typedef struct Com Com;

#include "cc.h"

typedef struct Com Com;
struct Com
{
int n;
Node *t[500];
};

int compar(Node*, int);
static void comma(Node*);
static Node* commas(Com*, Node*);

void
complex(Node *n)
{

if(n == Z)
return;

nearln = n->lineno;
if(debug['t'])
if(n->op != OCONST)
prtree(n, "pre complex");
if(tcom(n))
return;
if(debug['y'] || 1)
comma(n);
if(debug['t'])
if(n->op != OCONST)
prtree(n, "t complex");
ccom(n);
if(debug['t'])
if(n->op != OCONST)
prtree(n, "c complex");
acom(n);
if(debug['t'])
if(n->op != OCONST)
prtree(n, "a complex");
xcom(n);
if(debug['t'])
if(n->op != OCONST)
prtree(n, "x complex");
}

/*
* evaluate types
* evaluate lvalues (addable == 1)
*/
enum
{
ADDROF = 1<<0,
CASTOF = 1<<1,
ADDROP = 1<<2,
};

int
tcom(Node *n)
{

return tcomo(n, ADDROF);
}

int
tcomo(Node *n, int f)
{
Node *l, *r;
Type *t;
int o;

if(n == Z) {
diag(Z, "Z in tcom");
errorexit();
}
n->addable = 0;
l = n->left;
r = n->right;

switch(n->op) {
default:
diag(n, "unknown op in type complex: %O", n->op);
goto bad;

case ODOTDOT:
/*
* tcom has already been called on this subtree
*/
*n = *n->left;
if(n->type == T)
goto bad;
break;

case OCAST:
if(n->type == T)
break;
if(n->type->width == types[TLONG]->width) {
if(tcomo(l, ADDROF|CASTOF))
goto bad;
} else
if(tcom(l))
goto bad;
if(isfunct(n))
break;
if(tcompat(n, l->type, n->type, tcast))
goto bad;
break;

case ORETURN:
if(l == Z) {
if(n->type->etype != TVOID)
warn(n, "null return of a typed function");
break;
}
if(tcom(l))
goto bad;
typeext(n->type, l);
if(tcompat(n, n->type, l->type, tasign))
break;
constas(n, n->type, l->type);
if(!sametype(n->type, l->type)) {
l = new1(OCAST, l, Z);
l->type = n->type;
n->left = l;
}
break;

case OASI: /* same as as, but no test for const */
n->op = OAS;
o = tcom(l);
if(o | tcom(r))
goto bad;

typeext(l->type, r);
if(tlvalue(l) || tcompat(n, l->type, r->type, tasign))
goto bad;
if(!sametype(l->type, r->type)) {
r = new1(OCAST, r, Z);
r->type = l->type;
n->right = r;
}
n->type = l->type;
break;

case OAS:
o = tcom(l);
if(o | tcom(r))
goto bad;
if(tlvalue(l))
goto bad;
if(isfunct(n))
break;
typeext(l->type, r);
if(tcompat(n, l->type, r->type, tasign))
goto bad;
constas(n, l->type, r->type);
if(!sametype(l->type, r->type)) {
r = new1(OCAST, r, Z);
r->type = l->type;
n->right = r;
}
n->type = l->type;
break;

case OASADD:
case OASSUB:
o = tcom(l);
if(o | tcom(r))
goto bad;
if(tlvalue(l))
goto bad;
if(isfunct(n))
break;
typeext1(l->type, r);
if(tcompat(n, l->type, r->type, tasadd))
goto bad;
constas(n, l->type, r->type);
t = l->type;
arith(n, 0);
while(n->left->op == OCAST)
n->left = n->left->left;
if(!mixedasop(t, n->type)) {
if(!sametype(t, n->type)) {
r = new1(OCAST, n->right, Z);
r->type = t;
n->right = r;
n->type = t;
}
} else
n->type = t;
break;

case OASMUL:
case OASLMUL:
case OASDIV:
case OASLDIV:
o = tcom(l);
if(o | tcom(r))
goto bad;
if(tlvalue(l))
goto bad;
if(isfunct(n))
break;
typeext1(l->type, r);
if(tcompat(n, l->type, r->type, tmul))
goto bad;
constas(n, l->type, r->type);
t = l->type;
arith(n, 0);
while(n->left->op == OCAST)
n->left = n->left->left;
if(!mixedasop(t, n->type)) {
if(!sametype(t, n->type)) {
r = new1(OCAST, n->right, Z);
r->type = t;
n->right = r;
n->type = t;
}
} else {
n->type = t;
break;
}
if(typeu[n->type->etype]) {
if(n->op == OASDIV)
n->op = OASLDIV;
if(n->op == OASMUL)
n->op = OASLMUL;
}
break;

case OASLSHR:
case OASASHR:
case OASASHL:
o = tcom(l);
if(o | tcom(r))
goto bad;
if(tlvalue(l))
goto bad;
if(isfunct(n))
break;
if(tcompat(n, l->type, r->type, tand))
goto bad;
n->type = l->type;
n->right = new1(OCAST, r, Z);
n->right->type = types[TINT];
if(typeu[n->type->etype]) {
if(n->op == OASASHR)
n->op = OASLSHR;
}
break;

case OASMOD:
case OASLMOD:
case OASOR:
case OASAND:
case OASXOR:
o = tcom(l);
if(o | tcom(r))
goto bad;
if(tlvalue(l))
goto bad;
if(isfunct(n))
break;
if(tcompat(n, l->type, r->type, tand))
goto bad;
t = l->type;
arith(n, 0);
while(n->left->op == OCAST)
n->left = n->left->left;
if(!mixedasop(t, n->type)) {
if(!sametype(t, n->type)) {
r = new1(OCAST, n->right, Z);
r->type = t;
n->right = r;
n->type = t;
}
}else
n->type = t;
if(typeu[n->type->etype]) {
if(n->op == OASMOD)
n->op = OASLMOD;
}
break;

case OPREINC:
case OPREDEC:
case OPOSTINC:
case OPOSTDEC:
if(tcom(l))
goto bad;
if(tlvalue(l))
goto bad;
if(isfunct(n))
break;
if(tcompat(n, l->type, types[TINT], tadd))
goto bad;
n->type = l->type;
if(n->type->etype == TIND)
if(n->type->link->width < 1) {
snap(n->type->link);
if(n->type->link->width < 1)
diag(n, "inc/dec of a void pointer");
}
break;

case OEQ:
case ONE:
o = tcom(l);
if(o | tcom(r))
goto bad;
if(isfunct(n))
break;
typeext(l->type, r);
typeext(r->type, l);
if(tcompat(n, l->type, r->type, trel))
goto bad;
arith(n, 0);
n->type = types[TINT];
break;

case OLT:
case OGE:
case OGT:
case OLE:
o = tcom(l);
if(o | tcom(r))
goto bad;
if(isfunct(n))
break;
typeext1(l->type, r);
typeext1(r->type, l);
if(tcompat(n, l->type, r->type, trel))
goto bad;
arith(n, 0);
if(typeu[n->type->etype])
n->op = logrel[relindex(n->op)];
n->type = types[TINT];
break;

case OCOND:
o = tcom(l);
o |= tcom(r->left);
if(o | tcom(r->right))
goto bad;
if(r->right->type->etype == TIND && zpconst(r->left)) {
r->type = r->right->type;
r->left->type = r->right->type;
r->left->vconst = 0;
}
if(r->left->type->etype == TIND && zpconst(r->right)) {
r->type = r->left->type;
r->right->type = r->left->type;
r->right->vconst = 0;
}
if(sametype(r->right->type, r->left->type)) {
r->type = r->right->type;
n->type = r->type;
break;
}
if(tcompat(r, r->left->type, r->right->type, trel))
goto bad;
arith(r, 0);
n->type = r->type;
break;

case OADD:
o = tcom(l);
if(o | tcom(r))
goto bad;
if(isfunct(n))
break;
if(tcompat(n, l->type, r->type, tadd))
goto bad;
arith(n, 1);
break;

case OSUB:
o = tcom(l);
if(o | tcom(r))
goto bad;
if(isfunct(n))
break;
if(tcompat(n, l->type, r->type, tsub))
goto bad;
arith(n, 1);
break;

case OMUL:
case OLMUL:
case ODIV:
case OLDIV:
o = tcom(l);
if(o | tcom(r))
goto bad;
if(isfunct(n))
break;
if(tcompat(n, l->type, r->type, tmul))
goto bad;
arith(n, 1);
if(typeu[n->type->etype]) {
if(n->op == ODIV)
n->op = OLDIV;
if(n->op == OMUL)
n->op = OLMUL;
}
break;

case OLSHR:
case OASHL:
case OASHR:
o = tcom(l);
if(o | tcom(r))
goto bad;
if(isfunct(n))
break;
if(tcompat(n, l->type, r->type, tand))
goto bad;
n->right = Z;
arith(n, 1);
n->right = new1(OCAST, r, Z);
n->right->type = types[TINT];
if(typeu[n->type->etype])
if(n->op == OASHR)
n->op = OLSHR;
break;

case OAND:
case OOR:
case OXOR:
o = tcom(l);
if(o | tcom(r))
goto bad;
if(isfunct(n))
break;
if(tcompat(n, l->type, r->type, tand))
goto bad;
arith(n, 1);
break;

case OMOD:
case OLMOD:
o = tcom(l);
if(o | tcom(r))
goto bad;
if(isfunct(n))
break;
if(tcompat(n, l->type, r->type, tand))
goto bad;
arith(n, 1);
if(typeu[n->type->etype])
n->op = OLMOD;
break;

case OPOS:
if(tcom(l))
goto bad;
if(isfunct(n))
break;

r = l;
l = new(OCONST, Z, Z);
l->vconst = 0;
l->type = types[TINT];
n->op = OADD;
n->right = r;
n->left = l;

if(tcom(l))
goto bad;
if(tcompat(n, l->type, r->type, tsub))
goto bad;
arith(n, 1);
break;

case ONEG:
if(tcom(l))
goto bad;
if(isfunct(n))
break;

if(!machcap(n)) {
r = l;
l = new(OCONST, Z, Z);
l->vconst = 0;
l->type = types[TINT];
n->op = OSUB;
n->right = r;
n->left = l;

if(tcom(l))
goto bad;
if(tcompat(n, l->type, r->type, tsub))
goto bad;
}
arith(n, 1);
break;

case OCOM:
if(tcom(l))
goto bad;
if(isfunct(n))
break;

if(!machcap(n)) {
r = l;
l = new(OCONST, Z, Z);
l->vconst = -1;
l->type = types[TINT];
n->op = OXOR;
n->right = r;
n->left = l;

if(tcom(l))
goto bad;
if(tcompat(n, l->type, r->type, tand))
goto bad;
}
arith(n, 1);
break;

case ONOT:
if(tcom(l))
goto bad;
if(isfunct(n))
break;
if(tcompat(n, T, l->type, tnot))
goto bad;
n->type = types[TINT];
break;

case OANDAND:
case OOROR:
o = tcom(l);
if(o | tcom(r))
goto bad;
if(tcompat(n, T, l->type, tnot) |
tcompat(n, T, r->type, tnot))
goto bad;
n->type = types[TINT];
break;

case OCOMMA:
o = tcom(l);
if(o | tcom(r))
goto bad;
n->type = r->type;
break;

case OSIGN: /* extension signof(type) returns a hash */
if(l != Z) {
if(l->op != OSTRING && l->op != OLSTRING)
if(tcomo(l, 0))
goto bad;
if(l->op == OBIT) {
diag(n, "signof bitfield");
goto bad;
}
n->type = l->type;
}
if(n->type == T)
goto bad;
if(n->type->width < 0) {
diag(n, "signof undefined type");
goto bad;
}
n->op = OCONST;
n->left = Z;
n->right = Z;
n->vconst = convvtox(signature(n->type), TULONG);
n->type = types[TULONG];
break;

case OSIZE:
if(l != Z) {
if(l->op != OSTRING && l->op != OLSTRING)
if(tcomo(l, 0))
goto bad;
if(l->op == OBIT) {
diag(n, "sizeof bitfield");
goto bad;
}
n->type = l->type;
}
if(n->type == T)
goto bad;
if(n->type->width <= 0) {
diag(n, "sizeof undefined type");
goto bad;
}
if(n->type->etype == TFUNC) {
diag(n, "sizeof function");
goto bad;
}
n->op = OCONST;
n->left = Z;
n->right = Z;
n->vconst = convvtox(n->type->width, TINT);
n->type = types[TINT];
break;

case OFUNC:
o = tcomo(l, 0);
if(o)
goto bad;
if(l->type->etype == TIND && l->type->link->etype == TFUNC) {
l = new1(OIND, l, Z);
l->type = l->left->type->link;
n->left = l;
}
if(tcompat(n, T, l->type, tfunct))
goto bad;
if(o | tcoma(l, r, l->type->down, 1))
goto bad;
n->type = l->type->link;
if(!debug['B']){
if(l->type->down == T){
if(!debug['T'])
nerrors--;
diag(n, "function not declared: %F", l);
}else if(l->type->down->etype == TOLD) {
nerrors--;
diag(n, "function args not checked: %F", l);
}
}
dpcheck(n);
break;

case ONAME:
if(n->type == T) {
diag(n, "name not declared: %F", n);
goto bad;
}
if(n->type->etype == TENUM) {
n->op = OCONST;
n->type = n->sym->tenum;
if(!typefd[n->type->etype])
n->vconst = n->sym->vconst;
else
n->fconst = n->sym->fconst;
break;
}
n->addable = 1;
if(n->class == CEXREG) {
n->op = OREGISTER;
if(thechar == '8')
n->op = OEXREG;
n->reg = n->sym->offset;
n->xoffset = 0;
break;
}
break;

case OLSTRING:
if(n->type->link != types[TRUNE]) {
o = outstring(0, 0);
while(o & 3) {
Rune str[1] = {0};
outlstring(str, sizeof(Rune));
o = outlstring(0, 0);
}
}
n->op = ONAME;
n->xoffset = outlstring(n->rstring, n->type->width);
n->addable = 1;
break;

case OSTRING:
if(n->type->link != types[TCHAR]) {
o = outstring(0, 0);
while(o & 3) {
outstring("", 1);
o = outstring(0, 0);
}
}
n->op = ONAME;
n->xoffset = outstring(n->cstring, n->type->width);
n->addable = 1;
break;

case OCONST:
break;

case ODOT:
if(tcom(l))
goto bad;
if(tcompat(n, T, l->type, tdot))
goto bad;
if(tcomd(n))
goto bad;
break;

case OADDR:
if(tcomo(l, ADDROP))
goto bad;
if(tlvalue(l))
goto bad;
if(l->type->nbits) {
diag(n, "address of a bit field");
goto bad;
}
if(l->op == OREGISTER) {
diag(n, "address of a register");
goto bad;
}
n->type = typ(TIND, l->type);
n->type->width = types[TIND]->width;
break;

case OIND:
if(tcom(l))
goto bad;
if(tcompat(n, T, l->type, tindir))
goto bad;
n->type = l->type->link;
n->addable = 1;
break;

case OSTRUCT:
if(tcomx(n))
goto bad;
break;
}
t = n->type;
if(t == T)
goto bad;
if(t->width < 0) {
snap(t);
if(t->width < 0) {
if(typesu[t->etype] && t->tag)
diag(n, "structure not fully declared %s", t->tag->name);
else
diag(n, "structure not fully declared");
goto bad;
}
}
if(typeaf[t->etype]) {
if(f & ADDROF)
goto addaddr;
if(f & ADDROP)
warn(n, "address of array/func ignored");
}
return 0;

addaddr:
if(tlvalue(n))
goto bad;
l = new1(OXXX, Z, Z);
*l = *n;
n->op = OADDR;
if(l->type->etype == TARRAY)
l->type = l->type->link;
n->left = l;
n->right = Z;
n->addable = 0;
n->type = typ(TIND, l->type);
n->type->width = types[TIND]->width;
return 0;

bad:
n->type = T;
return 1;
}

int
tcoma(Node *l, Node *n, Type *t, int f)
{
Node *n1;
int o;

if(t != T)
if(t->etype == TOLD || t->etype == TDOT) /* .../old in prototype */
t = T;
if(n == Z) {
if(t != T && !sametype(t, types[TVOID])) {
diag(n, "not enough function arguments: %F", l);
return 1;
}
return 0;
}
if(n->op == OLIST) {
o = tcoma(l, n->left, t, 0);
if(t != T) {
t = t->down;
if(t == T)
t = types[TVOID];
}
return o | tcoma(l, n->right, t, 1);
}
if(f && t != T)
tcoma(l, Z, t->down, 0);
if(tcom(n) || tcompat(n, T, n->type, targ))
return 1;
if(sametype(t, types[TVOID])) {
diag(n, "too many function arguments: %F", l);
return 1;
}
if(t != T) {
typeext(t, n);
if(stcompat(nodproto, t, n->type, tasign)) {
diag(l, "argument prototype mismatch \"%T\" for \"%T\": %F",
n->type, t, l);
return 1;
}
switch(t->etype) {
case TCHAR:
case TSHORT:
t = types[TINT];
break;

case TUCHAR:
case TUSHORT:
t = types[TUINT];
break;
}
} else
switch(n->type->etype)
{
case TCHAR:
case TSHORT:
t = types[TINT];
break;

case TUCHAR:
case TUSHORT:
t = types[TUINT];
break;

case TFLOAT:
t = types[TDOUBLE];
}
if(t != T && !sametype(t, n->type)) {
n1 = new1(OXXX, Z, Z);
*n1 = *n;
n->op = OCAST;
n->left = n1;
n->right = Z;
n->type = t;
n->addable = 0;
}
return 0;
}

int
tcomd(Node *n)
{
Type *t;
long o;

o = 0;
t = dotsearch(n->sym, n->left->type->link, n, &o);
if(t == T) {
diag(n, "not a member of struct/union: %F", n);
return 1;
}
makedot(n, t, o);
return 0;
}

int
tcomx(Node *n)
{
Type *t;
Node *l, *r, **ar, **al;
int e;

e = 0;
if(n->type->etype != TSTRUCT) {
diag(n, "constructor must be a structure");
return 1;
}
l = invert(n->left);
n->left = l;
al = &n->left;
for(t = n->type->link; t != T; t = t->down) {
if(l == Z) {
diag(n, "constructor list too short");
return 1;
}
if(l->op == OLIST) {
r = l->left;
ar = &l->left;
al = &l->right;
l = l->right;
} else {
r = l;
ar = al;
l = Z;
}
if(tcom(r))
e++;
typeext(t, r);
if(tcompat(n, t, r->type, tasign))
e++;
constas(n, t, r->type);
if(!e && !sametype(t, r->type)) {
r = new1(OCAST, r, Z);
r->type = t;
*ar = r;
}
}
if(l != Z) {
diag(n, "constructor list too long");
return 1;
}
return e;
}

int
tlvalue(Node *n)
{

if(!n->addable) {
diag(n, "not an l-value");
return 1;
}
return 0;
}

/*
* hoist comma operators out of expressions
* (a,b) OP c => (a, b OP c)
* OP(a,b) => (a, OP b)
* a OP (b,c) => (b, a OP c)
*/

static Node*
comargs(Com *com, Node *n)
{
if(n != Z && n->op == OLIST){
n->left = comargs(com, n->left);
n->right = comargs(com, n->right);
}
return commas(com, n);
}

static Node*
commas(Com *com, Node *n)
{
Node *t;

if(n == Z)
return n;
switch(n->op){
case OREGISTER:
case OINDREG:
case OCONST:
case ONAME:
case OSTRING:
/* leaf */
return n;

case OCOMMA:
t = commas(com, n->left);
if(com->n >= nelem(com->t))
fatal(n, "comma list overflow");
com->t[com->n++] = t;
return commas(com, n->right);

case OFUNC:
n->left = commas(com, n->left);
n->right = comargs(com, n->right);
return n;

case OCOND:
n->left = commas(com, n->left);
comma(n->right->left);
comma(n->right->right);
return n;

case OANDAND:
case OOROR:
n->left = commas(com, n->left);
comma(n->right);
return n;

case ORETURN:
comma(n->left);
return n;
}
n->left = commas(com, n->left);
if(n->right != Z)
n->right = commas(com, n->right);
return n;
}

static void
comma(Node *n)
{
Com com;
Node *nn;

com.n = 0;
nn = commas(&com, n);
if(com.n > 0){
if(debug['y'])print("n=%d\n", com.n);
if(debug['y']) prtree(nn, "res");
if(nn != n)
*n = *nn;
while(com.n > 0){
if(debug['y']) prtree(com.t[com.n-1], "tree");
nn = new1(OXXX, Z, Z);
*nn = *n;
n->op = OCOMMA;
n->type = nn->type;
n->left = com.t[--com.n];
n->right = nn;
n->lineno = n->left->lineno;
}
if(debug['y']) prtree(n, "final");
}else if(n != nn)
fatal(n, "odd tree");
}

/*
* general rewrite
* (IND(ADDR x)) ==> x
* (ADDR(IND x)) ==> x
* remove some zero operands
* remove no op casts
* evaluate constants
* Note: ccom may be called on the same node
* multiple times.
*/
void
ccom(Node *n)
{
Node *l, *r;
int t;

loop:
if(n == Z)
return;
l = n->left;
r = n->right;
switch(n->op) {

case OAS:
case OASXOR:
case OASAND:
case OASOR:
case OASMOD:
case OASLMOD:
case OASLSHR:
case OASASHR:
case OASASHL:
case OASDIV:
case OASLDIV:
case OASMUL:
case OASLMUL:
case OASSUB:
case OASADD:
ccom(l);
ccom(r);
if(n->op == OASMOD || n->op == OASLMOD || n->op == OASDIV || n->op == OASLDIV)
if(r->op == OCONST){
if(!typefd[r->type->etype] && r->vconst == 0) {
if(n->op == OASMOD || n->op == OASLMOD)
diag(n, "modulo by zero");
else
diag(n, "divide by zero");
r->vconst = ~0;
}
if(typefd[r->type->etype] && r->fconst == 0.) {
if(n->op == OASMOD || n->op == OASLMOD)
diag(n, "modulo by zero");
else
diag(n, "divide by zero");
r->fconst = 1e10;
}
}
if(n->op == OASLSHR || n->op == OASASHR || n->op == OASASHL)
if(r->op == OCONST) {
t = n->type->width * 8; /* bits per byte */
if(r->vconst >= t || r->vconst < 0)
warn(n, "stupid shift: %lld", r->vconst);
}
break;

case OCAST:
if(n->type == types[TVOID] && !side(l)){
n->left = Z;
n->type = T;
}
if(n->left == Z)
break;
if(castucom(n))
warn(n, "32-bit unsigned complement zero-extended to 64 bits");
ccom(l);
if(l->type == T){
n->left = Z;
n->type = T;
break;
}
if(l->op == OCONST) {
evconst(n);
if(n->op == OCONST)
break;
}
if(nocast(l->type, n->type) &&
(!typefd[l->type->etype] || typeu[l->type->etype] && typeu[n->type->etype])) {
l->type = n->type;
*n = *l;
}
break;

case OCOND:
ccom(l);
ccom(r);
if(l->op == OCONST)
if(vconst(l) == 0)
*n = *r->right;
else
*n = *r->left;
break;

case OREGISTER:
case OINDREG:
case OCONST:
case ONAME:
break;

case OADDR:
ccom(l);
l->etype = TVOID;
if(l->op == OIND) {
l->left->type = n->type;
*n = *l->left;
break;
}
goto common;

case OIND:
ccom(l);
if(l->op == OADDR) {
l->left->type = n->type;
*n = *l->left;
break;
}
goto common;

case OEQ:
case ONE:

case OLE:
case OGE:
case OLT:
case OGT:

case OLS:
case OHS:
case OLO:
case OHI:
ccom(l);
ccom(r);
if(compar(n, 0) || compar(n, 1))
break;
relcon(l, r);
relcon(r, l);
goto common;

case OASHR:
case OASHL:
case OLSHR:
ccom(l);
if(vconst(l) == 0 && !side(r)) {
*n = *l;
break;
}
ccom(r);
if(vconst(r) == 0) {
*n = *l;
break;
}
if(r->op == OCONST) {
t = n->type->width * 8; /* bits per byte */
if(r->vconst >= t || r->vconst <= -t)
warn(n, "stupid shift: %lld", r->vconst);
}
goto common;

case OMUL:
case OLMUL:
ccom(l);
t = vconst(l);
if(t == 0 && !side(r)) {
*n = *l;
break;
}
if(t == 1) {
*n = *r;
goto loop;
}
ccom(r);
t = vconst(r);
if(t == 0 && !side(l)) {
*n = *r;
break;
}
if(t == 1) {
*n = *l;
break;
}
goto common;

case ODIV:
case OLDIV:
ccom(l);
if(vconst(l) == 0 && !side(r)) {
*n = *l;
break;
}
ccom(r);
t = vconst(r);
if(t == 0) {
diag(n, "divide check");
*n = *r;
break;
}
if(t == 1) {
*n = *l;
break;
}
goto common;

case OSUB:
ccom(r);
if(r->op == OCONST) {
if(typefd[r->type->etype]) {
n->op = OADD;
r->fconst = -r->fconst;
goto loop;
} else {
n->op = OADD;
r->vconst = -r->vconst;
goto loop;
}
}
ccom(l);
goto common;

case OXOR:
case OOR:
case OADD:
ccom(l);
if(vconst(l) == 0) {
*n = *r;
goto loop;
}
ccom(r);
if(vconst(r) == 0) {
*n = *l;
break;
}
goto commute;

case OAND:
ccom(l);
ccom(r);
if(vconst(l) == 0 && !side(r)) {
*n = *l;
break;
}
if(vconst(r) == 0 && !side(l)) {
*n = *r;
break;
}

commute:
/* look for commutative constant */
if(r->op == OCONST) {
if(l->op == n->op) {
if(l->left->op == OCONST) {
n->right = l->right;
l->right = r;
goto loop;
}
if(l->right->op == OCONST) {
n->right = l->left;
l->left = r;
goto loop;
}
}
}
if(l->op == OCONST) {
if(r->op == n->op) {
if(r->left->op == OCONST) {
n->left = r->right;
r->right = l;
goto loop;
}
if(r->right->op == OCONST) {
n->left = r->left;
r->left = l;
goto loop;
}
}
}
goto common;

case OANDAND:
ccom(l);
if(vconst(l) == 0) {
*n = *l;
break;
}
ccom(r);
goto common;

case OOROR:
ccom(l);
if(l->op == OCONST && l->vconst != 0) {
*n = *l;
n->vconst = 1;
break;
}
ccom(r);
goto common;

default:
if(l != Z)
ccom(l);
if(r != Z)
ccom(r);
common:
if(l != Z)
if(l->op != OCONST)
break;
if(r != Z)
if(r->op != OCONST)
break;
evconst(n);
}
}

/* OEQ, ONE, OLE, OLS, OLT, OLO, OGE, OHS, OGT, OHI */
static char *cmps[12] =
{
"==", "!=", "<=", "<=", "<", "<", ">=", ">=", ">", ">",
};

/* 128-bit numbers */
typedef struct Big Big;
struct Big
{
vlong a;
uvlong b;
};
static int
cmp(Big x, Big y)
{
if(x.a != y.a){
if(x.a < y.a)
return -1;
return 1;
}
if(x.b != y.b){
if(x.b < y.b)
return -1;
return 1;
}
return 0;
}
static Big
add(Big x, int y)
{
uvlong ob;

ob = x.b;
x.b += y;
if(y > 0 && x.b < ob)
x.a++;
if(y < 0 && x.b > ob)
x.a--;
return x;
}

Big
big(vlong a, uvlong b)
{
Big x;

x.a = a;
x.b = b;
return x;
}

int
compar(Node *n, int reverse)
{
Big lo, hi, x;
int op;
char xbuf[40], cmpbuf[50];
Node *l, *r;
Type *lt, *rt;

/*
* The point of this function is to diagnose comparisons
* that can never be true or that look misleading because
* of the `usual arithmetic conversions'. As an example
* of the latter, if x is a ulong, then if(x <= -1) really means
* if(x <= 0xFFFFFFFF), while if(x <= -1LL) really means
* what it says (but 8c compiles it wrong anyway).
*/

if(reverse){
r = n->left;
l = n->right;
op = comrel[relindex(n->op)];
}else{
l = n->left;
r = n->right;
op = n->op;
}

/*
* Skip over left casts to find out the original expression range.
*/
while(l->op == OCAST){
lt = l->type;
rt = l->left->type;
if(lt == T || rt == T)
return 0;
if(lt->width < rt->width)
break;
if(lt->width == rt->width && ((lt->etype ^ rt->etype) & 1) != 0)
break;
l = l->left;
}
if(l->op == OCONST)
return 0;
lt = l->type;
if(lt == T || lt->etype == TXXX || lt->etype > TUVLONG)
return 0;

/*
* Skip over the right casts to find the on-screen value.
*/
if(r->op != OCONST)
return 0;
while(r->oldop == OCAST && !r->xcast)
r = r->left;
rt = r->type;
if(rt == T)
return 0;

x.b = r->vconst;
x.a = 0;
if((rt->etype&1) && r->vconst < 0) /* signed negative */
x.a = ~0ULL;

if(lt->etype & 1){
/* signed */
lo = big(~0ULL, -(1LL<<(lt->width*8-1)));
hi = big(0, (1LL<<(lt->width*8-1))-1);
} else {
/* unsigned */
lo = big(0, 0);
if(lt->width == 8)
hi = big(0, ~0ULL);
else
hi = big(0, (1LL<<(lt->width*8))-1);
}

switch(op){
case OLT:
case OLO:
case OGE:
case OHS:
if(cmp(x, lo) <= 0)
goto useless;
if(cmp(x, add(hi, 1)) >= 0)
goto useless;
break;
case OLE:
case OLS:
case OGT:
case OHI:
if(cmp(x, add(lo, -1)) <= 0)
goto useless;
if(cmp(x, hi) >= 0)
goto useless;
break;
case OEQ:
case ONE:
/*
* Don't warn about comparisons if the expression
* is as wide as the value: the compiler-supplied casts
* will make both outcomes possible.
*/
if(lt->width >= rt->width && debug['w'] < 2)
return 0;
if(cmp(x, lo) < 0 || cmp(x, hi) > 0)
goto useless;
break;
}
return 0;

useless:
if((x.a==0 && x.b<=9) || (x.a==~0LL && x.b >= -9ULL))
snprint(xbuf, sizeof xbuf, "%lld", x.b);
else if(x.a == 0)
snprint(xbuf, sizeof xbuf, "%#llux", x.b);
else
snprint(xbuf, sizeof xbuf, "%#llx", x.b);
if(reverse)
snprint(cmpbuf, sizeof cmpbuf, "%s %s %T",
xbuf, cmps[relindex(n->op)], lt);
else
snprint(cmpbuf, sizeof cmpbuf, "%T %s %s",
lt, cmps[relindex(n->op)], xbuf);
if(debug['y']) prtree(n, "strange");
warn(n, "useless or misleading comparison: %s", cmpbuf);
return 0;
}