Safe Haskell | Safe-Inferred |
---|---|

Language | Haskell2010 |

## Synopsis

- data DominatorSet
- = ImmediateDominator { }
- | EntryNode

- data GraphWithDominators node = GraphWithDominators {}
- data RPNum
- graphWithDominators :: forall node. (NonLocal node, HasDebugCallStack) => GenCmmGraph node -> GraphWithDominators node
- graphMap :: GenCmmGraph n -> LabelMap (Block n C C)
- gwdRPNumber :: HasDebugCallStack => GraphWithDominators node -> Label -> RPNum
- gwdDominatorsOf :: HasDebugCallStack => GraphWithDominators node -> Label -> DominatorSet
- gwdDominatorTree :: GraphWithDominators node -> Tree Label
- dominatorsMember :: Label -> DominatorSet -> Bool
- intersectDominators :: DominatorSet -> DominatorSet -> DominatorSet

# Dominator analysis and representation of results

data DominatorSet Source #

# 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.

ImmediateDominator | |

- ds_label :: Label
Label of the immediate dominator. - ds_parent :: DominatorSet
Set of nodes dominating the immediate dominator.
| |

EntryNode |

#### Instances

Outputable DominatorSet Source # | |

Defined in GHC.Cmm.Dominators ppr :: DominatorSet -> SDoc Source # | |

Eq DominatorSet Source # | |

Defined in GHC.Cmm.Dominators (==) :: DominatorSet -> DominatorSet -> Bool # (/=) :: DominatorSet -> DominatorSet -> Bool # |

data GraphWithDominators node Source #

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.

Reverse postorder number of a node in a CFG

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

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

gwdRPNumber :: HasDebugCallStack => GraphWithDominators node -> Label -> RPNum Source #

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 :: HasDebugCallStack => GraphWithDominators node -> Label -> DominatorSet Source #

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 :: GraphWithDominators node -> Tree Label Source #

# Utility functions on dominator sets

dominatorsMember :: Label -> DominatorSet -> Bool Source #

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 Source #

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.