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4ce06f4b5c
Ordinary switch statements are rewritten into a sequence of if statements. Staticly dead cases were not being eliminated because the rewrite introduced a temporary, which hid the fact that the case was a constant. Stop doing that. This eliminates dead code in the standard library at: runtime/cgocall.go:219 runtime/cgocall.go:269 debug/gosym/pclntab.go:175 debug/macho/file.go:208 math/big/nat.go:635 math/big/nat.go:850 math/big/nat.go:1058 cmd/pprof/internal/commands/commands.go:86 net/sock_bsd.go:19 cmd/go/build.go:2657 cmd/go/env.go:90 Fixes #9608. Change-Id: Ic23a05dfbb1ad91d5f62a6506b35a13e51b33e38 Reviewed-on: https://go-review.googlesource.com/3980 Reviewed-by: Keith Randall <khr@golang.org>
74 lines
901 B
Go
74 lines
901 B
Go
// 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 main
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func fail() // unimplemented, to test dead code elimination
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// Test dead code elimination in if statements
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func init() {
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if false {
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fail()
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}
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if 0 == 1 {
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fail()
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}
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}
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// Test dead code elimination in ordinary switch statements
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func init() {
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const x = 0
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switch x {
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case 1:
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fail()
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}
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switch 1 {
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case x:
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fail()
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}
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switch {
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case false:
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fail()
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}
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const a = "a"
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switch a {
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case "b":
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fail()
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}
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const snowman = '☃'
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switch snowman {
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case '☀':
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fail()
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}
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const zero = float64(0.0)
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const one = float64(1.0)
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switch one {
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case -1.0:
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fail()
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case zero:
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fail()
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}
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switch 1.0i {
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case 1:
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fail()
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case -1i:
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fail()
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}
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const no = false
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switch no {
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case true:
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fail()
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}
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}
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func main() {
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}
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