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mirror of https://github.com/golang/go synced 2024-11-13 17:40:23 -07:00
go/test/live_syscall.go
Keith Randall 13baf4b2cd cmd/compile: encourage inlining of functions with single-call bodies
This is a simple tweak to allow a bit more mid-stack inlining.
In cases like this:

func f() {
    g()
}

We'd really like to inline f into its callers. It can't hurt.

We implement this optimization by making calls a bit cheaper, enough
to afford a single call in the function body, but not 2.
The remaining budget allows for some argument modification, or perhaps
a wrapping conditional:

func f(x int) {
    g(x, 0)
}
func f(x int) {
    if x > 0 {
        g()
    }
}

Update #19348

Change-Id: Ifb1ea0dd1db216c3fd5c453c31c3355561fe406f
Reviewed-on: https://go-review.googlesource.com/c/147361
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: David Chase <drchase@google.com>
2018-11-08 17:29:23 +00:00

41 lines
1.2 KiB
Go

// errorcheck -0 -m -live
// +build !windows,!js
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Test escape analysis and liveness inferred for syscall.Syscall-like functions.
package p
import (
"syscall"
"unsafe"
)
func f(uintptr) // ERROR "f assuming arg#1 is unsafe uintptr"
func g() { // ERROR "can inline g"
var t int
f(uintptr(unsafe.Pointer(&t))) // ERROR "live at call to f: .?autotmp" "g &t does not escape" "stack object .autotmp_[0-9]+ unsafe.Pointer$"
}
func h() { // ERROR "can inline h"
var v int
syscall.Syscall(0, 1, uintptr(unsafe.Pointer(&v)), 2) // ERROR "live at call to Syscall: .?autotmp" "h &v does not escape" "stack object .autotmp_[0-9]+ unsafe.Pointer$"
}
func i() { // ERROR "can inline i"
var t int
p := unsafe.Pointer(&t) // ERROR "i &t does not escape"
f(uintptr(p)) // ERROR "live at call to f: .?autotmp" "stack object .autotmp_[0-9]+ unsafe.Pointer$"
}
func j() { // ERROR "can inline j"
var v int
p := unsafe.Pointer(&v) // ERROR "j &v does not escape"
syscall.Syscall(0, 1, uintptr(p), 2) // ERROR "live at call to Syscall: .?autotmp" "stack object .autotmp_[0-9]+ unsafe.Pointer$"
}