symbols.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

	    frp = findframe(cur);
	    if (frp == nil) {
		panic("unexpected nil frame for \"%s\"", symname(s));
	    }
	}
	if (islocaloff(s)) {
	    addr = locals_base(frp) + s->symvalue.offset;
	} else if (isparamoff(s)) {
	    addr = args_base(frp) + s->symvalue.offset;
	} else if (isreg(s)) {
	    addr = savereg(s->symvalue.offset, frp);
	} else {
	    panic("address: bad symbol \"%s\"", symname(s));
	}
    }
    return addr;
}

/*
 * Define a symbol used to access register values.
 */

public defregname(n, r)
Name n;
Integer r;
{
    register Symbol s, t;

    s = insert(n);
    t = newSymbol(nil, 0, PTR, t_int, nil);
    t->language = primlang;
    s->language = t->language;
    s->class = VAR;
    s->level = -3;
    s->type = t;
    s->block = program;
    s->symvalue.offset = r;
}

/*
 * Resolve an "abstract" type reference.
 *
 * It is possible in C to define a pointer to a type, but never define
 * the type in a particular source file.  Here we try to resolve
 * the type definition.  This is problematic, it is possible to
 * have multiple, different definitions for the same name type.
 */

public findtype(s)
Symbol s;
{
    register Symbol t, u, prev;

    u = s;
    prev = nil;
    while (u != nil and u->class != BADUSE) {
	if (u->name != nil) {
	    prev = u;
	}
	u = u->type;
    }
    if (prev == nil) {
	error("couldn't find link to type reference");
    }
    find(t, prev->name) where
	t != prev and t->block->class == MODULE and t->class == prev->class and
	t->type != nil and t->type->type != nil and
	t->type->type->class != BADUSE
    endfind(t);
    if (t == nil) {
	error("couldn't resolve reference");
    } else {
	prev->type = t->type;
    }
}

/*
 * Find the size in bytes of the given type.
 *
 * This is probably the WRONG thing to do.  The size should be kept
 * as an attribute in the symbol information as is done for structures
 * and fields.  I haven't gotten around to cleaning this up yet.
 */

#define MAXUCHAR 255
#define MAXUSHORT 65535L
#define MINCHAR -128
#define MAXCHAR 127
#define MINSHORT -32768
#define MAXSHORT 32767

/*
 * When necessary, compute the upper bound for an open array (Modula-2 style).
 */

public chkOpenArray (sym)
Symbol sym;
{
    Symbol t;
    Address a;
    integer n;

    if (sym->class == REF or sym->class == VAR) {
	t = rtype(sym->type);
	if (t->class == ARRAY and t->chain == t_open) {
	    a = address(sym, nil);
	    dread(&n, a + sizeof(Word), sizeof(n));
	    t->chain->type->symvalue.rangev.upper = n - 1;
	}
    }
}

public findbounds (u, lower, upper)
Symbol u;
long *lower, *upper;
{
    Rangetype lbt, ubt;
    long lb, ub;

    if (u->class == RANGE) {
	lbt = u->symvalue.rangev.lowertype;
	ubt = u->symvalue.rangev.uppertype;
	lb = u->symvalue.rangev.lower;
	ub = u->symvalue.rangev.upper;
	if (lbt == R_ARG or lbt == R_TEMP) {
	    if (not getbound(u, lb, lbt, lower)) {
		error("dynamic bounds not currently available");
	    }
	} else {
	    *lower = lb;
	}
	if (ubt == R_ARG or ubt == R_TEMP) {
	    if (not getbound(u, ub, ubt, upper)) {
		error("dynamic bounds not currently available");
	    }
	} else {
	    *upper = ub;
	}
    } else if (u->class == SCAL) {
	*lower = 0;
	*upper = u->symvalue.iconval - 1;
    } else {
	panic("unexpected array bound type");
    }
}

public integer size(sym)
Symbol sym;
{
    register Symbol s, t, u;
    register integer nel, elsize;
    long lower, upper;
    integer r, off, len;

    t = sym;
    checkref(t);
    if (t->class == TYPEREF) {
	resolveRef(t);
    }
    switch (t->class) {
	case RANGE:
	    lower = t->symvalue.rangev.lower;
	    upper = t->symvalue.rangev.upper;
	    if (upper == 0 and lower > 0) {
		/* real */
		r = lower;
	    } else if (lower > upper) {
		/* unsigned long */
		r = sizeof(long);
	    } else if (
  		(lower >= MINCHAR and upper <= MAXCHAR) or
  		(lower >= 0 and upper <= MAXUCHAR)
  	      ) {
		r = sizeof(char);
  	    } else if (
  		(lower >= MINSHORT and upper <= MAXSHORT) or
  		(lower >= 0 and upper <= MAXUSHORT)
  	      ) {
		r = sizeof(short);
	    } else {
		r = sizeof(long);
	    }
	    break;

	case ARRAY:
	    elsize = size(t->type);
	    nel = 1;
	    for (t = t->chain; t != nil; t = t->chain) {
		u = rtype(t);
		findbounds(u, &lower, &upper);
		nel *= (upper-lower+1);
	    }
	    r = nel*elsize;
	    break;

	case REF:
	case VAR:
	case FVAR:
	    chkOpenArray(t);
	    r = size(t->type);
	    /*
	     *
	    if (r < sizeof(Word) and isparam(t)) {
		r = sizeof(Word);
	    }
	    */
	    break;

	case CONST:
	    r = size(t->type);
	    break;

	case TYPE:
	    if (t->type->class == PTR and t->type->type->class == BADUSE) {
		findtype(t);
	    }
	    r = size(t->type);
	    break;

	case TAG:
	    r = size(t->type);
	    break;

	case FIELD:
	    off = t->symvalue.field.offset;
	    len = t->symvalue.field.length;
	    r = (off + len + 7) div 8 - (off div 8);
	    /* r = (t->symvalue.field.length + 7) div 8; */
	    break;

	case RECORD:
	case VARNT:
	    r = t->symvalue.offset;
	    if (r == 0 and t->chain != nil) {
		panic("missing size information for record");
	    }
	    break;

	case PTR:
	case FILET:
	    r = sizeof(Word);
	    break;

	case SCAL:
	    r = sizeof(Word);
	    /*
	     *
	    if (t->symvalue.iconval > 255) {
		r = sizeof(short);
	    } else {
		r = sizeof(char);
	    }
	     *
	     */
	    break;

	case FPROC:
	case FFUNC:
	    r = sizeof(Word);
	    break;

	case PROC:
	case FUNC:
	case MODULE:
	case PROG:
	    r = sizeof(Symbol);
	    break;

	case SET:
	    u = rtype(t->type);
	    switch (u->class) {
		case RANGE:
		    r = u->symvalue.rangev.upper - u->symvalue.rangev.lower + 1;
		    break;

		case SCAL:
		    r = u->symvalue.iconval;
		    break;

		default:
		    error("expected range for set base type");
		    break;
	    }
	    r = (r + BITSPERBYTE - 1) div BITSPERBYTE;
	    break;

	default:
	    if (ord(t->class) > ord(TYPEREF)) {
		panic("size: bad class (%d)", ord(t->class));
	    } else {
		fprintf(stderr, "!! size(%s) ??", classname(t));
	    }
	    r = 0;
	    break;
    }
    return r;
}

/*
 * Test if a symbol is a parameter.  This is true if there
 * is a cycle from s->block to s via chain pointers.
 */

public Boolean isparam(s)
Symbol s;
{
    register Symbol t;

    t = s->block;
    while (t != nil and t != s) {
	t = t->chain;
    }
    return (Boolean) (t != nil);
}

/*
 * Test if a type is an open array parameter type.
 */

public Boolean isopenarray (t)
Symbol t;
{
    return (Boolean) (t->class == ARRAY and t->chain == t_open);
}

/*
 * Test if a symbol is a var parameter, i.e. has class REF but
 * is not an open array parameter (those are treated special).
 */

public Boolean isvarparam(s)
Symbol s;
{
    return (Boolean) (s->class == REF);
}

/*
 * Test if a symbol is a variable (actually any addressible quantity
 * with do).
 */

public Boolean isvariable(s)
register Symbol s;
{
    return (Boolean) (s->class == VAR or s->class == FVAR or s->class == REF);
}

/*
 * Test if a symbol is a block, e.g. function, procedure, or the
 * main program.
 *
 * This function is now expanded inline for efficiency.
 *
 * public Boolean isblock(s)
register Symbol s;
{
    return (Boolean) (
	s->class == FUNC or s->class == PROC or
	s->class == MODULE or s->class == PROG
    );
}
 *
 */

/*
 * Test if a symbol is a module.
 */

public Boolean ismodule(s)
register Symbol s;
{
    return (Boolean) (s->class == MODULE);
}

/*
 * Test if a symbol is builtin, that is, a predefined type or
 * reserved word.
 */

public Boolean isbuiltin(s)
register Symbol s;
{
    return (Boolean) (s->level == 0 and s->class != PROG and s->class != VAR);
}

/*
 * Mark a procedure or function as internal, meaning that it is called
 * with a different calling sequence.
 */

public markInternal (s)
Symbol s;
{
    s->symvalue.funcv.intern = true;
}

public boolean isinternal (s)
Symbol s;
{
    return s->symvalue.funcv.intern;
}

/*
 * Test if two types match.
 * Equivalent names implies a match in any language.
 *
 * Special symbols must be handled with care.
 */

public Boolean compatible(t1, t2)
register Symbol t1, t2;
{
    Boolean b;
    Symbol rt1, rt2;

    if (t1 == t2) {
	b = true;
    } else if (t1 == nil or t2 == nil) {
	b = false;
    } else if (t1 == procsym) {
	b = isblock(t2);
    } else if (t2 == procsym) {
	b = isblock(t1);
    } else if (t1->language == primlang) {
	if (t2->language == primlang) {
	    rt1 = rtype(t1);
	    rt2 = rtype(t2);
	    b = (boolean) (
		(rt1->type == t_open and rt2->type == t_int) or
		(rt2->type == t_open and rt1->type == t_int) or
		rt1 == rt2
	    );
	} else {
	    b = (boolean) (*language_op(t2->language, L_TYPEMATCH))(t1, t2);
	}
    } else if (t2->language == primlang) {
	b = (boolean) (*language_op(t1->language, L_TYPEMATCH))(t1, t2);
    } else if (t1->language == nil) {
	if (t2->language == nil) {
	    b = false;
	} else {
	    b = (boolean) (*language_op(t2->language, L_TYPEMATCH))(t1, t2);
	}
    } else if (t2->language == nil) {
	b = (boolean) (*language_op(t1->language, L_TYPEMATCH))(t1, t2);
    } else if (isbuiltin(t1) or isbuiltin(t1->type)) {
	b = (boolean) (*language_op(t2->language, L_TYPEMATCH))(t1, t2);
    } else {
	b = (boolean) (*language_op(t1->language, L_TYPEMATCH))(t1, t2);
    }
    return b;
}

/*
 * Check for a type of the given name.
 */

public Boolean istypename(type, name)
Symbol type;
String name;
{
    Symbol t;
    Boolean b;

    t = type;
    checkref(t);
    b = (Boolean) (
	t->class == TYPE and streq(ident(t->name), name)
    );
    return b;
}

/*
 * Determine if a (value) parameter should actually be passed by address.
 */

public boolean passaddr (p, exprtype)
Symbol p, exprtype;
{
    boolean b;
    Language def;

    if (p == nil) {
	def = findlanguage(".c");
	b = (boolean) (*language_op(def, L_PASSADDR))(p, exprtype);
    } else if (p->language == nil or p->language == primlang) {
	b = false;
    } else if (isopenarray(p->type)) {
	b = true;
    } else {
	b = (boolean) (*language_op(p->language, L_PASSADDR))(p, exprtype);
    }
    return b;
}

/*
 * Test if the name of a symbol is uniquely defined or not.
 */

public Boolean isambiguous(s)
register Symbol s;
{
    register Symbol t;

    find(t, s->name) where t != s endfind(t);
    return (Boolean) (t != nil);
}

typedef char *Arglist;

#define nextarg(type)  ((type *) (ap += sizeof(type)))[-1]

private Symbol mkstring();
private Symbol namenode();

/*
 * Determine the type of a parse tree.
 * Also make some symbol-dependent changes to the tree such as
 * changing removing RVAL nodes for constant symbols.
 */

public assigntypes(p)
register Node p;
{
    register Node p1;
    register Symbol s;

    switch (p->op) {