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
|
#include "all.h"
typedef struct RList RList;
struct RList {
int t;
RList *l;
};
static Ref
copyof(Ref r, Ref *cp)
{
if (rtype(r) == RTmp)
return cp[r.val];
else
return r;
}
static void
update(Ref r, Ref rcp, Ref *cp, RList **w)
{
RList *l;
if (!req(cp[r.val], rcp)) {
cp[r.val] = rcp;
l = emalloc(sizeof *l);
l->t = r.val;
l->l = *w;
*w = l;
}
}
static void
visitphi(Phi *p, Ref *cp, RList **w)
{
uint a;
Ref r, r1;
r = R;
for (a=0; a<p->narg; a++) {
r1 = copyof(p->arg[a], cp);
if (req(r1, R) || req(r1, p->to))
continue;
if (req(r, R) || req(r, r1))
r = r1;
else {
r = p->to;
break;
}
}
update(p->to, r, cp, w);
}
static void
visitins(Ins *i, Ref *cp, RList **w)
{
Ref r;
if (i->op == Ocopy) {
r = copyof(i->arg[0], cp);
update(i->to, r, cp, w);
} else if (!req(i->to, R)) {
assert(rtype(i->to) == RTmp);
update(i->to, i->to, cp, w);
}
}
static void
subst(Ref *r, Ref *cp)
{
assert((rtype(*r) != RTmp || !req(copyof(*r, cp), R)) && "ssa invariant broken");
*r = copyof(*r, cp);
}
void
copy(Fn *fn)
{
Blk *b;
Ref *cp, r;
RList *w, *w1;
Use *u, *u1;
Ins *i;
Phi *p, **pp;
uint a;
int t;
w = 0;
cp = emalloc(fn->ntmp * sizeof cp[0]);
for (b=fn->start; b; b=b->link) {
for (p=b->phi; p; p=p->link)
visitphi(p, cp, &w);
for (i=b->ins; i-b->ins < b->nins; i++)
visitins(i, cp, &w);
}
while ((w1=w)) {
t = w->t;
w = w->l;
free(w1);
u = fn->tmp[t].use;
u1 = u + fn->tmp[t].nuse;
for (; u<u1; u++)
switch (u->type) {
case UPhi:
visitphi(u->u.phi, cp, &w);
break;
case UIns:
visitins(u->u.ins, cp, &w);
break;
case UJmp:
break;
default:
die("invalid use %d", u->type);
}
}
for (b=fn->start; b; b=b->link) {
for (pp=&b->phi; (p=*pp);) {
r = cp[p->to.val];
if (!req(r, p->to)) {
*pp = p->link;
continue;
}
for (a=0; a<p->narg; a++)
subst(&p->arg[a], cp);
pp=&p->link;
}
for (i=b->ins; i-b->ins < b->nins; i++) {
r = copyof(i->to, cp);
if (!req(r, i->to)) {
*i = (Ins){.op = Onop};
continue;
}
for (a=0; a<2; a++)
subst(&i->arg[a], cp);
}
subst(&b->jmp.arg, cp);
}
if (debug['C']) {
fprintf(stderr, "\n> Copy information:");
for (t=Tmp0; t<fn->ntmp; t++) {
if (req(cp[t], R)) {
fprintf(stderr, "\n%10s not seen!",
fn->tmp[t].name);
}
else if (!req(cp[t], TMP(t))) {
fprintf(stderr, "\n%10s copy of ",
fn->tmp[t].name);
printref(cp[t], fn, stderr);
}
}
fprintf(stderr, "\n\n> After copy elimination:\n");
printfn(fn, stderr);
}
free(cp);
}
|
