Show stmt.c syntax highlighted
#include "c.h"
#define SWSIZE 512
#define den(i,j) ((j-buckets[i]+1.0)/(v[j]-v[buckets[i]]+1))
struct code codehead = { Start };
Code codelist = &codehead;
float density = 0.5;
Table stmtlabs;
static int foldcond(Tree e1, Tree e2);
static void caselabel(Swtch, long, int);
static void cmp(int, Symbol, long, int);
static Tree conditional(int);
static void dostmt(int, Swtch, int);
static int equal(Symbol, Symbol);
static void forstmt(int, Swtch, int);
static void ifstmt(int, int, Swtch, int);
static Symbol localaddr(Tree);
static void stmtlabel(void);
static void swstmt(int, int, int);
static void whilestmt(int, Swtch, int);
Code code(int kind) {
Code cp;
if (!reachable(kind))
warning("unreachable code\n");
NEW(cp, FUNC);
cp->kind = kind;
cp->prev = codelist;
cp->next = NULL;
codelist->next = cp;
codelist = cp;
return cp;
}
int reachable(int kind) {
Code cp;
if (kind > Start) {
Code cp;
for (cp = codelist; cp->kind < Label; )
cp = cp->prev;
if (cp->kind == Jump || cp->kind == Switch)
return 0;
}
return 1;
}
void addlocal(Symbol p) {
if (!p->defined) {
code(Local)->u.var = p;
p->defined = 1;
p->scope = level;
}
}
void definept(Coordinate *p) {
Code cp = code(Defpoint);
cp->u.point.src = p ? *p : src;
cp->u.point.point = npoints;
if (ncalled > 0) {
int n = findcount(cp->u.point.src.file,
cp->u.point.src.x, cp->u.point.src.y);
if (n > 0)
refinc = (float)n/ncalled;
}
if (glevel > 2) locus(identifiers, &cp->u.point.src);
if (events.points && reachable(Gen))
{
Tree e = NULL;
apply(events.points, &cp->u.point.src, &e);
if (e)
listnodes(e, 0, 0);
}
}
void statement(int loop, Swtch swp, int lev) {
float ref = refinc;
if (Aflag >= 2 && lev == 15)
warning("more than 15 levels of nested statements\n");
switch (t) {
case IF: ifstmt(genlabel(2), loop, swp, lev + 1);
break;
case WHILE: whilestmt(genlabel(3), swp, lev + 1); break;
case DO: dostmt(genlabel(3), swp, lev + 1); expect(';');
break;
case FOR: forstmt(genlabel(4), swp, lev + 1);
break;
case BREAK: walk(NULL, 0, 0);
definept(NULL);
if (swp && swp->lab > loop)
branch(swp->lab + 1);
else if (loop)
branch(loop + 2);
else
error("illegal break statement\n");
t = gettok(); expect(';');
break;
case CONTINUE: walk(NULL, 0, 0);
definept(NULL);
if (loop)
branch(loop + 1);
else
error("illegal continue statement\n");
t = gettok(); expect(';');
break;
case SWITCH: swstmt(loop, genlabel(2), lev + 1);
break;
case CASE: {
int lab = genlabel(1);
if (swp == NULL)
error("illegal case label\n");
definelab(lab);
while (t == CASE) {
static char stop[] = { IF, ID, 0 };
Tree p;
t = gettok();
p = constexpr(0);
if (generic(p->op) == CNST && isint(p->type)) {
if (swp) {
needconst++;
p = cast(p, swp->sym->type);
if (p->type->op == UNSIGNED)
p->u.v.i = extend(p->u.v.u, p->type);
needconst--;
caselabel(swp, p->u.v.i, lab);
}
} else
error("case label must be a constant integer expression\n");
test(':', stop);
}
statement(loop, swp, lev);
} break;
case DEFAULT: if (swp == NULL)
error("illegal default label\n");
else if (swp->deflab)
error("extra default label\n");
else {
swp->deflab = findlabel(swp->lab);
definelab(swp->deflab->u.l.label);
}
t = gettok();
expect(':');
statement(loop, swp, lev); break;
case RETURN: {
Type rty = freturn(cfunc->type);
t = gettok();
definept(NULL);
if (t != ';')
if (rty == voidtype) {
error("extraneous return value\n");
expr(0);
retcode(NULL);
} else
retcode(expr(0));
else {
if (rty != voidtype)
warning("missing return value\n");
retcode(NULL);
}
branch(cfunc->u.f.label);
} expect(';');
break;
case '{': compound(loop, swp, lev + 1); break;
case ';': definept(NULL); t = gettok(); break;
case GOTO: walk(NULL, 0, 0);
definept(NULL);
t = gettok();
if (t == ID) {
Symbol p = lookup(token, stmtlabs);
if (p == NULL) {
p = install(token, &stmtlabs, 0, FUNC);
p->scope = LABELS;
p->u.l.label = genlabel(1);
p->src = src;
}
use(p, src);
branch(p->u.l.label);
t = gettok();
} else
error("missing label in goto\n"); expect(';');
break;
case ID: if (getchr() == ':') {
stmtlabel();
statement(loop, swp, lev);
break;
}
default: definept(NULL);
if (kind[t] != ID) {
error("unrecognized statement\n");
t = gettok();
} else {
Tree e = expr0(0);
listnodes(e, 0, 0);
if (nodecount == 0 || nodecount > 200)
walk(NULL, 0, 0);
else if (glevel) walk(NULL, 0, 0);
deallocate(STMT);
} expect(';');
break;
}
if (kind[t] != IF && kind[t] != ID
&& t != '}' && t != EOI) {
static char stop[] = { IF, ID, '}', 0 };
error("illegal statement termination\n");
skipto(0, stop);
}
refinc = ref;
}
static void ifstmt(int lab, int loop, Swtch swp, int lev) {
t = gettok();
expect('(');
definept(NULL);
walk(conditional(')'), 0, lab);
refinc /= 2.0;
statement(loop, swp, lev);
if (t == ELSE) {
branch(lab + 1);
t = gettok();
definelab(lab);
statement(loop, swp, lev);
if (findlabel(lab + 1)->ref)
definelab(lab + 1);
} else
definelab(lab);
}
static Tree conditional(int tok) {
Tree p = expr(tok);
if (Aflag > 1 && isfunc(p->type))
warning("%s used in a conditional expression\n",
funcname(p));
return cond(p);
}
static void stmtlabel(void) {
Symbol p = lookup(token, stmtlabs);
if (p == NULL) {
p = install(token, &stmtlabs, 0, FUNC);
p->scope = LABELS;
p->u.l.label = genlabel(1);
p->src = src;
}
if (p->defined)
error("redefinition of label `%s' previously defined at %w\n", p->name, &p->src);
p->defined = 1;
definelab(p->u.l.label);
t = gettok();
expect(':');
}
static void forstmt(int lab, Swtch swp, int lev) {
int once = 0;
Tree e1 = NULL, e2 = NULL, e3 = NULL;
Coordinate pt2, pt3;
t = gettok();
expect('(');
definept(NULL);
if (kind[t] == ID)
e1 = texpr(expr0, ';', FUNC);
else
expect(';');
walk(e1, 0, 0);
pt2 = src;
refinc *= 10.0;
if (kind[t] == ID)
e2 = texpr(conditional, ';', FUNC);
else
expect(';');
pt3 = src;
if (kind[t] == ID)
e3 = texpr(expr0, ')', FUNC);
else {
static char stop[] = { IF, ID, '}', 0 };
test(')', stop);
}
if (e2) {
once = foldcond(e1, e2);
if (!once)
branch(lab + 3);
}
definelab(lab);
statement(lab, swp, lev);
definelab(lab + 1);
definept(&pt3);
if (e3)
walk(e3, 0, 0);
if (e2) {
if (!once)
definelab(lab + 3);
definept(&pt2);
walk(e2, lab, 0);
} else {
definept(&pt2);
branch(lab);
}
if (findlabel(lab + 2)->ref)
definelab(lab + 2);
}
static void swstmt(int loop, int lab, int lev) {
Tree e;
struct swtch sw;
Code head, tail;
t = gettok();
expect('(');
definept(NULL);
e = expr(')');
if (!isint(e->type)) {
error("illegal type `%t' in switch expression\n",
e->type);
e = retype(e, inttype);
}
e = cast(e, promote(e->type));
if (generic(e->op) == INDIR && isaddrop(e->kids[0]->op)
&& e->kids[0]->u.sym->type == e->type
&& !isvolatile(e->kids[0]->u.sym->type)) {
sw.sym = e->kids[0]->u.sym;
walk(NULL, 0, 0);
} else {
sw.sym = genident(REGISTER, e->type, level);
addlocal(sw.sym);
walk(asgn(sw.sym, e), 0, 0);
}
head = code(Switch);
sw.lab = lab;
sw.deflab = NULL;
sw.ncases = 0;
sw.size = SWSIZE;
sw.values = newarray(SWSIZE, sizeof *sw.values, FUNC);
sw.labels = newarray(SWSIZE, sizeof *sw.labels, FUNC);
refinc /= 10.0;
statement(loop, &sw, lev);
if (sw.deflab == NULL) {
sw.deflab = findlabel(lab);
definelab(lab);
if (sw.ncases == 0)
warning("switch statement with no cases\n");
}
if (findlabel(lab + 1)->ref)
definelab(lab + 1);
tail = codelist;
codelist = head->prev;
codelist->next = head->prev = NULL;
if (sw.ncases > 0)
swgen(&sw);
branch(lab);
head->next->prev = codelist;
codelist->next = head->next;
codelist = tail;
}
static void caselabel(Swtch swp, long val, int lab) {
int k;
if (swp->ncases >= swp->size)
{
long *vals = swp->values;
Symbol *labs = swp->labels;
swp->size *= 2;
swp->values = newarray(swp->size, sizeof *swp->values, FUNC);
swp->labels = newarray(swp->size, sizeof *swp->labels, FUNC);
for (k = 0; k < swp->ncases; k++) {
swp->values[k] = vals[k];
swp->labels[k] = labs[k];
}
}
k = swp->ncases;
for ( ; k > 0 && swp->values[k-1] >= val; k--) {
swp->values[k] = swp->values[k-1];
swp->labels[k] = swp->labels[k-1];
}
if (k < swp->ncases && swp->values[k] == val)
error("duplicate case label `%d'\n", val);
swp->values[k] = val;
swp->labels[k] = findlabel(lab);
++swp->ncases;
if (Aflag >= 2 && swp->ncases == 258)
warning("more than 257 cases in a switch\n");
}
void swgen(Swtch swp) {
int *buckets, k, n;
long *v = swp->values;
buckets = newarray(swp->ncases + 1,
sizeof *buckets, FUNC);
for (n = k = 0; k < swp->ncases; k++, n++) {
buckets[n] = k;
while (n > 0 && den(n-1, k) >= density)
n--;
}
buckets[n] = swp->ncases;
swcode(swp, buckets, 0, n - 1);
}
void swcode(Swtch swp, int b[], int lb, int ub) {
int hilab, lolab, l, u, k = (lb + ub)/2;
long *v = swp->values;
if (k > lb && k < ub) {
lolab = genlabel(1);
hilab = genlabel(1);
} else if (k > lb) {
lolab = genlabel(1);
hilab = swp->deflab->u.l.label;
} else if (k < ub) {
lolab = swp->deflab->u.l.label;
hilab = genlabel(1);
} else
lolab = hilab = swp->deflab->u.l.label;
l = b[k];
u = b[k+1] - 1;
if (u - l + 1 <= 3)
{
int i;
for (i = l; i <= u; i++)
cmp(EQ, swp->sym, v[i], swp->labels[i]->u.l.label);
if (k > lb && k < ub)
cmp(GT, swp->sym, v[u], hilab);
else if (k > lb)
cmp(GT, swp->sym, v[u], hilab);
else if (k < ub)
cmp(LT, swp->sym, v[l], lolab);
else
assert(lolab == hilab),
branch(lolab);
walk(NULL, 0, 0);
}
else {
Tree e;
Type ty = signedint(swp->sym->type);
Symbol table = genident(STATIC,
array(voidptype, u - l + 1, 0), GLOBAL);
(*IR->defsymbol)(table);
if (!isunsigned(swp->sym->type) || v[l] != 0)
cmp(LT, swp->sym, v[l], lolab);
cmp(GT, swp->sym, v[u], hilab);
e = (*optree['-'])(SUB, cast(idtree(swp->sym), ty), cnsttree(ty, v[l]));
if (e->type->size < unsignedptr->size)
e = cast(e, unsignedlong);
walk(tree(JUMP, voidtype,
rvalue((*optree['+'])(ADD, pointer(idtree(table)), e)), NULL),
0, 0);
code(Switch);
codelist->u.swtch.table = table;
codelist->u.swtch.sym = swp->sym;
codelist->u.swtch.deflab = swp->deflab;
codelist->u.swtch.size = u - l + 1;
codelist->u.swtch.values = &v[l];
codelist->u.swtch.labels = &swp->labels[l];
if (v[u] - v[l] + 1 >= 10000)
warning("switch generates a huge table\n");
}
if (k > lb) {
assert(lolab != swp->deflab->u.l.label);
definelab(lolab);
swcode(swp, b, lb, k - 1);
}
if (k < ub) {
assert(hilab != swp->deflab->u.l.label);
definelab(hilab);
swcode(swp, b, k + 1, ub);
}
}
static void cmp(int op, Symbol p, long n, int lab) {
Type ty = signedint(p->type);
listnodes(eqtree(op,
cast(idtree(p), ty),
cnsttree(ty, n)),
lab, 0);
}
void retcode(Tree p) {
Type ty;
if (p == NULL) {
if (events.returns)
apply(events.returns, cfunc, NULL);
return;
}
p = pointer(p);
ty = assign(freturn(cfunc->type), p);
if (ty == NULL) {
error("illegal return type; found `%t' expected `%t'\n",
p->type, freturn(cfunc->type));
return;
}
p = cast(p, ty);
if (retv)
{
if (iscallb(p))
p = tree(RIGHT, p->type,
tree(CALL+B, p->type,
p->kids[0]->kids[0], idtree(retv)),
rvalue(idtree(retv)));
else
p = asgntree(ASGN, rvalue(idtree(retv)), p);
walk(p, 0, 0);
if (events.returns)
apply(events.returns, cfunc, rvalue(idtree(retv)));
return;
}
if (events.returns)
{
Symbol t1 = genident(AUTO, p->type, level);
addlocal(t1);
walk(asgn(t1, p), 0, 0);
apply(events.returns, cfunc, idtree(t1));
p = idtree(t1);
}
if (!isfloat(p->type))
p = cast(p, promote(p->type));
if (isptr(p->type))
{
Symbol q = localaddr(p);
if (q && (q->computed || q->generated))
warning("pointer to a %s is an illegal return value\n",
q->scope == PARAM ? "parameter" : "local");
else if (q)
warning("pointer to %s `%s' is an illegal return value\n",
q->scope == PARAM ? "parameter" : "local", q->name);
}
walk(tree(mkop(RET,p->type), p->type, p, NULL), 0, 0);
}
void definelab(int lab) {
Code cp;
Symbol p = findlabel(lab);
assert(lab);
walk(NULL, 0, 0);
code(Label)->u.forest = newnode(LABEL+V, NULL, NULL, p);
for (cp = codelist->prev; cp->kind <= Label; )
cp = cp->prev;
while ( cp->kind == Jump
&& cp->u.forest->kids[0]
&& specific(cp->u.forest->kids[0]->op) == ADDRG+P
&& cp->u.forest->kids[0]->syms[0] == p) {
assert(cp->u.forest->kids[0]->syms[0]->u.l.label == lab);
p->ref--;
assert(cp->next);
assert(cp->prev);
cp->prev->next = cp->next;
cp->next->prev = cp->prev;
cp = cp->prev;
while (cp->kind <= Label)
cp = cp->prev;
}
}
Node jump(int lab) {
Symbol p = findlabel(lab);
p->ref++;
return newnode(JUMP+V, newnode(ADDRG+ttob(voidptype), NULL, NULL, p),
NULL, NULL);
}
void branch(int lab) {
Code cp;
Symbol p = findlabel(lab);
assert(lab);
walk(NULL, 0, 0);
code(Label)->u.forest = jump(lab);
for (cp = codelist->prev; cp->kind < Label; )
cp = cp->prev;
while ( cp->kind == Label
&& cp->u.forest->op == LABEL+V
&& !equal(cp->u.forest->syms[0], p)) {
equatelab(cp->u.forest->syms[0], p);
assert(cp->next);
assert(cp->prev);
cp->prev->next = cp->next;
cp->next->prev = cp->prev;
cp = cp->prev;
while (cp->kind < Label)
cp = cp->prev;
}
if (cp->kind == Jump || cp->kind == Switch) {
p->ref--;
codelist->prev->next = NULL;
codelist = codelist->prev;
} else {
codelist->kind = Jump;
if (cp->kind == Label
&& cp->u.forest->op == LABEL+V
&& equal(cp->u.forest->syms[0], p))
warning("source code specifies an infinite loop");
}
}
void equatelab(Symbol old, Symbol new) {
assert(old->u.l.equatedto == NULL);
old->u.l.equatedto = new;
new->ref++;
}
static int equal(Symbol lprime, Symbol dst) {
assert(dst && lprime);
for ( ; dst; dst = dst->u.l.equatedto)
if (lprime == dst)
return 1;
return 0;
}
/* dostmt - do statement while ( expression ) */
static void dostmt(int lab, Swtch swp, int lev) {
refinc *= 10.0;
t = gettok();
definelab(lab);
statement(lab, swp, lev);
definelab(lab + 1);
expect(WHILE);
expect('(');
definept(NULL);
walk(conditional(')'), lab, 0);
if (findlabel(lab + 2)->ref)
definelab(lab + 2);
}
/* foldcond - check if initial test in for(e1;e2;e3) S is necessary */
static int foldcond(Tree e1, Tree e2) {
int op = generic(e2->op);
Symbol v;
if (e1 == 0 || e2 == 0)
return 0;
if (generic(e1->op) == ASGN && isaddrop(e1->kids[0]->op)
&& generic(e1->kids[1]->op) == CNST) {
v = e1->kids[0]->u.sym;
e1 = e1->kids[1];
} else
return 0;
if ((op==LE || op==LT || op==EQ || op==NE || op==GT || op==GE)
&& generic(e2->kids[0]->op) == INDIR
&& e2->kids[0]->kids[0]->u.sym == v
&& e2->kids[1]->op == e1->op) {
e1 = simplify(op, e2->type, e1, e2->kids[1]);
if (e1->op == CNST+I)
return e1->u.v.i;
}
return 0;
}
/* localaddr - returns q if p yields the address of local/parameter q; otherwise returns 0 */
static Symbol localaddr(Tree p) {
if (p == NULL)
return NULL;
switch (generic(p->op)) {
case INDIR: case CALL: case ARG:
return NULL;
case ADDRL: case ADDRF:
return p->u.sym;
case RIGHT: case ASGN:
if (p->kids[1])
return localaddr(p->kids[1]);
return localaddr(p->kids[0]);
case COND: {
Symbol q;
assert(p->kids[1] && p->kids[1]->op == RIGHT);
if ((q = localaddr(p->kids[1]->kids[0])) != NULL)
return q;
return localaddr(p->kids[1]->kids[1]);
}
default: {
Symbol q;
if (p->kids[0] && (q = localaddr(p->kids[0])) != NULL)
return q;
return localaddr(p->kids[1]);
}
}
}
/* whilestmt - while ( expression ) statement */
static void whilestmt(int lab, Swtch swp, int lev) {
Coordinate pt;
Tree e;
refinc *= 10.0;
t = gettok();
expect('(');
walk(NULL, 0, 0);
pt = src;
e = texpr(conditional, ')', FUNC);
branch(lab + 1);
definelab(lab);
statement(lab, swp, lev);
definelab(lab + 1);
definept(&pt);
walk(e, lab, 0);
if (findlabel(lab + 2)->ref)
definelab(lab + 2);
}
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