ref: d6bd40e37b085aec922c6bb56e867e85a6c36982
dir: /6/isel.c/
#include <stdlib.h>
#include <stdio.h>
#include <inttypes.h>
#include <stdarg.h>
#include <inttypes.h>
#include <ctype.h>
#include <string.h>
#include <assert.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include "util.h"
#include "parse.h"
#include "mi.h"
#include "asm.h"
#include "../config.h"
/* forward decls */
Loc *selexpr(Isel *s, Node *n);
#define Nfloatregargs 8
#define Nintregargs 6
regid floatargregs[] = {
Rxmm0d, Rxmm1d, Rxmm2d, Rxmm3d,
Rxmm4d, Rxmm5d, Rxmm6d, Rxmm7d,
};
regid intargregs[] = {Rrdi, Rrsi, Rrdx, Rrcx, Rr8, Rr9};
/* used to decide which operator is appropriate
* for implementing various conditional operators */
struct {
AsmOp test;
AsmOp jmp;
AsmOp getflag;
} reloptab[Numops] = {
[Olnot] = {Itest, Ijz, Isetz}, /* lnot invalid for floats */
/* signed int */
[Oeq] = {Icmp, Ijz, Isetz},
[One] = {Icmp, Ijnz, Isetnz},
[Ogt] = {Icmp, Ijg, Isetg},
[Oge] = {Icmp, Ijge, Isetge},
[Olt] = {Icmp, Ijl, Isetl},
[Ole] = {Icmp, Ijle, Isetle},
/* unsigned int */
[Oueq] = {Icmp, Ijz, Isetz},
[Oune] = {Icmp, Ijnz, Isetnz},
[Ougt] = {Icmp, Ija, Iseta},
[Ouge] = {Icmp, Ijae, Isetae},
[Oult] = {Icmp, Ijb, Isetb},
[Oule] = {Icmp, Ijbe, Isetbe},
/* float */
[Ofeq] = {Icomis, Ijz, Isetz},
[Ofne] = {Icomis, Ijnz, Isetnz},
[Ofgt] = {Icomis, Ija, Iseta},
[Ofge] = {Icomis, Ijae, Isetae},
[Oflt] = {Icomis, Ijb, Isetb},
[Ofle] = {Icomis, Ijbe, Isetbe},
};
static Mode tymode(Type *t)
{
/* FIXME: What should the mode for, say, structs be when we have no
* intention of loading /through/ the pointer? For now, we'll just say it's
* the pointer mode, since we expect to address through the pointer */
t = tybase(t);
switch (t->type) {
case Tyflt32: return ModeF; break;
case Tyflt64: return ModeD; break;
default:
if (isstacktype(t))
return ModeQ;
switch (tysize(t)) {
case 1: return ModeB; break;
case 2: return ModeW; break;
case 4: return ModeL; break;
case 8: return ModeQ; break;
}
break;
}
return ModeNone;
}
static Mode mode(Node *n)
{
if (n->type == Nexpr)
return tymode(exprtype(n));
else if (n->type == Ndecl)
return tymode(n->decl.type);
else
die("invalid node type");
return ModeNone;
}
static Loc *varloc(Isel *s, Node *n)
{
ssize_t off;
Loc *l, *rip;
/* we need to try getting it from the stack first, in case we
* forced it to stack for addressing */
if (hthas(s->globls, n)) {
rip = locphysreg(Rrip);
l = locmeml(htget(s->globls, n), rip, NULL, mode(n));
} else if (hthas(s->envoff, n)) {
off = ptoi(htget(s->envoff, n));
l = locmem(off, s->envp, NULL, mode(n));
} else if (hthas(s->stkoff, n)) {
off = ptoi(htget(s->stkoff, n));
l = locmem(-off, locphysreg(Rrbp), NULL, mode(n));
} else if (stacknode(n)) {
assert(0);
} else {
l = htget(s->reglocs, n);
if (!l) {
l = locreg(mode(n));
htput(s->reglocs, n, l);
}
}
return l;
}
static Loc *loc(Isel *s, Node *n)
{
Node *v;
Loc *l;
if (n->type == Ndecl) {
l = varloc(s, n);
} else {
switch (exprop(n)) {
case Ovar:
l = varloc(s, n);
break;
case Olit:
v = n->expr.args[0];
switch (v->lit.littype) {
case Lvoid: l = NULL; break;
case Lchr: l = loclit(v->lit.chrval, mode(n)); break;
case Lbool: l = loclit(v->lit.boolval, mode(n)); break;
case Lint: l = loclit(v->lit.intval, mode(n)); break;
default:
die("Literal type %s should be blob", litstr[v->lit.littype]);
}
break;
default:
die("Node %s not leaf in loc()", opstr[exprop(n)]);
break;
}
}
return l;
}
static Insn *mkinsnv(AsmOp op, va_list ap)
{
Loc *l;
Insn *i;
int n;
static size_t insnid;
n = 0;
i = malloc(sizeof(Insn));
i->op = op;
i->uid = insnid++;
while ((l = va_arg(ap, Loc*)) != NULL)
i->args[n++] = l;
i->nargs = n;
return i;
}
Insn *mkinsn(int op, ...)
{
va_list ap;
Insn *i;
va_start(ap, op);
i = mkinsnv(op, ap);
va_end(ap);
return i;
}
static void g(Isel *s, int op, ...)
{
va_list ap;
Insn *i;
va_start(ap, op);
i = mkinsnv(op, ap);
va_end(ap);
if (debugopt['i']) {
printf("GEN[uid=%zd] ", i->uid);
dbgiprintf(stdout, i);
}
lappend(&s->curbb->il, &s->curbb->ni, i);
}
static void movz(Isel *s, Loc *src, Loc *dst)
{
if (src->mode == dst->mode)
g(s, Imov, src, dst, NULL);
else
g(s, Imovzx, src, dst, NULL);
}
static void load(Isel *s, Loc *a, Loc *b)
{
Loc *l;
assert(b->type == Locreg);
if (a->type == Locreg)
l = locmem(0, b, NULL, a->mode);
else
l = a;
if (isfloatmode(b->mode))
g(s, Imovs, l, b, NULL);
else
g(s, Imov, l, b, NULL);
}
static void stor(Isel *s, Loc *a, Loc *b)
{
Loc *l;
assert(a->type == Locreg || a->type == Loclit);
if (b->type == Locreg)
l = locmem(0, b, NULL, b->mode);
else
l = b;
if (isfloatmode(b->mode))
g(s, Imovs, a, l, NULL);
else
g(s, Imov, a, l, NULL);
}
/* ensures that a location is within a reg */
static Loc *newr(Isel *s, Loc *a)
{
Loc *r;
r = locreg(a->mode);
if (a->type == Locreg) {
if (isfloatmode(a->mode))
g(s, Imovs, a, r, NULL);
else
g(s, Imov, a, r, NULL);
} else {
load(s, a, r);
}
return r;
}
static Loc *inr(Isel *s, Loc *a)
{
if (a->type == Locreg)
return a;
return newr(s, a);
}
/* ensures that a location is within a reg or an imm */
static Loc *inri(Isel *s, Loc *a)
{
if (a->type == Locreg || a->type == Loclit)
return a;
else
return newr(s, a);
}
/* If we're testing equality, etc, it's a bit silly
* to generate the test, store it to a bite, expand it
* to the right width, and then test it again. Try to optimize
* for these common cases.
*
* if we're doing the optimization to avoid
* multiple tests, we want to eval the children
* of the first arg, instead of the first arg
* directly */
static void selcjmp(Isel *s, Node *n, Node **args)
{
Loc *a, *b;
Loc *l1, *l2;
AsmOp cond, jmp;
cond = reloptab[exprop(args[0])].test;
jmp = reloptab[exprop(args[0])].jmp;
/* if we have a cond, we're knocking off the redundant test,
* and want to eval the children */
if (cond) {
a = selexpr(s, args[0]->expr.args[0]);
if (args[0]->expr.nargs == 2)
b = selexpr(s, args[0]->expr.args[1]);
else
b = a;
a = newr(s, a);
} else {
cond = Itest;
jmp = Ijnz;
b = newr(s, selexpr(s, args[0])); /* cond */
a = b;
}
/* the jump targets will always be evaluated the same way */
l1 = loclbl(args[1]); /* if true */
l2 = loclbl(args[2]); /* if false */
g(s, cond, b, a, NULL);
g(s, jmp, l1, NULL);
g(s, Ijmp, l2, NULL);
}
/* Generate variable length jump. There are 3 cases
* for this:
*
* 1) Short list: Simple comparison sequence.
* 2) Sparse list: binary search
* 3) Dense list: Jump table
*
* If a value is not in the jump table, then the 0th
* value is used.
*/
static void selvjmp(Isel *s, Node *n, Node **args)
{
}
static Loc *binop(Isel *s, AsmOp op, Node *x, Node *y)
{
Loc *a, *b;
a = selexpr(s, x);
b = selexpr(s, y);
a = newr(s, a);
g(s, op, b, a, NULL);
return a;
}
/* We have a few common cases to optimize here:
* Oaddr(expr)
* or:
* Oadd(
* reg,
* reg||const)
*
* or:
* Oadd(
* reg,
* Omul(reg,
* 2 || 4 || 8)))
*/
static int ismergablemul(Node *n, int *r)
{
int v;
if (exprop(n) != Omul)
return 0;
if (exprop(n->expr.args[1]) != Olit)
return 0;
if (n->expr.args[1]->expr.args[0]->type != Nlit)
return 0;
if (n->expr.args[1]->expr.args[0]->lit.littype != Lint)
return 0;
v = n->expr.args[1]->expr.args[0]->lit.intval;
if (v != 2 && v != 4 && v != 8)
return 0;
*r = v;
return 1;
}
static Loc *memloc(Isel *s, Node *e, Mode m)
{
Node **args;
Loc *l, *b, *o; /* location, base, offset */
int scale;
scale = 1;
l = NULL;
args = e->expr.args;
if (exprop(e) == Oadd) {
b = selexpr(s, args[0]);
if (ismergablemul(args[1], &scale))
o = selexpr(s, args[1]->expr.args[0]);
else
o = selexpr(s, args[1]);
if (b->type != Locreg)
b = inr(s, b);
if (o->type == Loclit) {
l = locmem(scale*o->lit, b, NULL, m);
} else {
b = inr(s, b);
o = inr(s, o);
l = locmems(0, b, o, scale, m);
}
} else {
l = selexpr(s, e);
l = inr(s, l);
l = locmem(0, l, NULL, m);
}
assert(l != NULL);
return l;
}
static const Mode szmodes[] = {
[8] = ModeQ,
[4] = ModeL,
[2] = ModeW,
[1] = ModeB
};
static void blit(Isel *s, Loc *to, Loc *from, size_t dstoff, size_t srcoff, size_t sz, size_t align)
{
size_t i, modesz;
Loc *sp, *dp; /* pointers to src, dst */
Loc *tmp, *src, *dst; /* source memory, dst memory */
assert(szmodes[align] != ModeNone); /* make sure we have a valid alignment */
if (!sz)
return;
sp = inr(s, from);
dp = inr(s, to);
i = 0;
if (align == 0)
align = 8;
for (modesz = align; szmodes[modesz] != ModeNone; modesz /= 2) {
tmp = locreg(szmodes[modesz]);
while (i + modesz <= sz) {
src = locmem(i + srcoff, sp, NULL, szmodes[modesz]);
dst = locmem(i + dstoff, dp, NULL, szmodes[modesz]);
g(s, Imov, src, tmp, NULL);
g(s, Imov, tmp, dst, NULL);
i += modesz;
}
}
}
static void clear(Isel *s, Loc *val, size_t sz, size_t align)
{
Loc *dp, *zero, *dst; /* source memory, dst memory */
size_t modesz, i;
i = 0;
dp = inr(s, val);
if (align == 0)
align = 8;
for (modesz = align; szmodes[modesz] != ModeNone; modesz /= 2) {
zero = locreg(szmodes[modesz]);
g(s, Ixor, zero, zero, NULL);
while (i + modesz <= sz) {
dst = locmem(i, dp, NULL, szmodes[modesz]);
g(s, Imov, zero, dst, NULL);
i += modesz;
}
}
}
static void call(Isel *s, Node *n)
{
AsmOp op;
Node *fn;
Loc *f, *e;
if (exprop(n) == Ocall) {
op = Icall;
fn = n->expr.args[0];
assert(tybase(exprtype(fn))->type == Tycode);
f = locmeml(htget(s->globls, fn), NULL, NULL, mode(fn));
} else {
op = Icallind;
f = selexpr(s, n->expr.args[0]);
e = selexpr(s, n->expr.args[1]);
g(s, Imov, e, locphysreg(Rrax), NULL);
}
g(s, op, f, NULL);
}
static size_t countargs(Type *t)
{
size_t nargs;
t = tybase(t);
nargs = t->nsub - 1;
if (isstacktype(t->sub[0]))
nargs++;
/* valists are replaced with hidden type parameter,
* which we want on the stack for ease of ABI */
if (tybase(t->sub[t->nsub - 1])->type == Tyvalist)
nargs--;
return nargs;
}
static Loc *gencall(Isel *s, Node *n)
{
Loc *src, *dst, *arg; /* values we reduced */
size_t argsz, argoff, nargs, vasplit;
size_t nfloats, nints;
Loc *retloc, *rsp, *ret; /* hard-coded registers */
Loc *stkbump; /* calculated stack offset */
Type *t, *fn;
Node **args;
size_t i, a;
int vararg;
rsp = locphysreg(Rrsp);
t = exprtype(n);
if (tybase(t)->type == Tyvoid || isstacktype(t)) {
retloc = NULL;
ret = NULL;
} else if (istyfloat(t)) {
retloc = coreg(Rxmm0d, mode(n));
ret = locreg(mode(n));
} else {
retloc = coreg(Rrax, mode(n));
ret = locreg(mode(n));
}
fn = tybase(exprtype(n->expr.args[0]));
/* calculate the number of args we expect to see, adjust
* for a hidden return argument. */
vasplit = countargs(fn);
argsz = 0;
if (exprop(n) == Ocall) {
args = &n->expr.args[1];
nargs = n->expr.nargs - 1;
} else {
args = &n->expr.args[2];
nargs = n->expr.nargs - 2;
}
/* Have to calculate the amount to bump the stack
* pointer by in one pass first, otherwise if we push
* one at a time, we evaluate the args in reverse order.
* Not good.
*
* Skip the first operand, since it's the function itself */
for (i = 0; i < nargs; i++) {
argsz = align(argsz, min(size(args[i]), Ptrsz));
argsz += size(args[i]);
}
argsz = align(argsz, 16);
stkbump = loclit(argsz, ModeQ);
if (argsz)
g(s, Isub, stkbump, rsp, NULL);
/* Now, we can evaluate the arguments */
argoff = 0;
nfloats = 0;
nints = 0;
vararg = 0;
for (i = 0; i < nargs; i++) {
arg = selexpr(s, args[i]);
argoff = alignto(argoff, exprtype(args[i]));
if (i >= vasplit)
vararg = 1;
if (stacknode(args[i])) {
src = locreg(ModeQ);
g(s, Ilea, arg, src, NULL);
a = tyalign(exprtype(args[i]));
blit(s, rsp, src, argoff, 0, size(args[i]), a);
argoff += size(args[i]);
} else if (!vararg && isfloatmode(arg->mode) && nfloats < Nfloatregargs) {
dst = coreg(floatargregs[nfloats], arg->mode);
arg = inri(s, arg);
g(s, Imovs, arg, dst, NULL);
nfloats++;
} else if (!vararg && isintmode(arg->mode) && nints < Nintregargs) {
dst = coreg(intargregs[nints], arg->mode);
arg = inri(s, arg);
g(s, Imov, arg, dst, NULL);
nints++;
} else {
dst = locmem(argoff, rsp, NULL, arg->mode);
arg = inri(s, arg);
stor(s, arg, dst);
argoff += size(args[i]);
}
}
call(s, n);
if (argsz)
g(s, Iadd, stkbump, rsp, NULL);
if (retloc) {
if (isfloatmode(retloc->mode))
g(s, Imovs, retloc, ret, NULL);
else
g(s, Imov, retloc, ret, NULL);
}
return ret;
}
Loc *selexpr(Isel *s, Node *n)
{
Loc *a, *b, *c, *d, *r;
Loc *edx, *cl; /* x86 wants some hard-coded regs */
Node **args;
size_t al;
Op op;
args = n->expr.args;
edx = locphysreg(Redx);
cl = locphysreg(Rcl);
r = NULL;
switch (exprop(n)) {
case Oadd: r = binop(s, Iadd, args[0], args[1]); break;
case Osub: r = binop(s, Isub, args[0], args[1]); break;
case Obor: r = binop(s, Ior, args[0], args[1]); break;
case Oband: r = binop(s, Iand, args[0], args[1]); break;
case Obxor: r = binop(s, Ixor, args[0], args[1]); break;
case Omul:
if (size(args[0]) == 1) {
a = selexpr(s, args[0]);
b = inr(s, selexpr(s, args[1]));
c = locphysreg(Ral);
r = locreg(a->mode);
g(s, Imov, a, c, NULL);
g(s, Iimul_r, b, NULL);
g(s, Imov, c, r, NULL);
} else {
r = binop(s, Iimul, args[0], args[1]);
}
break;
case Odiv:
case Omod:
/* these get clobbered by the div insn */
a = selexpr(s, args[0]);
b = selexpr(s, args[1]);
b = newr(s, b);
c = coreg(Reax, mode(n));
r = locreg(a->mode);
g(s, Imov, a, c, NULL);
if (istysigned(exprtype(args[0]))) {
switch (r->mode) {
case ModeB: g(s, Imovsx, c, coreg(Rrax, ModeW), NULL); break;
case ModeW: g(s, Icwd, NULL); break;
case ModeL: g(s, Icdq, NULL); break;
case ModeQ: g(s, Icqo, NULL); break;
default: die("invalid mode in division"); break;
}
g(s, Iidiv, b, NULL);
} else {
if (r->mode == ModeB)
g(s, Ixor, locphysreg(Rah), locphysreg(Rah), NULL);
else
g(s, Ixor, edx, edx, NULL);
g(s, Idiv, b, NULL);
}
if (exprop(n) == Odiv)
d = coreg(Reax, mode(n));
else if (r->mode != ModeB)
d = coreg(Redx, mode(n));
else
d = locphysreg(Rah);
g(s, Imov, d, r, NULL);
break;
case Oneg:
r = selexpr(s, args[0]);
r = newr(s, r);
g(s, Ineg, r, NULL);
break;
/* fp expressions */
case Ofadd: r = binop(s, Iadds, args[0], args[1]); break;
case Ofsub: r = binop(s, Isubs, args[0], args[1]); break;
case Ofmul: r = binop(s, Imuls, args[0], args[1]); break;
case Ofdiv: r = binop(s, Idivs, args[0], args[1]); break;
case Ofneg:
r = selexpr(s, args[0]);
r = newr(s, r);
a = NULL;
b = NULL;
if (mode(args[0]) == ModeF) {
a = locreg(ModeF);
b = loclit(1LL << (31), ModeF);
g(s, Imovs, r, a);
} else if (mode(args[0]) == ModeD) {
a = locreg(ModeQ);
b = loclit(1LL << 63, ModeQ);
g(s, Imov, r, a, NULL);
}
g(s, Ixor, b, a, NULL);
g(s, Imov, a, r, NULL);
break;
case Obsl:
case Obsr:
a = newr(s, selexpr(s, args[0]));
b = selexpr(s, args[1]);
if (b->type == Loclit) {
d = b;
} else {
c = coreg(Rcl, b->mode);
g(s, Imov, b, c, NULL);
d = cl;
}
if (exprop(n) == Obsr) {
if (istysigned(n->expr.type))
g(s, Isar, d, a, NULL);
else
g(s, Ishr, d, a, NULL);
} else {
g(s, Ishl, d, a, NULL);
}
r = a;
break;
case Obnot:
r = selexpr(s, args[0]);
r = newr(s, r);
g(s, Inot, r, NULL);
break;
case Oderef:
r = memloc(s, args[0], mode(n));
break;
case Oaddr:
a = selexpr(s, args[0]);
if (a->type == Loclbl || (a->type == Locmeml && !a->mem.base)) {
r = loclitl(a->lbl);
} else {
r = locreg(ModeQ);
g(s, Ilea, a, r, NULL);
}
break;
case Olnot:
a = newr(s, selexpr(s, args[0]));
b = locreg(ModeB);
r = locreg(mode(n));
/* lnot only valid for integer-like values */
g(s, reloptab[exprop(n)].test, a, a, NULL);
g(s, reloptab[exprop(n)].getflag, b, NULL);
movz(s, b, r);
break;
case Oeq: case One: case Ogt: case Oge: case Olt: case Ole:
case Ofeq: case Ofne: case Ofgt: case Ofge: case Oflt: case Ofle:
case Oueq: case Oune: case Ougt: case Ouge: case Oult: case Oule:
a = selexpr(s, args[0]);
b = selexpr(s, args[1]);
a = newr(s, a);
c = locreg(ModeB);
r = locreg(mode(n));
g(s, reloptab[exprop(n)].test, b, a, NULL);
g(s, reloptab[exprop(n)].getflag, c, NULL);
movz(s, c, r);
return r;
case Oasn: /* relabel */
die("Unimplemented op %s", opstr[exprop(n)]);
break;
case Oset:
op = exprop(args[0]);
assert(op == Ovar || op == Oderef || op == Ogap);
assert(!stacknode(args[0]));
if (op == Ogap)
break;
b = selexpr(s, args[1]);
if (exprop(args[0]) == Oderef)
a = memloc(s, args[0]->expr.args[0], mode(n));
else
a = selexpr(s, args[0]);
b = inri(s, b);
if (isfloatmode(b->mode))
g(s, Imovs, b, a, NULL);
else
g(s, Imov, b, a, NULL);
r = b;
break;
case Ocall:
case Ocallind:
r = gencall(s, n);
break;
case Oret:
a = locstrlbl(s->cfg->end->lbls[0]);
g(s, Ijmp, a, NULL);
break;
case Ojmp:
g(s, Ijmp, loclbl(args[0]), NULL);
break;
case Ocjmp:
selcjmp(s, n, args);
break;
case Ovjmp:
selvjmp(s, n, args);
break;
case Olit:
r = loc(s, n);
break;
case Ovar:
if (isconstfn(n)) {
r = locreg(ModeQ);
a = loc(s, n);
g(s, Ilea, a, r, NULL);
} else {
r = loc(s, n);
}
break;
case Ogap:
break;
case Oblit:
a = selexpr(s, args[0]);
r = selexpr(s, args[1]);
al = alignto(1, args[0]->expr.type->sub[0]);
blit(s, a, r, 0, 0, args[2]->expr.args[0]->lit.intval, al);
break;
case Oclear:
a = selexpr(s, args[0]);
clear(s, a, args[1]->expr.args[0]->lit.intval, 0);
break;
/* cast operators that actually modify the values */
case Otrunc:
a = selexpr(s, args[0]);
a = inr(s, a);
r = locreg(mode(n));
g(s, Imov, a, r, NULL);
break;
case Ozwiden:
a = selexpr(s, args[0]);
a = inr(s, a);
r = locreg(mode(n));
movz(s, a, r);
break;
case Oswiden:
a = selexpr(s, args[0]);
a = inr(s, a);
r = locreg(mode(n));
g(s, Imovsx, a, r, NULL);
break;
case Oint2flt:
a = selexpr(s, args[0]);
r = locreg(mode(n));
g(s, Icvttsi2sd, a, r, NULL);
break;
case Oflt2int:
a = selexpr(s, args[0]);
r = locreg(mode(n));
g(s, Icvttsd2si, a, r, NULL);
break;
case Oflt2flt:
a = selexpr(s, args[0]);
r = locreg(mode(n));
if (a->mode == ModeD)
g(s, Icvttsd2ss, a, r, NULL);
else
g(s, Icvttss2sd, a, r, NULL);
break;
case Odead:
case Oundef:
case Odef:
/* nothing */
break;
/* These operators should never show up in the reduced trees,
* since they should have been replaced with more primitive
* expressions by now */
case Obad: case Opreinc: case Opostinc: case Opredec:
case Opostdec: case Olor: case Oland: case Oaddeq:
case Osubeq: case Omuleq: case Odiveq: case Omodeq: case Oboreq:
case Obandeq: case Obxoreq: case Obsleq: case Obsreq: case Omemb:
case Oslbase: case Osllen: case Ocast: case Outag: case Oudata:
case Oucon: case Otup: case Oarr: case Ostruct:
case Oslice: case Oidx: case Osize: case Otupget:
case Obreak: case Ocontinue:
case Numops:
dump(n, stdout);
die("Should not see %s in isel", opstr[exprop(n)]);
break;
}
return r;
}
static void isel(Isel *s, Node *n)
{
switch (n->type) {
case Nexpr:
selexpr(s, n);
break;
case Ndecl:
break;
default:
die("Bad node type in isel()");
break;
}
}
/* %rax is for int returns, %xmm0d is for floating returns */
Reg savedregs[] = {
Rr12, Rr13, Rr14, Rr15,
Rnone
};
void addarglocs(Isel *s, Func *fn)
{
size_t i, nints, nfloats, nargs;
size_t argoff;
int vararg;
Node *arg;
Loc *a, *l;
argoff = 0;
nfloats = 0;
nints = 0;
vararg = 0;
nargs = countargs(fn->type);
for (i = 0; i < fn->nargs; i++) {
arg = fn->args[i];
argoff = alignto(argoff, decltype(arg));
if (i >= nargs)
vararg = 1;
if (stacknode(arg)) {
htput(s->stkoff, arg, itop(-(argoff + 2*Ptrsz)));
argoff += size(arg);
} else if (!vararg && isfloatmode(mode(arg)) && nfloats < Nfloatregargs) {
a = coreg(floatargregs[nfloats], mode(arg));
l = loc(s, arg);
g(s, Imovs, a, l, NULL);
htput(s->reglocs, arg, l);
nfloats++;
} else if (!vararg && isintmode(mode(arg)) && nints < Nintregargs) {
a = coreg(intargregs[nints], mode(arg));
l = loc(s, arg);
g(s, Imov, a, l, NULL);
htput(s->reglocs, arg, l);
nints++;
} else if (tybase(decltype(arg))->type != Tyvoid) {
/* varargs go on the stack */
htput(s->stkoff, arg, itop(-(argoff + 2*Ptrsz)));
argoff += size(arg);
}
}
}
static void prologue(Isel *s, Func *fn, size_t sz)
{
Loc *rsp;
Loc *rbp;
Loc *stksz;
Loc *phys;
size_t i;
rsp = locphysreg(Rrsp);
rbp = locphysreg(Rrbp);
stksz = loclit(sz, ModeQ);
/* enter function */
g(s, Ipush, rbp, NULL);
g(s, Imov, rsp, rbp, NULL);
g(s, Isub, stksz, rsp, NULL);
/* save registers */
for (i = 0; savedregs[i] != Rnone; i++) {
phys = locphysreg(savedregs[i]);
s->calleesave[i] = locreg(phys->mode);
if (isfloatmode(phys->mode)) {
g(s, Imovs, phys, s->calleesave[i], NULL);
} else {
g(s, Imov, phys, s->calleesave[i], NULL);
}
}
if (s->envp)
g(s, Imov, locphysreg(Rrax), s->envp, NULL);
addarglocs(s, fn);
s->nsaved = i;
s->stksz = stksz; /* need to update if we spill */
}
static void epilogue(Isel *s)
{
Loc *rsp, *rbp;
Loc *ret;
size_t i;
rsp = locphysreg(Rrsp);
rbp = locphysreg(Rrbp);
if (s->ret) {
ret = loc(s, s->ret);
if (istyfloat(exprtype(s->ret)))
g(s, Imovs, ret, coreg(Rxmm0d, ret->mode), NULL);
else
g(s, Imov, ret, coreg(Rax, ret->mode), NULL);
}
/* restore registers */
for (i = 0; savedregs[i] != Rnone; i++) {
if (isfloatmode(s->calleesave[i]->mode)) {
g(s, Imovs, s->calleesave[i], locphysreg(savedregs[i]), NULL);
} else {
g(s, Imov, s->calleesave[i], locphysreg(savedregs[i]), NULL);
}
}
/* leave function */
g(s, Imov, rbp, rsp, NULL);
g(s, Ipop, rbp, NULL);
g(s, Iret, NULL);
}
static Asmbb *mkasmbb(Bb *bb)
{
Asmbb *as;
if (!bb)
return NULL;
as = zalloc(sizeof(Asmbb));
as->id = bb->id;
as->pred = bsdup(bb->pred);
as->succ = bsdup(bb->succ);
as->lbls = memdup(bb->lbls, bb->nlbls*sizeof(char*));
as->nlbls = bb->nlbls;
return as;
}
void selfunc(Isel *is, Func *fn, Htab *globls, Htab *strtab)
{
Node *n;
Bb *bb;
size_t i, j;
char buf[128];
for (i = 0; i < fn->cfg->nbb; i++)
lappend(&is->bb, &is->nbb, mkasmbb(fn->cfg->bb[i]));
is->curbb = is->bb[0];
prologue(is, fn, fn->stksz);
for (j = 0; j < fn->cfg->nbb - 1; j++) {
is->curbb = is->bb[j];
if (!is->bb[j])
continue;
bb = fn->cfg->bb[j];
for (i = 0; i < bb->nnl; i++) {
/* put in a comment that says where this line comes from */
n = bb->nl[i];
bprintf(buf, sizeof buf, "bb = %ld, bbidx = %ld, %s:%d",
j, i, file->file.files[n->loc.file], n->loc.line);
g(is, Icomment, locstrlbl(buf), NULL);
isel(is, fn->cfg->bb[j]->nl[i]);
}
}
is->curbb = is->bb[is->nbb - 1];
epilogue(is);
peep(is);
regalloc(is);
is->stksz->lit = align(is->stksz->lit, 16);
}