c11.c

unix v7是最后一个广泛发布的研究型UNIX版本

#
/*
 *  C compiler
 */

#include "c1.h"

max(a, b)
{
	if (a>b)
		return(a);
	return(b);
}

degree(at)
struct tnode *at;
{
	register struct tnode *t, *t1;

	if ((t=at)==0 || t->op==0)
		return(0);
	if (t->op == CON)
		return(-3);
	if (t->op == AMPER)
		return(-2);
	if (t->op==ITOL) {
		if ((t1 = isconstant(t)) && (t1->value>=0 || t1->type==UNSIGN))
			return(-2);
		if ((t1=t->tr1)->type==UNSIGN && opdope[t1->op]&LEAF)
			return(-1);
	}
	if ((opdope[t->op] & LEAF) != 0) {
		if (t->type==CHAR || t->type==FLOAT)
			return(1);
		return(0);
	}
	return(t->degree);
}

pname(ap, flag)
struct tnode *ap;
{
	register i;
	register struct tnode *p;
	struct { int intx[2]; };

	p = ap;
loop:
	switch(p->op) {

	case LCON:
		printf("$%o", flag>10? p->lvalue.intx[1]:p->lvalue.intx[0]);
		return;

	case SFCON:
	case CON:
		printf("$");
		psoct(p->value);
		return;

	case FCON:
		printf("L%d", (p->value>0? p->value: -p->value));
		return;

	case NAME:
		i = p->offset;
		if (flag>10)
			i =+ 2;
		if (i) {
			psoct(i);
			if (p->class!=OFFS)
				putchar('+');
			if (p->class==REG)
				regerr();
		}
		switch(p->class) {

		case SOFFS:
		case XOFFS:
			pbase(p);

		case OFFS:
			printf("(r%d)", p->regno);
			return;

		case EXTERN:
		case STATIC:
			pbase(p);
			return;

		case REG:
			printf("r%d", p->nloc);
			return;

		}
		error("Compiler error: pname");
		return;

	case AMPER:
		putchar('$');
		p = p->tr1;
		if (p->op==NAME && p->class==REG)
			regerr();
		goto loop;

	case AUTOI:
		printf("(r%d)%c", p->nloc, flag==1?0:'+');
		return;

	case AUTOD:
		printf("%c(r%d)", flag==2?0:'-', p->nloc);
		return;

	case STAR:
		p = p->tr1;
		putchar('*');
		goto loop;

	}
	error("pname called illegally");
}

regerr()
{
	error("Illegal use of register");
}

pbase(ap)
struct tnode *ap;
{
	register struct tnode *p;

	p = ap;
	if (p->class==SOFFS || p->class==STATIC)
		printf("L%d", p->nloc);
	else
		printf("%.8s", &(p->nloc));
}

xdcalc(ap, nrleft)
struct tnode *ap;
{
	register struct tnode *p;
	register d;

	p = ap;
	d = dcalc(p, nrleft);
	if (d<20 && p->type==CHAR) {
		if (nrleft>=1)
			d = 20;
		else
			d = 24;
	}
	return(d);
}

dcalc(ap, nrleft)
struct tnode *ap;
{
	register struct tnode *p, *p1;

	if ((p=ap)==0)
		return(0);
	switch (p->op) {

	case NAME:
		if (p->class==REG)
			return(9);

	case AMPER:
	case FCON:
	case LCON:
	case AUTOI:
	case AUTOD:
		return(12);

	case CON:
	case SFCON:
		if (p->value==0)
			return(4);
		if (p->value==1)
			return(5);
		if (p->value > 0)
			return(8);
		return(12);

	case STAR:
		p1 = p->tr1;
		if (p1->op==NAME||p1->op==CON||p1->op==AUTOI||p1->op==AUTOD)
			if (p->type!=LONG)
				return(12);
	}
	if (p->type==LONG)
		nrleft--;
	return(p->degree <= nrleft? 20: 24);
}

notcompat(ap, ast, op)
struct tnode *ap;
{
	register at, st;
	register struct tnode *p;

	p = ap;
	at = p->type;
	st = ast;
	if (st==0)		/* word, byte */
		return(at!=CHAR && at!=INT && at!=UNSIGN && at<PTR);
	if (st==1)		/* word */
		return(at!=INT && at!=UNSIGN && at<PTR);
	if (st==9 && (at&XTYPE))
		return(0);
	st =- 2;
	if ((at&(~(TYPE+XTYPE))) != 0)
		at = 020;
	if ((at&(~TYPE)) != 0)
		at = at&TYPE | 020;
	if (st==FLOAT && at==DOUBLE)
		at = FLOAT;
	if (p->op==NAME && p->class==REG && op==ASSIGN && st==CHAR)
		return(0);
	return(st != at);
}

prins(op, c, itable)
struct instab *itable;
{
	register struct instab *insp;
	register char *ip;

	for (insp=itable; insp->op != 0; insp++) {
		if (insp->op == op) {
			ip = c? insp->str2: insp->str1;
			if (ip==0)
				break;
			printf("%s", ip);
			return;
		}
	}
	error("No match' for op %d", op);
}

collcon(ap)
struct tnode *ap;
{
	register op;
	register struct tnode *p;

	p = ap;
	if (p->op==STAR) {
		if (p->type==LONG+PTR) /* avoid *x(r); *x+2(r) */
			return(0);
		p = p->tr1;
	}
	if (p->op==PLUS) {
		op = p->tr2->op;
		if (op==CON || op==AMPER)
			return(1);
	}
	return(0);
}

isfloat(at)
struct tnode *at;
{
	register struct tnode *t;

	t = at;
	if ((opdope[t->op]&RELAT)!=0)
		t = t->tr1;
	if (t->type==FLOAT || t->type==DOUBLE) {
		nfloat = 1;
		return('f');
	}
	return(0);
}

oddreg(t, areg)
struct tnode *t;
{
	register reg;

	reg = areg;
	if (!isfloat(t)) {
		if (opdope[t->op]&RELAT) {
			if (t->tr1->type==LONG)
				return((reg+1) & ~01);
			return(reg);
		}
		switch(t->op) {
		case LLSHIFT:
		case ASLSHL:
			return((reg+1)&~01);

		case DIVIDE:
		case MOD:
		case ASDIV:
		case ASMOD:
		case PTOI:
		case ULSH:
		case ASULSH:
			reg++;

		case TIMES:
		case ASTIMES:
			return(reg|1);
		}
	}
	return(reg);
}

arlength(t)
{
	if (t>=PTR)
		return(2);
	switch(t) {

	case INT:
	case CHAR:
	case UNSIGN:
		return(2);

	case LONG:
		return(4);

	case FLOAT:
	case DOUBLE:
		return(8);
	}
	return(1024);
}

/*
 * Strings for switch code.
 */

char	dirsw[] {"\
cmp	r0,$%o\n\
jhi	L%d\n\
asl	r0\n\
jmp	*L%d(r0)\n\
.data\n\
L%d:\
" };

char	hashsw[] {"\
mov	r0,r1\n\
clr	r0\n\
div	$%o,r0\n\
asl	r1\n\
jmp	*L%d(r1)\n\
.data\n\
L%d:\
"};

/*
 * If the unsigned casts below won't compile,
 * try using the calls to lrem and ldiv.
 */

pswitch(afp, alp, deflab)
struct swtab *afp, *alp;
{
	int ncase, i, j, tabs, worst, best, range;
	register struct swtab *swp, *fp, *lp;
	int *poctab;

	fp = afp;
	lp = alp;
	if (fp==lp) {
		printf("jbr	L%d\n", deflab);
		return;
	}
	isn++;
	if (sort(fp, lp))
		return;
	ncase = lp-fp;
	lp--;
	range = lp->swval - fp->swval;
	/* direct switch */
	if (range>0 && range <= 3*ncase) {
		if (fp->swval)
			printf("sub	$%o,r0\n", fp->swval);
		printf(dirsw, range, deflab, isn, isn);
		isn++;
		for (i=fp->swval; ; i++) {
			if (i==fp->swval) {
				printf("L%d\n", fp->swlab);
				if (fp==lp)
					break;
				fp++;
			} else
				printf("L%d\n", deflab);
		}
		printf(".text\n");
		return;
	}
	/* simple switch */
	if (ncase<10) {
		for (fp = afp; fp<=lp; fp++)
			breq(fp->swval, fp->swlab);
		printf("jbr	L%d\n", deflab);
		return;
	}
	/* hash switch */
	best = 077777;
	poctab = getblk(((ncase+2)/2) * sizeof(*poctab));
	for (i=ncase/4; i<=ncase/2; i++) {
		for (j=0; j<i; j++)
			poctab[j] = 0;
		for (swp=fp; swp<=lp; swp++)
			/* lrem(0, swp->swval, i) */
			poctab[(unsigned)swp->swval%i]++;
		worst = 0;
		for (j=0; j<i; j++)
			if (poctab[j]>worst)
				worst = poctab[j];
		if (i*worst < best) {
			tabs = i;
			best = i*worst;
		}
	}
	i = isn++;
	printf(hashsw, tabs, i, i);
	isn++;
	for (i=0; i<tabs; i++)
		printf("L%d\n", isn+i);
	printf(".text\n");
	for (i=0; i<tabs; i++) {
		printf("L%d:", isn++);
		for (swp=fp; swp<=lp; swp++) {
			/* lrem(0, swp->swval, tabs) */
			if ((unsigned)swp->swval%tabs == i) {
				/* ldiv(0, swp->swval, tabs) */
				breq((unsigned)swp->swval/tabs, swp->swlab);
			}
		}
		printf("jbr	L%d\n", deflab);
	}
}

breq(v, l)
{
	if (v==0)
		printf("tst	r0\n");
	else
		printf("cmp	r0,$%o\n", v);
	printf("jeq	L%d\n", l);
}

sort(afp, alp)
struct swtab *afp, *alp;
{
	register struct swtab *cp, *fp, *lp;
	int intch, t;

	fp = afp;
	lp = alp;
	while (fp < --lp) {
		intch = 0;
		for (cp=fp; cp<lp; cp++) {
			if (cp->swval == cp[1].swval) {
				error("Duplicate case (%d)", cp->swval);
				return(1);
			}
			if (cp->swval > cp[1].swval) {
				intch++;
				t = cp->swval;
				cp->swval = cp[1].swval;
				cp[1].swval = t;
				t = cp->swlab;
				cp->swlab = cp[1].swlab;
				cp[1].swlab = t;
			}
		}
		if (intch==0)
			break;
	}
	return(0);
}

ispow2(atree)
{
	register int d;
	register struct tnode *tree;

	tree = atree;
	if (!isfloat(tree) && tree->tr2->op==CON) {
		d = tree->tr2->value;
		if (d>1 && (d&(d-1))==0)
			return(d);
	}
	return(0);
}

pow2(atree)
struct tnode *atree;
{
	register int d, i;
	register struct tnode *tree;

	tree = atree;
	if (d = ispow2(tree)) {
		for (i=0; (d=>>1)!=0; i++);
		tree->tr2->value = i;
		switch (tree->op) {

		case TIMES:
			tree->op = LSHIFT;
			break;

		case ASTIMES:
			tree->op = ASLSH;
			break;

		case DIVIDE:
			tree->op = ULSH;
			tree->tr2->value = -i;
			break;

		case ASDIV:
			tree->op = ASULSH;
			tree->tr2->value = -i;
			break;

		case MOD:
			tree->op = AND;
			tree->tr2->value = (1<<i)-1;
			break;

		case ASMOD:
			tree->op = ASAND;
			tree->tr2->value = (1<<i)-1;
			break;

		default:
			error("pow2 botch");
		}
		tree = optim(tree);
	}
	return(tree);
}

cbranch(atree, albl, cond, areg)
struct tnode *atree;
{
	int l1, op;
	register lbl, reg;
	register struct tnode *tree;

	lbl = albl;
	reg = areg;
again:
	if ((tree=atree)==0)
		return;
	switch(tree->op) {

	case LOGAND:
		if (cond) {
			cbranch(tree->tr1, l1=isn++, 0, reg);
			cbranch(tree->tr2, lbl, 1, reg);
			label(l1);
		} else {
			cbranch(tree->tr1, lbl, 0, reg);
			cbranch(tree->tr2, lbl, 0, reg);
		}
		return;

	case LOGOR:
		if (cond) {
			cbranch(tree->tr1, lbl, 1, reg);
			cbranch(tree->tr2, lbl, 1, reg);
		} else {
			cbranch(tree->tr1, l1=isn++, 1, reg);
			cbranch(tree->tr2, lbl, 0, reg);
			label(l1);
		}
		return;

	case EXCLA:
		cbranch(tree->tr1, lbl, !cond, reg);
		return;

	case SEQNC: