> BackwardRewrites m l a AGraph
+ -> BackwardRewrites m l a
-> a -- fact flowing in at exit
-> Graph m l
- -> UniqSupply
-> FuelMonad (BackwardFixedPoint m l a (Graph m l))
-rewrite_b_agraph depth start_facts name lattice transfers rewrites exit_fact g u =
- runDFM u lattice $
+rewrite_b_agraph depth start_facts name lattice transfers rewrites exit_fact g =
+ runDFM lattice $
do fuel <- fuelRemaining
- (fp, fuel') <- backward_rew maybeRewriteWithFuel areturn depth start_facts name
+ (fp, fuel') <- backward_rew maybeRewriteWithFuel depth start_facts name
transfers rewrites g exit_fact fuel
fuelDecrement name fuel fuel'
return fp
{-# INLINE backward_sol #-}
backward_sol
- :: forall m l g a .
+ :: forall m l a .
(DebugNodes m l, LastNode l, Outputable a)
=> (forall a . Fuel -> Maybe a -> Maybe a)
- -> (g m l -> DFM a (Graph m l)) -- option on what to rewrite
-> RewritingDepth
-> PassName
-> BlockEnv a
-> BackwardTransfers m l a
- -> BackwardRewrites m l a g
+ -> BackwardRewrites m l a
-> Graph m l
-> a
-> Fuel
-> DFM a (BackwardFixedPoint m l a (), Fuel)
-backward_sol check_maybe return_graph = back
+backward_sol check_maybe = back
where
back :: RewritingDepth
-> PassName
-> BlockEnv a
-> BackwardTransfers m l a
- -> BackwardRewrites m l a g
+ -> BackwardRewrites m l a
-> Graph m l
-> a
-> Fuel
do { fp <- bwd_pure_anal name emptyBlockEnv transfers g out
; return $ zdfFpOutputFact fp }
- subsolve :: g m l -> a -> Fuel -> DFM a (a, Fuel)
+ subsolve :: AGraph m l -> a -> Fuel -> DFM a (a, Fuel)
subsolve =
case rewrite of
RewriteDeep -> \g a fuel ->
- subAnalysis' $ do { g <- return_graph g; solve g a (oneLessFuel fuel) }
+ subAnalysis' $ do { g <- areturn g; solve g a (oneLessFuel fuel) }
RewriteShallow -> \g a fuel ->
- subAnalysis' $ do { g <- return_graph g; a <- anal_b g a
+ subAnalysis' $ do { g <- areturn g; a <- anal_b g a
; return (a, oneLessFuel fuel) }
solve :: Graph m l -> a -> Fuel -> DFM a (a, Fuel)
set_head_fact (G.ZFirst id) a fuel =
case check_maybe fuel $ br_first rewrites a id of
- Nothing -> do { setFact id a; return fuel }
+ Nothing -> do { my_trace "set_head_fact" (ppr id) $
+ setFact id $ bt_first_in transfers a id
+ ; return fuel }
Just g -> do { (a, fuel) <- subsolve g a fuel
; setFact id a
; return fuel
}
in fixed_point
-bwd_pure_anal :: (DebugNodes m l, Outputable a)
+bwd_pure_anal :: (DebugNodes m l, LastNode l, Outputable a)
=> PassName
-> BlockEnv a
-> BackwardTransfers m l a
do (fp, _) <- anal_b name env transfers panic_rewrites g exit_fact panic_fuel
return fp
where -- another case of "I love lazy evaluation"
- anal_b = backward_sol (\_ _ -> Nothing) panic_return panic_depth
+ anal_b = backward_sol (\_ _ -> Nothing) panic_depth
panic_rewrites = panic "pure analysis asked for a rewrite function"
panic_fuel = panic "pure analysis asked for fuel"
- panic_return = panic "pure analysis tried to return a rewritten graph"
panic_depth = panic "pure analysis asked for a rewrite depth"
{-# INLINE backward_rew #-}
backward_rew
- :: forall m l g a .
+ :: forall m l a .
(DebugNodes m l, LastNode l, Outputable a)
=> (forall a . Fuel -> Maybe a -> Maybe a)
- -> (g m l -> DFM a (Graph m l)) -- option on what to rewrite
-> RewritingDepth
-> BlockEnv a
-> PassName
-> BackwardTransfers m l a
- -> BackwardRewrites m l a g
+ -> BackwardRewrites m l a
-> Graph m l
-> a
-> Fuel
-> DFM a (BackwardFixedPoint m l a (Graph m l), Fuel)
-backward_rew check_maybe return_graph = back
+backward_rew check_maybe = back
where
- solve = backward_sol check_maybe return_graph
+ solve = backward_sol check_maybe
back :: RewritingDepth
-> BlockEnv a
-> PassName
-> BackwardTransfers m l a
- -> BackwardRewrites m l a g
+ -> BackwardRewrites m l a
-> Graph m l
-> a
-> Fuel
let Graph entry blockenv = g
blocks = reverse $ G.postorder_dfs_from blockenv entry
in do { solve depth name start transfers rewrites g exit_fact fuel
+ ; env <- getAllFacts
+ ; my_trace "facts after solving" (ppr env) $ return ()
; eid <- freshBlockId "temporary entry id"
- ; (rewritten, fuel) <- rewrite_blocks blocks emptyBlockEnv fuel
- ; (rewritten, fuel) <- rewrite_blocks [Block eid entry] rewritten fuel
+ ; (rewritten, fuel) <- rewrite_blocks True blocks emptyBlockEnv fuel
+ -- We can't have the fact check fail on the bogus entry, which _may_ change
+ ; (rewritten, fuel) <- rewrite_blocks False [Block eid entry] rewritten fuel
; a <- getFact eid
; return (a, lgraphToGraph (LGraph eid rewritten), fuel)
}
- don't_rewrite g exit_fact fuel =
+ don't_rewrite facts g exit_fact fuel =
do { (fp, _) <-
- solve depth name emptyBlockEnv transfers rewrites g exit_fact fuel
+ solve depth name facts transfers rewrites g exit_fact fuel
; return (zdfFpOutputFact fp, g, fuel) }
- inner_rew = case depth of RewriteShallow -> don't_rewrite
- RewriteDeep -> rewrite emptyBlockEnv
inner_rew :: Graph m l -> a -> Fuel -> DFM a (a, Graph m l, Fuel)
+ inner_rew g a f = getAllFacts >>= \facts -> inner_rew' facts g a f
+ where inner_rew' = case depth of RewriteShallow -> don't_rewrite
+ RewriteDeep -> rewrite
fixed_pt_and_fuel =
do { (a, g, fuel) <- rewrite xstart_facts gx exit_fact fuelx
; facts <- getAllFacts
; let fp = FP facts a changed (panic "no decoration?!") g
; return (fp, fuel)
}
- rewrite_blocks :: [Block m l] -> (BlockEnv (Block m l))
+ rewrite_blocks :: Bool -> [Block m l] -> (BlockEnv (Block m l))
-> Fuel -> DFM a (BlockEnv (Block m l), Fuel)
- rewrite_blocks bs rewritten fuel =
+ rewrite_blocks check bs rewritten fuel =
do { env <- factsEnv
; let rew [] r f = return (r, f)
rew (b : bs) r f =
- do { (r, f) <- rewrite_block env b r f; rew bs r f }
+ do { (r, f) <- rewrite_block check env b r f; rew bs r f }
; rew bs rewritten fuel }
- rewrite_block env b rewritten fuel =
+ rewrite_block check env b rewritten fuel =
let (h, l) = G.goto_end (G.unzip b) in
case maybeRewriteWithFuel fuel $ either_last env l of
- Nothing -> propagate fuel h (last_in env l) (ZLast l) rewritten
+ Nothing -> propagate check fuel h (last_in env l) (ZLast l) rewritten
Just g ->
do { markGraphRewritten
- ; g <- return_graph g
+ ; g <- areturn g
; (a, g, fuel) <- inner_rew g exit_fact fuel
; let G.Graph t new_blocks = g
; let rewritten' = new_blocks `plusUFM` rewritten
- ; propagate fuel h a t rewritten' -- continue at entry of g
+ ; propagate check fuel h a t rewritten' -- continue at entry of g
}
either_last _env (LastExit) = br_exit rewrites
either_last env (LastOther l) = br_last rewrites env l
last_in _env (LastExit) = exit_fact
last_in env (LastOther l) = bt_last_in transfers env l
- propagate fuel (ZHead h m) a tail rewritten =
+ propagate check fuel (ZHead h m) a tail rewritten =
case maybeRewriteWithFuel fuel $ br_middle rewrites a m of
Nothing ->
- propagate fuel h (bt_middle_in transfers a m) (ZTail m tail) rewritten
+ propagate check fuel h (bt_middle_in transfers a m) (ZTail m tail) rewritten
Just g ->
do { markGraphRewritten
- ; g <- return_graph g
- ; my_trace "Rewrote middle node"
+ ; g <- areturn g
+ ; my_trace "With Facts" (ppr a) $ return ()
+ ; my_trace " Rewrote middle node"
(f4sep [ppr m, text "to", pprGraph g]) $
return ()
; (a, g, fuel) <- inner_rew g a fuel
; let Graph t newblocks = G.splice_tail g tail
- ; propagate fuel h a t (newblocks `plusUFM` rewritten) }
- propagate fuel (ZFirst id) a tail rewritten =
+ ; propagate check fuel h a t (newblocks `plusUFM` rewritten) }
+ propagate check fuel (ZFirst id) a tail rewritten =
case maybeRewriteWithFuel fuel $ br_first rewrites a id of
- Nothing -> do { checkFactMatch id a
+ Nothing -> do { if check then checkFactMatch id $ bt_first_in transfers a id
+ else return ()
; return (insertBlock (Block id tail) rewritten, fuel) }
Just g ->
do { markGraphRewritten
- ; g <- return_graph g
+ ; g <- areturn g
; my_trace "Rewrote first node"
(f4sep [ppr id <> colon, text "to", pprGraph g]) $ return ()
; (a, g, fuel) <- inner_rew g a fuel
- ; checkFactMatch id a
+ ; if check then checkFactMatch id a else return ()
; let Graph t newblocks = G.splice_tail g tail
; let r = insertBlock (Block id t) (newblocks `plusUFM` rewritten)
; return (r, fuel) }
my_nest depth sdoc = my_trace "" $ nest (3*depth) sdoc
ppIter depth n = my_nest depth (empty $$ text "*************** iteration" <+> pp_i n)
pp_i n = int n <+> text "of" <+> text name <+> text "on" <+> graphId
- unchanged depth = my_nest depth (text "facts are unchanged")
+ unchanged depth =
+ my_nest depth (text "facts for" <+> graphId <+> text "are unchanged")
+ graphId = case blocks of { Block id _ : _ -> ppr id ; [] -> text "<empty>" }
+ show_blocks = my_trace "Blocks:" (vcat (map pprBlock blocks))
+ pprBlock (Block id t) = nest 2 (pprFact (id, t))
pprFacts depth n env =
my_nest depth (text "facts for iteration" <+> pp_i n <+> text "are:" $$
(nest 2 $ vcat $ map pprFact $ ufmToList env))
pprFact (id, a) = hang (ppr id <> colon) 4 (ppr a)
- graphId = case blocks of { Block id _ : _ -> ppr id ; [] -> text "<empty>" }
- show_blocks = my_trace "Blocks:" (vcat (map pprBlock blocks))
- pprBlock (Block id t) = nest 2 (pprFact (id, t))
f4sep :: [SDoc] -> SDoc