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go/test/uintptrescapes2.go
Keith Randall 389e942745 cmd/compile: reuse temporaries in order pass
Instead of allocating a new temporary each time one
is needed, keep a list of temporaries which are free
(have already been VARKILLed on every path) and use
one of them.

Should save a lot of stack space. In a function like this:

func main() {
     fmt.Printf("%d %d\n", 2, 3)
     fmt.Printf("%d %d\n", 4, 5)
     fmt.Printf("%d %d\n", 6, 7)
}

The three [2]interface{} arrays used to hold the ... args
all use the same autotmp, instead of 3 different autotmps
as happened previous to this CL.

Change-Id: I2d728e226f81e05ae68ca8247af62014a1b032d3
Reviewed-on: https://go-review.googlesource.com/c/140301
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
2018-10-14 05:21:00 +00:00

44 lines
1.5 KiB
Go

// errorcheck -0 -m -live
// Copyright 2016 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 uintptrescapes functions.
package p
import (
"unsafe"
)
//go:uintptrescapes
//go:noinline
func F1(a uintptr) {} // ERROR "escaping uintptr"
//go:uintptrescapes
//go:noinline
func F2(a ...uintptr) {} // ERROR "escaping ...uintptr" "a does not escape"
//go:uintptrescapes
//go:noinline
func F3(uintptr) {} // ERROR "escaping uintptr"
//go:uintptrescapes
//go:noinline
func F4(...uintptr) {} // ERROR "escaping ...uintptr"
func G() {
var t int // ERROR "moved to heap"
F1(uintptr(unsafe.Pointer(&t))) // ERROR "live at call to F1: .?autotmp" "&t escapes to heap" "stack object .autotmp_[0-9]+ unsafe.Pointer$"
var t2 int // ERROR "moved to heap"
F3(uintptr(unsafe.Pointer(&t2))) // ERROR "live at call to F3: .?autotmp" "&t2 escapes to heap"
}
func H() {
var v int // ERROR "moved to heap"
F2(0, 1, uintptr(unsafe.Pointer(&v)), 2) // ERROR "live at call to newobject: .?autotmp" "live at call to F2: .?autotmp" "escapes to heap" "stack object .autotmp_[0-9]+ unsafe.Pointer$"
var v2 int // ERROR "moved to heap"
F4(0, 1, uintptr(unsafe.Pointer(&v2)), 2) // ERROR "live at call to newobject: .?autotmp" "live at call to F4: .?autotmp" "escapes to heap"
}