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
|
#include <limits.h>
#include <stdbool.h>
#include <stddef.h>
#include "util.h"
#include "cc.h"
enum {
F = 1<<8,
S = 2<<8
};
static void
cast(struct expr *expr)
{
unsigned size;
unsigned long long m;
size = expr->type->size;
if (expr->type->prop & PROPFLOAT) {
if (size == 4)
expr->u.constant.f = (float)expr->u.constant.f;
} else if (expr->type->prop & PROPINT) {
expr->u.constant.u &= -1ull >> CHAR_BIT * sizeof(unsigned long long) - size * 8;
if (expr->type->u.basic.issigned) {
m = 1ull << size * 8 - 1;
expr->u.constant.u = (expr->u.constant.u ^ m) - m;
}
}
}
static void
unary(struct expr *expr, enum tokenkind op, struct expr *l)
{
expr->kind = EXPRCONST;
if (l->type->prop & PROPFLOAT)
op |= F;
switch (op) {
case TSUB: expr->u.constant.u = -l->u.constant.u; break;
case TSUB|F: expr->u.constant.f = -l->u.constant.f; break;
default:
fatal("internal error; unknown unary expression");
}
cast(expr);
}
static void
binary(struct expr *expr, enum tokenkind op, struct expr *l, struct expr *r)
{
expr->kind = EXPRCONST;
if (l->type->prop & PROPFLOAT)
op |= F;
else if (l->type->prop & PROPINT && l->type->u.basic.issigned)
op |= S;
switch (op) {
case TMUL:
case TMUL|S: expr->u.constant.u = l->u.constant.u * r->u.constant.u; break;
case TMUL|F: expr->u.constant.f = l->u.constant.f * r->u.constant.f; break;
case TDIV: expr->u.constant.u = l->u.constant.u / r->u.constant.u; break;
case TDIV|S: expr->u.constant.i = l->u.constant.i / r->u.constant.i; break;
case TDIV|F: expr->u.constant.f = l->u.constant.f / r->u.constant.f; break;
case TMOD: expr->u.constant.u = l->u.constant.u % r->u.constant.u; break;
case TMOD|S: expr->u.constant.i = l->u.constant.i % r->u.constant.i; break;
case TADD:
case TADD|S: expr->u.constant.u = l->u.constant.u + r->u.constant.u; break;
case TADD|F: expr->u.constant.f = l->u.constant.f + r->u.constant.f; break;
case TSUB:
case TSUB|S: expr->u.constant.u = l->u.constant.u - r->u.constant.u; break;
case TSUB|F: expr->u.constant.f = l->u.constant.f - r->u.constant.f; break;
case TSHL:
case TSHL|S: expr->u.constant.u = l->u.constant.u << (r->u.constant.u & 63); break;
case TSHR: expr->u.constant.u = l->u.constant.u >> (r->u.constant.u & 63); break;
case TSHR|S: expr->u.constant.i = l->u.constant.i >> (r->u.constant.u & 63); break;
case TBAND:
case TBAND|S: expr->u.constant.u = l->u.constant.u & r->u.constant.u; break;
case TBOR:
case TBOR|S: expr->u.constant.u = l->u.constant.u | r->u.constant.u; break;
case TXOR:
case TXOR|S: expr->u.constant.u = l->u.constant.u ^ r->u.constant.u; break;
case TLESS: expr->u.constant.u = l->u.constant.u < r->u.constant.u; break;
case TLESS|S: expr->u.constant.u = l->u.constant.i < r->u.constant.i; break;
case TLESS|F: expr->u.constant.u = l->u.constant.f < r->u.constant.f; break;
case TGREATER: expr->u.constant.u = l->u.constant.u > r->u.constant.u; break;
case TGREATER|S: expr->u.constant.u = l->u.constant.i > r->u.constant.i; break;
case TGREATER|F: expr->u.constant.u = l->u.constant.f > r->u.constant.f; break;
case TLEQ: expr->u.constant.u = l->u.constant.u <= r->u.constant.u; break;
case TLEQ|S: expr->u.constant.u = l->u.constant.i <= r->u.constant.i; break;
case TLEQ|F: expr->u.constant.u = l->u.constant.f <= r->u.constant.f; break;
case TGEQ: expr->u.constant.u = l->u.constant.u >= r->u.constant.u; break;
case TGEQ|S: expr->u.constant.u = l->u.constant.i >= r->u.constant.i; break;
case TGEQ|F: expr->u.constant.u = l->u.constant.f >= r->u.constant.f; break;
case TEQL:
case TEQL|S: expr->u.constant.u = l->u.constant.u == r->u.constant.u; break;
case TEQL|F: expr->u.constant.u = l->u.constant.f == r->u.constant.f; break;
case TNEQ:
case TNEQ|S: expr->u.constant.u = l->u.constant.u != r->u.constant.u; break;
case TNEQ|F: expr->u.constant.u = l->u.constant.f != r->u.constant.f; break;
default:
fatal("internal error; unknown binary expression");
}
cast(expr);
}
struct expr *
eval(struct expr *expr)
{
struct expr *l, *r, *c;
struct decl *d;
struct type *t;
t = expr->type;
switch (expr->kind) {
case EXPRIDENT:
if (expr->u.ident.decl->kind != DECLCONST)
break;
expr->kind = EXPRCONST;
expr->u.constant.u = intconstvalue(expr->u.ident.decl->value);
break;
case EXPRCOMPOUND:
if (expr->u.compound.decl->u.obj.storage != SDSTATIC)
break;
d = mkdecl(NULL, DECLOBJECT, t, expr->qual, LINKNONE);
d->value = mkglobal(d);
emitdata(d, expr->u.compound.init);
expr->kind = EXPRIDENT;
expr->u.ident.decl = d;
break;
case EXPRUNARY:
l = eval(expr->base);
switch (expr->op) {
case TBAND:
switch (l->kind) {
case EXPRUNARY:
if (l->op == TMUL)
expr = eval(l->base);
break;
case EXPRSTRING:
l->u.ident.decl = stringdecl(l);
l->kind = EXPRIDENT;
expr->base = l;
break;
}
break;
case TMUL:
break;
default:
if (l->kind != EXPRCONST)
break;
unary(expr, expr->op, l);
break;
}
break;
case EXPRCAST:
l = eval(expr->base);
if (l->kind == EXPRCONST) {
expr->kind = EXPRCONST;
if (l->type->prop & PROPINT && t->prop & PROPFLOAT) {
if (l->type->u.basic.issigned)
expr->u.constant.f = l->u.constant.i;
else
expr->u.constant.f = l->u.constant.u;
} else if (l->type->prop & PROPFLOAT && t->prop & PROPINT) {
if (t->u.basic.issigned) {
if (l->u.constant.f < -0x1p63 || l->u.constant.f >= 0x1p63)
error(&tok.loc, "integer part of floating-point constant %g cannot be represented as signed integer", l->u.constant.f);
expr->u.constant.i = l->u.constant.f;
} else {
if (l->u.constant.f < 0.0 || l->u.constant.f >= 0x1p64)
error(&tok.loc, "integer part of floating-point constant %g cannot be represented as unsigned integer", l->u.constant.f);
expr->u.constant.u = l->u.constant.f;
}
} else {
expr->u.constant = l->u.constant;
}
cast(expr);
} else if (l->type->kind == TYPEPOINTER) {
/*
A cast from a pointer to integer is not a valid constant
expression, but C11 allows implementations to recognize
other forms of constant expressions (6.6p10), and some
programs expect this functionality.
*/
if (t->kind == TYPEPOINTER || t->prop & PROPINT && t->size == typelong.size)
expr = l;
}
break;
case EXPRBINARY:
l = eval(expr->u.binary.l);
r = eval(expr->u.binary.r);
expr->u.binary.l = l;
expr->u.binary.r = r;
switch (expr->op) {
case TADD:
if (r->kind == EXPRBINARY)
c = l, l = r, r = c;
/* fallthrough */
case TSUB:
if (r->kind != EXPRCONST)
break;
if (l->kind == EXPRCONST) {
binary(expr, expr->op, l, r);
} else if (l->kind == EXPRBINARY && l->type->kind == TYPEPOINTER && l->op == TADD && l->u.binary.r->kind == EXPRCONST) {
/* (P + C1) ± C2 -> P + (C1 ± C2) */
binary(expr->u.binary.r, expr->op, l->u.binary.r, r);
expr->op = TADD;
expr->u.binary.l = l->u.binary.l;
}
break;
case TLOR:
if (l->kind != EXPRCONST)
break;
return l->u.constant.u ? l : r;
case TLAND:
if (l->kind != EXPRCONST)
break;
return l->u.constant.u ? r : l;
default:
if (l->kind != EXPRCONST || r->kind != EXPRCONST)
break;
binary(expr, expr->op, l, r);
}
break;
}
return expr;
}
|
