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cmd/cgo: add and use runtime/cgo.Incomplete instead of //go:notinheap

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Updates #46731

Change-Id: Ia83f27c177cc2f57e240cb5c6708d4552423f5be
Reviewed-on: https://go-review.googlesource.com/c/go/+/421879
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
This commit is contained in:
Cuong Manh Le 2022-08-07 18:41:42 +07:00
parent a6219737e3
commit 846c378b8c
5 changed files with 47 additions and 36 deletions
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14
api/next/46731.txt Normal file
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@ -0,0 +1,14 @@
pkg runtime/cgo (darwin-amd64-cgo), type Incomplete struct #46731
pkg runtime/cgo (freebsd-386-cgo), type Incomplete struct #46731
pkg runtime/cgo (freebsd-amd64-cgo), type Incomplete struct #46731
pkg runtime/cgo (freebsd-arm-cgo), type Incomplete struct #46731
pkg runtime/cgo (linux-386-cgo), type Incomplete struct #46731
pkg runtime/cgo (linux-amd64-cgo), type Incomplete struct #46731
pkg runtime/cgo (linux-arm-cgo), type Incomplete struct #46731
pkg runtime/cgo (netbsd-386-cgo), type Incomplete struct #46731
pkg runtime/cgo (netbsd-amd64-cgo), type Incomplete struct #46731
pkg runtime/cgo (netbsd-arm-cgo), type Incomplete struct #46731
pkg runtime/cgo (netbsd-arm64-cgo), type Incomplete struct #46731
pkg runtime/cgo (openbsd-386-cgo), type Incomplete struct #46731
pkg runtime/cgo (openbsd-amd64-cgo), type Incomplete struct #46731
pkg runtime/cgo, type Incomplete struct #46731

36
src/cmd/cgo/gcc.go
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@ -2154,8 +2154,8 @@ type typeConv struct {
// Type names X for which there exists an XGetTypeID function with type func() CFTypeID.
getTypeIDs map[string]bool
// badStructs contains C structs that should be marked NotInHeap.
notInHeapStructs map[string]bool
// incompleteStructs contains C structs that should be marked Incomplete.
incompleteStructs map[string]bool
// Predeclared types.
bool ast.Expr
@ -2168,7 +2168,6 @@ type typeConv struct {
string ast.Expr
goVoid ast.Expr // _Ctype_void, denotes C's void
goVoidPtr ast.Expr // unsafe.Pointer or *byte
goVoidPtrNoHeap ast.Expr // *_Ctype_void_notinheap, like goVoidPtr but marked NotInHeap
ptrSize int64
intSize int64
@ -2192,7 +2191,7 @@ func (c *typeConv) Init(ptrSize, intSize int64) {
c.m = make(map[string]*Type)
c.ptrs = make(map[string][]*Type)
c.getTypeIDs = make(map[string]bool)
c.notInHeapStructs = make(map[string]bool)
c.incompleteStructs = make(map[string]bool)
c.bool = c.Ident("bool")
c.byte = c.Ident("byte")
c.int8 = c.Ident("int8")
@ -2211,7 +2210,6 @@ func (c *typeConv) Init(ptrSize, intSize int64) {
c.void = c.Ident("void")
c.string = c.Ident("string")
c.goVoid = c.Ident("_Ctype_void")
c.goVoidPtrNoHeap = c.Ident("*_Ctype_void_notinheap")
// Normally cgo translates void* to unsafe.Pointer,
// but for historical reasons -godefs uses *byte instead.
@ -2561,19 +2559,13 @@ func (c *typeConv) loadType(dtype dwarf.Type, pos token.Pos, parent string) *Typ
// other than try to determine a Go representation.
tt := *t
tt.C = &TypeRepr{"%s %s", []interface{}{dt.Kind, tag}}
tt.Go = c.Ident("struct{}")
if dt.Kind == "struct" {
// We don't know what the representation of this struct is, so don't let
// anyone allocate one on the Go side. As a side effect of this annotation,
// pointers to this type will not be considered pointers in Go. They won't
// get writebarrier-ed or adjusted during a stack copy. This should handle
// all the cases badPointerTypedef used to handle, but hopefully will
// continue to work going forward without any more need for cgo changes.
tt.NotInHeap = true
// TODO: we should probably do the same for unions. Unions can't live
// on the Go heap, right? It currently doesn't work for unions because
// they are defined as a type alias for struct{}, not a defined type.
}
tt.Go = c.Ident("_cgopackage.Incomplete")
typedef[name.Name] = &tt
break
}
@ -2599,7 +2591,9 @@ func (c *typeConv) loadType(dtype dwarf.Type, pos token.Pos, parent string) *Typ
tt.C = &TypeRepr{"struct %s", []interface{}{tag}}
}
tt.Go = g
tt.NotInHeap = c.notInHeapStructs[tag]
if c.incompleteStructs[tag] {
tt.Go = c.Ident("_cgopackage.Incomplete")
}
typedef[name.Name] = &tt
}
@ -2644,9 +2638,9 @@ func (c *typeConv) loadType(dtype dwarf.Type, pos token.Pos, parent string) *Typ
}
}
if c.badVoidPointerTypedef(dt) {
// Treat this typedef as a pointer to a NotInHeap void.
// Treat this typedef as a pointer to a _cgopackage.Incomplete.
s := *sub
s.Go = c.goVoidPtrNoHeap
s.Go = c.Ident("*_cgopackage.Incomplete")
sub = &s
// Make sure we update any previously computed type.
if oldType := typedef[name.Name]; oldType != nil {
@ -2654,22 +2648,21 @@ func (c *typeConv) loadType(dtype dwarf.Type, pos token.Pos, parent string) *Typ
}
}
// Check for non-pointer "struct <tag>{...}; typedef struct <tag> *<name>"
// typedefs that should be marked NotInHeap.
// typedefs that should be marked Incomplete.
if ptr, ok := dt.Type.(*dwarf.PtrType); ok {
if strct, ok := ptr.Type.(*dwarf.StructType); ok {
if c.badStructPointerTypedef(dt.Name, strct) {
c.notInHeapStructs[strct.StructName] = true
c.incompleteStructs[strct.StructName] = true
// Make sure we update any previously computed type.
name := "_Ctype_struct_" + strct.StructName
if oldType := typedef[name]; oldType != nil {
oldType.NotInHeap = true
oldType.Go = c.Ident("_cgopackage.Incomplete")
}
}
}
}
t.Go = name
t.BadPointer = sub.BadPointer
t.NotInHeap = sub.NotInHeap
if unionWithPointer[sub.Go] {
unionWithPointer[t.Go] = true
}
@ -2680,7 +2673,6 @@ func (c *typeConv) loadType(dtype dwarf.Type, pos token.Pos, parent string) *Typ
tt := *t
tt.Go = sub.Go
tt.BadPointer = sub.BadPointer
tt.NotInHeap = sub.NotInHeap
typedef[name.Name] = &tt
}
@ -3204,7 +3196,7 @@ func (c *typeConv) anonymousStructTypedef(dt *dwarf.TypedefType) bool {
// non-pointers in this type.
// TODO: Currently our best solution is to find these manually and list them as
// they come up. A better solution is desired.
// Note: DEPRECATED. There is now a better solution. Search for NotInHeap in this file.
// Note: DEPRECATED. There is now a better solution. Search for _cgopackage.Incomplete in this file.
func (c *typeConv) badPointerTypedef(dt *dwarf.TypedefType) bool {
if c.badCFType(dt) {
return true
@ -3218,7 +3210,7 @@ func (c *typeConv) badPointerTypedef(dt *dwarf.TypedefType) bool {
return false
}
// badVoidPointerTypedef is like badPointerTypeDef, but for "void *" typedefs that should be NotInHeap.
// badVoidPointerTypedef is like badPointerTypeDef, but for "void *" typedefs that should be _cgopackage.Incomplete.
func (c *typeConv) badVoidPointerTypedef(dt *dwarf.TypedefType) bool {
// Match the Windows HANDLE type (#42018).
if goos != "windows" || dt.Name != "HANDLE" {

1
src/cmd/cgo/main.go
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@ -153,7 +153,6 @@ type Type struct {
EnumValues map[string]int64
Typedef string
BadPointer bool // this pointer type should be represented as a uintptr (deprecated)
NotInHeap bool // this type should have a go:notinheap annotation
}
// A FuncType collects information about a function type in both the C and Go worlds.

13
src/cmd/cgo/out.go
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@ -81,11 +81,14 @@ func (p *Package) writeDefs() {
fmt.Fprintf(fgo2, "// Code generated by cmd/cgo; DO NOT EDIT.\n\n")
fmt.Fprintf(fgo2, "package %s\n\n", p.PackageName)
fmt.Fprintf(fgo2, "import \"unsafe\"\n\n")
if !*gccgo && *importRuntimeCgo {
fmt.Fprintf(fgo2, "import _ \"runtime/cgo\"\n\n")
}
if *importSyscall {
fmt.Fprintf(fgo2, "import \"syscall\"\n\n")
}
if *importRuntimeCgo {
fmt.Fprintf(fgo2, "import _cgopackage \"runtime/cgo\"\n\n")
fmt.Fprintf(fgo2, "type _ _cgopackage.Incomplete\n") // prevent import-not-used error
}
if *importSyscall {
fmt.Fprintf(fgo2, "var _ syscall.Errno\n")
}
fmt.Fprintf(fgo2, "func _Cgo_ptr(ptr unsafe.Pointer) unsafe.Pointer { return ptr }\n\n")
@ -109,9 +112,6 @@ func (p *Package) writeDefs() {
sort.Strings(typedefNames)
for _, name := range typedefNames {
def := typedef[name]
if def.NotInHeap {
fmt.Fprintf(fgo2, "//go:notinheap\n")
}
fmt.Fprintf(fgo2, "type %s ", name)
// We don't have source info for these types, so write them out without source info.
// Otherwise types would look like:
@ -136,7 +136,6 @@ func (p *Package) writeDefs() {
fmt.Fprintf(fgo2, "%s", buf.Bytes())
fmt.Fprintf(fgo2, "\n\n")
}
fmt.Fprintf(fgo2, "//go:notinheap\ntype _Ctype_void_notinheap struct{}\n\n")
if *gccgo {
fmt.Fprintf(fgo2, "type _Ctype_void byte\n")
} else {

7
src/runtime/cgo/cgo.go
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@ -31,3 +31,10 @@ package cgo
*/
import "C"
import "runtime/internal/sys"
// Incomplete is used specifically for the semantics of incomplete C types.
type Incomplete struct {
_ sys.NotInHeap
}