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37f138df6b
[git-generate] cd src/cmd/compile/internal/gc rf ' mv bench_test.go constFold_test.go dep_test.go \ fixedbugs_test.go iface_test.go float_test.go global_test.go \ inl_test.go lang_test.go logic_test.go \ reproduciblebuilds_test.go shift_test.go ssa_test.go \ truncconst_test.go zerorange_test.go \ cmd/compile/internal/test ' mv testdata ../test Change-Id: I041971b7e9766673f7a331679bfe1c8110dcda66 Reviewed-on: https://go-review.googlesource.com/c/go/+/279480 Trust: Russ Cox <rsc@golang.org> Run-TryBot: Russ Cox <rsc@golang.org> Reviewed-by: Matthew Dempsky <mdempsky@google.com>
145 lines
3 KiB
Go
145 lines
3 KiB
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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import (
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"runtime"
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"testing"
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"unsafe"
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)
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// global pointer slot
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var a *[8]uint
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// unfoldable true
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var always = true
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// Test to make sure that a pointer value which is alive
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// across a call is retained, even when there are matching
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// conversions to/from uintptr around the call.
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// We arrange things very carefully to have to/from
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// conversions on either side of the call which cannot be
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// combined with any other conversions.
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func f_ssa() *[8]uint {
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// Make x a uintptr pointing to where a points.
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var x uintptr
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if always {
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x = uintptr(unsafe.Pointer(a))
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} else {
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x = 0
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}
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// Clobber the global pointer. The only live ref
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// to the allocated object is now x.
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a = nil
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// Convert to pointer so it should hold
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// the object live across GC call.
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p := unsafe.Pointer(x)
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// Call gc.
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runtime.GC()
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// Convert back to uintptr.
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y := uintptr(p)
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// Mess with y so that the subsequent cast
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// to unsafe.Pointer can't be combined with the
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// uintptr cast above.
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var z uintptr
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if always {
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z = y
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} else {
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z = 0
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}
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return (*[8]uint)(unsafe.Pointer(z))
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}
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// g_ssa is the same as f_ssa, but with a bit of pointer
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// arithmetic for added insanity.
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func g_ssa() *[7]uint {
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// Make x a uintptr pointing to where a points.
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var x uintptr
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if always {
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x = uintptr(unsafe.Pointer(a))
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} else {
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x = 0
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}
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// Clobber the global pointer. The only live ref
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// to the allocated object is now x.
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a = nil
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// Offset x by one int.
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x += unsafe.Sizeof(int(0))
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// Convert to pointer so it should hold
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// the object live across GC call.
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p := unsafe.Pointer(x)
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// Call gc.
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runtime.GC()
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// Convert back to uintptr.
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y := uintptr(p)
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// Mess with y so that the subsequent cast
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// to unsafe.Pointer can't be combined with the
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// uintptr cast above.
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var z uintptr
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if always {
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z = y
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} else {
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z = 0
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}
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return (*[7]uint)(unsafe.Pointer(z))
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}
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func testf(t *testing.T) {
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a = new([8]uint)
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for i := 0; i < 8; i++ {
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a[i] = 0xabcd
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}
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c := f_ssa()
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for i := 0; i < 8; i++ {
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if c[i] != 0xabcd {
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t.Fatalf("%d:%x\n", i, c[i])
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}
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}
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}
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func testg(t *testing.T) {
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a = new([8]uint)
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for i := 0; i < 8; i++ {
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a[i] = 0xabcd
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}
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c := g_ssa()
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for i := 0; i < 7; i++ {
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if c[i] != 0xabcd {
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t.Fatalf("%d:%x\n", i, c[i])
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}
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}
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}
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func alias_ssa(ui64 *uint64, ui32 *uint32) uint32 {
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*ui32 = 0xffffffff
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*ui64 = 0 // store
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ret := *ui32 // load from same address, should be zero
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*ui64 = 0xffffffffffffffff // store
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return ret
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}
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func testdse(t *testing.T) {
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x := int64(-1)
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// construct two pointers that alias one another
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ui64 := (*uint64)(unsafe.Pointer(&x))
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ui32 := (*uint32)(unsafe.Pointer(&x))
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if want, got := uint32(0), alias_ssa(ui64, ui32); got != want {
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t.Fatalf("alias_ssa: wanted %d, got %d\n", want, got)
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}
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}
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func TestUnsafe(t *testing.T) {
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testf(t)
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testg(t)
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testdse(t)
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}
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