sam/libqbe
1
0
Fork 0
Code Issues Pull requests Projects Releases 1 Packages Wiki Activity Actions

start work on comparisons

Browse source 
There are two things I overlooked so far.

1. Binary instructions like cmp that do not have a result
   in registers need the size suffix sometimes, for example
   when comparing a spill location with a constant.

2. The register allocator needs to be adapted to support the
   comparison instruction: it is not possible to compare two
   spill locations without using a register.
This commit is contained in:
Quentin Carbonneaux 2015-08-05 11:37:10 -04:00
parent 1477dffe32
commit 246a48ba94
6 changed files with 109 additions and 22 deletions
Download patch file Download diff file Expand all files Collapse all files

38
lisc/isel.c
View file

@ -40,15 +40,16 @@ newtmp(int type, Fn *fn)
}
static void
sel(Ins *i, Fn *fn)
sel(Ins i, Fn *fn)
{
Ref r0, r1, ra, rd;
int t;
int t, ty, c;
switch (i->op) {
switch (i.op) {
case ODiv:
case ORem:
switch (fn->tmp[i->to.val].type) {
ty = fn->tmp[i.to.val].type;
switch (ty) {
default:
diag("isel: invalid division");
case TWord:
@ -60,35 +61,42 @@ sel(Ins *i, Fn *fn)
rd = REG(RDX);
break;
}
r0 = i->op == ODiv ? ra : rd;
r1 = i->op == ODiv ? rd : ra;
emit(OCopy, i->to, r0, R);
r0 = i.op == ODiv ? ra : rd;
r1 = i.op == ODiv ? rd : ra;
emit(OCopy, i.to, r0, R);
emit(OCopy, R, r1, R);
if (rtype(i->arg[1]) == RCon) {
if (rtype(i.arg[1]) == RCon) {
/* immediates not allowed for
* divisions in x86
*/
t = newtmp(fn->tmp[i->to.val].type, fn);
t = newtmp(ty, fn);
r0 = TMP(t);
} else
r0 = i->arg[1];
r0 = i.arg[1];
emit(OXDiv, R, r0, R);
emit(OSign, rd, ra, R);
emit(OCopy, ra, i->arg[0], R);
if (rtype(i->arg[1]) == RCon)
emit(OCopy, r0, i->arg[1], R);
emit(OCopy, ra, i.arg[0], R);
if (rtype(i.arg[1]) == RCon)
emit(OCopy, r0, i.arg[1], R);
break;
case OAdd:
case OSub:
case OCopy:
emit(i->op, i->to, i->arg[0], i->arg[1]);
emit(i.op, i.to, i.arg[0], i.arg[1]);
break;
default:
if (OCmp <= i.op && i.op <= OCmp1) {
c = i.op - OCmp;
emit(OXSet+c, i.to, R, R);
emit(OXCmp, R, i.arg[0], i.arg[1]);
break;
}
diag("isel: non-exhaustive implementation");
}
}
/* instruction selection
* requires use counts (as given by parsing)
*/
void
isel(Fn *fn)
@ -100,7 +108,7 @@ isel(Fn *fn)
for (b=fn->start; b; b=b->link) {
curi = &insb[NIns];
for (i=&b->ins[b->nins]; i!=b->ins;) {
sel(--i, fn);
sel(*--i, fn);
}
nins = &insb[NIns] - curi;
free(b->ins);