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expr.c
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expr.c
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#include "cc.h"
static int precedence[] = {
7, /* SLASH */
7, /* STAR */
7, /* MOD */
6, /* PLUS */
6, /* MINUS */
5, /* LSHIFT */
5, /* RSHIFT */
4, /* GREATER */
4, /* GTEQ */
4, /* LESS */
4, /* LTEQ */
3, /* EQUAL */
3, /* NOTEQ */
2, /* AMPER */
1, /* CARET */
0, /* PIPE */
};
static int asgmnt(int *lv);
static int cast(int *lv);
static int prefix(int *lv);
/*
* cfactor :=
* INTLIT
* | IDENT
* | - cfactor
* | ~ cfactor
* | ( constexpr )
*
* cterm :=
* cfactor
* | cterm * cprefix
* | cterm / cprefix
* | cterm % cprefix
*
* csum :=
* cterm
* | csum + cterm
* | csum - cterm
*
* cshift :=
* csum
* | cshift << csum
* | cshift >> csum
*
* crelation :=
* cshift
* | crelation < cshift
* | crelation > cshift
* | crelation <= cshift
* | crelation >= cshift
*
* cequation :=
* crelation
* | cequation == crelation
* | cequation != crelation
*
* cbinand :=
* cequation
* | cbinand & cequation
*
* cbinxor :=
* cbinand
* | cbinxor ^ cbinand
*
* cbinor :=
* cbinxor
* | cbinor ^ cbinxor
*
* constexpr :=
* cbinor
*/
static int constfac(void)
{
int y, v = Value;
if (INTLIT == Token)
{
Token = scan();
return v;
}
if (MINUS == Token)
{
Token = scan();
return -constfac();
}
if (TILDE == Token)
{
Token = scan();
return ~constfac();
}
if (LPAREN == Token)
{
Token = scan();
v = constexpr();
rparen();
return v;
}
if (Token == IDENT)
{
y = findsym(Text);
if (!y || symbols[y].type != TCONSTANT)
error("not a constant: %s", Text);
Token = scan();
return y ? symbols[y].value : 0;
}
else
{
error("constant expression expected at: %s", Text);
Token = scan();
return 1;
}
}
static int constop(int op, int v1, int v2)
{
if ((SLASH == op || MOD == op) && 0 == v2)
{
error("constant divide by zero", NULL);
return 0;
}
switch (op)
{
case SLASH:
v1 /= v2;
break;
case STAR:
v1 *= v2;
break;
case MOD:
v1 %= v2;
break;
case PLUS:
v1 += v2;
break;
case MINUS:
v1 -= v2;
break;
case LSHIFT:
v1 <<= v2;
break;
case RSHIFT:
v1 >>= v2;
break;
case GREATER:
v1 = v1 > v2;
break;
case GTEQ:
v1 = v1 >= v2;
break;
case LESS:
v1 = v1 < v2;
break;
case LTEQ:
v1 = v1 <= v2;
break;
case EQUAL:
v1 = v1 == v2;
break;
case NOTEQ:
v1 = v1 != v2;
break;
case AMPER:
v1 &= v2;
break;
case CARET:
v1 ^= v2;
break;
case PIPE:
v1 |= v2;
break;
}
return v1;
}
int constexpr(void)
{
int v, ops[9], vals[10], sp = 0;
vals[0] = constfac();
while (SLASH == Token || STAR == Token || MOD == Token || PLUS == Token || MINUS == Token || LSHIFT == Token || RSHIFT == Token || GREATER == Token || GTEQ == Token || LESS == Token || LTEQ == Token || EQUAL == Token || NOTEQ == Token || AMPER == Token || CARET == Token || PIPE == Token)
{
while (sp > 0 && precedence[Token] <= precedence[ops[sp - 1]])
{
v = constop(ops[sp - 1], vals[sp - 1], vals[sp]);
vals[--sp] = v;
}
ops[sp++] = Token;
Token = scan();
vals[sp] = constfac();
}
while (sp > 0)
{
v = constop(ops[sp - 1], vals[sp - 1], vals[sp]);
vals[--sp] = v;
}
return vals[0];
}
/*
* primary :=
* IDENT
* | INTLIT
* | string
* | ( expr )
*
* string :=
* STRLIT
* | STRLIT string
*/
static int primary(int *lv)
{
int a, y, lab, k;
char name[NAMELEN + 1];
lv[LVSYM] = lv[LVPRIM] = 0;
switch (Token)
{
case IDENT:
y = findsym(Text);
copyname(name, Text);
Token = scan();
if (!y)
{
if (LPAREN == Token)
{
y = addglob(name, PINT, TFUNCTION, CEXTERN, -1, 0, NULL, 0);
}
else
{
error("undeclared variable: %s", name);
y = addloc(name, PINT, TVARIABLE, CAUTO, 0, 0, 0);
}
}
lv[LVSYM] = y;
lv[LVPRIM] = symbols[y].prims;
if (TFUNCTION == symbols[y].type)
{
if (LPAREN != Token)
{
lv[LVPRIM] = FUNPTR;
genaddr(y);
}
return 0;
}
if (TCONSTANT == symbols[y].type)
{
genlit(symbols[y].value);
return 0;
}
if (TARRAY == symbols[y].type)
{
genaddr(y);
lv[LVPRIM] = pointerto(lv[LVPRIM]);
return 0;
}
if (comptype(symbols[y].prims))
{
genaddr(y);
lv[LVSYM] = 0;
return 0;
}
return 1;
case INTLIT:
genlit(Value);
Token = scan();
lv[LVPRIM] = PINT;
return 0;
case STRLIT:
gendata();
lab = label();
genlab(lab);
k = 0;
while (STRLIT == Token)
{
gendefs(Text, Value);
k += Value - 2;
Token = scan();
}
gendefb(0);
genalign(k + 1);
genldlab(lab);
lv[LVPRIM] = CHARPTR;
return 0;
case LPAREN:
Token = scan();
a = expr(lv);
rparen();
return a;
default:
error("syntax error at: %s", Text);
Token = synch(SEMI);
return 0;
}
}
int typematch(int p1, int p2)
{
if (p1 == p2)
return 1;
if (inttype(p1) && inttype(p2))
return 1;
if (!inttype(p1) && VOIDPTR == p2)
return 1;
if (VOIDPTR == p1 && !inttype(p2))
return 1;
return 0;
}
/*
* fnargs :=
* asgmnt
* | asgmnt , fnargs
*/
static int fnargs(int fn)
{
int lv[LV];
int na = 0;
int *types;
char msg[100];
int sgn[MAXFNARGS + 1];
types = (int *) (fn ? symbols[fn].mtext: NULL);
na = 0;
while (RPAREN != Token)
{
if (asgmnt(lv))
rvalue(lv);
if (comptype(lv[LVPRIM]))
{
error("struct/union passed by reference", NULL);
lv[LVPRIM] = pointerto(lv[LVPRIM]);
}
if (types && *types)
{
if (!typematch(*types, lv[LVPRIM]))
{
sprintf(msg, "wrong type in argument %d of call to: %%s", na + 1);
error(msg, symbols[fn].name);
}
types++;
}
if (na < MAXFNARGS)
sgn[na] = lv[LVPRIM], sgn[na + 1] = 0;
na++;
if (COMMA == Token)
Token = scan();
else
break;
}
if (fn && TFUNCTION == symbols[fn].type && !symbols[fn].mtext)
{
symbols[fn].mtext = galloc((na + 1) * sizeof(int));
memcpy(symbols[fn].mtext, sgn, (na + 1) * sizeof(int));
}
rparen();
genpushlit(na);
return na;
}
int deref(int p)
{
int y;
switch (p)
{
case INTPP:
return INTPTR;
case INTPTR:
return PINT;
case CHARPP:
return CHARPTR;
case CHARPTR:
return PCHAR;
case VOIDPP:
return VOIDPTR;
case VOIDPTR:
return PCHAR;
case FUNPTR:
return PCHAR;
}
y = p & ~STCMASK;
switch (p & STCMASK)
{
case STCPP:
return STCPTR | y;
case STCPTR:
return PSTRUCT | y;
case UNIPP:
return UNIPTR | y;
case UNIPTR:
return PUNION | y;
}
return -1;
}
static int indirection(int a, int *lv)
{
int p;
if (a)
rvalue(lv);
if (VOIDPTR == lv[LVPRIM])
error("dereferencing void pointer", NULL);
if ((p = deref(lv[LVPRIM])) < 0)
{
if (lv[LVSYM])
error("indirection through non-pointer: %s", symbols[lv[LVSYM]].name);
else
error("indirection through non-pointer", NULL);
p = lv[LVPRIM];
}
lv[LVPRIM] = p;
lv[LVSYM] = 0;
return p;
}
static void badcall(int *lv)
{
if (lv[LVSYM])
error("call of non-function: %s", symbols[lv[LVSYM]].name);
else
error("call of non-function", NULL);
}
static int argsok(int na, int nf)
{
return na == nf || nf < 0 && na >= -nf - 1;
}
static int stc_access(int *pprim, int ptr)
{
int y, p, a = 1;
p = *pprim & STCMASK;
if (IDENT != Token)
{
Token = scan();
error("struct/union member name expected after '%s'", ptr ? "->" : ".");
return PINT;
}
y = findmem(*pprim & ~STCMASK, Text);
if (0 == y)
error("struct/union has no such member: %s", Text);
if ((PSTRUCT == p || STCPTR == p) && symbols[y].value)
{
genlit(symbols[y].value);
genadd(PINT, PINT, 1);
}
Token = scan();
p = symbols[y].prims;
if (TARRAY == symbols[y].type)
{
p = pointerto(p);
a = 0;
}
*pprim = p;
return a;
}
/*
* postfix :=
* primary
* | postfix [ expr ]
* | postfix ( )
* | postfix ( fnargs )
* | postfix ++
* | postfix --
* | postfix . identifier
* | postfix -> identifier
*/
static int postfix(int *lv)
{
int lv2[LV], p, na;
int a = primary(lv);
for (;;)
{
switch (Token)
{
case LBRACK:
while (LBRACK == Token)
{
p = indirection(a, lv);
Token = scan();
if (expr(lv2))
rvalue(lv2);
if (PINT != lv2[LVPRIM])
error("non-integer subscript", NULL);
if (PINT == p || INTPTR == p || CHARPTR == p || VOIDPTR == p || STCPTR == (p & STCMASK) || UNIPTR == (p & STCMASK))
genscale();
genadd(PINT, PINT, 1);
rbrack();
lv[LVSYM] = 0;
a = 1;
}
break;
case LPAREN:
Token = scan();
na = fnargs(lv[LVSYM]);
if (lv[LVSYM] && TFUNCTION == symbols[lv[LVSYM]].type)
{
if (!argsok(na, symbols[lv[LVSYM]].size))
error("wrong number of arguments: %s", symbols[lv[LVSYM]].name);
gencall(lv[LVSYM]);
}
else
{
if (lv[LVPRIM] != FUNPTR)
badcall(lv);
clear(0);
rvalue(lv);
gencalr();
lv[LVPRIM] = PINT;
}
genstack((na + 1) * arch_intsize());
a = 0;
break;
case INCR:
case DECR:
if (a)
{
if (INCR == Token)
geninc(lv, 1, 0);
else
geninc(lv, 0, 0);
}
else
error("lvalue required before '%s'", Text);
Token = scan();
a = 0;
break;
case DOT:
Token = scan();
if (comptype(lv[LVPRIM]))
a = stc_access(&lv[LVPRIM], 0);
else
error("struct/union expected before '.'", NULL);
break;
case ARROW:
Token = scan();
if (a)
rvalue(lv);
p = lv[LVPRIM] & STCMASK;
if (p == STCPTR || p == UNIPTR)
a = stc_access(&lv[LVPRIM], 1);
else
error("struct/union pointer expected before '->'", NULL);
lv[LVSYM] = 0;
break;
default:
return a;
}
}
}
void comp_size(void)
{
int k, y, lv[LV];
if (CHAR == Token || INT == Token || VOID == Token || STRUCT == Token || UNION == Token)
{
switch (Token)
{
case CHAR:
k = CHARSIZE;
break;
case INT:
k = arch_intsize();
break;
case STRUCT:
case UNION:
k = primtype(Token, NULL);
k = objsize(k, TVARIABLE, 1);
break;
}
Token = scan();
if (STAR == Token)
{
k = arch_pointersize();
Token = scan();
if (STAR == Token)
Token = scan();
}
else if (0 == k)
{
error("sizeof(void) is unknown", NULL);
}
}
else
{
y = prefix(lv) ? lv[LVSYM] : 0;
k = y ? objsize(symbols[y].prims, symbols[y].type, symbols[y].size) : objsize(lv[LVPRIM], TVARIABLE, 1);
if (0 == k)
error("cannot compute sizeof: %s", Text);
clear(1);
}
genlit(k);
}
/*
* prefix :=
* postfix
* | ++ prefix
* | -- prefix
* | & cast
* | * cast
* | + cast
* | - cast
* | ~ cast
* | ! cast
* | SIZEOF ( type )
* | SIZEOF ( type * )
* | SIZEOF ( type * * )
* | SIZEOF ( IDENT )
*
* type :=
* INT
* | CHAR
* | VOID
* | STRUCT IDENT
* | UNION IDENT
*/
static int prefix(int *lv)
{
int t, a;
switch (Token)
{
case INCR:
case DECR:
t = Token;
Token = scan();
if (prefix(lv))
{
if (INCR == t)
geninc(lv, 1, 1);
else
geninc(lv, 0, 1);
}
else
{
error("lvalue expected after '%s'", t == INCR ? "++" : "--");
}
return 0;
case STAR:
Token = scan();
a = cast(lv);
indirection(a, lv);
return 1;
case PLUS:
Token = scan();
if (cast(lv))
rvalue(lv);
if (!inttype(lv[LVPRIM]))
error("bad operand to unary '+'", NULL);
return 0;
case MINUS:
Token = scan();
if (cast(lv))
rvalue(lv);
if (!inttype(lv[LVPRIM]))
error("bad operand to unary '-'", NULL);
genneg();
return 0;
case TILDE:
Token = scan();
if (cast(lv))
rvalue(lv);
if (!inttype(lv[LVPRIM]))
error("bad operand to '~'", NULL);
gennot();
return 0;
case XMARK:
Token = scan();