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cmd/compile: pointers to notinheap types need their own shape

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They should not share a shape with regular pointers. We could coalesce
multiple pointer-to-not-in-heap types, but doesn't seem worth it - just
make them fully stenciled.

Fixes #51733

Change-Id: Ie8158177226fbc46a798e71c51897a82f15153df
Reviewed-on: https://go-review.googlesource.com/c/go/+/393895
Trust: Keith Randall <khr@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
This commit is contained in:
Keith Randall 2022-03-18 10:46:15 -07:00
parent 7e5804cb70
commit fcf6afb82d
2 changed files with 33 additions and 1 deletions
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2
src/cmd/compile/internal/typecheck/subr.go
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@ -1532,7 +1532,7 @@ func Shapify(t *types.Type, index int, tparam *types.Type) *types.Type {
// Note: pointers to arrays are special because of slice-to-array-pointer
// conversions. See issue 49295.
if u.Kind() == types.TPTR && u.Elem().Kind() != types.TARRAY &&
tparam.Bound().StructuralType() == nil {
tparam.Bound().StructuralType() == nil && !u.Elem().NotInHeap() {
u = types.Types[types.TUINT8].PtrTo()
}

32
test/typeparam/issue51733.go Normal file
View File

@ -0,0 +1,32 @@
// run
// Copyright 2022 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.
package main
import (
"log"
"unsafe"
)
//go:notinheap
type S struct{}
func main() {
p := (*S)(unsafe.Pointer(uintptr(0x8000)))
var v any = p
p2 := v.(*S)
if p != p2 {
log.Fatalf("%p != %p", unsafe.Pointer(p), unsafe.Pointer(p2))
}
p2 = typeAssert[*S](v)
if p != p2 {
log.Fatalf("%p != %p from typeAssert", unsafe.Pointer(p), unsafe.Pointer(p2))
}
}
func typeAssert[T any](v any) T {
return v.(T)
}