c21.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

static	char sccsid[] = "@(#)c21.c 4.7 7/8/81";
/* char C21[] = {"@(#)c21.c 1.83 80/10/16 21:18:22 JFR"}; /* sccs ident */

/*
 * C object code improver-- second part
 */

#include "c2.h"
#include <stdio.h>
#include <ctype.h>

#define NUSE 6
int ioflag;
int biti[NUSE] = {1,2,4,8,16,32};
int bitsize[4] = {0,8,16,32}; /* index by type codes */
int pos,siz; long f; /* for bit field communication */
struct node *uses[NUSE]; /* for backwards flow analysis */
char *lastrand; /* last operand of instruction */
struct node *bflow();
struct node *bicopt();
char *findcon();

redun3(p,split) register struct node *p; int split; {
/* check for 3 addr instr which should be 2 addr */
	if (OP3==((p->subop>>4)&0xF)) {
		if (split) splitrand(p);
		if (equstr(regs[RT1],regs[RT3])
		  && (p->op==ADD || p->op==MUL || p->op==BIS || p->op==XOR)) {
			register char *t=regs[RT1]; regs[RT1]=regs[RT2]; regs[RT2]=t;
		}
		if (equstr(regs[RT2],regs[RT3])) {
			p->subop=(p->subop&0xF)|(OP2<<4); p->pop=0;
			lastrand=regs[RT2]; *regs[RT3]=0; return(1);
		}
	} return(0);
}

bmove() {
	register struct node *p, *lastp; register char *cp1,*cp2; register int r;
	refcount();
	for (p=lastp= &first; 0!=(p=p->forw); lastp=p);
	clearreg(); clearuse();
	for (p=lastp; p!= &first; p=p->back) {
	if (debug) {
		printf("Uses:\n");
		for (r=NUSE;--r>=0;) if (uses[r])
			printf("%d: %s\n",r,uses[r]->code? uses[r]->code:"");
		printf("-\n");
	}
	r=(p->subop>>4)&0xF;
	if (OP2==r && (cp1=p->code, *cp1++)=='$' && *cp1++=='0' && *cp1++==',' &&
			!source(cp1)) {/* a no-op unless MUL or DIV */
		if (p->op==MUL) {p->op=MOV; p->subop&=0xF; p->pop=0;}
		else if (p->op==DIV) fprintf(stderr,"c2: zero divide\n");
		else {delnode(p); redunm++; continue;}
	}
	if (OP3==r && 0!=redun3(p,1)) {newcode(p); redunm++;}
	switch (p->op) {
	case LABEL: case DLABEL:
		for (r=NUSE; --r>=0;)
			if (uses[r]) p->ref=(struct node *) (((int)p->ref)|biti[r]);
		break;
	case CALLS:
		clearuse(); goto std;
	case 0:
		clearuse(); break;
	case SUB:
		if ((p->subop&0xF)!=LONG) goto std; cp1=p->code;
		if (*cp1++!='$') goto std; splitrand(p);
		if (equstr(regs[RT2],"fp") && !indexa(regs[RT1])) {/* address comp. */
			char buf[C2_ASIZE]; cp2=buf; *cp2++='-'; 
			cp1=regs[RT1]+1; while (*cp2++= *cp1++); --cp2;
			cp1="(fp),"; while (*cp2++= *cp1++); --cp2;
			cp1=regs[RT3]; while (*cp2++= *cp1++);
			p->code=copy(buf); p->combop=T(MOVA,LONG); p->pop=0;
		} else if (*cp1++=='-' && 0<=(r=getnum(cp1))) {
			p->op=ADD; p->pop=0; *--cp1='$'; p->code=cp1;
		} goto std;
	case ADD:
		if ((p->subop&0xF)!=LONG) goto std; cp1=p->code;
		if (*cp1++!='$') goto std; splitrand(p);
		if (isstatic(cp1) && (r=isreg(regs[RT2]))>=0 && r<NUSE && uses[r]==p->forw)
		{
			/* address comp:
			**	addl2	$_foo,r0  \	movab	_foo[r0],bar
			**	movl	r0,bar	  /
			*/
			register struct	node	*pnext = p->forw;
			char	buf[C2_ASIZE];

			if (pnext->op == MOV && pnext->subop == LONG)
			{
				cp1 = &regs[RT1][1]; cp2 = &buf[0];
				while (*cp2++ = *cp1++) ; cp2--;
				splitrand(pnext);
				if (r == isreg(regs[RT1]))
				{
					delnode(p); p = pnext;
					p->op = MOVA; p->subop = BYTE;
					p->pop = 0;
					cp1 = regs[RT1]; *cp2++ = '[';
					while (*cp2++ = *cp1++) ; cp2--;
					*cp2++ = ']'; *cp2++ = ',';
					cp1 = regs[RT2];
					while (*cp2++ = *cp1++) ;
					p->code = copy(buf);
				}
			}
		}
		else
		if (equstr(regs[RT2],"fp") && !indexa(regs[RT1])) {/* address comp. */
			cp2=cp1-1; cp1=regs[RT1]+1; while (*cp2++= *cp1++); --cp2;
			cp1="(fp)"; while (*cp2++= *cp1++); *--cp2=',';
			p->combop=T(MOVA,LONG); p->pop=0;
		} else if (*cp1++=='-' && 0<=(r=getnum(cp1))) {
			p->op=SUB; p->pop=0; *--cp1='$'; p->code=cp1;
		}
		/* fall thru ... */
	case CASE:
	default: std:
		p=bflow(p); break;
	case MUL:
	{
		/*
		** Change multiplication by constant powers of 2 to
		**	shifts.
		*/
		splitrand(p);
		if (regs[RT1][0] != '$' || regs[RT1][1] == '-') goto std;
		if ((r = ispow2(getnum(&regs[RT1][1]))) < 0) goto std;
		switch (r)
		{
		case 0:		/* mull3 $1,x,y */
			if (p->subop == U(LONG,OP3))
			{
				if (equstr(regs[RT2], regs[RT3]))
				{
					delnode(p); p = p->forw;
				}
				else
				{
					p->op = MOV; p->subop = LONG;
					p->pop = 0; newcode(p); nchange++;
				}
			}
			else
			if (p->subop == U(LONG,OP2))
			{
				delnode(p); p = p->forw;
			}
			goto std;

		case 1:		/* mull2 $2,x */
			if (p->subop == U(LONG, OP2) && !source(regs[RT2]))
			{
				strcpy(regs[RT1], regs[RT2]);
				p->op = ADD; p->pop = 0; newcode(p); nchange++;
			}
			goto std;
		}
		if(p->subop==U(LONG,OP3)||(p->subop==U(LONG,OP2)&&!source(regs[RT2])))
		{
			if (p->subop == U(LONG,OP2))
				strcpy(regs[RT3], regs[RT2]);
			sprintf(regs[RT1], "$%d", r);
			p->op = ASH; p->subop = LONG;
			p->pop = 0; newcode(p); nchange++;
		}
		goto std;
	}
	case ASH:
	{
		/* address comp:
		**	ashl	$1,bar,r0  \	movl	bar,r0
		**	movab	_foo[r0]   /	movaw	_foo[r0]
		**
		**	ashl	$2,r0,r0   \	moval	_foo[r0]
		**	movab	_foo[r0]   /
		*/
		register struct	node	*pf;
		register int	shfrom, shto;
		long	shcnt;
		char	*regfrom;

		splitrand(p);
		if (regs[RT1][0] != '$') goto std;
		if ((shcnt = getnum(&regs[RT1][1])) < 1 || shcnt > 3) goto std;
		if ((shfrom = isreg(regs[RT2])) >= 0)
			regfrom = copy(regs[RT2],"]");
		if ((shto = isreg(regs[RT3])) >= 0 && shto<NUSE)
		{
			int	regnum;

			if (uses[shto] != (pf = p->forw)) goto ashadd;
			if (pf->op != MOVA && pf->op != PUSHA) goto ashadd;
			if (pf->subop != BYTE) goto ashadd;
			splitrand(pf);
			if (!indexa(regs[RT1])) goto std;
			cp2 = regs[RT1];
			if(!isstatic(cp2)) goto std;
			while (*cp2++ != '[') ;
			if (*cp2++ != 'r' || !isdigit(*cp2)) goto std;
			regnum = *cp2++ - '0';
			if (isdigit(*cp2))
			{
				if (cp2[1] != ']') goto std;
				regnum *= 10; regnum += *cp2 - '0';
			}
			if (regnum != shto) goto std;
			if (shfrom >= 0)	/* ashl $N,r*,r0 */
			{
				delnode(p);
				if (shfrom != shto)
				{
					uses[shto] = NULL; splitrand(pf);
					cp2=regs[RT1]; while (*cp2++!='[');
					cp1=regfrom; while (*cp2++= *cp1++);
					newcode(pf);
				}
			}
			else
			{
				p->op = MOV; splitrand(p);
				strcpy(regs[RT1], regs[RT2]);
				strcpy(regs[RT2], regs[RT3]);
				regs[RT3][0] = '\0';
				p->pop = 0; newcode(p);
			}
			switch (shcnt)
			{
			case 1:	pf->subop = WORD; break;
			case 2:	pf->subop = LONG; break;
			case 3:	pf->subop = QUAD; break;
			}
			redunm++; nsaddr++; nchange++;
		}
		goto std;
ashadd:
		/* at this point, RT2 and RT3 are guaranteed to be simple regs*/
		if (shcnt == 1 && equstr(regs[RT2], regs[RT3]))
		{
			/*
			** quickie:
			**	ashl	$1,A,A	>	addl2	A,A
			*/
			p->op = ADD; p->subop = U(LONG,OP2); p->pop = 0;
			strcpy(regs[RT1], regs[RT2]); regs[RT3][0] = '\0';
			newcode(p); nchange++;
		}
		goto std;
	}

	case EXTV:
	case EXTZV:
	{
		/* bit tests:
		**	extv	A,$1,B,rC  \
		**	tstl	rC	    >	jbc	A,B,D
		**	jeql	D	   /
		**
		** also byte- and word-size fields:
		**	extv	$n*8,$8,A,B	>	cvtbl	n+A,B
		**	extv	$n*16,$16,A,B	>	cvtwl	n+A,B
		**	extzv	$n*8,$8,A,B	>	movzbl	n+A,B
		**	extzv	$n*16,$16,A,B	>	movzwl	n+A,B
		*/
		register struct	node	*pf;	/* forward node */
		register struct	node	*pn;	/* next node (after pf) */
		int	flen;			/* field length */

		splitrand(p);
		if (regs[RT2][0] != '$') goto std;
		if ((flen = getnum(&regs[RT2][1])) < 0) goto std;
		if (flen == 1)
		{
			register int	extreg;		/* reg extracted to */

			extreg = isreg(regs[RT4]);
			if (extreg < 0 || extreg >= NUSE) goto std;
			if ((pf = p->forw)->op != TST) goto std;
			if (uses[extreg] && uses[extreg] != pf) goto std;
			splitrand(pf);
			if (extreg != isreg(regs[RT1])) goto std;
			if ((pn = pf->forw)->op != CBR) goto std;
			if (pn->subop != JEQ && pn->subop != JNE) goto std;
			delnode(p); delnode(pf);
			pn->subop = (pn->subop == JEQ) ? JBC : JBS;
			for(cp2=p->code; *cp2++!=',';);
			for(cp1=cp2;     *cp1++!=',';);
			while (*cp1!=',') *cp2++= *cp1++; *cp2='\0';
			pn->code = p->code; pn->pop = NULL;
			uses[extreg] = NULL;
		}
		else
		if (flen == 8 || flen == 16)
		{
			register int	boff;	/* bit offset */
			register int	coff;	/* chunk (byte or word) offset*/

			if (regs[RT1][0] != '$') goto std;
			if ((boff = getnum(&regs[RT1][1])) < 0) goto std;
			coff = boff / flen;
			if (coff && (isreg(regs[RT3]) >= 0)) goto std;
			if (boff < 0 || (boff % flen) != 0) goto std;
			p->op = (p->op == EXTV) ? CVT : MOVZ;
			p->subop = U((flen == 8 ? BYTE : WORD), LONG);
			if (coff == 0)
				strcpy(regs[RT1], regs[RT3]);
			else
				sprintf(regs[RT1], "%d%s%s", coff, regs[RT3][0]=='(' ? "":"+",
					regs[RT3]);
			strcpy(regs[RT2], regs[RT4]);
			regs[RT3][0] = '\0'; regs[RT4][0] = '\0';
			p->pop = 0; newcode(p);
		}
		nchange++;
		goto std;
	}

	case CMP:
	{
		/* comparison to -63 to -1:
		**	cmpl	r0,$-1	>	incl	r0
		**	jeql	...
		**
		**	cmpl	r0,$-63	>	addl2	$63,r0
		**	jeql	...
		*/
		register int	num;
		register int	reg;
		register struct	node	*regp = p->back;

		if (p->forw->op != CBR) goto std;
		if (p->forw->subop != JEQ && p->forw->subop != JNE) goto std;
		splitrand(p);
		if (strncmp(regs[RT2], "$-", 2) != 0) goto std;
		reg = r = isreg(regs[RT1]);
		if (r < 0) goto std;
		if (r < NUSE && uses[r] != 0) goto std;
		if (r >= NUSE && regp->op == MOV && p->subop == regp->subop)
		{
			if (*regp->code != 'r') goto std;
			reg = regp->code[1] - '0';
			if (isdigit(regp->code[2]) || reg >= NUSE || uses[reg])
				goto std;
		}
		if (r >= NUSE) goto std;
		if (reg != r)
			sprintf(regs[RT1], "r%d", reg);
		if ((num = getnum(&regs[RT2][2])) <= 0 || num > 63) goto std;
		if (num == 1)
		{
			p->op = INC; regs[RT2][0] = '\0';
		}
		else
		{
			register char	*t;

			t=regs[RT1];regs[RT1]=regs[RT2];regs[RT2]=t;
			p->op = ADD; p->subop = U(p->subop, OP2);
			for (t = &regs[RT1][2]; t[-1] = *t; t++) ;
		}
		p->pop = 0; newcode(p);
		nchange++;
		goto std;
	}

	case JSB:
		if (equstr(p->code,"mcount")) {uses[0]=p; regs[0][0]= -1;}
		goto std;
	case JBR: case JMP:
		clearuse();
		if (p->subop==RET || p->subop==RSB) {uses[0]=p; regs[0][0]= -1; break;}
		if (p->ref==0) goto std;	/* jmp (r0) */
		/* fall through */
	case CBR:
		if (p->ref->ref!=0) for (r=NUSE;--r>=0;)
			if (biti[r] & (int)p->ref->ref) {uses[r]=p; regs[r][0]= -1;}
	case EROU: case JSW:
	case TEXT: case DATA: case BSS: case ALIGN: case WGEN: case END: ;
	}
	}
	for (p= &first; p!=0; p=p->forw)
		if (p->op==LABEL || p->op==DLABEL) p->ref=0;	/* erase our tracks */
}

rmove()
{
	register struct node *p, *lastp;
	register int r;
	int r1;

	clearreg();
	for (p=first.forw; p!=0; p = p->forw) {
	lastp=p;
	if (debug) {
		printf("Regs:\n");
		for (r=0; r<NREG; r++)
			if (regs[r][0]) {
				r1=regs[r][0];
				printf("%d: %d%d %s\n", r, r1&0xF, r1>>4, regs[r]+1);
			}
		printf("-\n");
	}
	switch (p->op) {

	case CVT:
		splitrand(p); goto mov;

	case MOV:
		splitrand(p);
		if ((r = findrand(regs[RT1],p->subop)) >= 0) {
			if (r == isreg(regs[RT2]) && p->forw->op!=CBR) {
				delnode(p); redunm++; break;
			}
		}
mov:
		repladdr(p);
		r = isreg(regs[RT1]);
		r1 = isreg(regs[RT2]);
		dest(regs[RT2],p->subop);
		if (r>=0) {
			if (r1>=0) savereg(r1, regs[r]+1, p->subop);
			else if (p->op!=CVT) savereg(r, regs[RT2], p->subop);
		} else if (r1>=0) savereg(r1, regs[RT1], p->subop);
		else if (p->op!=CVT) setcon(regs[RT1], regs[RT2], p->subop);
		break;

/* .rx,.wx */
	case MFPR:
	case COM:
	case NEG:
/* .rx,.wx or .rx,.rx,.wx */
	case ADD:
	case SUB:
	case BIC:
	case BIS:
	case XOR:
	case MUL:
	case DIV:
	case ASH:
	case MOVZ:
/* .rx,.rx,.rx,.wx */
	case EXTV:
	case EXTZV:
	case INSV:
		splitrand(p);
		repladdr(p);
		dest(lastrand,p->subop);
		if (p->op==INSV) ccloc[0]=0;
		break;

/* .mx or .wx */
	case CLR: