x86.md

LCC4.2 C编译器源码

static void target(Node p) {
        assert(p);
        switch (specific(p->op)) {
        case MUL+U:
                setreg(p, quo);
                rtarget(p, 0, intreg[EAX]);
                break;
        case DIV+I: case DIV+U:
                setreg(p, quo);
                rtarget(p, 0, quo);
                break;
        case MOD+I: case MOD+U:
                setreg(p, rem);
                rtarget(p, 0, quo);
                break;
        case ASGN+B:
                rtarget(p, 0, intreg[EDI]);
                rtarget(p->kids[1], 0, intreg[ESI]);
                break;
        case ARG+B:
                rtarget(p->kids[0], 0, intreg[ESI]);
                break;
        case CVF+I:
                setreg(p, intreg[EAX]);
                break;
        case CALL+I: case CALL+U: case CALL+P: case CALL+V:
                setreg(p, intreg[EAX]);
                break;
        case RET+I: case RET+U: case RET+P:
                rtarget(p, 0, intreg[EAX]);
                break;
        }
}

static void clobber(Node p) {
        static int nstack = 0;

        assert(p);
        nstack = ckstack(p, nstack);
        switch (specific(p->op)) {
        case RSH+I: case RSH+U: case LSH+I: case LSH+U:
                if (generic(p->kids[1]->op) != CNST
                && !(   generic(p->kids[1]->op) == INDIR
                     && specific(p->kids[1]->kids[0]->op) == VREG+P
                     && p->kids[1]->syms[RX]->u.t.cse
                     && generic(p->kids[1]->syms[RX]->u.t.cse->op) == CNST
)) {
                        spill(1<<ECX, 1, p);
                }
                break;
        case ASGN+B: case ARG+B:
                spill(1<<ECX | 1<<ESI | 1<<EDI, IREG, p);
                break;
        case EQ+F: case LE+F: case GE+F: case LT+F: case GT+F: case NE+F:
                spill(1<<EAX, IREG, p);
                if (specific(p->op) == EQ+F)
                        p->syms[1] = findlabel(genlabel(1));
                break;
        case CALL+F:
                spill(1<<EDX | 1<<EAX | 1<<ECX, IREG, p);
                break;
        case CALL+I: case CALL+U: case CALL+P: case CALL+V:
                spill(1<<EDX | 1<<ECX, IREG, p);
                break;
        }
}
#define isfp(p) (optype((p)->op)==F)

int ckstack(Node p, int n) {
        int i;

        for (i = 0; i < NELEMS(p->x.kids) && p->x.kids[i]; i++)
                if (isfp(p->x.kids[i]))
                        n--;
        if (isfp(p) && p->count > 0)
                n++;
        if (n > 8)
                error("expression too complicated\n");
        debug(fprint(stderr, "(ckstack(%x)=%d)\n", p, n));
        assert(n >= 0);
        return n;
}
int memop(Node p) {
        assert(p);
        assert(generic(p->op) == ASGN);
        assert(p->kids[0]);
        assert(p->kids[1]);
        if (generic(p->kids[1]->kids[0]->op) == INDIR
        && sametree(p->kids[0], p->kids[1]->kids[0]->kids[0]))
                return 3;
        else
                return LBURG_MAX;
}
int sametree(Node p, Node q) {
        return p == NULL && q == NULL
        || p && q && p->op == q->op && p->syms[0] == q->syms[0]
                && sametree(p->kids[0], q->kids[0])
                && sametree(p->kids[1], q->kids[1]);
}
static void emit2(Node p) {
        int op = specific(p->op);
#define preg(f) ((f)[getregnum(p->x.kids[0])]->x.name)

        if (op == CVI+I && opsize(p->op) == 4 && opsize(p->x.kids[0]->op) == 1)
                print("movsx %s,%s\n", p->syms[RX]->x.name
, preg(charreg));
        else if (op == CVI+U && opsize(p->op) == 4 && opsize(p->x.kids[0]->op) == 1)
                print("movsx %s,%s\n", p->syms[RX]->x.name
, preg(charreg));
        else if (op == CVI+I && opsize(p->op) == 4 && opsize(p->x.kids[0]->op) == 2)
                print("movsx %s,%s\n", p->syms[RX]->x.name
, preg(shortreg));
        else if (op == CVI+U && opsize(p->op) == 4 && opsize(p->x.kids[0]->op) == 2)
                print("movsx %s,%s\n", p->syms[RX]->x.name
, preg(shortreg));

        else if (op == CVU+I && opsize(p->op) == 4 && opsize(p->x.kids[0]->op) == 1)
                print("movzx %s,%s\n", p->syms[RX]->x.name
, preg(charreg));
        else if (op == CVU+U && opsize(p->op) == 4 && opsize(p->x.kids[0]->op) == 1)
                print("movzx %s,%s\n", p->syms[RX]->x.name
, preg(charreg));
        else if (op == CVU+I && opsize(p->op) == 4 && opsize(p->x.kids[0]->op) == 2)
                print("movzx %s,%s\n", p->syms[RX]->x.name
, preg(shortreg));
        else if (op == CVU+U && opsize(p->op) == 4 && opsize(p->x.kids[0]->op) == 2)
                print("movzx %s,%s\n", p->syms[RX]->x.name
, preg(shortreg));
        else if (generic(op) == CVI || generic(op) == CVU || generic(op) == LOAD) {
                char *dst = intreg[getregnum(p)]->x.name;
                char *src = preg(intreg);
                assert(opsize(p->op) <= opsize(p->x.kids[0]->op));
                if (dst != src)
                        print("mov %s,%s\n", dst, src);
        }
        else if (op == ARG+B)
                print("sub esp,%d\nmov edi,esp\nmov ecx,%d\nrep movsb\n",
                        roundup(p->syms[0]->u.c.v.i, 4), p->syms[0]->u.c.v.i);
}

static void doarg(Node p) {
        assert(p && p->syms[0]);
        mkactual(4, p->syms[0]->u.c.v.i);
}
static void blkfetch(int k, int off, int reg, int tmp) {}
static void blkstore(int k, int off, int reg, int tmp) {}
static void blkloop(int dreg, int doff, int sreg, int soff,
        int size, int tmps[]) {}
static void local(Symbol p) {
        if (isfloat(p->type))
                p->sclass = AUTO;
        if (askregvar(p, (*IR->x.rmap)(ttob(p->type))) == 0) {
                assert(p->sclass == AUTO);
                offset = roundup(offset + p->type->size,
                        p->type->align < 4 ? 4 : p->type->align);
                p->x.offset = -offset;
                p->x.name = stringd(-offset);
        }
}
static void function(Symbol f, Symbol caller[], Symbol callee[], int n) {
        int i;

        print("%s:\n", f->x.name);
        print("push ebx\n");
        print("push esi\n");
        print("push edi\n");
        print("push ebp\n");
        print("mov ebp,esp\n");
        usedmask[0] = usedmask[1] = 0;
        freemask[0] = freemask[1] = ~(unsigned)0;
        offset = 16 + 4;
        for (i = 0; callee[i]; i++) {
                Symbol p = callee[i];
                Symbol q = caller[i];
                assert(q);
                p->x.offset = q->x.offset = offset;
                p->x.name = q->x.name = stringf("%d", p->x.offset);
                p->sclass = q->sclass = AUTO;
                offset += roundup(q->type->size, 4);
        }
        assert(caller[i] == 0);
        offset = maxoffset = 0;
        gencode(caller, callee);
        framesize = roundup(maxoffset, 4);
        if (framesize >= 4096)
                print("mov eax,%d\ncall __chkstk\n", framesize);
        else if (framesize > 0)
                print("sub esp,%d\n", framesize);
        emitcode();
        print("mov esp,ebp\n");
        print("pop ebp\n");
        print("pop edi\n");
        print("pop esi\n");
        print("pop ebx\n");
        print("ret\n");
        if (framesize >= 4096) {
                int oldseg = cseg;
                segment(0);
                print("extrn __chkstk:near\n");
                segment(oldseg);
        }
}
static void defsymbol(Symbol p) {
        if (p->scope >= LOCAL && p->sclass == STATIC)
                p->x.name = stringf("L%d", genlabel(1));
        else if (p->generated)
                p->x.name = stringf("L%s", p->name);
        else if (p->scope == GLOBAL || p->sclass == EXTERN)
                p->x.name = stringf("_%s", p->name);
        else if (p->scope == CONSTANTS
        && (isint(p->type) || isptr(p->type))
        && p->name[0] == '0' && p->name[1] == 'x')
                p->x.name = stringf("0%sH", &p->name[2]);
        else
                p->x.name = p->name;
}
static void address(Symbol q, Symbol p, long n) {
        if (p->scope == GLOBAL
        || p->sclass == STATIC || p->sclass == EXTERN)
                q->x.name = stringf("%s%s%D",
                        p->x.name, n >= 0 ? "+" : "", n);
        else {
                assert(n <= INT_MAX && n >= INT_MIN);
                q->x.offset = p->x.offset + n;
                q->x.name = stringd(q->x.offset);
        }
}
static void defconst(int suffix, int size, Value v) {
        if (suffix == I && size == 1)
                print("db %d\n",   v.u);
        else if (suffix == I && size == 2)
                print("dw %d\n",   v.i);
        else if (suffix == I && size == 4)
                print("dd %d\n",   v.i);
        else if (suffix == U && size == 1)
                print("db 0%xH\n", (unsigned)((unsigned char)v.u));
        else if (suffix == U && size == 2)
                print("dw 0%xH\n", (unsigned)((unsigned short)v.u));
        else if (suffix == U && size == 4)
                print("dd 0%xH\n", (unsigned)v.u);
        else if (suffix == P && size == 4)
                print("dd 0%xH\n", (unsigned)v.p);
        else if (suffix == F && size == 4) {
                float f = v.d;
                print("dd 0%xH\n", *(unsigned *)&f);
        }
        else if (suffix == F && size == 8) {
                double d = v.d;
                unsigned *p = (unsigned *)&d;
                print("dd 0%xH\ndd 0%xH\n", p[swap], p[!swap]);
        }
        else assert(0);
}
static void defaddress(Symbol p) {
        print("dd %s\n", p->x.name);
}
static void defstring(int n, char *str) {
        char *s;

        for (s = str; s < str + n; s++)
                print("db %d\n", (*s)&0377);
}
static void export(Symbol p) {
        print("public %s\n", p->x.name);
}
static void import(Symbol p) {
        int oldseg = cseg;

        if (p->ref > 0) {
                segment(0);
                print("extrn %s:near\n", p->x.name);
                segment(oldseg);
        }
}
static void global(Symbol p) {
        print("align %d\n",
                p->type->align > 4 ? 4 : p->type->align);
        print("%s label byte\n", p->x.name);
}
static void space(int n) {
        print("db %d dup (0)\n", n);
}
Interface x86IR = {
        1, 1, 0,  /* char */
        2, 2, 0,  /* short */
        4, 4, 0,  /* int */
        4, 4, 0,  /* long */
        4, 4, 0,  /* long long */
        4, 4, 1,  /* float */
        8, 4, 1,  /* double */
        8, 4, 1,  /* long double */
        4, 4, 0,  /* T * */
        0, 1, 0,  /* struct */
        1,        /* little_endian */
        0,        /* mulops_calls */
        0,        /* wants_callb */
        1,        /* wants_argb */
        0,        /* left_to_right */
        0,        /* wants_dag */
        0,        /* unsigned_char */
        address,
        blockbeg,
        blockend,
        defaddress,
        defconst,
        defstring,
        defsymbol,
        emit,
        export,
        function,
        gen,
        global,
        import,
        local,
        progbeg,
        progend,
        segment,
        space,
        0, 0, 0, 0, 0, 0, 0,
        {1, rmap,
            blkfetch, blkstore, blkloop,
            _label,
            _rule,
            _nts,
            _kids,
            _string,
            _templates,
            _isinstruction,
            _ntname,
            emit2,
            doarg,
            target,
            clobber,
}
};
static char rcsid[] = "$Id: x86.md,v 1.1 2002/08/28 23:12:48 drh Exp $";