ref: c3ba64f6935322f09b6de5c2285544fd471c605d
dir: /sys/src/cmd/6c/sgen.c/
#include "gc.h"
void
noretval(int n)
{
if(n & 1) {
gins(ANOP, Z, Z);
p->to.type = REGRET;
}
if(n & 2) {
gins(ANOP, Z, Z);
p->to.type = FREGRET;
}
}
/* welcome to commute */
static void
commute(Node *n)
{
Node *l, *r;
l = n->left;
r = n->right;
if(r->complex > l->complex) {
n->left = r;
n->right = l;
}
}
void
indexshift(Node *n)
{
int g;
if(!typechlpv[n->type->etype])
return;
simplifyshift(n);
if(n->op == OASHL && n->right->op == OCONST){
g = vconst(n->right);
if(g >= 0 && g <= 3)
n->addable = 7;
}
}
/*
* calculate addressability as follows
* NAME ==> 10/11 name+value(SB/SP)
* REGISTER ==> 12 register
* CONST ==> 20 $value
* *(20) ==> 21 value
* &(10) ==> 13 $name+value(SB)
* &(11) ==> 1 $name+value(SP)
* (13) + (20) ==> 13 fold constants
* (1) + (20) ==> 1 fold constants
* *(13) ==> 10 back to name
* *(1) ==> 11 back to name
*
* (20) * (X) ==> 7 multiplier in indexing
* (X,7) + (13,1) ==> 8 adder in indexing (addresses)
* (8) ==> &9(OINDEX) index, almost addressable
*
* calculate complexity (number of registers)
*/
void
xcom(Node *n)
{
Node *l, *r;
int g;
if(n == Z)
return;
l = n->left;
r = n->right;
n->complex = 0;
n->addable = 0;
switch(n->op) {
case OCONST:
n->addable = 20;
break;
case ONAME:
n->addable = 10;
if(n->class == CPARAM || n->class == CAUTO)
n->addable = 11;
break;
case OREGISTER:
n->addable = 12;
break;
case OINDREG:
n->addable = 12;
break;
case OADDR:
xcom(l);
if(l->addable == 10)
n->addable = 13;
else
if(l->addable == 11)
n->addable = 1;
break;
case OADD:
xcom(l);
xcom(r);
if(n->type->etype != TIND &&
!(l->type->etype == TIND && r->type->etype == TIND))
break;
switch(r->addable) {
case 20:
switch(l->addable) {
case 1:
case 13:
commadd:
l->type = n->type;
*n = *l;
l = new(0, Z, Z);
*l = *(n->left);
l->xoffset += r->vconst;
n->left = l;
goto brk;
}
break;
case 1:
case 13:
case 10:
case 11:
/* l is the base, r is the index */
if(l->addable != 20)
n->addable = 8;
break;
}
switch(l->addable) {
case 20:
switch(r->addable) {
case 13:
case 1:
r = n->left;
l = n->right;
n->left = l;
n->right = r;
goto commadd;
}
break;
case 13:
case 1:
case 10:
case 11:
/* r is the base, l is the index */
if(r->addable != 20)
n->addable = 8;
break;
}
if(n->addable == 8 && !side(n)) {
indx(n);
l = new1(OINDEX, idx.basetree, idx.regtree);
l->scale = idx.scale;
l->addable = 9;
l->complex = l->right->complex;
if(l->complex == 0)
l->complex++;
l->type = l->left->type;
n->op = OADDR;
n->left = l;
n->right = Z;
n->addable = 8;
break;
}
break;
case OINDEX:
xcom(l);
xcom(r);
n->addable = 9;
break;
case OIND:
xcom(l);
if(l->op == OADDR) {
l = l->left;
l->type = n->type;
*n = *l;
return;
}
switch(l->addable) {
case 20:
n->addable = 21;
break;
case 1:
n->addable = 11;
break;
case 13:
n->addable = 10;
break;
}
break;
case OASHL:
xcom(l);
xcom(r);
indexshift(n);
break;
case OMUL:
case OLMUL:
xcom(l);
xcom(r);
g = vlog(l);
if(g >= 0) {
n->left = r;
n->right = l;
r = n->right;
}
g = vlog(r);
if(g >= 0) {
n->op = OASHL;
r->vconst = g;
r->type = types[TINT];
indexshift(n);
break;
}
commute(n);
break;
case OASLDIV:
xcom(l);
xcom(r);
g = vlog(r);
if(g >= 0) {
n->op = OASLSHR;
r->vconst = g;
r->type = types[TINT];
}
break;
case OLDIV:
xcom(l);
xcom(r);
g = vlog(r);
if(g >= 0) {
n->op = OLSHR;
r->vconst = g;
r->type = types[TINT];
indexshift(n);
break;
}
break;
case OASLMOD:
xcom(l);
xcom(r);
g = vlog(r);
if(g >= 0) {
n->op = OASAND;
r->vconst--;
}
break;
case OLMOD:
xcom(l);
xcom(r);
g = vlog(r);
if(g >= 0) {
n->op = OAND;
r->vconst--;
}
break;
case OASMUL:
case OASLMUL:
xcom(l);
xcom(r);
g = vlog(r);
if(g >= 0) {
n->op = OASASHL;
r->vconst = g;
}
break;
case OLSHR:
case OASHR:
xcom(l);
xcom(r);
indexshift(n);
break;
case OOR:
xcom(l);
xcom(r);
rolor(n);
break;
default:
if(l != Z)
xcom(l);
if(r != Z)
xcom(r);
break;
}
brk:
if(n->addable >= 10)
return;
l = n->left;
r = n->right;
if(l != Z)
n->complex = l->complex;
if(r != Z) {
if(r->complex == n->complex)
n->complex = r->complex+1;
else
if(r->complex > n->complex)
n->complex = r->complex;
}
if(n->complex == 0)
n->complex++;
switch(n->op) {
case OFUNC:
n->complex = FNX;
break;
case OCAST:
if(l != Z && l->type->etype == TUVLONG && typefd[n->type->etype])
n->complex += 2;
break;
case OLMOD:
case OMOD:
case OLMUL:
case OLDIV:
case OMUL:
case ODIV:
case OASLMUL:
case OASLDIV:
case OASLMOD:
case OASMUL:
case OASDIV:
case OASMOD:
if(r->complex >= l->complex) {
n->complex = l->complex + 3;
if(r->complex > n->complex)
n->complex = r->complex;
} else {
n->complex = r->complex + 3;
if(l->complex > n->complex)
n->complex = l->complex;
}
break;
case OROL:
case OLSHR:
case OASHL:
case OASHR:
case OASLSHR:
case OASASHL:
case OASASHR:
if(r->complex >= l->complex) {
n->complex = l->complex + 2;
if(r->complex > n->complex)
n->complex = r->complex;
} else {
n->complex = r->complex + 2;
if(l->complex > n->complex)
n->complex = l->complex;
}
break;
case OADD:
case OXOR:
case OAND:
case OOR:
/*
* immediate operators, make const on right
*/
if(l->op == OCONST) {
n->left = r;
n->right = l;
}
break;
case OEQ:
case ONE:
case OLE:
case OLT:
case OGE:
case OGT:
case OHI:
case OHS:
case OLO:
case OLS:
/*
* compare operators, make const on left
*/
if(r->op == OCONST) {
n->left = r;
n->right = l;
n->op = invrel[relindex(n->op)];
}
break;
}
}
void
indx(Node *n)
{
Node *l, *r;
if(debug['x'])
prtree(n, "indx");
l = n->left;
r = n->right;
if(l->addable == 1 || l->addable == 13 || r->complex > l->complex) {
n->right = l;
n->left = r;
l = r;
r = n->right;
}
if(l->addable != 7) {
idx.regtree = l;
idx.scale = 1;
} else
if(l->right->addable == 20) {
idx.regtree = l->left;
idx.scale = 1 << l->right->vconst;
} else
if(l->left->addable == 20) {
idx.regtree = l->right;
idx.scale = 1 << l->left->vconst;
} else
diag(n, "bad index");
idx.basetree = r;
if(debug['x']) {
print("scale = %d\n", idx.scale);
prtree(idx.regtree, "index");
prtree(idx.basetree, "base");
}
}