forop.c

早期freebsd实现

	    putdot( filename , line );
		/*
		 * compute and save the termination expression
		 */
	    putRV((char *) 0 , cbn , termnlp -> value[ NL_OFFS ] ,
		    termnlp -> extra_flags , PCCT_INT );
#	endif PC
#	ifdef OBJ
	    (void) gen(O_AS2, O_AS2, sizeof(long), width(inittype));
		/*
		 * compute and save the termination expression
		 */
	    (void) put(2, O_LV | cbn<<8+INDX, termnlp -> value[ NL_OFFS ] );
#	endif OBJ
	termtype = rvalue( term_node , fortype , RREQ );
	if ( incompat( termtype , fortype , term_node ) ) {
	    cerror("Type of limit expression clashed with index type in 'for' statement");
	    if (forvar != NLNIL) {
		forvar->value[ NL_FORV ] = FORVAR;
	    }
	    statement( stat_node );
	    goto byebye;
	}
#	ifdef PC
	    sconv(p2type(termtype), PCCT_INT);
	    putop( PCC_ASSIGN , PCCT_INT );
	    putdot( filename , line );
		/*
		 * we can skip the loop altogether if !( init <= term )
		 */
	    after = (int) getlab();
	    putRV((char *) 0 , cbn , initnlp -> value[ NL_OFFS ] ,
		    initnlp -> extra_flags , PCCT_INT );
	    putRV((char *) 0 , cbn , termnlp -> value[ NL_OFFS ] ,
		    termnlp -> extra_flags , PCCT_INT );
	    putop( ( tree_node->tag == T_FORU ? PCC_LE : PCC_GE ) , PCCT_INT );
	    putleaf( PCC_ICON , after , 0 , PCCT_INT, (char *) 0 );
	    putop( PCC_CBRANCH , PCCT_INT );
	    putdot( filename , line );
		/*
		 * okay, so we have to execute the loop body,
		 * but first, if checking is on,
		 * check that the termination expression
		 * is assignment compatible with the control-variable.
		 */
	    if (opt('t')) {
		precheck(fortype, "_RANG4", "_RSNG4");
		putRV((char *) 0, cbn, termnlp -> value[NL_OFFS],
		    termnlp -> extra_flags, PCCT_INT);
		postcheck(fortype, nl+T4INT);
		putdot(filename, line);
	    }
		/*
		 * assign the initial expression to the shadow
		 * checking the assignment if necessary.
		 */
	    putRV((char *) 0, cbn, shadownlp -> value[NL_OFFS],
		shadownlp -> extra_flags, forp2type);
	    if (opt('t')) {
		precheck(fortype, "_RANG4", "_RSNG4");
		putRV((char *) 0, cbn, initnlp -> value[NL_OFFS],
		    initnlp -> extra_flags, PCCT_INT);
		postcheck(fortype, nl+T4INT);
	    } else {
		putRV((char *) 0, cbn, initnlp -> value[NL_OFFS],
		    initnlp -> extra_flags, PCCT_INT);
	    }
	    sconv(PCCT_INT, forp2type);
	    putop(PCC_ASSIGN, forp2type);
	    putdot(filename, line);
		/*
		 * put down the label at the top of the loop
		 */
	    again = (int) getlab();
	    (void) putlab((char *) again );
		/*
		 * each time through the loop
		 * assign the shadow to the for variable.
		 */
	    (void) lvalue(lhs, NOUSE, RREQ);
	    putRV((char *) 0, cbn, shadownlp -> value[NL_OFFS],
		    shadownlp -> extra_flags, forp2type);
	    putop(PCC_ASSIGN, forp2type);
	    putdot(filename, line);
#	endif PC
#	ifdef OBJ
	    (void) gen(O_AS2, O_AS2, sizeof(long), width(termtype));
		/*
		 * we can skip the loop altogether if !( init <= term )
		 */
	    (void) put(2, O_RV4 | cbn<<8+INDX, initnlp -> value[ NL_OFFS ] );
	    (void) put(2, O_RV4 | cbn<<8+INDX, termnlp -> value[ NL_OFFS ] );
	    (void) gen(NIL, tree_node->tag == T_FORU ? T_LE : T_GE, sizeof(long),
			sizeof(long));
	    after = (int) getlab();
	    (void) put(2, O_IF, after);
		/*
		 * okay, so we have to execute the loop body,
		 * but first, if checking is on,
		 * check that the termination expression
		 * is assignment compatible with the control-variable.
		 */
	    if (opt('t')) {
		(void) put(2, O_LV | cbn<<8+INDX, shadownlp -> value[ NL_OFFS ] );
		(void) put(2, O_RV4 | cbn<<8+INDX, termnlp -> value[ NL_OFFS ] );
		rangechk(fortype, nl+T4INT);
		(void) gen(O_AS2, O_AS2, forwidth, sizeof(long));
	    }
		/*
		 * assign the initial expression to the shadow
		 * checking the assignment if necessary.
		 */
	    (void) put(2, O_LV | cbn<<8+INDX, shadownlp -> value[ NL_OFFS ] );
	    (void) put(2, O_RV4 | cbn<<8+INDX, initnlp -> value[ NL_OFFS ] );
	    rangechk(fortype, nl+T4INT);
	    (void) gen(O_AS2, O_AS2, forwidth, sizeof(long));
		/*
		 * put down the label at the top of the loop
		 */
	    again = (int) getlab();
	    (void) putlab( (char *) again );
		/*
		 * each time through the loop
		 * assign the shadow to the for variable.
		 */
	    (void) lvalue(lhs, NOUSE, RREQ);
	    (void) stackRV(shadownlp);
	    (void) gen(O_AS2, O_AS2, forwidth, sizeof(long));
#	endif OBJ
	    /*
	     *	shadowing the real for variable
	     *	with the shadow temporary:
	     *	save the real for variable flags (including nl_block).
	     *	replace them with the shadow's offset,
	     *	and mark the for variable as being a for variable.
	     */
	shadownlp -> nl_flags |= NLFLAGS(forvar -> nl_flags);
	*forvar = *shadownlp;
	forvar -> symbol = saved_nl.symbol;
	forvar -> nl_next = saved_nl.nl_next;
	forvar -> type = saved_nl.type;
	forvar -> value[ NL_FORV ] = FORVAR;
	    /*
	     * and don't forget ...
	     */
	putcnt();
	statement( stat_node );
	    /*
	     * wasn't that fun?  do we get to do it again?
	     *	we don't do it again if ( !( forvar < limit ) )
	     *	pretend we were doing this at the top of the loop
	     */
	line = f_node->line_no;
#	ifdef PC
	    if ( opt( 'p' ) ) {
		if ( opt('t') ) {
		    putleaf( PCC_ICON , 0 , 0 , PCCM_ADDTYPE( PCCTM_FTN | PCCT_INT , PCCTM_PTR )
			    , "_LINO" );
		    putop( PCCOM_UNARY PCC_CALL , PCCT_INT );
		    putdot( filename , line );
		} else {
		    putRV( STMTCOUNT , 0 , 0 , NGLOBAL , PCCT_INT );
		    putleaf( PCC_ICON , 1 , 0 , PCCT_INT , (char *) 0 );
		    putop( PCCOM_ASG PCC_PLUS , PCCT_INT );
		    putdot( filename , line );
		}
	    }
	    /*rvalue( lhs_node , NIL , RREQ );*/
	    putRV( (char *) 0 , cbn , shadownlp -> value[ NL_OFFS ] ,
		    shadownlp -> extra_flags , forp2type );
	    sconv(forp2type, PCCT_INT);
	    putRV( (char *) 0 , cbn , termnlp -> value[ NL_OFFS ] ,
		    termnlp -> extra_flags , PCCT_INT );
	    putop( ( tree_node->tag == T_FORU ? PCC_LT : PCC_GT ) , PCCT_INT );
	    putleaf( PCC_ICON , after , 0 , PCCT_INT , (char *) 0 );
	    putop( PCC_CBRANCH , PCCT_INT );
	    putdot( filename , line );
		/*
		 * okay, so we have to do it again,
		 * but first, increment the for variable.
		 * no need to rangecheck it, since we checked the
		 * termination value before we started.
		 */
	    /*lvalue( lhs , MOD , RREQ );*/
	    putRV( (char *) 0 , cbn , shadownlp -> value[ NL_OFFS ] ,
		    shadownlp -> extra_flags , forp2type );
	    /*rvalue( lhs_node , NIL , RREQ );*/
	    putRV( (char *) 0 , cbn , shadownlp -> value[ NL_OFFS ] ,
		    shadownlp -> extra_flags , forp2type );
	    sconv(forp2type, PCCT_INT);
	    putleaf( PCC_ICON , 1 , 0 , PCCT_INT , (char *) 0 );
	    putop( ( tree_node->tag == T_FORU ? PCC_PLUS : PCC_MINUS ) , PCCT_INT );
	    sconv(PCCT_INT, forp2type);
	    putop( PCC_ASSIGN , forp2type );
	    putdot( filename , line );
		/*
		 * and do it all again
		 */
	    putjbr( (long) again );
		/*
		 * and here we are
		 */
	    (void) putlab( (char *) after );
#	endif PC
#	ifdef OBJ
		/*
		 * okay, so we have to do it again.
		 * Luckily we have a magic opcode which increments the
		 * index variable, checks the limit falling through if
		 * it has been reached, else updating the index variable,
		 * and returning to the top of the loop.
		 */
	    putline();
	    (void) put(2, O_RV4 | cbn<<8+INDX, termnlp -> value[ NL_OFFS ] );
	    (void) put(2, O_LV | cbn<<8+INDX, shadownlp -> value[ NL_OFFS ] );
	    (void) put(2, (tree_node->tag == T_FORU ? O_FOR1U : O_FOR1D) + (forwidth >> 1),
		    again);
		/*
		 * and here we are
		 */
	    patch( (PTR_DCL) after );
#	endif OBJ
byebye:
	noreach = FALSE;
	if (forvar != NLNIL) {
	    saved_nl.nl_flags |= NLFLAGS(forvar -> nl_flags) & (NUSED|NMOD);
	    *forvar = saved_nl;
	}
	if ( goc != gocnt ) {
	    putcnt();
	}
    }