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![Keith Randall](/assets/img/avatar_default.png)
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>
183 lines
4.4 KiB
Go
183 lines
4.4 KiB
Go
// errorcheck -0 -m
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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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// Test, using compiler diagnostic flags, that inlining is working.
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// Compiles but does not run.
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package foo
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import (
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"errors"
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"runtime"
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"unsafe"
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)
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func add2(p *byte, n uintptr) *byte { // ERROR "can inline add2" "leaking param: p to result"
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return (*byte)(add1(unsafe.Pointer(p), n)) // ERROR "inlining call to add1"
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}
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func add1(p unsafe.Pointer, x uintptr) unsafe.Pointer { // ERROR "can inline add1" "leaking param: p to result"
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return unsafe.Pointer(uintptr(p) + x)
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}
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func f(x *byte) *byte { // ERROR "can inline f" "leaking param: x to result"
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return add2(x, 1) // ERROR "inlining call to add2" "inlining call to add1"
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}
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//go:noinline
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func g(x int) int {
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return x + 1
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}
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func h(x int) int { // ERROR "can inline h"
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return x + 2
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}
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func i(x int) int { // ERROR "can inline i"
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const y = 2
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return x + y
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}
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func j(x int) int { // ERROR "can inline j"
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switch {
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case x > 0:
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return x + 2
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default:
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return x + 1
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}
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}
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var somethingWrong error = errors.New("something went wrong")
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// local closures can be inlined
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func l(x, y int) (int, int, error) {
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e := func(err error) (int, int, error) { // ERROR "can inline l.func1" "func literal does not escape" "leaking param: err to result"
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return 0, 0, err
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}
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if x == y {
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e(somethingWrong) // ERROR "inlining call to l.func1"
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}
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return y, x, nil
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}
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// any re-assignment prevents closure inlining
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func m() int {
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foo := func() int { return 1 } // ERROR "can inline m.func1" "func literal does not escape"
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x := foo()
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foo = func() int { return 2 } // ERROR "can inline m.func2" "func literal does not escape"
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return x + foo()
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}
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// address taking prevents closure inlining
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func n() int {
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foo := func() int { return 1 } // ERROR "can inline n.func1" "func literal does not escape"
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bar := &foo // ERROR "&foo does not escape"
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x := (*bar)() + foo()
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return x
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}
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// make sure assignment inside closure is detected
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func o() int {
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foo := func() int { return 1 } // ERROR "can inline o.func1" "func literal does not escape"
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func(x int) { // ERROR "func literal does not escape"
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if x > 10 {
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foo = func() int { return 2 } // ERROR "can inline o.func2" "func literal escapes"
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}
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}(11)
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return foo()
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}
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func p() int {
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return func() int { return 42 }() // ERROR "can inline p.func1" "inlining call to p.func1"
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}
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func q(x int) int {
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foo := func() int { return x * 2 } // ERROR "can inline q.func1" "q func literal does not escape"
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return foo() // ERROR "inlining call to q.func1"
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}
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func r(z int) int {
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foo := func(x int) int { // ERROR "can inline r.func1" "r func literal does not escape"
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return x + z
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}
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bar := func(x int) int { // ERROR "r func literal does not escape"
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return x + func(y int) int { // ERROR "can inline r.func2.1"
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return 2*y + x*z
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}(x) // ERROR "inlining call to r.func2.1"
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}
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return foo(42) + bar(42) // ERROR "inlining call to r.func1"
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}
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func s0(x int) int {
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foo := func() { // ERROR "can inline s0.func1" "s0 func literal does not escape"
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x = x + 1
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}
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foo() // ERROR "inlining call to s0.func1" "&x does not escape"
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return x
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}
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func s1(x int) int {
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foo := func() int { // ERROR "can inline s1.func1" "s1 func literal does not escape"
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return x
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}
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x = x + 1
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return foo() // ERROR "inlining call to s1.func1" "&x does not escape"
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}
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// can't currently inline functions with a break statement
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func switchBreak(x, y int) int {
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var n int
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switch x {
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case 0:
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n = 1
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Done:
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switch y {
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case 0:
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n += 10
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break Done
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}
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n = 2
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}
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return n
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}
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// can't currently inline functions with a type switch
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func switchType(x interface{}) int { // ERROR "switchType x does not escape"
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switch x.(type) {
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case int:
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return x.(int)
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default:
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return 0
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}
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}
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type T struct{}
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func (T) meth(int, int) {} // ERROR "can inline T.meth"
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func k() (T, int, int) { return T{}, 0, 0 } // ERROR "can inline k"
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func _() { // ERROR "can inline _"
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T.meth(k()) // ERROR "inlining call to k" "inlining call to T.meth"
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}
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func small1() { // ERROR "can inline small1"
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runtime.GC()
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}
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func small2() int { // ERROR "can inline small2"
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return runtime.GOMAXPROCS(0)
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}
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func small3(t T) { // ERROR "can inline small3"
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t.meth2(3, 5)
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}
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func small4(t T) { // not inlineable - has 2 calls.
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t.meth2(runtime.GOMAXPROCS(0), 5)
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}
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func (T) meth2(int, int) { // not inlineable - has 2 calls.
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runtime.GC()
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runtime.GC()
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}
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