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[dev.typeparams] cmd/compile: remove special escape analysis tags

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This CL removes the special escape analysis tags added to support
//go:uintptrescapes and calls to external functions. Instead, these
are kept as function pragmas.

This CL by itself isn't very interesting, but I expect will help with
subsequent cleanups I have planned here.

Change-Id: Ifb960289a27e0a6295ce2d2f5ec233cac590522b
Reviewed-on: https://go-review.googlesource.com/c/go/+/329969
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Trust: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Trust: Matthew Dempsky <mdempsky@google.com>
This commit is contained in:
Matthew Dempsky 2021-06-21 22:03:02 -07:00
parent 859d903b06
commit 077100dfcd
3 changed files with 48 additions and 44 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
src/cmd/compile/internal/escape/escape.go
View File

@ -1132,7 +1132,7 @@ func (e *escape) tagHole(ks []hole, fn *ir.Name, param *types.Field) hole {
// Call to previously tagged function.
if param.Note == UintptrEscapesNote {
if fn.Func != nil && fn.Func.Pragma&ir.UintptrEscapes != 0 && (param.Type.IsUintptr() || param.IsDDD() && param.Type.Elem().IsUintptr()) {
k := e.heapHole()
k.uintptrEscapesHack = true
return k
@ -2048,15 +2048,6 @@ func HeapAllocReason(n ir.Node) string {
return ""
}
// This special tag is applied to uintptr variables
// that we believe may hold unsafe.Pointers for
// calls into assembly functions.
const UnsafeUintptrNote = "unsafe-uintptr"
// This special tag is applied to uintptr parameters of functions
// marked go:uintptrescapes.
const UintptrEscapesNote = "uintptr-escapes"
func (b *batch) paramTag(fn *ir.Func, narg int, f *types.Field) string {
name := func() string {
if f.Sym != nil {
@ -2072,11 +2063,13 @@ func (b *batch) paramTag(fn *ir.Func, narg int, f *types.Field) string {
// This really doesn't have much to do with escape analysis per se,
// but we are reusing the ability to annotate an individual function
// argument and pass those annotations along to importing code.
fn.Pragma |= ir.UintptrKeepAlive
if f.Type.IsUintptr() {
if base.Flag.LowerM != 0 {
base.WarnfAt(f.Pos, "assuming %v is unsafe uintptr", name())
}
return UnsafeUintptrNote
return ""
}
if !f.Type.HasPointers() { // don't bother tagging for scalars
@ -2102,18 +2095,20 @@ func (b *batch) paramTag(fn *ir.Func, narg int, f *types.Field) string {
}
if fn.Pragma&ir.UintptrEscapes != 0 {
fn.Pragma |= ir.UintptrKeepAlive
if f.Type.IsUintptr() {
if base.Flag.LowerM != 0 {
base.WarnfAt(f.Pos, "marking %v as escaping uintptr", name())
}
return UintptrEscapesNote
return ""
}
if f.IsDDD() && f.Type.Elem().IsUintptr() {
// final argument is ...uintptr.
if base.Flag.LowerM != 0 {
base.WarnfAt(f.Pos, "marking %v as escaping ...uintptr", name())
}
return UintptrEscapesNote
return ""
}
}

19
src/cmd/compile/internal/ir/node.go
View File

@ -436,18 +436,19 @@ func (s NameSet) Sorted(less func(*Name, *Name) bool) []*Name {
return res
}
type PragmaFlag int16
type PragmaFlag uint16
const (
// Func pragmas.
Nointerface PragmaFlag = 1 << iota
Noescape // func parameters don't escape
Norace // func must not have race detector annotations
Nosplit // func should not execute on separate stack
Noinline // func should not be inlined
NoCheckPtr // func should not be instrumented by checkptr
CgoUnsafeArgs // treat a pointer to one arg as a pointer to them all
UintptrEscapes // pointers converted to uintptr escape
Nointerface PragmaFlag = 1 << iota
Noescape // func parameters don't escape
Norace // func must not have race detector annotations
Nosplit // func should not execute on separate stack
Noinline // func should not be inlined
NoCheckPtr // func should not be instrumented by checkptr
CgoUnsafeArgs // treat a pointer to one arg as a pointer to them all
UintptrKeepAlive // pointers converted to uintptr must be kept alive (compiler internal only)
UintptrEscapes // pointers converted to uintptr escape
// Runtime-only func pragmas.
// See ../../../../runtime/README.md for detailed descriptions.

52
src/cmd/compile/internal/walk/order.go
View File

@ -9,7 +9,6 @@ import (
"go/constant"
"cmd/compile/internal/base"
"cmd/compile/internal/escape"
"cmd/compile/internal/ir"
"cmd/compile/internal/reflectdata"
"cmd/compile/internal/staticinit"
@ -554,37 +553,46 @@ func (o *orderState) call(nn ir.Node) {
n.X = o.expr(n.X, nil)
o.exprList(n.Args)
if n.Op() == ir.OCALLINTER {
// Pick out the function callee, if statically known.
// TODO(mdempsky): De-duplicate with similar code in escape analysis.
var callee *ir.Func
switch n.Op() {
case ir.OCALLFUNC:
if fn, ok := n.X.(*ir.Name); ok && fn.Op() == ir.ONAME && fn.Class == ir.PFUNC {
callee = fn.Func
}
case ir.OCALLMETH:
callee = ir.MethodExprName(n.X).Func
}
if callee == nil || callee.Pragma&ir.UintptrKeepAlive == 0 {
return
}
keepAlive := func(arg ir.Node) {
keepAlive := func(args []ir.Node) {
// If the argument is really a pointer being converted to uintptr,
// arrange for the pointer to be kept alive until the call returns,
// by copying it into a temp and marking that temp
// still alive when we pop the temp stack.
if arg.Op() == ir.OCONVNOP {
arg := arg.(*ir.ConvExpr)
if arg.X.Type().IsUnsafePtr() {
x := o.copyExpr(arg.X)
arg.X = x
x.SetAddrtaken(true) // ensure SSA keeps the x variable
n.KeepAlive = append(n.KeepAlive, x)
for _, arg := range args {
if arg.Op() == ir.OCONVNOP && arg.Type().IsUintptr() {
arg := arg.(*ir.ConvExpr)
if arg.X.Type().IsUnsafePtr() {
x := o.copyExpr(arg.X)
arg.X = x
x.SetAddrtaken(true) // ensure SSA keeps the x variable
n.KeepAlive = append(n.KeepAlive, x)
}
}
}
}
// Check for "unsafe-uintptr" tag provided by escape analysis.
for i, param := range n.X.Type().Params().FieldSlice() {
if param.Note == escape.UnsafeUintptrNote || param.Note == escape.UintptrEscapesNote {
if arg := n.Args[i]; arg.Op() == ir.OSLICELIT {
arg := arg.(*ir.CompLitExpr)
for _, elt := range arg.List {
keepAlive(elt)
}
} else {
keepAlive(arg)
}
}
last := len(n.Args) - 1
if n.IsDDD && n.Args[last].Op() == ir.OSLICELIT {
keepAlive(n.Args[:last])
keepAlive(n.Args[last].(*ir.CompLitExpr).List)
} else {
keepAlive(n.Args)
}
}