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[dev.regabi] cmd/compile: fix potential closure waste in Order

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I haven't measured this, but it's the only use of EditChildren
where we aren't careful to allocate a closure once and use it
for the whole recursion. This one is allocating a closure at
every level of the recursion, and it was an oversight that it
wasn't cleaned up in the original CL.

Passes buildall w/ toolstash -cmp.

Change-Id: I5e3f1795c6f64c5867a19c077f797643aa1066a3
Reviewed-on: https://go-review.googlesource.com/c/go/+/277914
Trust: Russ Cox <rsc@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
This commit is contained in:
Russ Cox 2020-12-07 16:07:38 -05:00
parent 578fbbe3aa
commit a997543292
1 changed files with 5 additions and 1 deletions
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6
src/cmd/compile/internal/gc/order.go
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@ -47,6 +47,7 @@ type Order struct {
out []ir.Node // list of generated statements
temp []*ir.Name // stack of temporary variables
free map[string][]*ir.Name // free list of unused temporaries, by type.LongString().
edit func(ir.Node) ir.Node // cached closure of o.exprNoLHS
}
// Order rewrites fn.Nbody to apply the ordering constraints
@ -1072,7 +1073,10 @@ func (o *Order) expr(n, lhs ir.Node) ir.Node {
switch n.Op() {
default:
ir.EditChildren(n, o.exprNoLHS)
if o.edit == nil {
o.edit = o.exprNoLHS // create closure once
}
ir.EditChildren(n, o.edit)
// Addition of strings turns into a function call.
// Allocate a temporary to hold the strings.