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mirror of https://github.com/golang/go synced 2024-11-23 06:10:05 -07:00
go/test/escape4.go
Matthew Dempsky 6113db0bb4 [dev.regabi] cmd/compile: convert OPANIC argument to interface{} during typecheck
Currently, typecheck leaves arguments to OPANIC as their original
type. This CL changes it to insert implicit OCONVIFACE operations to
convert arguments to `interface{}` like how any other function call
would be handled.

No immediate benefits, other than getting to remove a tiny bit of
special-case logic in order.go's handling of OPANICs. Instead, the
generic code path for handling OCONVIFACE is used, if necessary.
Longer term, this should be marginally helpful for #43753, as it
reduces the number of cases where we need values to be addressable for
runtime calls.

However, this does require adding some hacks to appease existing
tests:

1. We need yet another kludge in inline budgeting, to ensure that
reflect.flag.mustBe stays inlinable for cmd/compile/internal/test's
TestIntendedInlining.

2. Since the OCONVIFACE expressions are now being introduced during
typecheck, they're now visible to escape analysis. So expressions like
"panic(1)" are now seen as "panic(interface{}(1))", and escape
analysis warns that the "interface{}(1)" escapes to the heap. These
have always escaped to heap, just now we're accurately reporting about
it.

(Also, unfortunately fmt.go hides implicit conversions by default in
diagnostics messages, so instead of reporting "interface{}(1) escapes
to heap", it actually reports "1 escapes to heap", which is
confusing. However, this confusing messaging also isn't new.)

Change-Id: Icedf60e1d2e464e219441b8d1233a313770272af
Reviewed-on: https://go-review.googlesource.com/c/go/+/284412
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Trust: Matthew Dempsky <mdempsky@google.com>
2021-01-18 05:55:08 +00:00

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1.3 KiB
Go

// errorcheck -0 -m
// Copyright 2010 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, using compiler diagnostic flags, that the escape analysis is working.
// Compiles but does not run. Inlining is enabled.
package foo
var p *int
func alloc(x int) *int { // ERROR "can inline alloc" "moved to heap: x"
return &x
}
var f func()
func f1() {
p = alloc(2) // ERROR "inlining call to alloc" "moved to heap: x"
// Escape analysis used to miss inlined code in closures.
func() { // ERROR "can inline f1.func1"
p = alloc(3) // ERROR "inlining call to alloc"
}() // ERROR "inlining call to f1.func1" "inlining call to alloc" "moved to heap: x"
f = func() { // ERROR "func literal escapes to heap" "can inline f1.func2"
p = alloc(3) // ERROR "inlining call to alloc" "moved to heap: x"
}
f()
}
func f2() {} // ERROR "can inline f2"
// No inline for recover; panic now allowed to inline.
func f3() { panic(1) } // ERROR "can inline f3" "1 escapes to heap"
func f4() { recover() }
func f5() *byte {
type T struct {
x [1]byte
}
t := new(T) // ERROR "new.T. escapes to heap"
return &t.x[0]
}
func f6() *byte {
type T struct {
x struct {
y byte
}
}
t := new(T) // ERROR "new.T. escapes to heap"
return &t.x.y
}