mirror of https://github.com/tidwall/tile38.git
71 lines
1.5 KiB
Go
71 lines
1.5 KiB
Go
package functions
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import (
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"go/types"
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"honnef.co/go/tools/ir"
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)
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// Terminates reports whether fn is supposed to return, that is if it
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// has at least one theoretic path that returns from the function.
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// Explicit panics do not count as terminating.
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func Terminates(fn *ir.Function) bool {
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if fn.Blocks == nil {
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// assuming that a function terminates is the conservative
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// choice
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return true
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}
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for _, block := range fn.Blocks {
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if _, ok := block.Control().(*ir.Return); ok {
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if len(block.Preds) == 0 {
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return true
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}
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for _, pred := range block.Preds {
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switch ctrl := pred.Control().(type) {
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case *ir.Panic:
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// explicit panics do not count as terminating
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case *ir.If:
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// Check if we got here by receiving from a closed
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// time.Tick channel – this cannot happen at
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// runtime and thus doesn't constitute termination
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iff := ctrl
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if !ok {
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return true
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}
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ex, ok := iff.Cond.(*ir.Extract)
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if !ok {
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return true
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}
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if ex.Index != 1 {
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return true
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}
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recv, ok := ex.Tuple.(*ir.Recv)
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if !ok {
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return true
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}
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call, ok := recv.Chan.(*ir.Call)
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if !ok {
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return true
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}
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fn, ok := call.Common().Value.(*ir.Function)
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if !ok {
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return true
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}
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fn2, ok := fn.Object().(*types.Func)
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if !ok {
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return true
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}
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if fn2.FullName() != "time.Tick" {
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return true
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}
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default:
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// we've reached the exit block
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return true
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}
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}
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}
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}
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return false
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}
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