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start work on comparisons

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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
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44
lisc/emit.c
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@ -40,6 +40,36 @@ static char *rtoa[] = {
[R15D] = "r15d",
};
static char *rbtoa[] = {
[RXX] = "OH GOD!",
[RAX] = "al",
[RCX] = "cl",
[RDX] = "dl",
[RSI] = "sil",
[RDI] = "dil",
[R8] = "r8b",
[R9] = "r9b",
[R10] = "r10b",
[R11] = "r11b",
[RBX] = "bl",
[R12] = "r12b",
[R13] = "r13b",
[R14] = "r14b",
[R15] = "r15b",
[RBP] = "bpl",
[RSP] = "spl",
};
static char *ctoa[NCmp] = {
[Ceq] = "e",
[Csle] = "le",
};
static void
eref(Ref r, Fn *fn, FILE *f)
{
@ -87,7 +117,7 @@ eop(char *op, Ref a, Ref b, Fn *fn, FILE *f)
static void
eins(Ins i, Fn *fn, FILE *f)
{
static char *opi[] = {
static char *otoa[OLast] = {
[OAdd] = "add",
[OSub] = "sub",
};
@ -103,7 +133,7 @@ eins(Ins i, Fn *fn, FILE *f)
}
if (!req(i.to, i.arg[0]))
eop("mov", i.arg[0], i.to, fn, f);
eop(opi[i.op], i.arg[1], i.to, fn, f);
eop(otoa[i.op], i.arg[1], i.to, fn, f);
break;
case OStore:
i.to = i.arg[1];
@ -127,9 +157,19 @@ eins(Ins i, Fn *fn, FILE *f)
case OXDiv:
eop("idiv", i.arg[0], R, fn, f);
break;
case OXCmp:
eop("cmp", i.arg[0], i.arg[1], fn, f);
break;
case ONop:
break;
default:
if (OXSet <= i.op && i.op <= OXSet1) {
eop("mov $0,", i.to, R, fn, f);
fprintf(f, "\tset%s %%%s\n",
ctoa[i.op-OXSet],
rbtoa[BASE(i.to.val)]);
break;
}
diag("emit: unhandled instruction (3)");
}
}