ack/lang/cem/cemcom.ansi/arith.c

/*
 * (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
 * See the copyright notice in the ACK home directory, in the file "Copyright".
 */
/* $Header$ */
/*	A R I T H M E T I C   C O N V E R S I O N S	 */

/*	This file contains the routines for the various conversions that
	may befall operands in C. It is structurally a mess, but I haven't
	decided yet whether I can't find the right structure or the
	semantics of C is a mess.
*/

#include	<alloc.h>
#include	"lint.h"
#include	"nofloat.h"
#include	"nobitfield.h"
#include	"idf.h"
#include	"arith.h"
#include	"sizes.h"
#include	"type.h"
#include	"proto.h"
#include	"label.h"
#include	"expr.h"
#include	"Lpars.h"
#include	"field.h"
#include	"mes.h"
#include	"noRoption.h"

extern char *symbol2str();
extern char options[];

arithbalance(e1p, oper, e2p)	/* RM 6.6 */
	register struct expr **e1p, **e2p;
	int oper;
{
	/*	The expressions *e1p and *e2p are balanced to be operands
		of the arithmetic operator oper.
	*/
	register int t1, t2, u1, u2;

	t1 = any2arith(e1p, oper);
	t2 = any2arith(e2p, oper);
	/* Now t1 and t2 are either INT, LONG, FLOAT, DOUBLE, or LNGDBL */

#ifndef NOFLOAT
	/*	If any operand has the type long double, the other operand
		is converted to long double.
	*/
	if (t1 == LNGDBL) {
		if (t2 != LNGDBL)
			int2float(e2p, lngdbl_type);
		return;
	} else if (t2 == LNGDBL) {
		if (t1 != LNGDBL)
			int2float(e1p, lngdbl_type);
		return;
	}

	/*	If any operand has the type double, the other operand
		is converted to double.
	*/
	if (t1 == DOUBLE) {
		if (t2 != DOUBLE)
			int2float(e2p, double_type);
		return;
	} else if (t2 == DOUBLE) {
		if (t1 != DOUBLE)
			int2float(e1p, double_type);
		return;
	}

	/*	If any operand has the type float, the other operand
		is converted to float.
	*/
	if (t1 == FLOAT) {
		if (t2 != FLOAT)
			int2float(e2p, float_type);
		return;
	} else if (t2 == FLOAT) {
		if (t1 != FLOAT)
			int2float(e1p, float_type);
		return;
	}
#endif NOFLOAT

	/* Now they are INT or LONG */
	u1 = (*e1p)->ex_type->tp_unsigned;
	u2 = (*e2p)->ex_type->tp_unsigned;

	/*	If either operand has type unsigned long int, the other
		operand is converted to unsigned long int.
	*/
	if (t1 == LONG && u1 && (t2 != LONG || !u2))
		t2 = int2int(e2p, ulong_type);
	else if (t2 == LONG && u2 && (t1 != LONG || !u1))
		t1 = int2int(e1p, ulong_type);

	/*	If one operand has type long int and the other has type unsigned
		int, if a long int can represent all values of an unsigned int,
		the operand of type unsigned int is converted to long int; if
		a long int cannot represent all values of an unsigned int,
		both operands are converted to unsigned long int.
	*/
	if (t1 == LONG && t2 == INT && u2)
		t2 = int2int(e2p, (int_size<long_size)? long_type : ulong_type);
	else if (t2 == LONG && t1 == INT && u1)
		t1 = int2int(e1p, (int_size<long_size)? long_type : ulong_type);
	if (int_size > long_size) /* sanity check */
		crash("size of int exceeds size of long");

	/*	If either operand has type long int, the other operand is con-
		verted to long int.
	*/
	if (t1 == LONG && t2 != LONG)
		t2 = int2int(e2p, long_type);
	else
	if (t2 == LONG && t1 != LONG)
		t1 = int2int(e1p, long_type);

	/*	If either operand has type unsigned int, the other operand
		is converted to unsigned int.
		Otherwise, both operands have type int.
	*/
	if (u1 && !u2)
		t2 = int2int(e2p, (t1 == LONG) ? ulong_type : uint_type);
	else
	if (!u1 && u2)
		t1 = int2int(e1p, (t2 == LONG) ? ulong_type : uint_type);
}

relbalance(e1p, oper, e2p)
	register struct expr **e1p, **e2p;
{
	/*	The expressions *e1p and *e2p are balanced to be operands
		of the relational operator oper.
	*/
	if ((*e1p)->ex_type->tp_fund == FUNCTION)
		function2pointer(*e1p);
	if ((*e2p)->ex_type->tp_fund == FUNCTION)
		function2pointer(*e2p);
	if ((*e1p)->ex_type->tp_fund == POINTER)
		ch76pointer(e2p, oper, (*e1p)->ex_type);
	else
	if ((*e2p)->ex_type->tp_fund == POINTER)
		ch76pointer(e1p, oper, (*e2p)->ex_type);
	else
	if (	(*e1p)->ex_type == (*e2p)->ex_type &&
		(*e1p)->ex_type->tp_fund == ENUM
	)
		{}
	else
		arithbalance(e1p, oper, e2p);
}

ch76pointer(expp, oper, tp)
	struct expr **expp;
	register struct type *tp;
{
	/*	Checks whether *expp may be compared to tp using oper,
		as described in chapter 7.6 and 7.7.
		tp is known to be a pointer.
	*/
	register struct expr *exp = *expp;

	if (exp->ex_type->tp_fund == POINTER)	{
		if (exp->ex_type != tp)
			ch7cast(expp, oper, tp);
	}
	else
	if (	is_integral_type(exp->ex_type)
#ifndef NOROPTION
		&&
		(	!options['R'] /* we don't care */ ||
			(oper == EQUAL || oper == NOTEQUAL || oper == ':')
		)
#endif NOROPTION
	)		/* ch 7.7 */
		ch7cast(expp, CAST, tp);
	else	{
		expr_error(exp, "%s on %s and pointer",
				symbol2str(oper),
				symbol2str(exp->ex_type->tp_fund)
			);
		ch7cast(expp, oper, tp);
	}
}

int
any2arith(expp, oper)
	register struct expr **expp;
	register int oper;
{
	/*	Turns any expression into int_type, long_type or
		double_type.
	*/
	int fund;

	switch (fund = (*expp)->ex_type->tp_fund)	{
	case CHAR:
	case SHORT:
	case GENERIC:
		int2int(expp,
			(*expp)->ex_type->tp_unsigned ? uint_type : int_type);
		break;
	case INT:
	case LONG:
		break;
	case ENUM:
		/* test the admissibility of the operator */
		if (	is_test_op(oper) || oper == '=' || oper == PARCOMMA ||
			oper == ',' || oper == ':'
		)	{
			/* allowed by K & R */
		}
		else
#ifndef NOROPTION
		if (!options['R'])	{
			/* allowed by us */
		}
		else
			expr_warning(*expp, "%s on enum", symbol2str(oper));
#endif NOROPTION
#ifndef	LINT
		int2int(expp, int_type);
#endif	LINT
		break;
#ifndef	NOFLOAT
	case FLOAT:
/*
		float2float(expp, double_type);
		break;
*/
	case DOUBLE:
	case LNGDBL:
		break;
#endif	NOFLOAT
#ifndef NOBITFIELD
	case FIELD:
		field2arith(expp);
		break;
#endif NOBITFIELD
	default:
		expr_error(*expp, "operator %s on non-numerical operand (%s)",
			symbol2str(oper), symbol2str(fund));
	case ERRONEOUS:
		erroneous2int(expp);
		break;
	}

	return (*expp)->ex_type->tp_fund;
}

erroneous2int(expp)
	struct expr **expp;
{
	/*	the (erroneous) expression *expp is replaced by an
		int expression
	*/
	register struct expr *exp = *expp;
	int flags = exp->ex_flags;
	
	free_expression(exp);
	exp = intexpr((arith)0, INT);
	exp->ex_flags = (flags | EX_ERROR);
	*expp = exp;
}

struct expr *
arith2arith(tp, oper, expr)
	struct type *tp;
	int oper;
	register struct expr *expr;
{
	/*	arith2arith constructs a new expression containing a
		run-time conversion between some arithmetic types.
	*/
	register struct expr *new = new_expr();
	
	new->ex_file = expr->ex_file;
	new->ex_line = expr->ex_line;
	new->ex_type = tp;
	new->ex_class = Type;
	return new_oper(tp, new, oper, expr);
}

int
int2int(expp, tp)
	struct expr **expp;
	register struct type *tp;
{
	/*	The expression *expp, which is of some integral type, is
		converted to the integral type tp.
	*/
	register struct expr *exp = *expp;
	
	if (is_cp_cst(exp))	{
		register struct type *tp1 = exp->ex_type;

		exp->ex_type = tp;
		if (! tp1->tp_unsigned && tp->tp_unsigned) {
			/*	Avoid "unreal" overflow warnings, such as
				caused by f.i.:
					unsigned int x = ~0;
					unsigned int y = -1;
			*/
			extern long full_mask[];
			long remainder = exp->VL_VALUE &
						~full_mask[(int)(tp->tp_size)];

			if (remainder == 0 ||
			    remainder == ~full_mask[(int)(tp->tp_size)]) {
				exp->VL_VALUE &= ~remainder;
			}
		}
		cut_size(exp);
	}
	else	{
		exp = arith2arith(tp, INT2INT, exp);
	}
	*expp = exp;
	return exp->ex_type->tp_fund;
}

#ifndef NOFLOAT
int2float(expp, tp)
	register struct expr **expp;
	struct type *tp;
{
	/*	The expression *expp, which is of some integral type, is
		converted to the floating type tp.
	*/
	register struct expr *exp = *expp;
	char buf[32];
	
	fp_used = 1;
	if (is_cp_cst(exp)) {
		*expp = new_expr();
		**expp = *exp;
		sprint(buf+1, "%ld", (long)(exp->VL_VALUE));
		buf[0] = '-';
		exp = *expp;
		exp->ex_type = tp;
		exp->ex_class = Float;
		exp->FL_VALUE = Salloc(buf, (unsigned)strlen(buf)+2) + 1;
		exp->FL_DATLAB = 0;
	}
	else	*expp = arith2arith(tp, INT2FLOAT, *expp);
}

float2int(expp, tp)
	struct expr **expp;
	struct type *tp;
{
	/*	The expression *expp, which is of some floating type, is
		converted to the integral type tp.
	*/
	
	fp_used = 1;
	*expp = arith2arith(tp, FLOAT2INT, *expp);
}

float2float(expp, tp)
	register struct expr **expp;
	struct type *tp;
{
	/*	The expression *expp, which is of some floating type, is
		converted to the floating type tp.
		There is no need for an explicit conversion operator
		if the expression is a constant.
	*/
	
	fp_used = 1;
	if (is_fp_cst(*expp))
		(*expp)->ex_type = tp;
	else
		*expp = arith2arith(tp, FLOAT2FLOAT, *expp);
}
#endif NOFLOAT

array2pointer(exp)
	register struct expr *exp;
{
	/*	The expression, which must be an array, is converted
		to a pointer.
	*/
	exp->ex_type = construct_type(POINTER, exp->ex_type->tp_up, 0,
				     (arith)0, NO_PROTO);
}

function2pointer(exp)
	register struct expr *exp;
{
	/*	The expression, which must be a function, is converted
		to a pointer to the function.
	*/
	exp->ex_type = construct_type(POINTER, exp->ex_type, 0,
				     (arith)0, NO_PROTO);
}

string2pointer(ex)
	register struct expr *ex;
{
	/*	The expression, which must be a string constant, is converted
		to a pointer to the string-containing area.
	*/
	label lbl = data_label();

	code_string(ex->SG_VALUE, ex->SG_LEN, lbl);
	ex->ex_class = Value;
	ex->VL_CLASS = Label;
	ex->VL_LBL = lbl;
	ex->VL_VALUE = (arith)0;
}

opnd2integral(expp, oper)
	register struct expr **expp;
	int oper;
{
	register int fund = (*expp)->ex_type->tp_fund;

	if (fund != INT && fund != LONG)	{
		expr_error(*expp, "%s operand to %s",
				symbol2str(fund), symbol2str(oper));
		erroneous2int(expp);
		/* fund = INT; */
	}
}

opnd2logical(expp, oper)
	register struct expr **expp;
	int oper;
{
	int fund = (*expp)->ex_type->tp_fund;

	if (fund == FUNCTION || fund == ARRAY) {
		expr_warning(*expp, "%s operand to %s",
			symbol2str(fund),
			symbol2str(oper));
		if (fund == FUNCTION) {
			function2pointer(*expp);
		}
		else	array2pointer(*expp);
	}
#ifndef NOBITFIELD
	else
	if (fund == FIELD)
		field2arith(expp);
#endif NOBITFIELD
	switch (fund = (*expp)->ex_type->tp_fund) {
	case CHAR:
	case SHORT:
	case INT:
	case LONG:
	case ENUM:
	case POINTER:
#ifndef NOFLOAT
	case FLOAT:
	case DOUBLE:
#endif NOFLOAT
		break;
	default:
		expr_error(*expp, "%s operand to %s",
			symbol2str(fund), symbol2str(oper));
	case ERRONEOUS:
		erroneous2int(expp);
		break;
	}
}

opnd2test(expp, oper)
	register struct expr **expp;
{
	opnd2logical(expp, oper);
	if ((*expp)->ex_class == Oper && is_test_op((*expp)->OP_OPER))
		{ /* It is already a test */ }
	else
		ch7bin(expp, NOTEQUAL, intexpr((arith)0, INT));
}

int
is_test_op(oper)
{
	switch (oper)	{
	case '<':
	case '>':
	case LESSEQ:
	case GREATEREQ:
	case EQUAL:
	case NOTEQUAL:
	case '!':
	case AND:
	case OR:	/* && and || also impose a test	*/
		return 1;
	default:
		return 0;
	}
	/*NOTREACHED*/
}

any2opnd(expp, oper)
	register struct expr **expp;
{
	if (!*expp)
		return;
	switch ((*expp)->ex_type->tp_fund)	{	/* RM 7.1 */
	case CHAR:
	case SHORT:
	case ENUM:
#ifndef NOFLOAT
	case FLOAT:
#endif NOFLOAT
		any2arith(expp, oper);
		break;
	case ARRAY:
		array2pointer(*expp);
		break;
	case POINTER:
		if ((*expp)->ex_class == String)
			string2pointer(*expp);
		break;
#ifndef NOBITFIELD
	case FIELD:
		field2arith(expp);
		break;
#endif NOBITFIELD
	}
}

any2parameter(expp)
	register struct expr **expp;
{
	/*	To handle default argument promotions
	*/
	any2opnd(expp, '(');
#ifndef NOFLOAT
	if ((*expp)->ex_type->tp_fund == FLOAT)
		float2float(expp, double_type);
#endif NOFLOAT
}

#ifndef NOBITFIELD
field2arith(expp)
	register struct expr **expp;
{
	/*	The expression to extract the bitfield value from the
		memory word is put in the tree.
	*/
	register struct type *tp = (*expp)->ex_type->tp_up;
	register struct field *fd = (*expp)->ex_type->tp_field;
	register struct type *atype = tp->tp_unsigned ? uword_type : word_type;

	(*expp)->ex_type = atype;

	if (atype->tp_unsigned)	{	/* don't worry about the sign bit */
		ch7bin(expp, RIGHT, intexpr((arith)fd->fd_shift, INT));
		ch7bin(expp, '&', intexpr(fd->fd_mask, INT));
	}
	else	{	/* take care of the sign bit: sign extend if needed */
		arith bits_in_type = atype->tp_size * 8;

		ch7bin(expp, LEFT,
			intexpr(bits_in_type - fd->fd_width - fd->fd_shift,
						INT)
		);
		ch7bin(expp, RIGHT, intexpr(bits_in_type - fd->fd_width, INT));
	}
	ch7cast(expp, CAST, tp);	/* restore its original type */
}
#endif NOBITFIELD

#ifndef NOFLOAT
/*	switch_sign_fp() negates the given floating constant expression
	The lexical analyser has reserved an extra byte of space in front
	of the string containing the representation of the floating
	constant.  This byte contains the '-' character and we have to
	take care of the first byte the fl_value pointer points to.
*/
switch_sign_fp(expr)
	register struct expr *expr;
{
	if (*(expr->FL_VALUE) == '-')
		++(expr->FL_VALUE);
	else
		--(expr->FL_VALUE);
}
#endif NOFLOAT