.config/coc/extensions/coc-go-data/tools/pkg/mod/honnef.co/go/tools@v0.0.1-2020.1.5/functions/loops.go

   1 package functions
   2
   3 import "honnef.co/go/tools/ir"
   4
   5 type Loop struct{ *ir.BlockSet }
   6
   7 func FindLoops(fn *ir.Function) []Loop {
   8         if fn.Blocks == nil {
   9                 return nil
  10         }
  11         tree := fn.DomPreorder()
  12         var sets []Loop
  13         for _, h := range tree {
  14                 for _, n := range h.Preds {
  15                         if !h.Dominates(n) {
  16                                 continue
  17                         }
  18                         // n is a back-edge to h
  19                         // h is the loop header
  20                         if n == h {
  21                                 set := Loop{ir.NewBlockSet(len(fn.Blocks))}
  22                                 set.Add(n)
  23                                 sets = append(sets, set)
  24                                 continue
  25                         }
  26                         set := Loop{ir.NewBlockSet(len(fn.Blocks))}
  27                         set.Add(h)
  28                         set.Add(n)
  29                         for _, b := range allPredsBut(n, h, nil) {
  30                                 set.Add(b)
  31                         }
  32                         sets = append(sets, set)
  33                 }
  34         }
  35         return sets
  36 }
  37
  38 func allPredsBut(b, but *ir.BasicBlock, list []*ir.BasicBlock) []*ir.BasicBlock {
  39 outer:
  40         for _, pred := range b.Preds {
  41                 if pred == but {
  42                         continue
  43                 }
  44                 for _, p := range list {
  45                         // TODO improve big-o complexity of this function
  46                         if pred == p {
  47                                 continue outer
  48                         }
  49                 }
  50                 list = append(list, pred)
  51                 list = allPredsBut(pred, but, list)
  52         }
  53         return list
  54 }