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0e9f8a21f8
When we pass these types by reference, we usually have to allocate
temporaries on the stack, initialize them, then pass their address
to the conversion functions. It's simpler to pass these types
directly by value.
This particularly applies to conversions needed for fmt.Printf
(to interface{} for constructing a [...]interface{}).
func f(a, b, c string) {
fmt.Printf("%s %s\n", a, b)
fmt.Printf("%s %s\n", b, c)
}
This function's stack frame shrinks from 200 to 136 bytes, and
its code shrinks from 535 to 453 bytes.
The go binary shrinks 0.3%.
Update #24286
Aside: for this function f, we don't really need to allocate
temporaries for the convT2E function. We could use the address
of a, b, and c directly. That might get similar (or maybe better?)
improvements. I investigated a bit, but it seemed complicated
to do it safely. This change was much easier.
Change-Id: I78cbe51b501fb41e1e324ce4203f0de56a1db82d
Reviewed-on: https://go-review.googlesource.com/c/135377
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
25 lines
706 B
Go
25 lines
706 B
Go
// errorcheck -0 -live -l -d=compilelater
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// Copyright 2017 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Issue 20250: liveness differed with concurrent compilation
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// due to propagation of addrtaken to outer variables for
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// closure variables.
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package p
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type T struct {
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s [2]string
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}
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func f(a T) { // ERROR "live at entry to f: a"
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var e interface{} // ERROR "stack object e interface \{\}$"
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func() { // ERROR "live at entry to f.func1: a &e"
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e = a.s // ERROR "live at call to convT2E: &e" "stack object a T$"
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}()
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// Before the fix, both a and e were live at the previous line.
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_ = e
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}
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