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#include <limits.h>
#include <stdbool.h>
#include <stddef.h>
#include "util.h"
#include "cc.h"
#define F (1<<8)
#define 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);
}
#undef F
#undef S
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.storage != SDSTATIC)
break;
d = mkdecl(DECLOBJECT, t, expr->qual, LINKNONE);
d->value = mkglobal(NULL, true);
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;
}
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