ref: 4dbb99f478d68eaeea4c043a839454cb807c2c7d
dir: /sys/src/cmd/cc/pgen.c/
#include "gc.h"
void
codgen(Node *n, Node *nn)
{
Prog *sp;
Node *n1, nod, nod1;
cursafe = 0;
curarg = 0;
maxargsafe = 0;
hasdoubled = 0;
/*
* isolate name
*/
for(n1 = nn;; n1 = n1->left) {
if(n1 == Z) {
diag(nn, "cant find function name");
return;
}
if(n1->op == ONAME)
break;
}
nearln = nn->lineno;
gpseudo(ATEXT, n1->sym, nodconst(stkoff));
sp = p;
if(typecmplx[thisfn->link->etype]) {
if(nodret == Z) {
nodret = new(ONAME, Z, Z);
nodret->sym = slookup(".ret");
nodret->class = CPARAM;
nodret->type = types[TIND];
nodret->etype = TIND;
nodret = new(OIND, nodret, Z);
}
n1 = nodret->left;
if(n1->type == T || n1->type->link != thisfn->link) {
n1->type = typ(TIND, thisfn->link);
n1->etype = n1->type->etype;
nodret = new(OIND, n1, Z);
complex(nodret);
}
}
/*
* isolate first argument
*/
if(REGARG >= 0) {
if(typecmplx[thisfn->link->etype]) {
nod1 = *nodret->left;
nodreg(&nod, &nod1, REGARG);
gmove(&nod, &nod1);
} else
if(firstarg && typeword[firstargtype->etype]) {
nod1 = znode;
nod1.op = ONAME;
nod1.sym = firstarg;
nod1.type = firstargtype;
nod1.class = CPARAM;
nod1.xoffset = align(0, firstargtype, Aarg1);
nod1.etype = firstargtype->etype;
xcom(&nod1);
nodreg(&nod, &nod1, REGARG);
gmove(&nod, &nod1);
}
}
canreach = 1;
warnreach = 1;
gen(n);
if(canreach && thisfn->link->etype != TVOID){
if(debug['B'])
warn(Z, "no return at end of function: %s", n1->sym->name);
else
diag(Z, "no return at end of function: %s", n1->sym->name);
}
noretval(3);
gbranch(ORETURN);
if(!debug['N'] || debug['R'] || debug['P'])
regopt(sp);
if(thechar=='6' || thechar=='7' || thechar=='9' || hasdoubled) /* [sic] */
maxargsafe = round(maxargsafe, 8);
sp->to.offset += maxargsafe;
}
void
supgen(Node *n)
{
int owarn;
long spc;
Prog *sp;
if(n == Z)
return;
suppress++;
owarn = warnreach;
warnreach = 0;
spc = pc;
sp = lastp;
gen(n);
lastp = sp;
pc = spc;
sp->link = nil;
suppress--;
warnreach = owarn;
}
Node*
uncomma(Node *n)
{
while(n != Z && n->op == OCOMMA) {
cgen(n->left, Z);
n = n->right;
}
return n;
}
void
gen(Node *n)
{
Node *l, nod, rn;
Prog *sp, *spc, *spb;
Case *cn;
long sbc, scc;
int snbreak, sncontin;
int f, o, oldreach;
loop:
if(n == Z)
return;
nearln = n->lineno;
o = n->op;
if(debug['G'])
if(o != OLIST)
print("%L %O\n", nearln, o);
if(!canreach) {
switch(o) {
case OLABEL:
case OCASE:
case OLIST:
case OCOMMA:
case OBREAK:
case OFOR:
case OWHILE:
case ODWHILE:
/* all handled specially - see switch body below */
break;
default:
if(warnreach) {
warn(n, "unreachable code %O", o);
warnreach = 0;
}
}
}
switch(o) {
default:
complex(n);
cgen(n, Z);
break;
case OFUNC:
complex(n);
cgen(n, Z);
if(n->type == nil || (n->type->garb & GNORET) == 0)
break;
canreach = 0;
warnreach = !suppress;
/* existing assumption that branches are at least two jumps */
scc = pc;
gbranch(OGOTO);
patch(p, pc);
gbranch(OGOTO);
patch(p, scc);
break;
case OLIST:
case OCOMMA:
gen(n->left);
rloop:
n = n->right;
goto loop;
case ORETURN:
canreach = 0;
warnreach = !suppress;
complex(n);
if(n->type == T)
break;
l = uncomma(n->left);
if(l == Z) {
noretval(3);
gbranch(ORETURN);
break;
}
if(typecmplx[n->type->etype]) {
nod = znode;
nod.op = OAS;
nod.left = nodret;
nod.right = l;
nod.type = n->type;
nod.complex = l->complex;
cgen(&nod, Z);
noretval(3);
gbranch(ORETURN);
break;
}
if(newvlongcode && !typefd[n->type->etype]){
regret(&rn, n);
regfree(&rn);
nod = znode;
nod.op = OAS;
nod.left = &rn;
nod.right = l;
nod.type = n->type;
nod.complex = l->complex;
cgen(&nod, Z);
noretval(2);
gbranch(ORETURN);
break;
}
regret(&nod, n);
cgen(l, &nod);
regfree(&nod);
if(typefd[n->type->etype])
noretval(1);
else
noretval(2);
gbranch(ORETURN);
break;
case OLABEL:
canreach = 1;
l = n->left;
if(l) {
l->pc = pc;
if(l->label)
patch(l->label, pc);
}
gbranch(OGOTO); /* prevent self reference in reg */
patch(p, pc);
goto rloop;
case OGOTO:
canreach = 0;
warnreach = !suppress;
n = n->left;
if(n == Z)
return;
if(n->complex == 0) {
diag(Z, "label undefined: %s", n->sym->name);
return;
}
if(suppress)
return;
gbranch(OGOTO);
if(n->pc) {
patch(p, n->pc);
return;
}
if(n->label)
patch(n->label, pc-1);
n->label = p;
return;
case OCASE:
canreach = 1;
l = n->left;
if(cases == C)
diag(n, "case/default outside a switch");
if(l == Z) {
casf();
cases->val = 0;
cases->def = 1;
cases->label = pc;
cases->isv = 0;
goto rloop;
}
complex(l);
if(l->type == T)
goto rloop;
if(l->op != OCONST || !typeswitch[l->type->etype]) {
diag(n, "case expression must be integer constant");
goto rloop;
}
casf();
cases->val = l->vconst;
cases->def = 0;
cases->label = pc;
cases->isv = typev[l->type->etype];
goto rloop;
case OSWITCH:
l = n->left;
complex(l);
if(l->type == T)
break;
if(!typeswitch[l->type->etype]) {
diag(n, "switch expression must be integer");
break;
}
gbranch(OGOTO); /* entry */
sp = p;
cn = cases;
cases = C;
casf();
sbc = breakpc;
breakpc = pc;
snbreak = nbreak;
nbreak = 0;
gbranch(OGOTO);
spb = p;
gen(n->right); /* body */
if(canreach){
gbranch(OGOTO);
patch(p, breakpc);
nbreak++;
}
patch(sp, pc);
regalloc(&nod, l, Z);
/* always signed */
if(typev[l->type->etype])
nod.type = types[TVLONG];
else
nod.type = types[TLONG];
cgen(l, &nod);
doswit(&nod);
regfree(&nod);
patch(spb, pc);
cases = cn;
breakpc = sbc;
canreach = nbreak!=0;
if(canreach == 0)
warnreach = !suppress;
nbreak = snbreak;
break;
case OWHILE:
case ODWHILE:
l = n->left;
gbranch(OGOTO); /* entry */
sp = p;
scc = continpc;
continpc = pc;
gbranch(OGOTO);
spc = p;
sbc = breakpc;
breakpc = pc;
snbreak = nbreak;
nbreak = 0;
gbranch(OGOTO);
spb = p;
patch(spc, pc);
if(n->op == OWHILE)
patch(sp, pc);
bcomplex(l, Z); /* test */
patch(p, breakpc);
if(l->op != OCONST || vconst(l) == 0)
nbreak++;
if(n->op == ODWHILE)
patch(sp, pc);
gen(n->right); /* body */
gbranch(OGOTO);
patch(p, continpc);
patch(spb, pc);
continpc = scc;
breakpc = sbc;
canreach = nbreak!=0;
if(canreach == 0)
warnreach = !suppress;
nbreak = snbreak;
break;
case OFOR:
l = n->left;
if(!canreach && l->right->left && warnreach) {
warn(n, "unreachable code FOR");
warnreach = 0;
}
gen(l->right->left); /* init */
gbranch(OGOTO); /* entry */
sp = p;
/*
* if there are no incoming labels in the
* body and the top's not reachable, warn
*/
if(!canreach && warnreach && deadheads(n)) {
warn(n, "unreachable code %O", o);
warnreach = 0;
}
scc = continpc;
continpc = pc;
gbranch(OGOTO);
spc = p;
sbc = breakpc;
breakpc = pc;
snbreak = nbreak;
nbreak = 0;
sncontin = ncontin;
ncontin = 0;
gbranch(OGOTO);
spb = p;
patch(spc, pc);
gen(l->right->right); /* inc */
patch(sp, pc);
if(l->left != Z) { /* test */
bcomplex(l->left, Z);
patch(p, breakpc);
if(l->left->op != OCONST || vconst(l->left) == 0)
nbreak++;
}
canreach = 1;
gen(n->right); /* body */
if(canreach){
gbranch(OGOTO);
patch(p, continpc);
ncontin++;
}
if(!ncontin && l->right->right && warnreach) {
warn(l->right->right, "unreachable FOR inc");
warnreach = 0;
}
patch(spb, pc);
continpc = scc;
breakpc = sbc;
canreach = nbreak!=0;
if(canreach == 0)
warnreach = !suppress;
nbreak = snbreak;
ncontin = sncontin;
break;
case OCONTINUE:
if(continpc < 0) {
diag(n, "continue not in a loop");
break;
}
gbranch(OGOTO);
patch(p, continpc);
ncontin++;
canreach = 0;
warnreach = !suppress;
break;
case OBREAK:
if(breakpc < 0) {
diag(n, "break not in a loop");
break;
}
/*
* Don't complain about unreachable break statements.
* There are breaks hidden in yacc's output and some people
* write return; break; in their switch statements out of habit.
* However, don't confuse the analysis by inserting an
* unreachable reference to breakpc either.
*/
if(!canreach)
break;
gbranch(OGOTO);
patch(p, breakpc);
nbreak++;
canreach = 0;
warnreach = !suppress;
break;
case OIF:
l = n->left;
if(bcomplex(l, n->right)) {
if(typefd[l->type->etype])
f = !l->fconst;
else
f = !l->vconst;
if(debug['c'])
print("%L const if %s\n", nearln, f ? "false" : "true");
if(f) {
canreach = 1;
supgen(n->right->left);
oldreach = canreach;
canreach = 1;
gen(n->right->right);
/*
* treat constant ifs as regular ifs for
* reachability warnings.
*/
if(!canreach && oldreach && debug['w'] < 2)
warnreach = 0;
}
else {
canreach = 1;
gen(n->right->left);
oldreach = canreach;
canreach = 1;
supgen(n->right->right);
/*
* treat constant ifs as regular ifs for
* reachability warnings.
*/
if(!oldreach && canreach && debug['w'] < 2)
warnreach = 0;
canreach = oldreach;
}
}
else {
sp = p;
canreach = 1;
if(n->right->left != Z)
gen(n->right->left);
oldreach = canreach;
canreach = 1;
if(n->right->right != Z) {
gbranch(OGOTO);
patch(sp, pc);
sp = p;
gen(n->right->right);
}
patch(sp, pc);
canreach = canreach || oldreach;
if(canreach == 0)
warnreach = !suppress;
}
break;
case OSET:
case OUSED:
usedset(n->left, o);
break;
}
}
void
usedset(Node *n, int o)
{
if(n->op == OLIST) {
usedset(n->left, o);
usedset(n->right, o);
return;
}
complex(n);
switch(n->op) {
case OADDR: /* volatile */
gins(ANOP, n, Z);
break;
case ONAME:
if(o == OSET)
gins(ANOP, Z, n);
else
gins(ANOP, n, Z);
break;
}
}
int
bcomplex(Node *n, Node *c)
{
Node *b, nod;
complex(n);
if(n->type != T)
if(tcompat(n, T, n->type, tnot))
n->type = T;
if(n->type == T) {
gbranch(OGOTO);
return 0;
}
if(c != Z && n->op == OCONST && deadheads(c))
return 1;
/* this is not quite right yet, so ignore it for now */
if(0 && newvlongcode && typev[n->type->etype] && machcap(Z)) {
b = &nod;
b->op = ONE;
b->left = n;
b->right = new(0, Z, Z);
*b->right = *nodconst(0);
b->right->type = n->type;
b->type = types[TLONG];
cgen(b, Z);
return 0;
}
bool64(n);
boolgen(n, 1, Z);
return 0;
}