ref: f2227c6d0370cfc5c2b1472475fe9564dbb05e25
dir: /src/cmd/cc/cc1/stmt.c/
#include <stddef.h>
#include <setjmp.h>
#include <scc/cstd.h>
#include <scc/scc.h>
#include "cc1.h"
#define NEGATE 1
#define NONEGATE 0
Symbol *curfun;
static void stmt(Symbol *lbreak, Symbol *lcont, Switch *lswitch);
static void
label(void)
{
Symbol *sym;
switch (yytoken) {
case IDEN:
case TYPEIDEN:
sym = lookup(NS_LABEL, yytext, ALLOC);
if (sym->flags & SDEFINED)
error("label '%s' already defined", yytext);
if ((sym->flags & SDECLARED) == 0)
sym = install(NS_LABEL, sym);
sym->flags |= SDEFINED;
emit(OLABEL, sym);
next();
expect(':');
break;
default:
unexpected();
}
}
static void
stmtexp(Symbol *lbreak, Symbol *lcont, Switch *lswitch)
{
Node *np;
if (accept(';'))
return;
if (yytoken == IDEN && ahead() == ':') {
label();
stmt(lbreak, lcont, lswitch);
return;
}
np = expr();
if ((np->flags & NEFFECT) == 0)
warn("expression without side effects");
emit(OEXPR, np);
expect(';');
}
static Node *
condition(int neg)
{
Node *np;
expect('(');
np = condexpr(neg);
expect(')');
return np;
}
static void
While(Symbol *lbreak, Symbol *lcont, Switch *lswitch)
{
Symbol *begin;
Node *np;
begin = newlabel();
lcont = newlabel();
lbreak = newlabel();
expect(WHILE);
np = condition(NONEGATE);
emit(OJUMP, lcont);
emit(OBLOOP, NULL);
emit(OLABEL, begin);
stmt(lbreak, lcont, lswitch);
emit(OLABEL, lcont);
emit(OBRANCH, begin);
emit(OEXPR, np);
emit(OELOOP, NULL);
emit(OLABEL, lbreak);
}
static void
For(Symbol *lbreak, Symbol *lcont, Switch *lswitch)
{
Symbol *begin, *cond;
Node *econd, *einc;
begin = newlabel();
lcont = newlabel();
cond = newlabel();
lbreak = newlabel();
pushctx();
expect(FOR);
expect('(');
switch (yytoken) {
case TYPE:
case TYPEIDEN:
case TQUALIFIER:
case SCLASS:
decl();
break;
default:
emit(OEXPR, expr());
case ';':
expect(';');
break;
}
econd = (yytoken != ';') ? condexpr(NONEGATE) : NULL;
expect(';');
einc = (yytoken != ')') ? expr() : NULL;
expect(')');
emit(OJUMP, cond);
emit(OBLOOP, NULL);
emit(OLABEL, begin);
stmt(lbreak, lcont, lswitch);
emit(OLABEL, lcont);
emit(OEXPR, einc);
emit(OLABEL, cond);
emit((econd) ? OBRANCH : OJUMP, begin);
emit(OEXPR, econd);
emit(OELOOP, NULL);
emit(OLABEL, lbreak);
popctx();
}
static void
Dowhile(Symbol *lbreak, Symbol *lcont, Switch *lswitch)
{
Symbol *begin;
Node *np;
begin = newlabel();
lcont = newlabel();
lbreak = newlabel();
expect(DO);
emit(OBLOOP, NULL);
emit(OLABEL, begin);
stmt(lbreak, lcont, lswitch);
expect(WHILE);
np = condition(NONEGATE);
emit(OLABEL, lcont);
emit(OBRANCH, begin);
emit(OEXPR, np);
emit(OELOOP, NULL);
emit(OLABEL, lbreak);
}
static void
Return(Symbol *lbreak, Symbol *lcont, Switch *lswitch)
{
Node *np;
Type *tp = curfun->type->type;
expect(RETURN);
np = (yytoken != ';') ? decay(expr()) : NULL;
expect(';');
if (!np) {
if (tp != voidtype)
warn("function returning non void returns no value");
tp = voidtype;
} else if (np->type != tp) {
if (tp == voidtype)
warn("function returning void returns a value");
else if ((np = convert(np, tp, 0)) == NULL)
errorp("incorrect type in return");
}
emit(ORET, NULL);
emit(OEXPR, np);
}
static void
Break(Symbol *lbreak, Symbol *lcont, Switch *lswitch)
{
expect(BREAK);
if (!lbreak) {
errorp("break statement not within loop or switch");
} else {
emit(OJUMP, lbreak);
expect(';');
}
}
static void
Continue(Symbol *lbreak, Symbol *lcont, Switch *lswitch)
{
expect(CONTINUE);
if (!lcont) {
errorp("continue statement not within loop");
} else {
emit(OJUMP, lcont);
expect(';');
}
}
static void
Goto(Symbol *lbreak, Symbol *lcont, Switch *lswitch)
{
Symbol *sym;
namespace = NS_LABEL;
next();
namespace = NS_IDEN;
if (yytoken != IDEN)
unexpected();
sym = yylval.sym;
if ((sym->flags & SDECLARED) == 0)
sym = install(NS_LABEL, sym);
sym->flags |= SUSED;
emit(OJUMP, sym);
next();
expect(';');
}
static void
Swtch(Symbol *obr, Symbol *lcont, Switch *osw)
{
Switch sw = {0};
Node *cond;
Symbol *lbreak;
expect(SWITCH);
expect ('(');
if ((cond = convert(expr(), inttype, 0)) == NULL) {
errorp("incorrect type in switch statement");
cond = constnode(zero);
}
expect (')');
lbreak = newlabel();
emit(OBSWITCH, NULL);
emit(OEXPR, cond);
stmt(lbreak, lcont, &sw);
emit(OESWITCH, lbreak);
emit(OLABEL, lbreak);
}
static void
Case(Symbol *lbreak, Symbol *lcont, Switch *sw)
{
Node *np;
Symbol *label;
expect(CASE);
if ((np = constexpr()) == NULL)
errorp("case label does not reduce to an integer constant");
if (!sw) {
errorp("case label not within a switch statement");
} else if (sw->nr >= 0 && ++sw->nr == NR_SWITCH) {
errorp("too many case labels for a switch statement");
sw->nr = -1;
}
expect(':');
label = newlabel();
emit(OCASE, label);
emit(OEXPR, np);
emit(OLABEL, label);
stmt(lbreak, lcont, sw);
}
static void
Default(Symbol *lbreak, Symbol *lcont, Switch *sw)
{
Symbol *label = newlabel();
if (sw->hasdef)
errorp("multiple default labels in one switch");
sw->hasdef = 1;
expect(DEFAULT);
expect(':');
emit(ODEFAULT, label);
emit(OLABEL, label);
stmt(lbreak, lcont, sw);
}
static void
If(Symbol *lbreak, Symbol *lcont, Switch *lswitch)
{
Symbol *end, *lelse;
Node *np;
lelse = newlabel();
expect(IF);
np = condition(NEGATE);
emit(OBRANCH, lelse);
emit(OEXPR, np);
stmt(lbreak, lcont, lswitch);
if (accept(ELSE)) {
end = newlabel();
emit(OJUMP, end);
emit(OLABEL, lelse);
stmt(lbreak, lcont, lswitch);
emit(OLABEL, end);
} else {
emit(OLABEL, lelse);
}
}
static void
blockit(Symbol *lbreak, Symbol *lcont, Switch *lswitch)
{
switch (yytoken) {
case TYPEIDEN:
if (ahead() == ':')
goto parse_stmt;
case TYPE:
case TQUALIFIER:
case SCLASS:
decl();
return;
default:
parse_stmt:
stmt(lbreak, lcont, lswitch);
}
}
void
compound(Symbol *lbreak, Symbol *lcont, Switch *lswitch)
{
static int nested;
pushctx();
expect('{');
if (nested == NR_BLOCK)
error("too many nesting levels of compound statements");
++nested;
for (;;) {
if (yytoken == '}')
break;
blockit(lbreak, lcont, lswitch);
}
--nested;
popctx();
expect('}');
}
static void
stmt(Symbol *lbreak, Symbol *lcont, Switch *lswitch)
{
void (*fun)(Symbol *, Symbol *, Switch *);
switch (yytoken) {
case '{': fun = compound; break;
case RETURN: fun = Return; break;
case WHILE: fun = While; break;
case FOR: fun = For; break;
case DO: fun = Dowhile; break;
case IF: fun = If; break;
case BREAK: fun = Break; break;
case CONTINUE: fun = Continue; break;
case GOTO: fun = Goto; break;
case SWITCH: fun = Swtch; break;
case CASE: fun = Case; break;
case DEFAULT: fun = Default; break;
default: fun = stmtexp; break;
}
(*fun)(lbreak, lcont, lswitch);
}