Language specification says that variables are captured by reference.
And that is what gc compiler does. However, in lots of cases it is
possible to capture variables by value under the hood without
affecting visible behavior of programs. For example, consider
the following typical pattern:
func (o *Obj) requestMany(urls []string) []Result {
wg := new(sync.WaitGroup)
wg.Add(len(urls))
res := make([]Result, len(urls))
for i := range urls {
i := i
go func() {
res[i] = o.requestOne(urls[i])
wg.Done()
}()
}
wg.Wait()
return res
}
Currently o, wg, res, and i are captured by reference causing 3+len(urls)
allocations (e.g. PPARAM o is promoted to PPARAMREF and moved to heap).
But all of them can be captured by value without changing behavior.
This change implements simple strategy for capturing by value:
if a captured variable is not addrtaken and never assigned to,
then it is captured by value (it is effectively const).
This simple strategy turned out to be very effective:
~80% of all captures in std lib are turned into value captures.
The remaining 20% are mostly in defers and non-escaping closures,
that is, they do not cause allocations anyway.
benchmark old allocs new allocs delta
BenchmarkCompressedZipGarbage 153 126 -17.65%
BenchmarkEncodeDigitsSpeed1e4 91 69 -24.18%
BenchmarkEncodeDigitsSpeed1e5 178 129 -27.53%
BenchmarkEncodeDigitsSpeed1e6 1510 1051 -30.40%
BenchmarkEncodeDigitsDefault1e4 100 75 -25.00%
BenchmarkEncodeDigitsDefault1e5 193 139 -27.98%
BenchmarkEncodeDigitsDefault1e6 1420 985 -30.63%
BenchmarkEncodeDigitsCompress1e4 100 75 -25.00%
BenchmarkEncodeDigitsCompress1e5 193 139 -27.98%
BenchmarkEncodeDigitsCompress1e6 1420 985 -30.63%
BenchmarkEncodeTwainSpeed1e4 109 81 -25.69%
BenchmarkEncodeTwainSpeed1e5 211 151 -28.44%
BenchmarkEncodeTwainSpeed1e6 1588 1097 -30.92%
BenchmarkEncodeTwainDefault1e4 103 77 -25.24%
BenchmarkEncodeTwainDefault1e5 199 143 -28.14%
BenchmarkEncodeTwainDefault1e6 1324 917 -30.74%
BenchmarkEncodeTwainCompress1e4 103 77 -25.24%
BenchmarkEncodeTwainCompress1e5 190 137 -27.89%
BenchmarkEncodeTwainCompress1e6 1327 919 -30.75%
BenchmarkConcurrentDBExec 16223 16220 -0.02%
BenchmarkConcurrentStmtQuery 17687 16182 -8.51%
BenchmarkConcurrentStmtExec 5191 5186 -0.10%
BenchmarkConcurrentTxQuery 17665 17661 -0.02%
BenchmarkConcurrentTxExec 15154 15150 -0.03%
BenchmarkConcurrentTxStmtQuery 17661 16157 -8.52%
BenchmarkConcurrentTxStmtExec 3677 3673 -0.11%
BenchmarkConcurrentRandom 14000 13614 -2.76%
BenchmarkManyConcurrentQueries 25 22 -12.00%
BenchmarkDecodeComplex128Slice 318 252 -20.75%
BenchmarkDecodeFloat64Slice 318 252 -20.75%
BenchmarkDecodeInt32Slice 318 252 -20.75%
BenchmarkDecodeStringSlice 2318 2252 -2.85%
BenchmarkDecode 11 8 -27.27%
BenchmarkEncodeGray 64 56 -12.50%
BenchmarkEncodeNRGBOpaque 64 56 -12.50%
BenchmarkEncodeNRGBA 67 58 -13.43%
BenchmarkEncodePaletted 68 60 -11.76%
BenchmarkEncodeRGBOpaque 64 56 -12.50%
BenchmarkGoLookupIP 153 139 -9.15%
BenchmarkGoLookupIPNoSuchHost 508 466 -8.27%
BenchmarkGoLookupIPWithBrokenNameServer 245 226 -7.76%
BenchmarkClientServer 62 59 -4.84%
BenchmarkClientServerParallel4 62 59 -4.84%
BenchmarkClientServerParallel64 62 59 -4.84%
BenchmarkClientServerParallelTLS4 79 76 -3.80%
BenchmarkClientServerParallelTLS64 112 109 -2.68%
BenchmarkCreateGoroutinesCapture 10 6 -40.00%
BenchmarkAfterFunc 1006 1005 -0.10%
Fixes #6632.
Change-Id: I0cd51e4d356331d7f3c5f447669080cd19b0d2ca
Reviewed-on: https://go-review.googlesource.com/3166
Reviewed-by: Russ Cox <rsc@golang.org>
for(l=func->cvars; l; l=l->next) {
v = l->n;
v->closure->closure = v->outer;
- v->heapaddr = nod(OADDR, oldname(v->sym), N);
+ v->outerexpr = oldname(v->sym);
}
return func;
void
typecheckclosure(Node *func, int top)
{
- Node *oldfn;
+ Node *oldfn, *n;
NodeList *l;
- Node *v;
+ int olddd;
+
+ for(l=func->cvars; l; l=l->next) {
+ n = l->n->closure;
+ if(!n->captured) {
+ n->captured = 1;
+ if(n->decldepth == 0)
+ fatal("typecheckclosure: var %hN does not have decldepth assigned", n);
+ // Ignore assignments to the variable in straightline code
+ // preceding the first capturing by a closure.
+ if(n->decldepth == decldepth)
+ n->assigned = 0;
+ }
+ }
+
+ for(l=func->dcl; l; l=l->next)
+ if(l->n->op == ONAME && (l->n->class == PPARAM || l->n->class == PPARAMOUT))
+ l->n->decldepth = 1;
oldfn = curfn;
typecheck(&func->ntype, Etype);
func->type = func->ntype->type;
-
+
// Type check the body now, but only if we're inside a function.
// At top level (in a variable initialization: curfn==nil) we're not
// ready to type check code yet; we'll check it later, because the
// underlying closure function we create is added to xtop.
if(curfn && func->type != T) {
curfn = func;
+ olddd = decldepth;
+ decldepth = 1;
typechecklist(func->nbody, Etop);
+ decldepth = olddd;
curfn = oldfn;
}
- // type check the & of closed variables outside the closure,
- // so that the outer frame also grabs them and knows they
- // escape.
- func->enter = nil;
- for(l=func->cvars; l; l=l->next) {
- v = l->n;
- if(v->type == T) {
- // if v->type is nil, it means v looked like it was
- // going to be used in the closure but wasn't.
- // this happens because when parsing a, b, c := f()
- // the a, b, c gets parsed as references to older
- // a, b, c before the parser figures out this is a
- // declaration.
- v->op = 0;
- continue;
- }
- // For a closure that is called in place, but not
- // inside a go statement, avoid moving variables to the heap.
- if ((top & (Ecall|Eproc)) == Ecall)
- v->heapaddr->etype = 1;
- typecheck(&v->heapaddr, Erv);
- func->enter = list(func->enter, v->heapaddr);
- v->heapaddr = N;
- }
+ // Remember closure context for capturevars.
+ func->etype = (top & (Ecall|Eproc)) == Ecall;
// Create top-level function
xtop = list(xtop, makeclosure(func));
static Node*
makeclosure(Node *func)
{
- Node *xtype, *v, *addr, *xfunc, *cv;
- NodeList *l, *body;
+ Node *xtype, *xfunc;
static int closgen;
- char *p;
- vlong offset;
/*
* wrap body in external function
xfunc->nname->funcdepth = func->funcdepth;
xfunc->funcdepth = func->funcdepth;
xfunc->endlineno = func->endlineno;
+
+ xfunc->nbody = func->nbody;
+ xfunc->dcl = concat(func->dcl, xfunc->dcl);
+ if(xfunc->nbody == nil)
+ fatal("empty body - won't generate any code");
+ typecheck(&xfunc, Etop);
+
+ xfunc->closure = func;
+ func->closure = xfunc;
- // declare variables holding addresses taken from closure
- // and initialize in entry prologue.
+ func->nbody = nil;
+ func->list = nil;
+ func->rlist = nil;
+
+ return xfunc;
+}
+
+// capturevars is called in a separate phase after all typechecking is done.
+// It decides whether each variable captured by a closure should be captured
+// by value or by reference.
+// We use value capturing for values <= 128 bytes that are never reassigned
+// after declaration.
+void
+capturevars(Node *xfunc)
+{
+ Node *func, *v, *addr, *cv, *outer;
+ NodeList *l, *body;
+ char *p;
+ vlong offset;
+ int nvar, lno;
+
+ lno = lineno;
+ lineno = xfunc->lineno;
+
+ nvar = 0;
body = nil;
offset = widthptr;
- xfunc->needctxt = func->cvars != nil;
+ func = xfunc->closure;
+ func->enter = nil;
for(l=func->cvars; l; l=l->next) {
v = l->n;
- if(v->op == 0)
+ if(v->type == T) {
+ // if v->type is nil, it means v looked like it was
+ // going to be used in the closure but wasn't.
+ // this happens because when parsing a, b, c := f()
+ // the a, b, c gets parsed as references to older
+ // a, b, c before the parser figures out this is a
+ // declaration.
+ v->op = OXXX;
continue;
+ }
+ nvar++;
+
+ // type check the & of closed variables outside the closure,
+ // so that the outer frame also grabs them and knows they escape.
+ dowidth(v->type);
+ outer = v->outerexpr;
+ v->outerexpr = N;
+ if(!v->closure->addrtaken && !v->closure->assigned && v->type->width <= 128)
+ v->byval = 1;
+ else {
+ outer = nod(OADDR, outer, N);
+ // For a closure that is called in place, but not
+ // inside a go statement, avoid moving variables to the heap.
+ outer->etype = func->etype;
+ }
+ if(debug['m'] > 1)
+ warnl(v->lineno, "%S capturing by %s: %S (addr=%d assign=%d width=%d)",
+ (v->curfn && v->curfn->nname) ? v->curfn->nname->sym : S, v->byval ? "value" : "ref",
+ v->sym, v->closure->addrtaken, v->closure->assigned, (int32)v->type->width);
+ typecheck(&outer, Erv);
+ func->enter = list(func->enter, outer);
+
+ // declare variables holding addresses taken from closure
+ // and initialize in entry prologue.
addr = nod(ONAME, N, N);
p = smprint("&%s", v->sym->name);
addr->sym = lookup(p);
xfunc->dcl = list(xfunc->dcl, addr);
v->heapaddr = addr;
cv = nod(OCLOSUREVAR, N, N);
- cv->type = ptrto(v->type);
- cv->xoffset = offset;
- body = list(body, nod(OAS, addr, cv));
- offset += widthptr;
+ if(v->byval) {
+ cv->type = v->type;
+ offset = rnd(offset, v->type->align);
+ cv->xoffset = offset;
+ offset += v->type->width;
+ body = list(body, nod(OAS, addr, nod(OADDR, cv, N)));
+ } else {
+ v->closure->addrtaken = 1;
+ cv->type = ptrto(v->type);
+ offset = rnd(offset, widthptr);
+ cv->xoffset = offset;
+ offset += widthptr;
+ body = list(body, nod(OAS, addr, cv));
+ }
}
typechecklist(body, Etop);
walkstmtlist(body);
xfunc->enter = body;
+ xfunc->needctxt = nvar > 0;
+ func->etype = 0;
- xfunc->nbody = func->nbody;
- xfunc->dcl = concat(func->dcl, xfunc->dcl);
- if(xfunc->nbody == nil)
- fatal("empty body - won't generate any code");
- typecheck(&xfunc, Etop);
-
- xfunc->closure = func;
- func->closure = xfunc;
-
- func->nbody = nil;
- func->list = nil;
- func->rlist = nil;
-
- return xfunc;
+ lineno = lno;
}
Node*
walkclosure(Node *func, NodeList **init)
{
- Node *clos, *typ;
+ Node *clos, *typ, *typ1, *v;
NodeList *l;
- char buf[20];
- int narg;
// If no closure vars, don't bother wrapping.
if(func->cvars == nil)
// the struct is unnamed so that closures in multiple packages with the
// same struct type can share the descriptor.
- narg = 0;
typ = nod(OTSTRUCT, N, N);
typ->list = list1(nod(ODCLFIELD, newname(lookup("F")), typenod(types[TUINTPTR])));
for(l=func->cvars; l; l=l->next) {
- if(l->n->op == 0)
+ v = l->n;
+ if(v->op == OXXX)
continue;
- snprint(buf, sizeof buf, "A%d", narg++);
- typ->list = list(typ->list, nod(ODCLFIELD, newname(lookup(buf)), l->n->heapaddr->ntype));
+ typ1 = typenod(v->type);
+ if(!v->byval)
+ typ1 = nod(OIND, typ1, N);
+ typ->list = list(typ->list, nod(ODCLFIELD, newname(v->sym), typ1));
}
clos = nod(OCOMPLIT, N, nod(OIND, typ, N));
c->funcdepth = funcdepth;
c->outer = n->closure;
n->closure = c;
- n->addrtaken = 1;
c->closure = n;
c->xoffset = 0;
curfn->cvars = list(curfn->cvars, c);
{
int lno;
NodeList *ll, *lr;
- Node *a;
+ Node *a, *v;
if(n == N)
return;
case OCLOSURE:
// Link addresses of captured variables to closure.
for(ll=n->cvars; ll; ll=ll->next) {
- if(ll->n->op == OXXX) // unnamed out argument; see dcl.c:/^funcargs
+ v = ll->n;
+ if(v->op == OXXX) // unnamed out argument; see dcl.c:/^funcargs
continue;
- a = nod(OADDR, ll->n->closure, N);
- a->lineno = ll->n->lineno;
- a->escloopdepth = e->loopdepth;
- typecheck(&a, Erv);
+ a = v->closure;
+ if(!v->byval) {
+ a = nod(OADDR, a, N);
+ a->lineno = v->lineno;
+ a->escloopdepth = e->loopdepth;
+ typecheck(&a, Erv);
+ }
escassign(e, n, a);
}
// fallthrough
if(n->embedded != 0)
fmtprint(fp, " embedded(%d)", n->embedded);
+ if(n->addrtaken != 0)
+ fmtprint(fp, " addrtaken");
+
+ if(n->assigned != 0)
+ fmtprint(fp, " assigned");
+
if(!c && n->used != 0)
fmtprint(fp, " used(%d)", n->used);
return 0;
uchar readonly;
uchar implicit;
uchar addrtaken; // address taken, even if not moved to heap
+ uchar assigned; // is the variable ever assigned to
+ uchar captured; // is the variable captured by a closure
+ uchar byval; // is the variable captured by value or by reference
uchar dupok; // duplicate definitions ok (for func)
uchar wrapper; // is method wrapper (for func)
uchar reslice; // this is a reslice x = x[0:y] or x = append(x, ...)
Node* pack; // real package for import . names
Node* curfn; // function for local variables
Type* paramfld; // TFIELD for this PPARAM; also for ODOT, curfn
+ int decldepth; // declaration loop depth, increased for every loop or label
// ONAME func param with PHEAP
Node* heapaddr; // temp holding heap address of param
+ Node* outerexpr; // expression copied into closure for variable
Node* stackparam; // OPARAM node referring to stack copy of param
Node* alloc; // allocation call
EXTERN int nerrors;
EXTERN int nsavederrors;
EXTERN int nsyntaxerrors;
+EXTERN int decldepth;
EXTERN int safemode;
EXTERN int nolocalimports;
EXTERN char namebuf[NSYMB];
EXTERN NodeList* xtop;
EXTERN NodeList* externdcl;
-EXTERN NodeList* closures;
EXTERN NodeList* exportlist;
EXTERN NodeList* importlist; // imported functions and methods with inlinable bodies
EXTERN NodeList* funcsyms;
Node* closurebody(NodeList *body);
void closurehdr(Node *ntype);
void typecheckclosure(Node *func, int top);
+void capturevars(Node *func);
Node* walkclosure(Node *func, NodeList **init);
void typecheckpartialcall(Node*, Node*);
Node* walkpartialcall(Node*, NodeList**);
Node* typecheckdef(Node *n);
void copytype(Node *n, Type *t);
void checkreturn(Node*);
-void checkassign(Node*);
+void checkassign(Node *stmt, Node*);
void queuemethod(Node *n);
/*
for(l=xtop; l; l=l->next) {
if(l->n->op == ODCLFUNC || l->n->op == OCLOSURE) {
curfn = l->n;
+ decldepth = 1;
saveerrors();
typechecklist(l->n->nbody, Etop);
checkreturn(l->n);
}
}
+ // Phase 4: Decide how to capture variables
+ // and transform closure bodies accordingly.
+ for(l=xtop; l; l=l->next) {
+ if(l->n->op == ODCLFUNC && l->n->closure) {
+ curfn = l->n;
+ capturevars(l->n);
+ }
+ }
+
curfn = nil;
if(nsavederrors+nerrors)
errorexit();
- // Phase 4: Inlining
+ // Phase 5: Inlining
if(debug['l'] > 1) {
// Typecheck imported function bodies if debug['l'] > 1,
// otherwise lazily when used or re-exported.
inlcalls(l->n);
}
- // Phase 5: Escape analysis.
+ // Phase 6: Escape analysis.
// Required for moving heap allocations onto stack,
// which in turn is required by the closure implementation,
// which stores the addresses of stack variables into the closure.
// Move large values off stack too.
movelarge(xtop);
- // Phase 6: Compile top level functions.
+ // Phase 7: Compile top level functions.
for(l=xtop; l; l=l->next)
if(l->n->op == ODCLFUNC)
funccompile(l->n, 0);
if(nsavederrors+nerrors == 0)
fninit(xtop);
- // Phase 7: Check external declarations.
+ // Phase 8: Check external declarations.
for(l=externdcl; l; l=l->next)
if(l->n->op == ONAME)
typecheck(&l->n, Erv);
v1->type = t1;
else if(v1->type != T && assignop(t1, v1->type, &why) == 0)
yyerror("cannot assign type %T to %lN in range%s", t1, v1, why);
- checkassign(v1);
+ checkassign(n, v1);
}
if(v2) {
if(v2->defn == n)
v2->type = t2;
else if(v2->type != T && assignop(t2, v2->type, &why) == 0)
yyerror("cannot assign type %T to %lN in range%s", t2, v2, why);
- checkassign(v2);
+ checkassign(n, v2);
}
out:
static void typecheckas(Node*);
static void typecheckfunc(Node*);
static void checklvalue(Node*, char*);
-static void checkassignlist(NodeList*);
+static void checkassignlist(Node*, NodeList*);
static void stringtoarraylit(Node**);
static Node* resolve(Node*);
static void checkdefergo(Node*);
goto ret;
case ONAME:
+ if(n->decldepth == 0)
+ n->decldepth = decldepth;
if(n->etype != 0) {
ok |= Ecall;
goto ret;
case OASOP:
ok |= Etop;
l = typecheck(&n->left, Erv);
- checkassign(n->left);
r = typecheck(&n->right, Erv);
+ checkassign(n, n->left);
if(l->type == T || r->type == T)
goto error;
op = n->etype;
goto error;
checklvalue(n->left, "take the address of");
r = outervalue(n->left);
- for(l = n->left; l != r; l = l->left)
+ for(l = n->left; l != r; l = l->left) {
l->addrtaken = 1;
+ if(l->closure)
+ l->closure->addrtaken = 1;
+ }
if(l->orig != l && l->op == ONAME)
fatal("found non-orig name node %N", l);
l->addrtaken = 1;
+ if(l->closure)
+ l->closure->addrtaken = 1;
defaultlit(&n->left, T);
l = n->left;
if((t = l->type) == T)
case ODCL:
case OEMPTY:
case OGOTO:
- case OLABEL:
case OXFALL:
case OVARKILL:
ok |= Etop;
goto ret;
+ case OLABEL:
+ ok |= Etop;
+ decldepth++;
+ goto ret;
+
case ODEFER:
ok |= Etop;
typecheck(&n->left, Etop|Erv);
case OFOR:
ok |= Etop;
typechecklist(n->ninit, Etop);
+ decldepth++;
typecheck(&n->ntest, Erv);
if(n->ntest != N && (t = n->ntest->type) != T && t->etype != TBOOL)
yyerror("non-bool %lN used as for condition", n->ntest);
typecheck(&n->nincr, Etop);
typechecklist(n->nbody, Etop);
+ decldepth--;
goto ret;
case OIF:
}
void
-checkassign(Node *n)
+checkassign(Node *stmt, Node *n)
{
+ Node *r, *l;
+
+ if(n->defn != stmt) {
+ r = outervalue(n);
+ for(l = n; l != r; l = l->left) {
+ l->assigned = 1;
+ if(l->closure)
+ l->closure->assigned = 1;
+ }
+ l->assigned = 1;
+ if(l->closure)
+ l->closure->assigned = 1;
+ }
+
if(islvalue(n))
return;
if(n->op == OINDEXMAP) {
}
static void
-checkassignlist(NodeList *l)
+checkassignlist(Node *stmt, NodeList *l)
{
for(; l; l=l->next)
- checkassign(l->n);
+ checkassign(stmt, l->n);
}
// Check whether l and r are the same side effect-free expression,
if(n->left->defn != n || n->left->ntype)
typecheck(&n->left, Erv | Easgn);
- checkassign(n->left);
typecheck(&n->right, Erv);
+ checkassign(n, n->left);
if(n->right && n->right->type != T) {
if(n->left->type != T)
n->right = assignconv(n->right, n->left->type, "assignment");
}
cl = count(n->list);
cr = count(n->rlist);
- checkassignlist(n->list);
if(cl > 1 && cr == 1)
typecheck(&n->rlist->n, Erv | Efnstruct);
else
typechecklist(n->rlist, Erv);
+ checkassignlist(n, n->list);
if(cl == cr) {
// easy
typecheckfunc(Node *n)
{
Type *t, *rcvr;
+ NodeList *l;
typecheck(&n->nname, Erv | Easgn);
if((t = n->nname->type) == T)
rcvr = getthisx(t)->type;
if(rcvr != nil && n->shortname != N && !isblank(n->shortname))
addmethod(n->shortname->sym, t, 1, n->nname->nointerface);
+
+ for(l=n->dcl; l; l=l->next)
+ if(l->n->op == ONAME && (l->n->class == PPARAM || l->n->class == PPARAMOUT))
+ l->n->decldepth = 1;
}
static void
{
while(n->op == ODOT || n->op == OPAREN || n->op == OCONVNOP || n->op == OINDEX && isfixedarray(n->left->type))
n = n->left;
-
+
switch(n->op) {
case ONAME:
switch(n->class) {
import (
"math"
"runtime"
+ "sync"
"sync/atomic"
"syscall"
"testing"
}
}
+func BenchmarkCreateGoroutinesCapture(b *testing.B) {
+ b.ReportAllocs()
+ for i := 0; i < b.N; i++ {
+ const N = 4
+ var wg sync.WaitGroup
+ wg.Add(N)
+ for i := 0; i < N; i++ {
+ i := i
+ go func() {
+ if i >= N {
+ b.Logf("bad") // just to capture b
+ }
+ wg.Done()
+ }()
+ }
+ wg.Wait()
+ }
+}
+
type Matrix [][]float64
func BenchmarkMatmult(b *testing.B) {
--- /dev/null
+// run
+
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func main() {
+ x := 0
+ func() {
+ x = 1
+ }()
+ func() {
+ if x != 1 {
+ panic("x != 1")
+ }
+ }()
+}
\ No newline at end of file
--- /dev/null
+// run
+
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Check that these do not use "by value" capturing,
+// because changes are made to the value during the closure.
+
+package main
+
+func main() {
+ type X struct {
+ v int
+ }
+ var x X
+ func() {
+ x.v++
+ }()
+ if x.v != 1 {
+ panic("x.v != 1")
+ }
+
+ type Y struct {
+ X
+ }
+ var y Y
+ func() {
+ y.v = 1
+ }()
+ if y.v != 1 {
+ panic("y.v != 1")
+ }
+
+ type Z struct {
+ a [3]byte
+ }
+ var z Z
+ func() {
+ i := 0
+ for z.a[1] = 1; i < 10; i++ {
+ }
+ }()
+ if z.a[1] != 1 {
+ panic("z.a[1] != 1")
+ }
+
+ w := 0
+ tmp := 0
+ f := func() {
+ if w != 1 {
+ panic("w != 1")
+ }
+ }
+ func() {
+ tmp = w // force capture of w, but do not write to it yet
+ func() {
+ func() {
+ w++ // write in a nested closure
+ }()
+ }()
+ }()
+ f()
+}
}
func foo21() func() int {
+ x := 42
+ return func() int { // ERROR "func literal escapes to heap"
+ return x
+ }
+}
+
+func foo21a() func() int {
x := 42 // ERROR "moved to heap: x"
return func() int { // ERROR "func literal escapes to heap"
- return x // ERROR "&x escapes to heap"
+ x++ // ERROR "&x escapes to heap"
+ return x
}
}
}()
}
-func foo23(x int) func() int { // ERROR "moved to heap: x"
+func foo23(x int) func() int {
return func() int { // ERROR "func literal escapes to heap"
- return x // ERROR "&x escapes to heap"
+ return x
}
}
-func foo23a(x int) func() int { // ERROR "moved to heap: x"
+func foo23a(x int) func() int {
f := func() int { // ERROR "func literal escapes to heap"
- return x // ERROR "&x escapes to heap"
+ return x
}
return f
}
-func foo23b(x int) *(func() int) { // ERROR "moved to heap: x"
- f := func() int { return x } // ERROR "moved to heap: f" "func literal escapes to heap" "&x escapes to heap"
+func foo23b(x int) *(func() int) {
+ f := func() int { return x } // ERROR "moved to heap: f" "func literal escapes to heap"
return &f // ERROR "&f escapes to heap"
}
+func foo23c(x int) func() int { // ERROR "moved to heap: x"
+ return func() int { // ERROR "func literal escapes to heap"
+ x++ // ERROR "&x escapes to heap"
+ return x
+ }
+}
+
func foo24(x int) int {
return func() int { // ERROR "func literal does not escape"
return x
// issue 2145
func foo73() {
+ s := []int{3, 2, 1} // ERROR "\[\]int literal does not escape"
+ for _, v := range s {
+ vv := v
+ // actually just escapes its scope
+ defer func() { // ERROR "func literal escapes to heap"
+ println(vv)
+ }()
+ }
+}
+
+func foo731() {
s := []int{3, 2, 1} // ERROR "\[\]int literal does not escape"
for _, v := range s {
vv := v // ERROR "moved to heap: vv"
// actually just escapes its scope
defer func() { // ERROR "func literal escapes to heap"
- println(vv) // ERROR "&vv escapes to heap"
+ vv = 42 // ERROR "&vv escapes to heap"
+ println(vv)
}()
}
}
func foo74() {
+ s := []int{3, 2, 1} // ERROR "\[\]int literal does not escape"
+ for _, v := range s {
+ vv := v
+ // actually just escapes its scope
+ fn := func() { // ERROR "func literal escapes to heap"
+ println(vv)
+ }
+ defer fn()
+ }
+}
+
+func foo74a() {
s := []int{3, 2, 1} // ERROR "\[\]int literal does not escape"
for _, v := range s {
vv := v // ERROR "moved to heap: vv"
// actually just escapes its scope
fn := func() { // ERROR "func literal escapes to heap"
- println(vv) // ERROR "&vv escapes to heap"
+ vv += 1 // ERROR "&vv escapes to heap"
+ println(vv)
}
defer fn()
}
// issue 3975
func foo74b() {
+ var array [3]func()
+ s := []int{3, 2, 1} // ERROR "\[\]int literal does not escape"
+ for i, v := range s {
+ vv := v
+ // actually just escapes its scope
+ array[i] = func() { // ERROR "func literal escapes to heap"
+ println(vv)
+ }
+ }
+}
+
+func foo74c() {
var array [3]func()
s := []int{3, 2, 1} // ERROR "\[\]int literal does not escape"
for i, v := range s {
vv := v // ERROR "moved to heap: vv"
// actually just escapes its scope
array[i] = func() { // ERROR "func literal escapes to heap"
- println(vv) // ERROR "&vv escapes to heap"
+ println(&vv) // ERROR "&vv escapes to heap" "&vv does not escape"
}
}
}
func foo135() {
var i int // ERROR "moved to heap: i"
- p := &i // ERROR "&i escapes to heap" "moved to heap: p"
+ p := &i // ERROR "&i escapes to heap"
go func() { // ERROR "func literal escapes to heap"
- q := p // ERROR "&p escapes to heap"
+ q := p
func() { // ERROR "func literal does not escape"
r := q
_ = r
func foo136() {
var i int // ERROR "moved to heap: i"
- p := &i // ERROR "&i escapes to heap" "moved to heap: p"
+ p := &i // ERROR "&i escapes to heap"
go func() { // ERROR "func literal escapes to heap"
- q := p // ERROR "&p escapes to heap" "leaking closure reference p"
+ q := p // ERROR "leaking closure reference p"
func() { // ERROR "func literal does not escape"
r := q // ERROR "leaking closure reference q"
px = r
var i int // ERROR "moved to heap: i"
p := &i // ERROR "&i escapes to heap"
func() { // ERROR "func literal does not escape"
- q := p // ERROR "leaking closure reference p" "moved to heap: q"
+ q := p // ERROR "leaking closure reference p"
go func() { // ERROR "func literal escapes to heap"
- r := q // ERROR "&q escapes to heap"
+ r := q
_ = r
}()
}()
}
func foo21() func() int {
+ x := 42
+ return func() int { // ERROR "func literal escapes to heap"
+ return x
+ }
+}
+
+func foo21a() func() int {
x := 42 // ERROR "moved to heap: x"
return func() int { // ERROR "func literal escapes to heap"
- return x // ERROR "&x escapes to heap"
+ x++ // ERROR "&x escapes to heap"
+ return x
}
}
}()
}
-func foo23(x int) func() int { // ERROR "moved to heap: x"
+func foo23(x int) func() int {
return func() int { // ERROR "func literal escapes to heap"
- return x // ERROR "&x escapes to heap"
+ return x
}
}
-func foo23a(x int) func() int { // ERROR "moved to heap: x"
+func foo23a(x int) func() int {
f := func() int { // ERROR "func literal escapes to heap"
- return x // ERROR "&x escapes to heap"
+ return x
}
return f
}
-func foo23b(x int) *(func() int) { // ERROR "moved to heap: x"
- f := func() int { return x } // ERROR "moved to heap: f" "func literal escapes to heap" "&x escapes to heap"
+func foo23b(x int) *(func() int) {
+ f := func() int { return x } // ERROR "moved to heap: f" "func literal escapes to heap"
return &f // ERROR "&f escapes to heap"
}
+func foo23c(x int) func() int { // ERROR "moved to heap: x"
+ return func() int { // ERROR "func literal escapes to heap"
+ x++ // ERROR "&x escapes to heap"
+ return x
+ }
+}
+
func foo24(x int) int {
return func() int { // ERROR "func literal does not escape"
return x
// issue 2145
func foo73() {
+ s := []int{3, 2, 1} // ERROR "\[\]int literal does not escape"
+ for _, v := range s {
+ vv := v
+ // actually just escapes its scope
+ defer func() { // ERROR "func literal escapes to heap"
+ println(vv)
+ }()
+ }
+}
+
+func foo731() {
s := []int{3, 2, 1} // ERROR "\[\]int literal does not escape"
for _, v := range s {
vv := v // ERROR "moved to heap: vv"
// actually just escapes its scope
defer func() { // ERROR "func literal escapes to heap"
- println(vv) // ERROR "&vv escapes to heap"
+ vv = 42 // ERROR "&vv escapes to heap"
+ println(vv)
}()
}
}
func foo74() {
+ s := []int{3, 2, 1} // ERROR "\[\]int literal does not escape"
+ for _, v := range s {
+ vv := v
+ // actually just escapes its scope
+ fn := func() { // ERROR "func literal escapes to heap"
+ println(vv)
+ }
+ defer fn()
+ }
+}
+
+func foo74a() {
s := []int{3, 2, 1} // ERROR "\[\]int literal does not escape"
for _, v := range s {
vv := v // ERROR "moved to heap: vv"
// actually just escapes its scope
fn := func() { // ERROR "func literal escapes to heap"
- println(vv) // ERROR "&vv escapes to heap"
+ vv += 1 // ERROR "&vv escapes to heap"
+ println(vv)
}
defer fn()
}
// issue 3975
func foo74b() {
+ var array [3]func()
+ s := []int{3, 2, 1} // ERROR "\[\]int literal does not escape"
+ for i, v := range s {
+ vv := v
+ // actually just escapes its scope
+ array[i] = func() { // ERROR "func literal escapes to heap"
+ println(vv)
+ }
+ }
+}
+
+func foo74c() {
var array [3]func()
s := []int{3, 2, 1} // ERROR "\[\]int literal does not escape"
for i, v := range s {
vv := v // ERROR "moved to heap: vv"
// actually just escapes its scope
array[i] = func() { // ERROR "func literal escapes to heap"
- println(vv) // ERROR "&vv escapes to heap"
+ println(&vv) // ERROR "&vv escapes to heap" "&vv does not escape"
}
}
}
func foo135() {
var i int // ERROR "moved to heap: i"
- p := &i // ERROR "&i escapes to heap" "moved to heap: p"
+ p := &i // ERROR "&i escapes to heap"
go func() { // ERROR "func literal escapes to heap"
- q := p // ERROR "&p escapes to heap"
+ q := p
func() { // ERROR "func literal does not escape"
r := q
_ = r
func foo136() {
var i int // ERROR "moved to heap: i"
- p := &i // ERROR "&i escapes to heap" "moved to heap: p"
+ p := &i // ERROR "&i escapes to heap"
go func() { // ERROR "func literal escapes to heap"
- q := p // ERROR "&p escapes to heap" "leaking closure reference p"
+ q := p // ERROR "leaking closure reference p"
func() { // ERROR "func literal does not escape"
r := q // ERROR "leaking closure reference q"
px = r
var i int // ERROR "moved to heap: i"
p := &i // ERROR "&i escapes to heap"
func() { // ERROR "func literal does not escape"
- q := p // ERROR "leaking closure reference p" "moved to heap: q"
+ q := p // ERROR "leaking closure reference p"
go func() { // ERROR "func literal escapes to heap"
- r := q // ERROR "&q escapes to heap"
+ r := q
_ = r
}()
}()