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[dev.regabi] cmd/compile: remove refersToCommonName

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After reorder3's simplification, the only remaining use of
refersToCommonName is in oaslit, where the LHS expression is always a
single name. We can replace the now overly-generalized
refersToCommonName with a simple ir.Any traversal with ir.Uses.

Passes toolstash -cmp.

Change-Id: Ice3020cdbbf6083d52e07866a687580f4eb134b8
Reviewed-on: https://go-review.googlesource.com/c/go/+/280439
Trust: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
This commit is contained in:
Matthew Dempsky 2020-12-26 21:33:17 -08:00
parent c98548e110
commit 676d794b81
2 changed files with 2 additions and 50 deletions
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49
src/cmd/compile/internal/walk/assign.go
View file

@ -495,55 +495,6 @@ func readsMemory(n ir.Node) bool {
return true
}
// refersToCommonName reports whether any name
// appears in common between l and r.
// This is called from sinit.go.
func refersToCommonName(l ir.Node, r ir.Node) bool {
if l == nil || r == nil {
return false
}
// This could be written elegantly as a Find nested inside a Find:
//
// found := ir.Find(l, func(l ir.Node) interface{} {
// if l.Op() == ir.ONAME {
// return ir.Find(r, func(r ir.Node) interface{} {
// if r.Op() == ir.ONAME && l.Name() == r.Name() {
// return r
// }
// return nil
// })
// }
// return nil
// })
// return found != nil
//
// But that would allocate a new closure for the inner Find
// for each name found on the left side.
// It may not matter at all, but the below way of writing it
// only allocates two closures, not O(|L|) closures.
var doL, doR func(ir.Node) error
var targetL *ir.Name
doR = func(r ir.Node) error {
if r.Op() == ir.ONAME && r.Name() == targetL {
return stop
}
return ir.DoChildren(r, doR)
}
doL = func(l ir.Node) error {
if l.Op() == ir.ONAME {
l := l.(*ir.Name)
targetL = l.Name()
if doR(r) == stop {
return stop
}
}
return ir.DoChildren(l, doL)
}
return doL(l) == stop
}
// expand append(l1, l2...) to
// init {
// s := l1

3
src/cmd/compile/internal/walk/complit.go
View file

@ -629,6 +629,7 @@ func oaslit(n *ir.AssignStmt, init *ir.Nodes) bool {
// not a special composite literal assignment
return false
}
x := n.X.(*ir.Name)
if !types.Identical(n.X.Type(), n.Y.Type()) {
// not a special composite literal assignment
return false
@ -640,7 +641,7 @@ func oaslit(n *ir.AssignStmt, init *ir.Nodes) bool {
return false
case ir.OSTRUCTLIT, ir.OARRAYLIT, ir.OSLICELIT, ir.OMAPLIT:
if refersToCommonName(n.X, n.Y) {
if ir.Any(n.Y, func(y ir.Node) bool { return ir.Uses(y, x) }) {
// not a special composite literal assignment
return false
}