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4224d81fae
These can be implemented with just a compare and a move instruction.
Do so, avoiding the overhead of a call into the runtime.
These assertions are a significant cost in Go code that uses interface{}
as a safe alternative to C's void* (or unsafe.Pointer), such as the
current version of the Go compiler.
*T here includes pointer to T but also any Go type represented as
a single pointer (chan, func, map). It does not include [1]*T or struct{*int}.
That requires more work in other parts of the compiler; there is a TODO.
Change-Id: I7ff681c20d2c3eb6ad11dd7b3a37b1f3dda23965
Reviewed-on: https://go-review.googlesource.com/7862
Reviewed-by: Rob Pike <r@golang.org>
54 lines
1.5 KiB
Go
54 lines
1.5 KiB
Go
// errorcheck -0 -d=typeassert
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// Copyright 2015 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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package p
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func assertptr(x interface{}) *int {
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return x.(*int) // ERROR "type assertion inlined"
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}
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func assertptr2(x interface{}) (*int, bool) {
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z, ok := x.(*int) // ERROR "type assertion inlined"
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return z, ok
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}
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func assertfunc(x interface{}) func() {
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return x.(func()) // ERROR "type assertion inlined"
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}
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func assertfunc2(x interface{}) (func(), bool) {
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z, ok := x.(func()) // ERROR "type assertion inlined"
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return z, ok
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}
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// TODO(rsc): struct{*int} is stored directly in the interface
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// and should be possible to fetch back out of the interface,
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// but more of the general data movement code needs to
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// realize that before we can inline the assertion.
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func assertstruct(x interface{}) struct{ *int } {
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return x.(struct{ *int }) // ERROR "type assertion not inlined"
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}
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func assertstruct2(x interface{}) (struct{ *int }, bool) {
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z, ok := x.(struct{ *int }) // ERROR "type assertion not inlined"
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return z, ok
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}
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func assertbig(x interface{}) complex128 {
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return x.(complex128) // ERROR "type assertion not inlined"
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}
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func assertbig2(x interface{}) (complex128, bool) {
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z, ok := x.(complex128) // ERROR "type assertion not inlined"
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return z, ok
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}
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func assertbig2ok(x interface{}) (complex128, bool) {
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_, ok := x.(complex128) // ERROR "type assertion [(]ok only[)] inlined"
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return 0, ok
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}
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