1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
|
// Copyright 2009 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.
/*
* function literals aka closures
*/
#include "go.h"
void
closurehdr(Node *ntype)
{
Node *n, *name, *a;
NodeList *l;
n = nod(OCLOSURE, N, N);
n->ntype = ntype;
n->funcdepth = funcdepth;
funchdr(n);
// steal ntype's argument names and
// leave a fresh copy in their place.
// references to these variables need to
// refer to the variables in the external
// function declared below; see walkclosure.
n->list = ntype->list;
n->rlist = ntype->rlist;
ntype->list = nil;
ntype->rlist = nil;
for(l=n->list; l; l=l->next) {
name = l->n->left;
if(name)
name = newname(name->sym);
a = nod(ODCLFIELD, name, l->n->right);
a->isddd = l->n->isddd;
if(name)
name->isddd = a->isddd;
ntype->list = list(ntype->list, a);
}
for(l=n->rlist; l; l=l->next) {
name = l->n->left;
if(name)
name = newname(name->sym);
ntype->rlist = list(ntype->rlist, nod(ODCLFIELD, name, l->n->right));
}
}
Node*
closurebody(NodeList *body)
{
Node *func, *v;
NodeList *l;
if(body == nil)
body = list1(nod(OEMPTY, N, N));
func = curfn;
l = func->dcl;
func->nbody = body;
funcbody(func);
// closure-specific variables are hanging off the
// ordinary ones in the symbol table; see oldname.
// unhook them.
// make the list of pointers for the closure call.
for(l=func->cvars; l; l=l->next) {
v = l->n;
v->closure->closure = v->outer;
v->heapaddr = nod(OADDR, oldname(v->sym), N);
}
return func;
}
void
typecheckclosure(Node *func, int top)
{
Node *oldfn;
NodeList *l;
Node *v;
oldfn = curfn;
typecheck(&func->ntype, Etype);
func->type = func->ntype->type;
if(func->type != T) {
curfn = func;
typechecklist(func->nbody, Etop);
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;
}
}
Node*
walkclosure(Node *func, NodeList **init)
{
int narg;
Node *xtype, *v, *addr, *xfunc, *call, *clos;
NodeList *l, *in;
static int closgen;
char *p;
/*
* wrap body in external function
* with extra closure parameters.
*/
xtype = nod(OTFUNC, N, N);
// each closure variable has a corresponding
// address parameter.
narg = 0;
for(l=func->cvars; l; l=l->next) {
v = l->n;
if(v->op == 0)
continue;
addr = nod(ONAME, N, N);
p = smprint("&%s", v->sym->name);
addr->sym = lookup(p);
free(p);
addr->ntype = nod(OIND, typenod(v->type), N);
addr->class = PPARAM;
addr->addable = 1;
addr->ullman = 1;
narg++;
v->heapaddr = addr;
xtype->list = list(xtype->list, nod(ODCLFIELD, addr, addr->ntype));
}
// then a dummy arg where the closure's caller pc sits
xtype->list = list(xtype->list, nod(ODCLFIELD, N, typenod(types[TUINTPTR])));
// then the function arguments
xtype->list = concat(xtype->list, func->list);
xtype->rlist = concat(xtype->rlist, func->rlist);
// create the function
xfunc = nod(ODCLFUNC, N, N);
snprint(namebuf, sizeof namebuf, "_func_%.3d", ++closgen);
xfunc->nname = newname(lookup(namebuf));
xfunc->nname->ntype = xtype;
xfunc->nname->defn = xfunc;
declare(xfunc->nname, PFUNC);
xfunc->nname->funcdepth = func->funcdepth;
xfunc->funcdepth = func->funcdepth;
xfunc->nbody = func->nbody;
xfunc->dcl = func->dcl;
if(xfunc->nbody == nil)
fatal("empty body - won't generate any code");
typecheck(&xfunc, Etop);
closures = list(closures, xfunc);
// prepare call of sys.closure that turns external func into func literal value.
clos = syslook("closure", 1);
clos->type = T;
clos->ntype = nod(OTFUNC, N, N);
in = list1(nod(ODCLFIELD, N, typenod(types[TINT]))); // siz
in = list(in, nod(ODCLFIELD, N, xtype));
for(l=func->cvars; l; l=l->next) {
if(l->n->op == 0)
continue;
in = list(in, nod(ODCLFIELD, N, l->n->heapaddr->ntype));
}
clos->ntype->list = in;
clos->ntype->rlist = list1(nod(ODCLFIELD, N, typenod(func->type)));
typecheck(&clos, Erv);
call = nod(OCALL, clos, N);
if(narg*widthptr > 100)
yyerror("closure needs too many variables; runtime will reject it");
in = list1(nodintconst(narg*widthptr));
in = list(in, xfunc->nname);
in = concat(in, func->enter);
call->list = in;
typecheck(&call, Erv);
walkexpr(&call, init);
return call;
}
// Special case for closures that get called in place.
// Optimize runtime.closure(X, __func__xxxx_, .... ) away
// to __func__xxxx_(Y ....).
// On entry, expect n->op == OCALL, n->left->op == OCLOSURE.
void
walkcallclosure(Node *n, NodeList **init)
{
Node *z;
NodeList *ll, *cargs;
walkexpr(&n->left, init);
cargs = n->left // FUNC runtime.closure
->list // arguments
->next // skip first
->next; // skip second
n->left = n->left // FUNC runtime.closure
->list // arguments
->next // skip first
->n // AS (to indreg)
->right; // argument == the generated function
// New arg list for n. First the closure-args, stolen from
// runtime.closure's 3rd and following,
ll = nil;
for (; cargs; cargs = cargs->next)
ll = list(ll, cargs->n->right); // cargs->n is the OAS(INDREG, arg)
// then an extra zero, to fill the dummy return pointer slot,
z = nod(OXXX, N, N);
nodconst(z, types[TUINTPTR], 0);
z->typecheck = 1;
ll = list(ll, z);
// and finally the original parameter list.
n->list = concat(ll, n->list);
}
|
