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runtime, cmd/gc, cmd/ld: ignore method wrappers in recover

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Bug #1:

Issue 5406 identified an interesting case:
        defer iface.M()
may end up calling a wrapper that copies an indirect receiver
from the iface value and then calls the real M method. That's
two calls down, not just one, and so recover() == nil always
in the real M method, even during a panic.

[For the purposes of this entire discussion, a wrapper's
implementation is a function containing an ordinary call, not
the optimized tail call form that is somtimes possible. The
tail call does not create a second frame, so it is already
handled correctly.]

Fix this bug by introducing g->panicwrap, which counts the
number of bytes on current stack segment that are due to
wrapper calls that should not count against the recover
check. All wrapper functions must now adjust g->panicwrap up
on entry and back down on exit. This adds slightly to their
expense; on the x86 it is a single instruction at entry and
exit; on the ARM it is three. However, the alternative is to
make a call to recover depend on being able to walk the stack,
which I very much want to avoid. We have enough problems
walking the stack for garbage collection and profiling.
Also, if performance is critical in a specific case, it is already
faster to use a pointer receiver and avoid this kind of wrapper
entirely.

Bug #2:

The old code, which did not consider the possibility of two
calls, already contained a check to see if the call had split
its stack and so the panic-created segment was one behind the
current segment. In the wrapper case, both of the two calls
might split their stacks, so the panic-created segment can be
two behind the current segment.

Fix this by propagating the Stktop.panic flag forward during
stack splits instead of looking backward during recover.

Fixes #5406.

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/13367052
This commit is contained in:
Russ Cox 2013-09-12 14:00:16 -04:00
parent 1ea0c480dc
commit 7276c02b41
19 changed files with 394 additions and 84 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

59
src/cmd/5l/noop.c
View File

@ -271,6 +271,35 @@ noops(void)
p->to.offset = -autosize;
p->to.reg = REGSP;
p->spadj = autosize;
if(cursym->text->reg & WRAPPER) {
// g->panicwrap += autosize;
// MOVW panicwrap_offset(g), R3
// ADD $autosize, R3
// MOVW R3 panicwrap_offset(g)
p = appendp(p);
p->as = AMOVW;
p->from.type = D_OREG;
p->from.reg = REGG;
p->from.offset = 2*PtrSize;
p->to.type = D_REG;
p->to.reg = 3;
p = appendp(p);
p->as = AADD;
p->from.type = D_CONST;
p->from.offset = autosize;
p->to.type = D_REG;
p->to.reg = 3;
p = appendp(p);
p->as = AMOVW;
p->from.type = D_REG;
p->from.reg = 3;
p->to.type = D_OREG;
p->to.reg = REGG;
p->to.offset = 2*PtrSize;
}
break;
case ARET:
@ -290,6 +319,36 @@ noops(void)
break;
}
}
if(cursym->text->reg & WRAPPER) {
// g->panicwrap -= autosize;
// MOVW panicwrap_offset(g), R3
// SUB $autosize, R3
// MOVW R3 panicwrap_offset(g)
p->as = AMOVW;
p->from.type = D_OREG;
p->from.reg = REGG;
p->from.offset = 2*PtrSize;
p->to.type = D_REG;
p->to.reg = 3;
p = appendp(p);
p->as = ASUB;
p->from.type = D_CONST;
p->from.offset = autosize;
p->to.type = D_REG;
p->to.reg = 3;
p = appendp(p);
p->as = AMOVW;
p->from.type = D_REG;
p->from.reg = 3;
p->to.type = D_OREG;
p->to.reg = REGG;
p->to.offset = 2*PtrSize;
p = appendp(p);
}
p->as = AMOVW;
p->scond |= C_PBIT;
p->from.type = D_OREG;

32
src/cmd/6l/pass.c
View File

@ -511,11 +511,12 @@ dostkoff(void)
diag("nosplit func likely to overflow stack");
q = P;
if(!(p->from.scale & NOSPLIT)) {
if(!(p->from.scale & NOSPLIT) || (p->from.scale & WRAPPER)) {
p = appendp(p);
p = load_g_cx(p); // load g into CX
p = stacksplit(p, autoffset, &q); // emit split check
}
if(!(cursym->text->from.scale & NOSPLIT))
p = stacksplit(p, autoffset, &q); // emit split check
if(autoffset) {
p = appendp(p);
@ -523,8 +524,6 @@ dostkoff(void)
p->from.type = D_CONST;
p->from.offset = autoffset;
p->spadj = autoffset;
if(q != P)
q->pcond = p;
} else {
// zero-byte stack adjustment.
// Insert a fake non-zero adjustment so that stkcheck can
@ -536,7 +535,19 @@ dostkoff(void)
p->as = ANOP;
p->spadj = PtrSize;
}
if(q != P)
q->pcond = p;
deltasp = autoffset;
if(cursym->text->from.scale & WRAPPER) {
// g->panicwrap += autoffset + PtrSize;
p = appendp(p);
p->as = AADDL;
p->from.type = D_CONST;
p->from.offset = autoffset + PtrSize;
p->to.type = D_INDIR+D_CX;
p->to.offset = 2*PtrSize;
}
if(debug['K'] > 1 && autoffset) {
// 6l -KK means double-check for stack overflow
@ -654,6 +665,19 @@ dostkoff(void)
if(autoffset != deltasp)
diag("unbalanced PUSH/POP");
if(cursym->text->from.scale & WRAPPER) {
p = load_g_cx(p);
p = appendp(p);
// g->panicwrap -= autoffset + PtrSize;
p->as = ASUBL;
p->from.type = D_CONST;
p->from.offset = autoffset + PtrSize;
p->to.type = D_INDIR+D_CX;
p->to.offset = 2*PtrSize;
p = appendp(p);
p->as = ARET;
}
if(autoffset) {
p->as = AADJSP;

32
src/cmd/8l/pass.c
View File

@ -444,11 +444,12 @@ dostkoff(void)
q = P;
if(!(p->from.scale & NOSPLIT)) {
if(!(p->from.scale & NOSPLIT) || (p->from.scale & WRAPPER)) {
p = appendp(p);
p = load_g_cx(p); // load g into CX
p = stacksplit(p, autoffset, &q); // emit split check
}
if(!(cursym->text->from.scale & NOSPLIT))
p = stacksplit(p, autoffset, &q); // emit split check
if(autoffset) {
p = appendp(p);
@ -456,8 +457,6 @@ dostkoff(void)
p->from.type = D_CONST;
p->from.offset = autoffset;
p->spadj = autoffset;
if(q != P)
q->pcond = p;
} else {
// zero-byte stack adjustment.
// Insert a fake non-zero adjustment so that stkcheck can
@ -469,8 +468,20 @@ dostkoff(void)
p->as = ANOP;
p->spadj = PtrSize;
}
if(q != P)
q->pcond = p;
deltasp = autoffset;
if(cursym->text->from.scale & WRAPPER) {
// g->panicwrap += autoffset + PtrSize;
p = appendp(p);
p->as = AADDL;
p->from.type = D_CONST;
p->from.offset = autoffset + PtrSize;
p->to.type = D_INDIR+D_CX;
p->to.offset = 2*PtrSize;
}
if(debug['Z'] && autoffset && !(cursym->text->from.scale&NOSPLIT)) {
// 8l -Z means zero the stack frame on entry.
// This slows down function calls but can help avoid
@ -540,6 +551,19 @@ dostkoff(void)
if(autoffset != deltasp)
diag("unbalanced PUSH/POP");
if(cursym->text->from.scale & WRAPPER) {
p = load_g_cx(p);
p = appendp(p);
// g->panicwrap -= autoffset + PtrSize;
p->as = ASUBL;
p->from.type = D_CONST;
p->from.offset = autoffset + PtrSize;
p->to.type = D_INDIR+D_CX;
p->to.offset = 2*PtrSize;
p = appendp(p);
p->as = ARET;
}
if(autoffset) {
p->as = AADJSP;

1
src/cmd/gc/go.h
View File

@ -272,6 +272,7 @@ struct Node
uchar implicit;
uchar addrtaken; // address taken, even if not moved to heap
uchar dupok; // duplicate definitions ok (for func)
uchar wrapper; // is method wrapper (for func)
schar likely; // likeliness of if statement
uchar hasbreak; // has break statement
uchar needzero; // if it contains pointers, needs to be zeroed on function entry

13
src/cmd/gc/pgen.c
View File

@ -95,7 +95,18 @@ compile(Node *fn)
nodconst(&nod1, types[TINT32], 0);
ptxt = gins(ATEXT, isblank(curfn->nname) ? N : curfn->nname, &nod1);
if(fn->dupok)
ptxt->TEXTFLAG = DUPOK;
ptxt->TEXTFLAG |= DUPOK;
if(fn->wrapper)
ptxt->TEXTFLAG |= WRAPPER;
// Clumsy but important.
// See test/recover.go for test cases and src/pkg/reflect/value.go
// for the actual functions being considered.
if(myimportpath != nil && strcmp(myimportpath, "reflect") == 0) {
if(strcmp(curfn->nname->sym->name, "callReflect") == 0 || strcmp(curfn->nname->sym->name, "callMethod") == 0)
ptxt->TEXTFLAG |= WRAPPER;
}
afunclit(&ptxt->from, curfn->nname);
ginit();

1
src/cmd/gc/subr.c
View File

@ -2588,6 +2588,7 @@ genwrapper(Type *rcvr, Type *method, Sym *newnam, int iface)
n->left = newname(methodsym(method->sym, methodrcvr, 0));
fn->nbody = list(fn->nbody, n);
} else {
fn->wrapper = 1; // ignore frame for panic+recover matching
call = nod(OCALL, dot, N);
call->list = args;
call->isddd = isddd;

2
src/cmd/ld/textflag.h
View File

@ -17,3 +17,5 @@
#define RODATA 8
// This data contains no pointers.
#define NOPTR 16
// This is a wrapper function and should not count as disabling 'recover'.
#define WRAPPER 32

4
src/pkg/reflect/asm_386.s
View File

@ -8,7 +8,7 @@
// See the comment on the declaration of makeFuncStub in makefunc.go
// for more details.
// No argsize here, gc generates argsize info at call site.
TEXT ·makeFuncStub(SB),NOSPLIT,$8
TEXT ·makeFuncStub(SB),(NOSPLIT|WRAPPER),$8
MOVL DX, 0(SP)
LEAL argframe+0(FP), CX
MOVL CX, 4(SP)
@ -19,7 +19,7 @@ TEXT ·makeFuncStub(SB),NOSPLIT,$8
// See the comment on the declaration of methodValueCall in makefunc.go
// for more details.
// No argsize here, gc generates argsize info at call site.
TEXT ·methodValueCall(SB),NOSPLIT,$8
TEXT ·methodValueCall(SB),(NOSPLIT|WRAPPER),$8
MOVL DX, 0(SP)
LEAL argframe+0(FP), CX
MOVL CX, 4(SP)

4
src/pkg/reflect/asm_amd64.s
View File

@ -8,7 +8,7 @@
// See the comment on the declaration of makeFuncStub in makefunc.go
// for more details.
// No argsize here, gc generates argsize info at call site.
TEXT ·makeFuncStub(SB),NOSPLIT,$16
TEXT ·makeFuncStub(SB),(NOSPLIT|WRAPPER),$16
MOVQ DX, 0(SP)
LEAQ argframe+0(FP), CX
MOVQ CX, 8(SP)
@ -19,7 +19,7 @@ TEXT ·makeFuncStub(SB),NOSPLIT,$16
// See the comment on the declaration of methodValueCall in makefunc.go
// for more details.
// No argsize here, gc generates argsize info at call site.
TEXT ·methodValueCall(SB),NOSPLIT,$16
TEXT ·methodValueCall(SB),(NOSPLIT|WRAPPER),$16
MOVQ DX, 0(SP)
LEAQ argframe+0(FP), CX
MOVQ CX, 8(SP)

4
src/pkg/reflect/asm_arm.s
View File

@ -8,7 +8,7 @@
// See the comment on the declaration of makeFuncStub in makefunc.go
// for more details.
// No argsize here, gc generates argsize info at call site.
TEXT ·makeFuncStub(SB),NOSPLIT,$8
TEXT ·makeFuncStub(SB),(NOSPLIT|WRAPPER),$8
MOVW R7, 4(R13)
MOVW $argframe+0(FP), R1
MOVW R1, 8(R13)
@ -19,7 +19,7 @@ TEXT ·makeFuncStub(SB),NOSPLIT,$8
// See the comment on the declaration of methodValueCall in makefunc.go
// for more details.
// No argsize here, gc generates argsize info at call site.
TEXT ·methodValueCall(SB),NOSPLIT,$8
TEXT ·methodValueCall(SB),(NOSPLIT|WRAPPER),$8
MOVW R7, 4(R13)
MOVW $argframe+0(FP), R1
MOVW R1, 8(R13)

8
src/pkg/reflect/value.go
View File

@ -497,6 +497,10 @@ func (v Value) call(op string, in []Value) []Value {
// frame into a call using Values.
// It is in this file so that it can be next to the call method above.
// The remainder of the MakeFunc implementation is in makefunc.go.
//
// NOTE: This function must be marked as a "wrapper" in the generated code,
// so that the linker can make it work correctly for panic and recover.
// The gc compilers know to do that for the name "reflect.callReflect".
func callReflect(ctxt *makeFuncImpl, frame unsafe.Pointer) {
ftyp := ctxt.typ
f := ctxt.fn
@ -650,6 +654,10 @@ func frameSize(t *rtype, rcvr bool) (total, in, outOffset, out uintptr) {
// to deal with individual Values for each argument.
// It is in this file so that it can be next to the two similar functions above.
// The remainder of the makeMethodValue implementation is in makefunc.go.
//
// NOTE: This function must be marked as a "wrapper" in the generated code,
// so that the linker can make it work correctly for panic and recover.
// The gc compilers know to do that for the name "reflect.callMethod".
func callMethod(ctxt *methodValue, frame unsafe.Pointer) {
t, fn, rcvr := methodReceiver("call", ctxt.rcvr, ctxt.method)
total, in, outOffset, out := frameSize(t, true)

2
src/pkg/runtime/asm_386.s
View File

@ -340,7 +340,7 @@ TEXT reflect·call(SB), NOSPLIT, $0-12
JMP AX
#define CALLFN(NAME,MAXSIZE) \
TEXT runtime·NAME(SB), 0, $MAXSIZE-12; \
TEXT runtime·NAME(SB), WRAPPER, $MAXSIZE-12; \
/* copy arguments to stack */ \
MOVL argptr+4(FP), SI; \
MOVL argsize+8(FP), CX; \

2
src/pkg/runtime/asm_amd64.s
View File

@ -319,7 +319,7 @@ TEXT reflect·call(SB), NOSPLIT, $0-20
JMP AX
#define CALLFN(NAME,MAXSIZE) \
TEXT runtime·NAME(SB), 0, $MAXSIZE-20; \
TEXT runtime·NAME(SB), WRAPPER, $MAXSIZE-20; \
/* copy arguments to stack */ \
MOVQ argptr+8(FP), SI; \
MOVLQZX argsize+16(FP), CX; \

2
src/pkg/runtime/asm_arm.s
View File

@ -300,7 +300,7 @@ TEXT reflect·call(SB), NOSPLIT, $-4-12
B (R1)
#define CALLFN(NAME,MAXSIZE) \
TEXT runtime·NAME(SB), 0, $MAXSIZE-12; \
TEXT runtime·NAME(SB), WRAPPER, $MAXSIZE-12; \
/* copy arguments to stack */ \
MOVW argptr+4(FP), R0; \
MOVW argsize+8(FP), R2; \

78
src/pkg/runtime/panic.c
View File

@ -339,69 +339,27 @@ runtime·unwindstack(G *gp, byte *sp)
void
runtime·recover(byte *argp, Eface ret)
{
Stktop *top, *oldtop;
Panic *p;
Stktop *top;
// Must be a panic going on.
if((p = g->panic) == nil || p->recovered)
goto nomatch;
// Frame must be at the top of the stack segment,
// because each deferred call starts a new stack
// segment as a side effect of using reflect.call.
// (There has to be some way to remember the
// variable argument frame size, and the segment
// code already takes care of that for us, so we
// reuse it.)
//
// As usual closures complicate things: the fp that
// the closure implementation function claims to have
// is where the explicit arguments start, after the
// implicit pointer arguments and PC slot.
// If we're on the first new segment for a closure,
// then fp == top - top->args is correct, but if
// the closure has its own big argument frame and
// allocated a second segment (see below),
// the fp is slightly above top - top->args.
// That condition can't happen normally though
// (stack pointers go down, not up), so we can accept
// any fp between top and top - top->args as
// indicating the top of the segment.
// Must be an unrecovered panic in progress.
// Must be on a stack segment created for a deferred call during a panic.
// Must be at the top of that segment, meaning the deferred call itself
// and not something it called. The top frame in the segment will have
// argument pointer argp == top - top->argsize.
// The subtraction of g->panicwrap allows wrapper functions that
// do not count as official calls to adjust what we consider the top frame
// while they are active on the stack. The linker emits adjustments of
// g->panicwrap in the prologue and epilogue of functions marked as wrappers.
top = (Stktop*)g->stackbase;
if(argp < (byte*)top - top->argsize || (byte*)top < argp)
goto nomatch;
// The deferred call makes a new segment big enough
// for the argument frame but not necessarily big
// enough for the function's local frame (size unknown
// at the time of the call), so the function might have
// made its own segment immediately. If that's the
// case, back top up to the older one, the one that
// reflect.call would have made for the panic.
//
// The fp comparison here checks that the argument
// frame that was copied during the split (the top->args
// bytes above top->fp) abuts the old top of stack.
// This is a correct test for both closure and non-closure code.
oldtop = (Stktop*)top->stackbase;
if(oldtop != nil && top->argp == (byte*)oldtop - top->argsize)
top = oldtop;
// Now we have the segment that was created to
// run this call. It must have been marked as a panic segment.
if(!top->panic)
goto nomatch;
// Okay, this is the top frame of a deferred call
// in response to a panic. It can see the panic argument.
p->recovered = 1;
ret = p->arg;
FLUSH(&ret);
return;
nomatch:
ret.type = nil;
ret.data = nil;
p = g->panic;
if(p != nil && !p->recovered && top->panic && argp == (byte*)top - top->argsize - g->panicwrap) {
p->recovered = 1;
ret = p->arg;
} else {
ret.type = nil;
ret.data = nil;
}
FLUSH(&ret);
}

1
src/pkg/runtime/proc.c
View File

@ -1773,6 +1773,7 @@ runtime·newproc1(FuncVal *fn, byte *argp, int32 narg, int32 nret, void *callerp
newg->gopc = (uintptr)callerpc;
newg->status = Grunnable;
newg->goid = runtime·xadd64(&runtime·sched.goidgen, 1);
newg->panicwrap = 0;
if(raceenabled)
newg->racectx = runtime·racegostart((void*)callerpc);
runqput(m->p, newg);

4
src/pkg/runtime/runtime.h
View File

@ -250,6 +250,8 @@ struct G
// stackguard0 can be set to StackPreempt as opposed to stackguard
uintptr stackguard0; // cannot move - also known to linker, libmach, runtime/cgo
uintptr stackbase; // cannot move - also known to libmach, runtime/cgo
uint32 panicwrap; // cannot move - also known to linker
uint32 selgen; // valid sudog pointer
Defer* defer;
Panic* panic;
Gobuf sched;
@ -264,7 +266,6 @@ struct G
void* param; // passed parameter on wakeup
int16 status;
int64 goid;
uint32 selgen; // valid sudog pointer
int8* waitreason; // if status==Gwaiting
G* schedlink;
bool ispanic;
@ -403,6 +404,7 @@ struct Stktop
uintptr stackbase;
Gobuf gobuf;
uint32 argsize;
uint32 panicwrap;
uint8* argp; // pointer to arguments in old frame
uintptr free; // if free>0, call stackfree using free as size

13
src/pkg/runtime/stack.c
View File

@ -174,6 +174,7 @@ runtime·oldstack(void)
gp->stackbase = top->stackbase;
gp->stackguard = top->stackguard;
gp->stackguard0 = gp->stackguard;
gp->panicwrap = top->panicwrap;
if(top->free != 0) {
gp->stacksize -= top->free;
@ -195,7 +196,7 @@ void
runtime·newstack(void)
{
int32 framesize, argsize, oldstatus;
Stktop *top;
Stktop *top, *oldtop;
byte *stk;
uintptr sp;
uintptr *src, *dst, *dstend;
@ -316,6 +317,16 @@ runtime·newstack(void)
// copy flag from panic
top->panic = gp->ispanic;
gp->ispanic = false;
// if this isn't a panic, maybe we're splitting the stack for a panic.
// if we're splitting in the top frame, propagate the panic flag
// forward so that recover will know we're in a panic.
oldtop = (Stktop*)top->stackbase;
if(oldtop != nil && oldtop->panic && top->argp == (byte*)oldtop - oldtop->argsize - gp->panicwrap)
top->panic = true;
top->panicwrap = gp->panicwrap;
gp->panicwrap = 0;
gp->stackbase = (uintptr)top;
gp->stackguard = (uintptr)stk + StackGuard;

216
test/recover.go
View File

@ -10,6 +10,7 @@ package main
import (
"os"
"reflect"
"runtime"
)
@ -26,15 +27,39 @@ func main() {
test6()
test6WithClosures()
test7()
test8()
test9()
test9reflect1()
test9reflect2()
test10()
test10reflect1()
test10reflect2()
test11()
test11reflect1()
test11reflect2()
test12()
test12reflect1()
test12reflect2()
test13()
test13reflect1()
test13reflect2()
test14()
test14reflect1()
test14reflect2()
test15()
}
func die() {
runtime.Breakpoint() // can't depend on panic
}
func mustRecover(x interface{}) {
mustNotRecover() // because it's not a defer call
v := recover()
func mustRecoverBody(v1, v2, v3, x interface{}) {
v := v1
if v != nil {
println("spurious recover", v)
die()
}
v = v2
if v == nil {
println("missing recover")
die() // panic is useless here
@ -45,13 +70,21 @@ func mustRecover(x interface{}) {
}
// the value should be gone now regardless
v = recover()
v = v3
if v != nil {
println("recover didn't recover")
die()
}
}
func doubleRecover() interface{} {
return recover()
}
func mustRecover(x interface{}) {
mustRecoverBody(doubleRecover(), recover(), recover(), x)
}
func mustNotRecover() {
v := recover()
if v != nil {
@ -277,3 +310,178 @@ func test8() {
die()
}
}
type I interface{ M() }
// pointer receiver, so no wrapper in i.M()
type T1 struct {}
func (*T1) M() {
mustRecoverBody(doubleRecover(), recover(), recover(), 9)
}
func test9() {
var i I = &T1{}
defer i.M()
panic(9)
}
func test9reflect1() {
f := reflect.ValueOf(&T1{}).Method(0).Interface().(func())
defer f()
panic(9)
}
func test9reflect2() {
f := reflect.TypeOf(&T1{}).Method(0).Func.Interface().(func(*T1))
defer f(&T1{})
panic(9)
}
// word-sized value receiver, so no wrapper in i.M()
type T2 uintptr
func (T2) M() {
mustRecoverBody(doubleRecover(), recover(), recover(), 10)
}
func test10() {
var i I = T2(0)
defer i.M()
panic(10)
}
func test10reflect1() {
f := reflect.ValueOf(T2(0)).Method(0).Interface().(func())
defer f()
panic(10)
}
func test10reflect2() {
f := reflect.TypeOf(T2(0)).Method(0).Func.Interface().(func(T2))
defer f(T2(0))
panic(10)
}
// tiny receiver, so basic wrapper in i.M()
type T3 struct {}
func (T3) M() {
mustRecoverBody(doubleRecover(), recover(), recover(), 11)
}
func test11() {
var i I = T3{}
defer i.M()
panic(11)
}
func test11reflect1() {
f := reflect.ValueOf(T3{}).Method(0).Interface().(func())
defer f()
panic(11)
}
func test11reflect2() {
f := reflect.TypeOf(T3{}).Method(0).Func.Interface().(func(T3))
defer f(T3{})
panic(11)
}
// large receiver, so basic wrapper in i.M()
type T4 [2]string
func (T4) M() {
mustRecoverBody(doubleRecover(), recover(), recover(), 12)
}
func test12() {
var i I = T4{}
defer i.M()
panic(12)
}
func test12reflect1() {
f := reflect.ValueOf(T4{}).Method(0).Interface().(func())
defer f()
panic(12)
}
func test12reflect2() {
f := reflect.TypeOf(T4{}).Method(0).Func.Interface().(func(T4))
defer f(T4{})
panic(12)
}
// enormous receiver, so wrapper splits stack to call M
type T5 [8192]byte
func (T5) M() {
mustRecoverBody(doubleRecover(), recover(), recover(), 13)
}
func test13() {
var i I = T5{}
defer i.M()
panic(13)
}
func test13reflect1() {
f := reflect.ValueOf(T5{}).Method(0).Interface().(func())
defer f()
panic(13)
}
func test13reflect2() {
f := reflect.TypeOf(T5{}).Method(0).Func.Interface().(func(T5))
defer f(T5{})
panic(13)
}
// enormous receiver + enormous method frame, so wrapper splits stack to call M,
// and then M splits stack to allocate its frame.
// recover must look back two frames to find the panic.
type T6 [8192]byte
var global byte
func (T6) M() {
var x [8192]byte
x[0] = 1
x[1] = 2
for i := range x {
global += x[i]
}
mustRecoverBody(doubleRecover(), recover(), recover(), 14)
}
func test14() {
var i I = T6{}
defer i.M()
panic(14)
}
func test14reflect1() {
f := reflect.ValueOf(T6{}).Method(0).Interface().(func())
defer f()
panic(14)
}
func test14reflect2() {
f := reflect.TypeOf(T6{}).Method(0).Func.Interface().(func(T6))
defer f(T6{})
panic(14)
}
// function created by reflect.MakeFunc
func reflectFunc(args []reflect.Value) (results []reflect.Value) {
mustRecoverBody(doubleRecover(), recover(), recover(), 15)
return nil
}
func test15() {
f := reflect.MakeFunc(reflect.TypeOf((func())(nil)), reflectFunc).Interface().(func())
defer f()
panic(15)
}