mirror of
https://github.com/golang/go
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Revert "cmd/compile,runtime: allocate defer records on the stack"
This reverts commit fff4f599fe.
Reason for revert: Seems to still have issues around GC.
Fixes #32452
Change-Id: Ibe7af629f9ad6a3d5312acd7b066123f484da7f0
Reviewed-on: https://go-review.googlesource.com/c/go/+/180761
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
This commit is contained in:
Keith Randall
parent
e9a136d185
commit
49200e3f3e
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@ -802,7 +802,6 @@ opSwitch:
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case ODEFER:
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if e.loopdepth == 1 { // top level
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n.Esc = EscNever // force stack allocation of defer record (see ssa.go)
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break
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}
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// arguments leak out of scope
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@ -882,7 +882,6 @@ func (e *Escape) augmentParamHole(k EscHole, where *Node) EscHole {
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// non-transient location to avoid arguments from being
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// transiently allocated.
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if where.Op == ODEFER && e.loopDepth == 1 {
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where.Esc = EscNever // force stack allocation of defer record (see ssa.go)
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// TODO(mdempsky): Eliminate redundant EscLocation allocs.
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return e.teeHole(k, e.newLoc(nil, false).asHole())
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}
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@ -287,7 +287,6 @@ var (
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assertI2I,
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assertI2I2,
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deferproc,
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deferprocStack,
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Deferreturn,
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Duffcopy,
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Duffzero,
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@ -317,48 +317,6 @@ func hiter(t *types.Type) *types.Type {
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return hiter
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}
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// deferstruct makes a runtime._defer structure, with additional space for
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// stksize bytes of args.
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func deferstruct(stksize int64) *types.Type {
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makefield := func(name string, typ *types.Type) *types.Field {
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f := types.NewField()
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f.Type = typ
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// Unlike the global makefield function, this one needs to set Pkg
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// because these types might be compared (in SSA CSE sorting).
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// TODO: unify this makefield and the global one above.
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f.Sym = &types.Sym{Name: name, Pkg: localpkg}
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return f
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}
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argtype := types.NewArray(types.Types[TUINT8], stksize)
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argtype.SetNoalg(true)
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argtype.Width = stksize
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argtype.Align = 1
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// These fields must match the ones in runtime/runtime2.go:_defer and
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// cmd/compile/internal/gc/ssa.go:(*state).call.
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fields := []*types.Field{
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makefield("siz", types.Types[TUINT32]),
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makefield("started", types.Types[TBOOL]),
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makefield("heap", types.Types[TBOOL]),
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makefield("sp", types.Types[TUINTPTR]),
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makefield("pc", types.Types[TUINTPTR]),
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// Note: the types here don't really matter. Defer structures
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// are always scanned explicitly during stack copying and GC,
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// so we make them uintptr type even though they are real pointers.
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makefield("fn", types.Types[TUINTPTR]),
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makefield("_panic", types.Types[TUINTPTR]),
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makefield("link", types.Types[TUINTPTR]),
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makefield("args", argtype),
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}
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// build struct holding the above fields
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s := types.New(TSTRUCT)
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s.SetNoalg(true)
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s.SetFields(fields)
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s.Width = widstruct(s, s, 0, 1)
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s.Align = uint8(Widthptr)
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return s
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}
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// f is method type, with receiver.
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// return function type, receiver as first argument (or not).
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func methodfunc(f *types.Type, receiver *types.Type) *types.Type {
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@ -68,7 +68,6 @@ func initssaconfig() {
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assertI2I = sysfunc("assertI2I")
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assertI2I2 = sysfunc("assertI2I2")
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deferproc = sysfunc("deferproc")
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deferprocStack = sysfunc("deferprocStack")
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Deferreturn = sysfunc("deferreturn")
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Duffcopy = sysvar("duffcopy") // asm func with special ABI
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Duffzero = sysvar("duffzero") // asm func with special ABI
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@ -865,11 +864,7 @@ func (s *state) stmt(n *Node) {
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}
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}
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case ODEFER:
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d := callDefer
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if n.Esc == EscNever {
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d = callDeferStack
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}
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s.call(n.Left, d)
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s.call(n.Left, callDefer)
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case OGO:
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s.call(n.Left, callGo)
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@ -2864,7 +2859,6 @@ type callKind int8
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const (
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callNormal callKind = iota
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callDefer
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callDeferStack
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callGo
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)
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@ -3805,132 +3799,74 @@ func (s *state) call(n *Node, k callKind) *ssa.Value {
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rcvr = s.newValue1(ssa.OpIData, types.Types[TUINTPTR], i)
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}
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dowidth(fn.Type)
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stksize := fn.Type.ArgWidth() // includes receiver, args, and results
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stksize := fn.Type.ArgWidth() // includes receiver
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// Run all assignments of temps.
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// The temps are introduced to avoid overwriting argument
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// slots when arguments themselves require function calls.
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s.stmtList(n.List)
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var call *ssa.Value
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if k == callDeferStack {
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// Make a defer struct d on the stack.
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t := deferstruct(stksize)
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d := tempAt(n.Pos, s.curfn, t)
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s.vars[&memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, d, s.mem())
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addr := s.addr(d, false)
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// Must match reflect.go:deferstruct and src/runtime/runtime2.go:_defer.
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// 0: siz
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s.store(types.Types[TUINT32],
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s.newValue1I(ssa.OpOffPtr, types.Types[TUINT32].PtrTo(), t.FieldOff(0), addr),
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s.constInt32(types.Types[TUINT32], int32(stksize)))
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// 1: started, set in deferprocStack
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// 2: heap, set in deferprocStack
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// 3: sp, set in deferprocStack
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// 4: pc, set in deferprocStack
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// 5: fn
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s.store(closure.Type,
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s.newValue1I(ssa.OpOffPtr, closure.Type.PtrTo(), t.FieldOff(5), addr),
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closure)
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// 6: panic, set in deferprocStack
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// 7: link, set in deferprocStack
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// Then, store all the arguments of the defer call.
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ft := fn.Type
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off := t.FieldOff(8)
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args := n.Rlist.Slice()
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// Set receiver (for interface calls). Always a pointer.
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if rcvr != nil {
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p := s.newValue1I(ssa.OpOffPtr, ft.Recv().Type.PtrTo(), off, addr)
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s.store(types.Types[TUINTPTR], p, rcvr)
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}
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// Set receiver (for method calls).
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if n.Op == OCALLMETH {
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f := ft.Recv()
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s.storeArgWithBase(args[0], f.Type, addr, off+f.Offset)
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args = args[1:]
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}
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// Set other args.
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for _, f := range ft.Params().Fields().Slice() {
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s.storeArgWithBase(args[0], f.Type, addr, off+f.Offset)
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args = args[1:]
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}
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// Call runtime.deferprocStack with pointer to _defer record.
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arg0 := s.constOffPtrSP(types.Types[TUINTPTR], Ctxt.FixedFrameSize())
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s.store(types.Types[TUINTPTR], arg0, addr)
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call = s.newValue1A(ssa.OpStaticCall, types.TypeMem, deferprocStack, s.mem())
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if stksize < int64(Widthptr) {
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// We need room for both the call to deferprocStack and the call to
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// the deferred function.
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stksize = int64(Widthptr)
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}
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call.AuxInt = stksize
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} else {
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// Store arguments to stack, including defer/go arguments and receiver for method calls.
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// These are written in SP-offset order.
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argStart := Ctxt.FixedFrameSize()
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// Defer/go args.
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if k != callNormal {
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// Write argsize and closure (args to newproc/deferproc).
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argsize := s.constInt32(types.Types[TUINT32], int32(stksize))
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addr := s.constOffPtrSP(s.f.Config.Types.UInt32Ptr, argStart)
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s.store(types.Types[TUINT32], addr, argsize)
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addr = s.constOffPtrSP(s.f.Config.Types.UintptrPtr, argStart+int64(Widthptr))
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s.store(types.Types[TUINTPTR], addr, closure)
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stksize += 2 * int64(Widthptr)
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argStart += 2 * int64(Widthptr)
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}
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// Set receiver (for interface calls).
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if rcvr != nil {
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addr := s.constOffPtrSP(s.f.Config.Types.UintptrPtr, argStart)
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s.store(types.Types[TUINTPTR], addr, rcvr)
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}
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// Write args.
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t := n.Left.Type
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args := n.Rlist.Slice()
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if n.Op == OCALLMETH {
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f := t.Recv()
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s.storeArg(args[0], f.Type, argStart+f.Offset)
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args = args[1:]
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}
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for i, n := range args {
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f := t.Params().Field(i)
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s.storeArg(n, f.Type, argStart+f.Offset)
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}
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// call target
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switch {
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case k == callDefer:
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call = s.newValue1A(ssa.OpStaticCall, types.TypeMem, deferproc, s.mem())
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case k == callGo:
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call = s.newValue1A(ssa.OpStaticCall, types.TypeMem, newproc, s.mem())
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case closure != nil:
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// rawLoad because loading the code pointer from a
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// closure is always safe, but IsSanitizerSafeAddr
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// can't always figure that out currently, and it's
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// critical that we not clobber any arguments already
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// stored onto the stack.
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codeptr = s.rawLoad(types.Types[TUINTPTR], closure)
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call = s.newValue3(ssa.OpClosureCall, types.TypeMem, codeptr, closure, s.mem())
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case codeptr != nil:
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call = s.newValue2(ssa.OpInterCall, types.TypeMem, codeptr, s.mem())
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case sym != nil:
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call = s.newValue1A(ssa.OpStaticCall, types.TypeMem, sym.Linksym(), s.mem())
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default:
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Fatalf("bad call type %v %v", n.Op, n)
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}
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call.AuxInt = stksize // Call operations carry the argsize of the callee along with them
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// Store arguments to stack, including defer/go arguments and receiver for method calls.
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// These are written in SP-offset order.
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argStart := Ctxt.FixedFrameSize()
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// Defer/go args.
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if k != callNormal {
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// Write argsize and closure (args to newproc/deferproc).
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argsize := s.constInt32(types.Types[TUINT32], int32(stksize))
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addr := s.constOffPtrSP(s.f.Config.Types.UInt32Ptr, argStart)
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s.store(types.Types[TUINT32], addr, argsize)
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addr = s.constOffPtrSP(s.f.Config.Types.UintptrPtr, argStart+int64(Widthptr))
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s.store(types.Types[TUINTPTR], addr, closure)
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stksize += 2 * int64(Widthptr)
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argStart += 2 * int64(Widthptr)
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}
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// Set receiver (for interface calls).
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if rcvr != nil {
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addr := s.constOffPtrSP(s.f.Config.Types.UintptrPtr, argStart)
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s.store(types.Types[TUINTPTR], addr, rcvr)
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}
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// Write args.
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t := n.Left.Type
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args := n.Rlist.Slice()
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if n.Op == OCALLMETH {
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f := t.Recv()
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s.storeArg(args[0], f.Type, argStart+f.Offset)
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args = args[1:]
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}
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for i, n := range args {
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f := t.Params().Field(i)
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s.storeArg(n, f.Type, argStart+f.Offset)
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}
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// call target
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var call *ssa.Value
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switch {
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case k == callDefer:
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call = s.newValue1A(ssa.OpStaticCall, types.TypeMem, deferproc, s.mem())
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case k == callGo:
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call = s.newValue1A(ssa.OpStaticCall, types.TypeMem, newproc, s.mem())
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case closure != nil:
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// rawLoad because loading the code pointer from a
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// closure is always safe, but IsSanitizerSafeAddr
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// can't always figure that out currently, and it's
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// critical that we not clobber any arguments already
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// stored onto the stack.
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codeptr = s.rawLoad(types.Types[TUINTPTR], closure)
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call = s.newValue3(ssa.OpClosureCall, types.TypeMem, codeptr, closure, s.mem())
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case codeptr != nil:
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call = s.newValue2(ssa.OpInterCall, types.TypeMem, codeptr, s.mem())
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case sym != nil:
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call = s.newValue1A(ssa.OpStaticCall, types.TypeMem, sym.Linksym(), s.mem())
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default:
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Fatalf("bad call type %v %v", n.Op, n)
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}
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call.AuxInt = stksize // Call operations carry the argsize of the callee along with them
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s.vars[&memVar] = call
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// Finish block for defers
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if k == callDefer || k == callDeferStack {
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if k == callDefer {
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b := s.endBlock()
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b.Kind = ssa.BlockDefer
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b.SetControl(call)
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@ -4425,27 +4361,17 @@ func (s *state) storeTypePtrs(t *types.Type, left, right *ssa.Value) {
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}
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func (s *state) storeArg(n *Node, t *types.Type, off int64) {
|
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s.storeArgWithBase(n, t, s.sp, off)
|
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}
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|
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func (s *state) storeArgWithBase(n *Node, t *types.Type, base *ssa.Value, off int64) {
|
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pt := types.NewPtr(t)
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var addr *ssa.Value
|
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if base == s.sp {
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// Use special routine that avoids allocation on duplicate offsets.
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addr = s.constOffPtrSP(pt, off)
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} else {
|
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addr = s.newValue1I(ssa.OpOffPtr, pt, off, base)
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}
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sp := s.constOffPtrSP(pt, off)
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|
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if !canSSAType(t) {
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a := s.addr(n, false)
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s.move(t, addr, a)
|
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s.move(t, sp, a)
|
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return
|
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}
|
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|
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a := s.expr(n)
|
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s.storeType(t, addr, a, 0, false)
|
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s.storeType(t, sp, a, 0, false)
|
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}
|
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|
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// slice computes the slice v[i:j:k] and returns ptr, len, and cap of result.
|
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|
|
|
|||
|
|
@ -712,31 +712,15 @@ func scanstack(gp *g, gcw *gcWork) {
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|
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// Find additional pointers that point into the stack from the heap.
|
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// Currently this includes defers and panics. See also function copystack.
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|
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// Find and trace all defer arguments.
|
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tracebackdefers(gp, scanframe, nil)
|
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|
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// Find and trace other pointers in defer records.
|
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for d := gp._defer; d != nil; d = d.link {
|
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// tracebackdefers above does not scan the func value, which could
|
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// be a stack allocated closure. See issue 30453.
|
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if d.fn != nil {
|
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// tracebackdefers above does not scan the func value, which could
|
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// be a stack allocated closure. See issue 30453.
|
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scanblock(uintptr(unsafe.Pointer(&d.fn)), sys.PtrSize, &oneptrmask[0], gcw, &state)
|
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}
|
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if d.link != nil {
|
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// The link field of a stack-allocated defer record might point
|
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// to a heap-allocated defer record. Keep that heap record live.
|
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scanblock(uintptr(unsafe.Pointer(&d.link)), sys.PtrSize, &oneptrmask[0], gcw, &state)
|
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}
|
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// Retain defers records themselves.
|
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// Defer records might not be reachable from the G through regular heap
|
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// tracing because the defer linked list might weave between the stack and the heap.
|
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if d.heap {
|
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scanblock(uintptr(unsafe.Pointer(&d)), sys.PtrSize, &oneptrmask[0], gcw, &state)
|
||||
}
|
||||
}
|
||||
if gp._panic != nil {
|
||||
// Panics are always stack allocated.
|
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state.putPtr(uintptr(unsafe.Pointer(gp._panic)))
|
||||
}
|
||||
|
||||
|
|
|
|||
|
|
@ -228,46 +228,6 @@ func deferproc(siz int32, fn *funcval) { // arguments of fn follow fn
|
|||
// been set and must not be clobbered.
|
||||
}
|
||||
|
||||
// deferprocStack queues a new deferred function with a defer record on the stack.
|
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// The defer record must have its siz and fn fields initialized.
|
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// All other fields can contain junk.
|
||||
// The defer record must be immediately followed in memory by
|
||||
// the arguments of the defer.
|
||||
// Nosplit because the arguments on the stack won't be scanned
|
||||
// until the defer record is spliced into the gp._defer list.
|
||||
//go:nosplit
|
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func deferprocStack(d *_defer) {
|
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gp := getg()
|
||||
if gp.m.curg != gp {
|
||||
// go code on the system stack can't defer
|
||||
throw("defer on system stack")
|
||||
}
|
||||
// siz and fn are already set.
|
||||
// The other fields are junk on entry to deferprocStack and
|
||||
// are initialized here.
|
||||
d.started = false
|
||||
d.heap = false
|
||||
d.sp = getcallersp()
|
||||
d.pc = getcallerpc()
|
||||
// The lines below implement:
|
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// d.panic = nil
|
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// d.link = gp._defer
|
||||
// gp._defer = d
|
||||
// But without write barriers. The first two are writes to
|
||||
// the stack so they don't need a write barrier, and furthermore
|
||||
// are to uninitialized memory, so they must not use a write barrier.
|
||||
// The third write does not require a write barrier because we
|
||||
// explicitly mark all the defer structures, so we don't need to
|
||||
// keep track of pointers to them with a write barrier.
|
||||
*(*uintptr)(unsafe.Pointer(&d._panic)) = 0
|
||||
*(*uintptr)(unsafe.Pointer(&d.link)) = uintptr(unsafe.Pointer(gp._defer))
|
||||
*(*uintptr)(unsafe.Pointer(&gp._defer)) = uintptr(unsafe.Pointer(d))
|
||||
|
||||
return0()
|
||||
// No code can go here - the C return register has
|
||||
// been set and must not be clobbered.
|
||||
}
|
||||
|
||||
// Small malloc size classes >= 16 are the multiples of 16: 16, 32, 48, 64, 80, 96, 112, 128, 144, ...
|
||||
// Each P holds a pool for defers with small arg sizes.
|
||||
// Assign defer allocations to pools by rounding to 16, to match malloc size classes.
|
||||
|
|
@ -389,7 +349,6 @@ func newdefer(siz int32) *_defer {
|
|||
}
|
||||
}
|
||||
d.siz = siz
|
||||
d.heap = true
|
||||
d.link = gp._defer
|
||||
gp._defer = d
|
||||
return d
|
||||
|
|
@ -409,9 +368,6 @@ func freedefer(d *_defer) {
|
|||
if d.fn != nil {
|
||||
freedeferfn()
|
||||
}
|
||||
if !d.heap {
|
||||
return
|
||||
}
|
||||
sc := deferclass(uintptr(d.siz))
|
||||
if sc >= uintptr(len(p{}.deferpool)) {
|
||||
return
|
||||
|
|
|
|||
|
|
@ -775,16 +775,9 @@ func extendRandom(r []byte, n int) {
|
|||
|
||||
// A _defer holds an entry on the list of deferred calls.
|
||||
// If you add a field here, add code to clear it in freedefer.
|
||||
// This struct must match the code in cmd/compile/internal/gc/reflect.go:deferstruct
|
||||
// and cmd/compile/internal/gc/ssa.go:(*state).call.
|
||||
// Some defers will be allocated on the stack and some on the heap.
|
||||
// All defers are logically part of the stack, so write barriers to
|
||||
// initialize them are not required. All defers must be manually scanned,
|
||||
// and for heap defers, marked.
|
||||
type _defer struct {
|
||||
siz int32 // includes both arguments and results
|
||||
siz int32
|
||||
started bool
|
||||
heap bool
|
||||
sp uintptr // sp at time of defer
|
||||
pc uintptr
|
||||
fn *funcval
|
||||
|
|
|
|||
|
|
@ -719,21 +719,16 @@ func adjustctxt(gp *g, adjinfo *adjustinfo) {
|
|||
}
|
||||
|
||||
func adjustdefers(gp *g, adjinfo *adjustinfo) {
|
||||
// Adjust defer argument blocks the same way we adjust active stack frames.
|
||||
tracebackdefers(gp, adjustframe, noescape(unsafe.Pointer(adjinfo)))
|
||||
|
||||
// Adjust pointers in the Defer structs.
|
||||
// We need to do this first because we need to adjust the
|
||||
// defer.link fields so we always work on the new stack.
|
||||
adjustpointer(adjinfo, unsafe.Pointer(&gp._defer))
|
||||
// Defer structs themselves are never on the stack.
|
||||
for d := gp._defer; d != nil; d = d.link {
|
||||
adjustpointer(adjinfo, unsafe.Pointer(&d.fn))
|
||||
adjustpointer(adjinfo, unsafe.Pointer(&d.sp))
|
||||
adjustpointer(adjinfo, unsafe.Pointer(&d._panic))
|
||||
adjustpointer(adjinfo, unsafe.Pointer(&d.link))
|
||||
}
|
||||
|
||||
// Adjust defer argument blocks the same way we adjust active stack frames.
|
||||
// Note: this code is after the loop above, so that if a defer record is
|
||||
// stack allocated, we work on the copy in the new stack.
|
||||
tracebackdefers(gp, adjustframe, noescape(unsafe.Pointer(adjinfo)))
|
||||
}
|
||||
|
||||
func adjustpanics(gp *g, adjinfo *adjustinfo) {
|
||||
|
|
|
|||
|
|
@ -799,58 +799,3 @@ func TestDeferLiveness(t *testing.T) {
|
|||
t.Errorf("output:\n%s\n\nwant no output", output)
|
||||
}
|
||||
}
|
||||
|
||||
func TestDeferHeapAndStack(t *testing.T) {
|
||||
P := 4 // processors
|
||||
N := 10000 //iterations
|
||||
D := 200 // stack depth
|
||||
|
||||
if testing.Short() {
|
||||
P /= 2
|
||||
N /= 10
|
||||
D /= 10
|
||||
}
|
||||
c := make(chan bool)
|
||||
for p := 0; p < P; p++ {
|
||||
go func() {
|
||||
for i := 0; i < N; i++ {
|
||||
if deferHeapAndStack(D) != 2*D {
|
||||
panic("bad result")
|
||||
}
|
||||
}
|
||||
c <- true
|
||||
}()
|
||||
}
|
||||
for p := 0; p < P; p++ {
|
||||
<-c
|
||||
}
|
||||
}
|
||||
|
||||
// deferHeapAndStack(n) computes 2*n
|
||||
func deferHeapAndStack(n int) (r int) {
|
||||
if n == 0 {
|
||||
return 0
|
||||
}
|
||||
if n%2 == 0 {
|
||||
// heap-allocated defers
|
||||
for i := 0; i < 2; i++ {
|
||||
defer func() {
|
||||
r++
|
||||
}()
|
||||
}
|
||||
} else {
|
||||
// stack-allocated defers
|
||||
defer func() {
|
||||
r++
|
||||
}()
|
||||
defer func() {
|
||||
r++
|
||||
}()
|
||||
}
|
||||
r = deferHeapAndStack(n - 1)
|
||||
escapeMe(new([1024]byte)) // force some GCs
|
||||
return
|
||||
}
|
||||
|
||||
// Pass a value to escapeMe to force it to escape.
|
||||
var escapeMe = func(x interface{}) {}
|
||||
|
|
|
|||
|
|
@ -248,6 +248,9 @@ func getclosureptr() uintptr
|
|||
//go:noescape
|
||||
func asmcgocall(fn, arg unsafe.Pointer) int32
|
||||
|
||||
// argp used in Defer structs when there is no argp.
|
||||
const _NoArgs = ^uintptr(0)
|
||||
|
||||
func morestack()
|
||||
func morestack_noctxt()
|
||||
func rt0_go()
|
||||
|
|
|
|||
|
|
@ -112,6 +112,7 @@ const _LOAD_LIBRARY_SEARCH_SYSTEM32 = 0x00000800
|
|||
//go:nosplit
|
||||
func syscall_loadsystemlibrary(filename *uint16, absoluteFilepath *uint16) (handle, err uintptr) {
|
||||
lockOSThread()
|
||||
defer unlockOSThread()
|
||||
c := &getg().m.syscall
|
||||
|
||||
if useLoadLibraryEx {
|
||||
|
|
@ -134,7 +135,6 @@ func syscall_loadsystemlibrary(filename *uint16, absoluteFilepath *uint16) (hand
|
|||
if handle == 0 {
|
||||
err = c.err
|
||||
}
|
||||
unlockOSThread() // not defer'd after the lockOSThread above to save stack frame size.
|
||||
return
|
||||
}
|
||||
|
||||
|
|
|
|||
|
|
@ -148,6 +148,11 @@ func gentraceback(pc0, sp0, lr0 uintptr, gp *g, skip int, pcbuf *uintptr, max in
|
|||
waspanic := false
|
||||
cgoCtxt := gp.cgoCtxt
|
||||
printing := pcbuf == nil && callback == nil
|
||||
_defer := gp._defer
|
||||
|
||||
for _defer != nil && _defer.sp == _NoArgs {
|
||||
_defer = _defer.link
|
||||
}
|
||||
|
||||
// If the PC is zero, it's likely a nil function call.
|
||||
// Start in the caller's frame.
|
||||
|
|
@ -314,14 +319,15 @@ func gentraceback(pc0, sp0, lr0 uintptr, gp *g, skip int, pcbuf *uintptr, max in
|
|||
// In the latter case, use a deferreturn call site as the continuation pc.
|
||||
frame.continpc = frame.pc
|
||||
if waspanic {
|
||||
if frame.fn.deferreturn != 0 {
|
||||
// We match up defers with frames using the SP.
|
||||
// However, if the function has an empty stack
|
||||
// frame, then it's possible (on LR machines)
|
||||
// for multiple call frames to have the same
|
||||
// SP. But, since a function with no frame
|
||||
// can't push a defer, the defer can't belong
|
||||
// to that frame.
|
||||
if _defer != nil && _defer.sp == frame.sp && frame.sp != frame.fp {
|
||||
frame.continpc = frame.fn.entry + uintptr(frame.fn.deferreturn) + 1
|
||||
// Note: this may perhaps keep return variables alive longer than
|
||||
// strictly necessary, as we are using "function has a defer statement"
|
||||
// as a proxy for "function actually deferred something". It seems
|
||||
// to be a minor drawback. (We used to actually look through the
|
||||
// gp._defer for a defer corresponding to this function, but that
|
||||
// is hard to do with defer records on the stack during a stack copy.)
|
||||
// Note: the +1 is to offset the -1 that
|
||||
// stack.go:getStackMap does to back up a return
|
||||
// address make sure the pc is in the CALL instruction.
|
||||
|
|
@ -330,6 +336,11 @@ func gentraceback(pc0, sp0, lr0 uintptr, gp *g, skip int, pcbuf *uintptr, max in
|
|||
}
|
||||
}
|
||||
|
||||
// Unwind our local defer stack past this frame.
|
||||
for _defer != nil && ((_defer.sp == frame.sp && frame.sp != frame.fp) || _defer.sp == _NoArgs) {
|
||||
_defer = _defer.link
|
||||
}
|
||||
|
||||
if callback != nil {
|
||||
if !callback((*stkframe)(noescape(unsafe.Pointer(&frame))), v) {
|
||||
return n
|
||||
|
|
@ -499,6 +510,13 @@ func gentraceback(pc0, sp0, lr0 uintptr, gp *g, skip int, pcbuf *uintptr, max in
|
|||
n = nprint
|
||||
}
|
||||
|
||||
// If callback != nil, we're being called to gather stack information during
|
||||
// garbage collection or stack growth. In that context, require that we used
|
||||
// up the entire defer stack. If not, then there is a bug somewhere and the
|
||||
// garbage collection or stack growth may not have seen the correct picture
|
||||
// of the stack. Crash now instead of silently executing the garbage collection
|
||||
// or stack copy incorrectly and setting up for a mysterious crash later.
|
||||
//
|
||||
// Note that panic != nil is okay here: there can be leftover panics,
|
||||
// because the defers on the panic stack do not nest in frame order as
|
||||
// they do on the defer stack. If you have:
|
||||
|
|
@ -539,6 +557,16 @@ func gentraceback(pc0, sp0, lr0 uintptr, gp *g, skip int, pcbuf *uintptr, max in
|
|||
// At other times, such as when gathering a stack for a profiling signal
|
||||
// or when printing a traceback during a crash, everything may not be
|
||||
// stopped nicely, and the stack walk may not be able to complete.
|
||||
// It's okay in those situations not to use up the entire defer stack:
|
||||
// incomplete information then is still better than nothing.
|
||||
if callback != nil && n < max && _defer != nil {
|
||||
print("runtime: g", gp.goid, ": leftover defer sp=", hex(_defer.sp), " pc=", hex(_defer.pc), "\n")
|
||||
for _defer = gp._defer; _defer != nil; _defer = _defer.link {
|
||||
print("\tdefer ", _defer, " sp=", hex(_defer.sp), " pc=", hex(_defer.pc), "\n")
|
||||
}
|
||||
throw("traceback has leftover defers")
|
||||
}
|
||||
|
||||
if callback != nil && n < max && frame.sp != gp.stktopsp {
|
||||
print("runtime: g", gp.goid, ": frame.sp=", hex(frame.sp), " top=", hex(gp.stktopsp), "\n")
|
||||
print("\tstack=[", hex(gp.stack.lo), "-", hex(gp.stack.hi), "] n=", n, " max=", max, "\n")
|
||||
|
|
|
|||
|
|
@ -109,8 +109,3 @@ func MightPanic(a []int, i, j, k, s int) {
|
|||
_ = i << s // panicShift
|
||||
_ = i / j // panicDivide
|
||||
}
|
||||
|
||||
func Defer() {
|
||||
// amd64:`CALL\truntime\.deferprocStack`
|
||||
defer func() {}()
|
||||
}
|
||||
|
|
|
|||
|
|
@ -687,7 +687,7 @@ type R struct{ *T } // ERRORAUTO "live at entry to \(\*R\)\.Foo: \.this ptr" "li
|
|||
// In particular, at printint r must be live.
|
||||
func f41(p, q *int) (r *int) { // ERROR "live at entry to f41: p q$"
|
||||
r = p
|
||||
defer func() { // ERROR "live at call to deferprocStack: q r$" "live at call to deferreturn: r$"
|
||||
defer func() { // ERROR "live at call to deferproc: q r$" "live at call to deferreturn: r$"
|
||||
recover()
|
||||
}()
|
||||
printint(0) // ERROR "live at call to printint: q r$"
|
||||
|
|
|
|||
Loading…
Reference in a new issue