module type ForwardsTransfer =sig
..end
Interface to provide for a forward dataflow analysis.
val name : string
For debugging purposes, the name of the analysis
val debug : bool Pervasives.ref
Whether to turn on debugging
type
t
The type of the data we compute for each block start. May be imperative.
val copy : t -> t
Make a deep copy of the data.
val pretty : Format.formatter -> t -> unit
Pretty-print the state.
val computeFirstPredecessor : Cil_types.stmt -> t -> t
computeFirstPredecessor s d
is called when s
is reached for the
first time (i.e. no previous data is associated with it). The data d
is propagated to s
from an unspecified preceding statement s'
.
The result of the call is stored as the new data for s
.
computeFirstPredecessor
usually leaves d
unchanged, but may
potentially change it. It is also possible to perform a side-effect,
for dataflows that store information out of the type t
.
val combinePredecessors : Cil_types.stmt ->
old:t ->
t -> t option
Take some old data for the given statement, and some new data for the same point. Return None if the combination is identical to the old data, to signify that a fixpoint is currently reached for this statement. Otherwise, compute the combination, and return it.
val doInstr : Cil_types.stmt ->
Cil_types.instr ->
t -> t Dataflow.action
The (forwards) transfer function for an instruction (which is englobed
by the given statement). The action Default
propagates the state
passed as an argument unchanged. The current location is updated before
this function is called.
val doGuard : Cil_types.stmt ->
Cil_types.exp ->
t ->
t Dataflow.guardaction *
t Dataflow.guardaction
Generate the successors act_th, act_el
to an If
statement. act_th
(resp. act_el
) corresponds to the case where the given expression
evaluates to zero (resp. non-zero). It is always possible to return
GDefault, GDefault
, especially for analyses that do not use guard
information. This is equivalent to returning GUse d, GUse d
, where d
is the input state. A return value of GUnreachable indicates
that this half of the branch will not be taken and should not be explored.
stmt
is the corresponding If
statement, passed as information only.
val doStmt : Cil_types.stmt ->
t ->
t Dataflow.stmtaction
The (forwards) transfer function for a statement. The (Cil.CurrentLoc.get
* is set before calling this. The default action is to do the
instructions * in this statement, if applicable, and continue with the
successors.
())
val filterStmt : Cil_types.stmt -> bool
Whether to put this statement in the worklist. This is called when a block would normally be put in the worklist.
val stmt_can_reach : Cil_types.stmt -> Cil_types.stmt -> bool
Must return true
if there is a path in the control-flow graph of the
function from the first statement to the second. Used to choose a "good"
node in the worklist. Suggested use is let stmt_can_reach =
, where
Stmts_graph.stmt_can_reach kfkf
is the kernel_function
being analyzed; let stmt_can_reach _ _ = true
is also correct,
albeit less efficient
val doEdge : Cil_types.stmt ->
Cil_types.stmt -> t -> t
what to do when following the edge between the two given statements. Can default to identity if nothing special is required.
module StmtStartData:Dataflow.StmtStartData
with type data = t
For each statement id, the data at the start.