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Revert "Revert "cmd/compile,runtime: allocate defer records on the stack""

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This reverts CL 180761

Reason for revert: Reinstate the stack-allocated defer CL.

There was nothing wrong with the CL proper, but stack allocation of defers exposed two other issues.

Issue #32477: Fix has been submitted as CL 181258.
Issue #32498: Possible fix is CL 181377 (not submitted yet).

Change-Id: I32b3365d5026600069291b068bbba6cb15295eb3
Reviewed-on: https://go-review.googlesource.com/c/go/+/181378
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This commit is contained in:
Keith Randall 2019-06-08 17:20:57 +00:00
parent daf944a531
commit 8f296f59de
15 changed files with 328 additions and 108 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
src/cmd/compile/internal/gc/esc.go
View File

@ -802,6 +802,7 @@ opSwitch:
case ODEFER:
if e.loopdepth == 1 { // top level
n.Esc = EscNever // force stack allocation of defer record (see ssa.go)
break
}
// arguments leak out of scope

1
src/cmd/compile/internal/gc/escape.go
View File

@ -882,6 +882,7 @@ func (e *Escape) augmentParamHole(k EscHole, where *Node) EscHole {
// non-transient location to avoid arguments from being
// transiently allocated.
if where.Op == ODEFER && e.loopDepth == 1 {
where.Esc = EscNever // force stack allocation of defer record (see ssa.go)
// TODO(mdempsky): Eliminate redundant EscLocation allocs.
return e.teeHole(k, e.newLoc(nil, false).asHole())
}

1
src/cmd/compile/internal/gc/go.go
View File

@ -291,6 +291,7 @@ var (
assertI2I,
assertI2I2,
deferproc,
deferprocStack,
Deferreturn,
Duffcopy,
Duffzero,

42
src/cmd/compile/internal/gc/reflect.go
View File

@ -317,6 +317,48 @@ func hiter(t *types.Type) *types.Type {
return hiter
}
// deferstruct makes a runtime._defer structure, with additional space for
// stksize bytes of args.
func deferstruct(stksize int64) *types.Type {
makefield := func(name string, typ *types.Type) *types.Field {
f := types.NewField()
f.Type = typ
// Unlike the global makefield function, this one needs to set Pkg
// because these types might be compared (in SSA CSE sorting).
// TODO: unify this makefield and the global one above.
f.Sym = &types.Sym{Name: name, Pkg: localpkg}
return f
}
argtype := types.NewArray(types.Types[TUINT8], stksize)
argtype.SetNoalg(true)
argtype.Width = stksize
argtype.Align = 1
// These fields must match the ones in runtime/runtime2.go:_defer and
// cmd/compile/internal/gc/ssa.go:(*state).call.
fields := []*types.Field{
makefield("siz", types.Types[TUINT32]),
makefield("started", types.Types[TBOOL]),
makefield("heap", types.Types[TBOOL]),
makefield("sp", types.Types[TUINTPTR]),
makefield("pc", types.Types[TUINTPTR]),
// Note: the types here don't really matter. Defer structures
// are always scanned explicitly during stack copying and GC,
// so we make them uintptr type even though they are real pointers.
makefield("fn", types.Types[TUINTPTR]),
makefield("_panic", types.Types[TUINTPTR]),
makefield("link", types.Types[TUINTPTR]),
makefield("args", argtype),
}
// build struct holding the above fields
s := types.New(TSTRUCT)
s.SetNoalg(true)
s.SetFields(fields)
s.Width = widstruct(s, s, 0, 1)
s.Align = uint8(Widthptr)
return s
}
// f is method type, with receiver.
// return function type, receiver as first argument (or not).
func methodfunc(f *types.Type, receiver *types.Type) *types.Type {

196
src/cmd/compile/internal/gc/ssa.go
View File

@ -68,6 +68,7 @@ func initssaconfig() {
assertI2I = sysfunc("assertI2I")
assertI2I2 = sysfunc("assertI2I2")
deferproc = sysfunc("deferproc")
deferprocStack = sysfunc("deferprocStack")
Deferreturn = sysfunc("deferreturn")
Duffcopy = sysvar("duffcopy") // asm func with special ABI
Duffzero = sysvar("duffzero") // asm func with special ABI
@ -864,7 +865,11 @@ func (s *state) stmt(n *Node) {
}
}
case ODEFER:
s.call(n.Left, callDefer)
d := callDefer
if n.Esc == EscNever {
d = callDeferStack
}
s.call(n.Left, d)
case OGO:
s.call(n.Left, callGo)
@ -2859,6 +2864,7 @@ type callKind int8
const (
callNormal callKind = iota
callDefer
callDeferStack
callGo
)
@ -3799,74 +3805,132 @@ func (s *state) call(n *Node, k callKind) *ssa.Value {
rcvr = s.newValue1(ssa.OpIData, types.Types[TUINTPTR], i)
}
dowidth(fn.Type)
stksize := fn.Type.ArgWidth() // includes receiver
stksize := fn.Type.ArgWidth() // includes receiver, args, and results
// Run all assignments of temps.
// The temps are introduced to avoid overwriting argument
// slots when arguments themselves require function calls.
s.stmtList(n.List)
// Store arguments to stack, including defer/go arguments and receiver for method calls.
// These are written in SP-offset order.
argStart := Ctxt.FixedFrameSize()
// Defer/go args.
if k != callNormal {
// Write argsize and closure (args to newproc/deferproc).
argsize := s.constInt32(types.Types[TUINT32], int32(stksize))
addr := s.constOffPtrSP(s.f.Config.Types.UInt32Ptr, argStart)
s.store(types.Types[TUINT32], addr, argsize)
addr = s.constOffPtrSP(s.f.Config.Types.UintptrPtr, argStart+int64(Widthptr))
s.store(types.Types[TUINTPTR], addr, closure)
stksize += 2 * int64(Widthptr)
argStart += 2 * int64(Widthptr)
}
// Set receiver (for interface calls).
if rcvr != nil {
addr := s.constOffPtrSP(s.f.Config.Types.UintptrPtr, argStart)
s.store(types.Types[TUINTPTR], addr, rcvr)
}
// Write args.
t := n.Left.Type
args := n.Rlist.Slice()
if n.Op == OCALLMETH {
f := t.Recv()
s.storeArg(args[0], f.Type, argStart+f.Offset)
args = args[1:]
}
for i, n := range args {
f := t.Params().Field(i)
s.storeArg(n, f.Type, argStart+f.Offset)
}
// call target
var call *ssa.Value
switch {
case k == callDefer:
call = s.newValue1A(ssa.OpStaticCall, types.TypeMem, deferproc, s.mem())
case k == callGo:
call = s.newValue1A(ssa.OpStaticCall, types.TypeMem, newproc, s.mem())
case closure != nil:
// rawLoad because loading the code pointer from a
// closure is always safe, but IsSanitizerSafeAddr
// can't always figure that out currently, and it's
// critical that we not clobber any arguments already
// stored onto the stack.
codeptr = s.rawLoad(types.Types[TUINTPTR], closure)
call = s.newValue3(ssa.OpClosureCall, types.TypeMem, codeptr, closure, s.mem())
case codeptr != nil:
call = s.newValue2(ssa.OpInterCall, types.TypeMem, codeptr, s.mem())
case sym != nil:
call = s.newValue1A(ssa.OpStaticCall, types.TypeMem, sym.Linksym(), s.mem())
default:
Fatalf("bad call type %v %v", n.Op, n)
if k == callDeferStack {
// Make a defer struct d on the stack.
t := deferstruct(stksize)
d := tempAt(n.Pos, s.curfn, t)
s.vars[&memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, d, s.mem())
addr := s.addr(d, false)
// Must match reflect.go:deferstruct and src/runtime/runtime2.go:_defer.
// 0: siz
s.store(types.Types[TUINT32],
s.newValue1I(ssa.OpOffPtr, types.Types[TUINT32].PtrTo(), t.FieldOff(0), addr),
s.constInt32(types.Types[TUINT32], int32(stksize)))
// 1: started, set in deferprocStack
// 2: heap, set in deferprocStack
// 3: sp, set in deferprocStack
// 4: pc, set in deferprocStack
// 5: fn
s.store(closure.Type,
s.newValue1I(ssa.OpOffPtr, closure.Type.PtrTo(), t.FieldOff(5), addr),
closure)
// 6: panic, set in deferprocStack
// 7: link, set in deferprocStack
// Then, store all the arguments of the defer call.
ft := fn.Type
off := t.FieldOff(8)
args := n.Rlist.Slice()
// Set receiver (for interface calls). Always a pointer.
if rcvr != nil {
p := s.newValue1I(ssa.OpOffPtr, ft.Recv().Type.PtrTo(), off, addr)
s.store(types.Types[TUINTPTR], p, rcvr)
}
// Set receiver (for method calls).
if n.Op == OCALLMETH {
f := ft.Recv()
s.storeArgWithBase(args[0], f.Type, addr, off+f.Offset)
args = args[1:]
}
// Set other args.
for _, f := range ft.Params().Fields().Slice() {
s.storeArgWithBase(args[0], f.Type, addr, off+f.Offset)
args = args[1:]
}
// Call runtime.deferprocStack with pointer to _defer record.
arg0 := s.constOffPtrSP(types.Types[TUINTPTR], Ctxt.FixedFrameSize())
s.store(types.Types[TUINTPTR], arg0, addr)
call = s.newValue1A(ssa.OpStaticCall, types.TypeMem, deferprocStack, s.mem())
if stksize < int64(Widthptr) {
// We need room for both the call to deferprocStack and the call to
// the deferred function.
stksize = int64(Widthptr)
}
call.AuxInt = stksize
} else {
// Store arguments to stack, including defer/go arguments and receiver for method calls.
// These are written in SP-offset order.
argStart := Ctxt.FixedFrameSize()
// Defer/go args.
if k != callNormal {
// Write argsize and closure (args to newproc/deferproc).
argsize := s.constInt32(types.Types[TUINT32], int32(stksize))
addr := s.constOffPtrSP(s.f.Config.Types.UInt32Ptr, argStart)
s.store(types.Types[TUINT32], addr, argsize)
addr = s.constOffPtrSP(s.f.Config.Types.UintptrPtr, argStart+int64(Widthptr))
s.store(types.Types[TUINTPTR], addr, closure)
stksize += 2 * int64(Widthptr)
argStart += 2 * int64(Widthptr)
}
// Set receiver (for interface calls).
if rcvr != nil {
addr := s.constOffPtrSP(s.f.Config.Types.UintptrPtr, argStart)
s.store(types.Types[TUINTPTR], addr, rcvr)
}
// Write args.
t := n.Left.Type
args := n.Rlist.Slice()
if n.Op == OCALLMETH {
f := t.Recv()
s.storeArg(args[0], f.Type, argStart+f.Offset)
args = args[1:]
}
for i, n := range args {
f := t.Params().Field(i)
s.storeArg(n, f.Type, argStart+f.Offset)
}
// call target
switch {
case k == callDefer:
call = s.newValue1A(ssa.OpStaticCall, types.TypeMem, deferproc, s.mem())
case k == callGo:
call = s.newValue1A(ssa.OpStaticCall, types.TypeMem, newproc, s.mem())
case closure != nil:
// rawLoad because loading the code pointer from a
// closure is always safe, but IsSanitizerSafeAddr
// can't always figure that out currently, and it's
// critical that we not clobber any arguments already
// stored onto the stack.
codeptr = s.rawLoad(types.Types[TUINTPTR], closure)
call = s.newValue3(ssa.OpClosureCall, types.TypeMem, codeptr, closure, s.mem())
case codeptr != nil:
call = s.newValue2(ssa.OpInterCall, types.TypeMem, codeptr, s.mem())
case sym != nil:
call = s.newValue1A(ssa.OpStaticCall, types.TypeMem, sym.Linksym(), s.mem())
default:
Fatalf("bad call type %v %v", n.Op, n)
}
call.AuxInt = stksize // Call operations carry the argsize of the callee along with them
}
call.AuxInt = stksize // Call operations carry the argsize of the callee along with them
s.vars[&memVar] = call
// Finish block for defers
if k == callDefer {
if k == callDefer || k == callDeferStack {
b := s.endBlock()
b.Kind = ssa.BlockDefer
b.SetControl(call)
@ -4361,17 +4425,27 @@ func (s *state) storeTypePtrs(t *types.Type, left, right *ssa.Value) {
}
func (s *state) storeArg(n *Node, t *types.Type, off int64) {
s.storeArgWithBase(n, t, s.sp, off)
}
func (s *state) storeArgWithBase(n *Node, t *types.Type, base *ssa.Value, off int64) {
pt := types.NewPtr(t)
sp := s.constOffPtrSP(pt, off)
var addr *ssa.Value
if base == s.sp {
// Use special routine that avoids allocation on duplicate offsets.
addr = s.constOffPtrSP(pt, off)
} else {
addr = s.newValue1I(ssa.OpOffPtr, pt, off, base)
}
if !canSSAType(t) {
a := s.addr(n, false)
s.move(t, sp, a)
s.move(t, addr, a)
return
}
a := s.expr(n)
s.storeType(t, sp, a, 0, false)
s.storeType(t, addr, a, 0, false)
}
// slice computes the slice v[i:j:k] and returns ptr, len, and cap of result.

20
src/runtime/mgcmark.go
View File

@ -712,15 +712,31 @@ func scanstack(gp *g, gcw *gcWork) {
// Find additional pointers that point into the stack from the heap.
// Currently this includes defers and panics. See also function copystack.
// Find and trace all defer arguments.
tracebackdefers(gp, scanframe, nil)
// Find and trace other pointers in defer records.
for d := gp._defer; d != nil; d = d.link {
// tracebackdefers above does not scan the func value, which could
// be a stack allocated closure. See issue 30453.
if d.fn != nil {
// tracebackdefers above does not scan the func value, which could
// be a stack allocated closure. See issue 30453.
scanblock(uintptr(unsafe.Pointer(&d.fn)), sys.PtrSize, &oneptrmask[0], gcw, &state)
}
if d.link != nil {
// The link field of a stack-allocated defer record might point
// to a heap-allocated defer record. Keep that heap record live.
scanblock(uintptr(unsafe.Pointer(&d.link)), sys.PtrSize, &oneptrmask[0], gcw, &state)
}
// Retain defers records themselves.
// Defer records might not be reachable from the G through regular heap
// tracing because the defer linked list might weave between the stack and the heap.
if d.heap {
scanblock(uintptr(unsafe.Pointer(&d)), sys.PtrSize, &oneptrmask[0], gcw, &state)
}
}
if gp._panic != nil {
// Panics are always stack allocated.
state.putPtr(uintptr(unsafe.Pointer(gp._panic)))
}

44
src/runtime/panic.go
View File

@ -228,6 +228,46 @@ 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.
// The defer record must have its siz and fn fields initialized.
// 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
func deferprocStack(d *_defer) {
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:
// d.panic = nil
// 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.
@ -349,6 +389,7 @@ func newdefer(siz int32) *_defer {
}
}
d.siz = siz
d.heap = true
d.link = gp._defer
gp._defer = d
return d
@ -368,6 +409,9 @@ 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

9
src/runtime/runtime2.go
View File

@ -775,9 +775,16 @@ 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
siz int32 // includes both arguments and results
started bool
heap bool
sp uintptr // sp at time of defer
pc uintptr
fn *funcval

13
src/runtime/stack.go
View File

@ -719,16 +719,21 @@ 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.
// Defer structs themselves are never on the stack.
// 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))
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) {

55
src/runtime/stack_test.go
View File

@ -799,3 +799,58 @@ 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{}) {}

3
src/runtime/stubs.go
View File

@ -248,9 +248,6 @@ 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()

2
src/runtime/syscall_windows.go
View File

@ -112,7 +112,6 @@ 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 {
@ -135,6 +134,7 @@ 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
}

42
src/runtime/traceback.go
View File

@ -148,11 +148,6 @@ 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.
@ -319,15 +314,14 @@ 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 {
// 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 {
if frame.fn.deferreturn != 0 {
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.
@ -336,11 +330,6 @@ 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
@ -510,13 +499,6 @@ 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:
@ -557,16 +539,6 @@ 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")

5
test/codegen/stack.go
View File

@ -109,3 +109,8 @@ func MightPanic(a []int, i, j, k, s int) {
_ = i << s // panicShift
_ = i / j // panicDivide
}
func Defer() {
// amd64:`CALL\truntime\.deferprocStack`
defer func() {}()
}

2
test/live.go
View File

@ -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$"
r = p
defer func() { // ERROR "live at call to deferproc: q r$" "live at call to deferreturn: r$"
defer func() { // ERROR "live at call to deferprocStack: q r$" "live at call to deferreturn: r$"
recover()
}()
printint(0) // ERROR "live at call to printint: q r$"