ref: 94e28af38c7cac02c5b592dbbb3d6205d37cb2f2
dir: /8/isel.c/
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <stdarg.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 "parse.h"
#include "opt.h"
#include "asm.h"
/* string tables */
char *insnfmts[] = {
#define Insn(val, fmt, use, def) fmt,
#include "insns.def"
#undef Insn
};
char modenames[] = {
[ModeB] = 'b',
[ModeS] = 's',
[ModeL] = 'l',
[ModeF] = 'f',
[ModeD] = 'd'
};
/* forward decls */
Loc *selexpr(Isel *s, Node *n);
/* 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},
[Oeq] = {Icmp, Ijz, Isetz},
[One] = {Icmp, Ijnz, Isetnz},
[Ogt] = {Icmp, Ijg, Isetgt},
[Oge] = {Icmp, Ijge, Isetge},
[Olt] = {Icmp, Ijl, Isetlt},
[Ole] = {Icmp, Ijle, Isetle}
};
static Loc *loc(Isel *s, Node *n)
{
Loc *l;
Node *v;
size_t stkoff;
switch (exprop(n)) {
case Ovar:
if (hthas(s->locs, n)) {
stkoff = (size_t)htget(s->locs, n);
l = locmem(-stkoff, locphysreg(Rebp), NULL, ModeL);
} else if (hthas(s->globls, n)) {
l = locstrlbl(htget(s->globls, n));
} else {
die("%s (id=%ld) not found", namestr(n->expr.args[0]), n->expr.did);
}
break;
case Olit:
v = n->expr.args[0];
switch (v->lit.littype) {
case Lchr: l = loclit(v->lit.chrval); break;
case Lbool: l = loclit(v->lit.boolval); break;
case Lint: l = loclit(v->lit.intval); 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 Mode mode(Node *n)
{
switch (exprtype(n)->type) {
case Tyfloat32: return ModeF; break;
case Tyfloat64: return ModeD; break;
default:
switch (size(n)) {
case 1: return ModeB; break;
case 2: return ModeS; break;
case 4: return ModeL; break;
}
break;
}
dump(n, stdout);
die("No mode for node");
return ModeNone;
}
static Loc *coreg(Reg r, Mode m)
{
Reg crtab[][Nmode + 1] = {
[Ral] = {Rnone, Ral, Rax, Reax},
[Rcl] = {Rnone, Rcl, Rcx, Recx},
[Rdl] = {Rnone, Rdl, Rdx, Redx},
[Rbl] = {Rnone, Rbl, Rbx, Rebx},
[Rax] = {Rnone, Ral, Rax, Reax},
[Rcx] = {Rnone, Rcl, Rcx, Recx},
[Rdx] = {Rnone, Rdl, Rdx, Redx},
[Rbx] = {Rnone, Rbl, Rbx, Rebx},
[Rsi] = {Rnone, Rnone, Rsi, Resi},
[Rdi] = {Rnone, Rnone, Rdi, Redi},
[Reax] = {Rnone, Ral, Rax, Reax},
[Recx] = {Rnone, Rcl, Rcx, Recx},
[Redx] = {Rnone, Rdl, Rdx, Redx},
[Rebx] = {Rnone, Rbl, Rbx, Rebx},
[Resi] = {Rnone, Rnone, Rsi, Resi},
[Redi] = {Rnone, Rnone, Rdi, Redi},
};
assert(crtab[r][m] != Rnone);
return locphysreg(crtab[r][m]);
}
static Insn *mkinsnv(AsmOp op, va_list ap)
{
Loc *l;
Insn *i;
int n;
n = 0;
i = malloc(sizeof(Insn));
i->op = op;
while ((l = va_arg(ap, Loc*)) != NULL)
i->args[n++] = l;
i->nargs = n;
return i;
}
static void g(Isel *s, AsmOp op, ...)
{
va_list ap;
Insn *i;
va_start(ap, op);
i = mkinsnv(op, ap);
va_end(ap);
lappend(&s->curbb->il, &s->curbb->ni, i);
}
static void load(Isel *s, Loc *a, Loc *b)
{
Loc *l;
assert(b->type == Locreg);
if (a->type == Locreg)
locmem(0, b, Rnone, a->mode);
else
l = a;
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)
locmem(0, b, Rnone, b->mode);
else
l = b;
g(s, Imov, a, l, NULL);
}
/* ensures that a location is within a reg */
static Loc *inr(Isel *s, Loc *a)
{
Loc *r;
if (a->type == Locreg)
return a;
r = locreg(a->mode);
load(s, a, r);
return r;
}
/* 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 inr(s, a);
}
/* ensures that a location is within a reg or an imm */
static Loc *inrm(Isel *s, Loc *a)
{
if (a->type == Locreg || a->type == Locmem)
return a;
else
return inr(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[1]);
b = selexpr(s, args[0]->expr.args[0]);
b = inr(s, b);
} else {
cond = Itest;
jmp = Ijnz;
a = inr(s, selexpr(s, args[0])); /* cond */
b = a;
}
/* 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, a, b, NULL);
g(s, jmp, l1, NULL);
g(s, Ijmp, l2, NULL);
}
static Loc *binop(Isel *s, AsmOp op, Node *x, Node *y)
{
Loc *a, *b;
a = selexpr(s, x);
b = selexpr(s, y);
a = inr(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) == Oaddr) {
l = selexpr(s, args[0]);
} else 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, Rnone, m);
} else if (o->type == Locreg) {
b = inr(s, b);
l = locmems(0, b, o, scale, m);
}
} else {
l = selexpr(s, e);
if (l->type == Locreg)
l = locmem(0, l, Rnone, m);
}
return l;
}
static void blit(Isel *s, Loc *to, Loc *from, size_t dstoff, size_t srcoff, size_t sz)
{
size_t i;
Loc *sp, *dp; /* pointers to src, dst */
Loc *tmp, *src, *dst; /* source memory, dst memory */
sp = inr(s, from);
dp = inr(s, to);
/* Slightly funny loop condition: We might have trailing bytes
* that we can't blit word-wise. */
tmp = locreg(ModeL);
for (i = 0; i < sz/4; i++) {
src = locmem(i*4 + srcoff, sp, NULL, ModeL);
dst = locmem(i*4 + dstoff, dp, NULL, ModeL);
g(s, Imov, src, tmp, NULL);
g(s, Imov, tmp, dst, NULL);
}
/* now, the trailing bytes */
tmp = locreg(ModeB);
for (; i < sz%4; i++) {
src = locmem(i, sp, NULL, ModeB);
dst = locmem(i, dp, NULL, ModeB);
g(s, Imov, src, tmp, NULL);
g(s, Imov, tmp, dst, NULL);
}
}
static Loc *gencall(Isel *s, Node *n)
{
Loc *src, *dst, *arg, *fn; /* values we reduced */
Loc *eax, *esp; /* hard-coded registers */
Loc *stkbump; /* calculated stack offset */
int argsz, argoff;
size_t i;
esp = locphysreg(Resp);
eax = locphysreg(Reax);
argsz = 0;
/* 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.
*
* We skip the first operand, since it's the function itself */
for (i = 1; i < n->expr.nargs; i++)
argsz += size(n->expr.args[i]);
stkbump = loclit(argsz);
if (argsz)
g(s, Isub, stkbump, esp, NULL);
/* Now, we can evaluate the arguments */
argoff = 0;
for (i = 1; i < n->expr.nargs; i++) {
arg = selexpr(s, n->expr.args[i]);
if (size(n->expr.args[i]) > 4) {
dst = locreg(ModeL);
src = locreg(ModeL);
g(s, Ilea, arg, src, NULL);
blit(s, esp, src, argoff, 0, size(n->expr.args[i]));
} else {
dst = locmem(argoff, esp, NULL, arg->mode);
arg = inri(s, arg);
stor(s, arg, dst);
}
argoff += size(n->expr.args[i]);
}
fn = selexpr(s, n->expr.args[0]);
g(s, Icall, fn, NULL);
if (argsz)
g(s, Iadd, stkbump, esp, NULL);
return eax;
}
Loc *selexpr(Isel *s, Node *n)
{
Loc *a, *b, *c, *d, *r;
Loc *eax, *edx, *cl; /* x86 wanst some hard-coded regs */
Node **args;
args = n->expr.args;
eax = locphysreg(Reax);
edx = locphysreg(Redx);
cl = locphysreg(Rcl);
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:
/* these get clobbered by the mul insn */
a = selexpr(s, args[0]);
b = selexpr(s, args[1]);
b = inr(s, b);
c = coreg(Reax, mode(n));
r = locreg(a->mode);
g(s, Imov, a, c, NULL);
g(s, Imul, b, NULL);
g(s, Imov, eax, r, NULL);
break;
case Odiv:
case Omod:
/* these get clobbered by the div insn */
a = selexpr(s, args[0]);
b = selexpr(s, args[1]);
b = inr(s, b);
c = coreg(Reax, mode(n));
r = locreg(a->mode);
g(s, Imov, a, c, NULL);
g(s, Ixor, edx, edx, NULL);
g(s, Idiv, b, NULL);
if (exprop(n) == Odiv)
d = eax;
else
d = edx;
g(s, Imov, d, r, NULL);
break;
case Oneg:
r = selexpr(s, args[0]);
r = inr(s, r);
g(s, Ineg, r, NULL);
break;
case Obsl:
case Obsr:
a = inr(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, cl, a, NULL);
}
r = a;
break;
case Obnot:
r = selexpr(s, args[0]);
r = inrm(s, r);
g(s, Inot, r, NULL);
break;
case Oderef:
a = selexpr(s, args[0]);
a = inr(s, a);
r = locreg(a->mode);
c = locmem(0, a, Rnone, a->mode);
g(s, Imov, c, r, NULL);
break;
case Oaddr:
a = selexpr(s, args[0]);
r = locreg(ModeL);
g(s, Ilea, a, r, NULL);
break;
case Olnot:
a = selexpr(s, args[0]);
b = locreg(ModeB);
r = locreg(mode(n));
g(s, reloptab[exprop(n)].test, a, a, NULL);
g(s, reloptab[exprop(n)].getflag, b, NULL);
g(s, Imovz, b, r, NULL);
break;
case Oeq: case One: case Ogt: case Oge: case Olt: case Ole:
a = selexpr(s, args[0]);
b = selexpr(s, args[1]);
b = inr(s, b);
c = locreg(ModeB);
r = locreg(mode(n));
g(s, reloptab[exprop(n)].test, a, b, NULL);
g(s, reloptab[exprop(n)].getflag, c, NULL);
g(s, Imovz, c, r, NULL);
return r;
case Oasn: /* relabel */
die("Unimplemented op %s", opstr(exprop(n)));
break;
case Ostor: /* reg -> mem */
b = selexpr(s, args[1]);
a = memloc(s, args[0], mode(args[0]));
b = inri(s, b);
g(s, Imov, b, a, NULL);
r = b;
break;
case Oload: /* mem -> reg */
b = memloc(s, args[0], mode(n));
r = locreg(mode(n));
g(s, Imov, b, r, NULL);
break;
case Ocall:
r = gencall(s, n);
break;
case Ojmp:
g(s, Ijmp, a = loclbl(args[0]), NULL);
break;
case Ocjmp:
selcjmp(s, n, args);
break;
case Olit: /* fall through */
r = loc(s, n);
break;
case Ovar:
r = loc(s, n);
break;
case Olbl:
r = loclbl(args[0]);
break;
case Oblit:
a = selexpr(s, args[0]);
b = selexpr(s, args[1]);
blit(s, a, b, 0, 0, args[2]->expr.args[0]->lit.intval);
r = b;
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 Oret: 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 Oslice: case Oidx: case Osize: case Numops:
case Oslbase: case Osllen: case Ocast: case Ocons:
dump(n, stdout);
die("Should not see %s in isel", opstr(exprop(n)));
break;
}
return r;
}
void locprint(FILE *fd, Loc *l)
{
switch (l->type) {
case Loclbl:
fprintf(fd, "%s", l->lbl);
break;
case Locreg:
if (l->reg.colour == Rnone)
fprintf(fd, "%%P.%ld", l->reg.id);
else
fprintf(fd, "%s", regnames[l->reg.colour]);
break;
case Locmem:
case Locmeml:
if (l->type == Locmem) {
if (l->mem.constdisp)
fprintf(fd, "%ld", l->mem.constdisp);
} else {
if (l->mem.lbldisp)
fprintf(fd, "%s", l->mem.lbldisp);
}
fprintf(fd, "(");
locprint(fd, l->mem.base);
if (l->mem.idx) {
fprintf(fd, ",");
locprint(fd, l->mem.idx);
}
if (l->mem.scale > 1)
fprintf(fd, ",%d", l->mem.scale);
if (l->mem.base)
fprintf(fd, ")");
break;
case Loclit:
fprintf(fd, "$%ld", l->lit);
break;
case Locnone:
die("Bad location in locprint()");
break;
}
}
void iprintf(FILE *fd, Insn *insn)
{
char *p;
int i;
int modeidx;
p = insnfmts[insn->op];
i = 0;
for (; *p; p++) {
if (*p != '%') {
fputc(*p, fd);
continue;
}
/* %-formating */
p++;
switch (*p) {
case '\0':
goto done; /* skip the final p++ */
case 'r':
case 'm':
case 'l':
case 'x':
case 'v':
locprint(fd, insn->args[i]);
i++;
break;
case 't':
modeidx = 0;
default:
/* the asm description uses 1-based indexing, so that 0
* can be used as a sentinel. */
if (isdigit(*p))
modeidx = strtol(p, &p, 10) - 1;
if (*p == 't')
fputc(modenames[insn->args[modeidx]->mode], fd);
else
die("Invalid %%-specifier '%c'", *p);
break;
}
}
done:
return;
}
static void isel(Isel *s, Node *n)
{
Loc *lbl;
switch (n->type) {
case Nlbl:
g(s, Ilbl, lbl = loclbl(n), NULL);
break;
case Nexpr:
selexpr(s, n);
break;
case Ndecl:
break;
default:
die("Bad node type in isel()");
break;
}
}
static void prologue(Isel *s, size_t sz)
{
Loc *esp;
Loc *ebp;
Loc *stksz;
esp = locphysreg(Resp);
ebp = locphysreg(Rebp);
stksz = loclit(sz);
g(s, Ipush, ebp, NULL);
g(s, Imov, esp, ebp, NULL);
g(s, Isub, stksz, esp, NULL);
s->stksz = stksz; /* need to update if we spill */
}
static void epilogue(Isel *s)
{
Loc *esp, *ebp, *eax;
Loc *ret;
esp = locphysreg(Resp);
ebp = locphysreg(Rebp);
eax = locphysreg(Reax);
if (s->ret) {
ret = loc(s, s->ret);
g(s, Imov, ret, eax, NULL);
}
g(s, Imov, ebp, esp, NULL);
g(s, Ipop, ebp, NULL);
g(s, Iret, NULL);
}
static void writeasm(FILE *fd, Isel *s, Func *fn)
{
size_t i, j;
if (fn->isglobl)
fprintf(fd, ".globl %s\n", fn->name);
fprintf(fd, "%s:\n", fn->name);
for (j = 0; j < s->cfg->nbb; j++) {
for (i = 0; i < s->bb[j]->nlbls; i++)
fprintf(fd, "%s:\n", s->bb[j]->lbls[i]);
for (i = 0; i < s->bb[j]->ni; i++)
iprintf(fd, s->bb[j]->il[i]);
}
}
static Asmbb *mkasmbb(Bb *bb)
{
Asmbb *as;
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;
}
static void writeblob(FILE *fd, char *p, size_t sz)
{
size_t i;
for (i = 0; i < sz; i++) {
if (i % 60 == 0)
fprintf(fd, "\t.ascii \"");
if (isprint(p[i]))
fprintf(fd, "%c", p[i]);
else
fprintf(fd, "\\%x", p[i]);
if (i % 60 == 59 || i == sz - 1)
fprintf(fd, "\"\n");
}
}
static void writelit(FILE *fd, Node *v)
{
char lbl[128];
switch (v->lit.littype) {
case Lbool: fprintf(fd, "\t.long %d\n", v->lit.boolval); break;
case Lchr: fprintf(fd, "\t.byte %d\n", v->lit.chrval); break;
case Lint: fprintf(fd, "\t.long %lld\n", v->lit.intval); break;
case Lflt: fprintf(fd, "\t.double %f\n", v->lit.fltval); break;
case Lstr: fprintf(fd, "\t.long %s\n", genlblstr(lbl, 128));
fprintf(fd, "\t.long %zd\n", strlen(v->lit.strval));
fprintf(fd, "%s:\n", lbl);
writeblob(fd, v->lit.strval, strlen(v->lit.strval));
break;
case Larray:
case Lfunc:
die("Generating this shit ain't ready yet ");
}
}
void genblob(FILE *fd, Node *blob, Htab *globls)
{
char *lbl;
/* lits and such also get wrapped in decls */
assert(blob->type == Ndecl);
assert(blob->decl.init != NULL);
lbl = htget(globls, blob);
fprintf(fd, "%s:\n", lbl);
if (exprop(blob->decl.init) != Olit)
die("Nonliteral initializer for global");
writelit(fd, blob->decl.init->expr.args[0]);
}
/* genasm requires all nodes in 'nl' to map cleanly to operations that are
* natively supported, as promised in the output of reduce(). No 64-bit
* operations on x32, no structures, and so on. */
void genasm(FILE *fd, Func *fn, Htab *globls)
{
Isel is = {0,};
size_t i, j;
char buf[128];
is.locs = fn->locs;
is.globls = globls;
is.ret = fn->ret;
is.cfg = fn->cfg;
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->stksz);
for (j = 0; j < fn->cfg->nbb - 1; j++) {
is.curbb = is.bb[j];
for (i = 0; i < fn->cfg->bb[j]->nnl; i++) {
/* put in a comment that says where this line comes from */
snprintf(buf, sizeof buf, "\n\t# bb = %zd, bbidx = %zd, line=%d",
j, i, fn->cfg->bb[j]->nl[i]->line);
isel(&is, fn->cfg->bb[j]->nl[i]);
g(&is, Ilbl, locstrlbl(buf), NULL);
}
}
is.curbb = is.bb[is.nbb - 1];
epilogue(&is);
regalloc(&is);
writeasm(fd, &is, fn);
}