54 lines
1 KiB
Go
54 lines
1 KiB
Go
package functions
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import "honnef.co/go/tools/ir"
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type Loop struct{ *ir.BlockSet }
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func FindLoops(fn *ir.Function) []Loop {
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if fn.Blocks == nil {
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return nil
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}
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tree := fn.DomPreorder()
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var sets []Loop
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for _, h := range tree {
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for _, n := range h.Preds {
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if !h.Dominates(n) {
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continue
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}
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// n is a back-edge to h
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// h is the loop header
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if n == h {
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set := Loop{ir.NewBlockSet(len(fn.Blocks))}
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set.Add(n)
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sets = append(sets, set)
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continue
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}
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set := Loop{ir.NewBlockSet(len(fn.Blocks))}
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set.Add(h)
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set.Add(n)
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for _, b := range allPredsBut(n, h, nil) {
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set.Add(b)
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}
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sets = append(sets, set)
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}
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}
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return sets
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}
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func allPredsBut(b, but *ir.BasicBlock, list []*ir.BasicBlock) []*ir.BasicBlock {
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outer:
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for _, pred := range b.Preds {
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if pred == but {
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continue
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}
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for _, p := range list {
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// TODO improve big-o complexity of this function
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if pred == p {
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continue outer
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}
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}
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list = append(list, pred)
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list = allPredsBut(pred, but, list)
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}
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return list
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}
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