Safe Haskell	None
Language	GHC2021

GHC.Cmm.Dominators

Contents

Dominator analysis and representation of results
Utility functions on graphs or graphs-with-dominators
Utility functions on dominator sets

Synopsis

data DominatorSet
- = ImmediateDominator {
  - ds_label :: Label
  - ds_parent :: DominatorSet
  }
- | EntryNode
data GraphWithDominators (node :: Extensibility -> Extensibility -> Type) = GraphWithDominators {
- gwd_graph :: GenCmmGraph node
- gwd_dominators :: LabelMap DominatorSet
- gwd_rpnumbering :: LabelMap RPNum
}
data RPNum
graphWithDominators :: forall (node :: Extensibility -> Extensibility -> Type). (NonLocal node, HasDebugCallStack) => GenCmmGraph node -> GraphWithDominators node
graphMap :: forall (n :: Extensibility -> Extensibility -> Type). GenCmmGraph n -> LabelMap (Block n C C)
gwdRPNumber :: forall (node :: Extensibility -> Extensibility -> Type). HasDebugCallStack => GraphWithDominators node -> Label -> RPNum
gwdDominatorsOf :: forall (node :: Extensibility -> Extensibility -> Type). HasDebugCallStack => GraphWithDominators node -> Label -> DominatorSet
gwdDominatorTree :: forall (node :: Extensibility -> Extensibility -> Type). GraphWithDominators node -> Tree Label
dominatorsMember :: Label -> DominatorSet -> Bool
intersectDominators :: DominatorSet -> DominatorSet -> DominatorSet

Dominator analysis and representation of results

data DominatorSet #

Dominator sets

Node X dominates node Y if and only if every path from the entry to Y includes X. Node Y technically dominates itself, but it is never included in the *representation* of its dominator set.

A dominator set is represented as a linked list in which each node points to its *immediate* dominator, which is its parent in the dominator tree. In many circumstances the immediate dominator will be the only dominator of interest.

Constructors

ImmediateDominator
Fields ds_label :: Label Label of the immediate dominator. ds_parent :: DominatorSet Set of nodes dominating the immediate dominator.
EntryNode

Instances

Instances details

Outputable DominatorSet #
Instance details Defined in GHC.Cmm.Dominators Methods ppr :: DominatorSet -> SDoc #
Eq DominatorSet #
Instance details Defined in GHC.Cmm.Dominators Methods (==) :: DominatorSet -> DominatorSet -> Bool Source # (/=) :: DominatorSet -> DominatorSet -> Bool Source #

data GraphWithDominators (node :: Extensibility -> Extensibility -> Type) #

The result of dominator analysis. Also includes a reverse postorder numbering, which is needed for dominator analysis and for other (downstream) analyses.

Invariant: Dominators, graph, and RP numberings include only *reachable* blocks.

Constructors

GraphWithDominators
Fields gwd_graph :: GenCmmGraph node gwd_dominators :: LabelMap DominatorSet gwd_rpnumbering :: LabelMap RPNum

data RPNum #

Reverse postorder number of a node in a CFG

Instances

Instances details

Outputable RPNum #
Instance details Defined in GHC.Cmm.Dominators Methods ppr :: RPNum -> SDoc #
Eq RPNum #
Instance details Defined in GHC.Cmm.Dominators Methods (==) :: RPNum -> RPNum -> Bool Source # (/=) :: RPNum -> RPNum -> Bool Source #
Ord RPNum #
Instance details Defined in GHC.Cmm.Dominators Methods compare :: RPNum -> RPNum -> Ordering Source # (<) :: RPNum -> RPNum -> Bool Source # (<=) :: RPNum -> RPNum -> Bool Source # (>) :: RPNum -> RPNum -> Bool Source # (>=) :: RPNum -> RPNum -> Bool Source # max :: RPNum -> RPNum -> RPNum Source # min :: RPNum -> RPNum -> RPNum Source #
Show RPNum #
Instance details Defined in GHC.Cmm.Dominators Methods showsPrec :: Int -> RPNum -> ShowS Source # show :: RPNum -> String Source # showList :: [RPNum] -> ShowS Source #

graphWithDominators :: forall (node :: Extensibility -> Extensibility -> Type). (NonLocal node, HasDebugCallStack) => GenCmmGraph node -> GraphWithDominators node #

Call this function with a CmmGraph to get back the results of a dominator analysis of that graph (as well as a reverse postorder numbering). The result also includes the subgraph of the original graph that contains only the reachable blocks.

Utility functions on graphs or graphs-with-dominators

graphMap :: forall (n :: Extensibility -> Extensibility -> Type). GenCmmGraph n -> LabelMap (Block n C C) #

Utility functions

Call graphMap to get the mapping from Label to Block that is embedded in every CmmGraph.

gwdRPNumber :: forall (node :: Extensibility -> Extensibility -> Type). HasDebugCallStack => GraphWithDominators node -> Label -> RPNum #

Use gwdRPNumber on the result of the dominator analysis to get a mapping from the Label of each reachable block to the reverse postorder number of that block.

gwdDominatorsOf :: forall (node :: Extensibility -> Extensibility -> Type). HasDebugCallStack => GraphWithDominators node -> Label -> DominatorSet #

Use gwdDominatorsOf on the result of the dominator analysis to get a mapping from the Label of each reachable block to the dominator set (and the immediate dominator) of that block. The implementation is space-efficient: intersecting dominator sets share the representation of their intersection.

gwdDominatorTree :: forall (node :: Extensibility -> Extensibility -> Type). GraphWithDominators node -> Tree Label #

Utility functions on dominator sets

dominatorsMember :: Label -> DominatorSet -> Bool #

Use to tell if the given label is in the given dominator set. Which is to say, does the bloc with with given label _properly_ and _non-vacuously_ dominate the node whose dominator set this is?

Takes linear time in the height of the dominator tree, but uses space efficiently.

intersectDominators :: DominatorSet -> DominatorSet -> DominatorSet #

Intersect two dominator sets to produce a third dominator set. This function takes time linear in the size of the sets. As such it is inefficient and should be used only for things like visualizations or linters.