ack/lang/cem/cemcom/ch7bin.c

/*
 * (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
 * See the copyright notice in the ACK home directory, in the file "Copyright".
 */
/* $Header$ */
/* SEMANTIC ANALYSIS (CHAPTER 7RM)  --  BINARY OPERATORS */

#include	"botch_free.h"
#include	<alloc.h>
#include	"nofloat.h"
#include	"lint.h"
#include	"idf.h"
#include	"arith.h"
#include	"type.h"
#include	"struct.h"
#include	"label.h"
#include	"expr.h"
#include	"Lpars.h"
#include	"noRoption.h"

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

/*	This chapter asks for the repeated application of code to handle
	an operation that may be executed at compile time or at run time,
	depending on the constancy of the operands.
*/

#define commutative_binop(expp, oper, expr)	mk_binop(expp, oper, expr, 1)
#define non_commutative_binop(expp, oper, expr)	mk_binop(expp, oper, expr, 0)

ch7bin(expp, oper, expr)
	register struct expr **expp;
	struct expr *expr;
{
	/*	apply binary operator oper between *expp and expr.
		NB: don't swap operands if op is one of the op= operators!!!
	*/

	any2opnd(expp, oper);
	any2opnd(&expr, oper);
	switch (oper)	{
	case '[':				/* RM 7.1 */
		/* RM 14.3 states that indexing follows the commutative laws */
		switch ((*expp)->ex_type->tp_fund)	{
		case POINTER:
		case ARRAY:
			break;
		case ERRONEOUS:
			return;
		default:		/* unindexable */
			switch (expr->ex_type->tp_fund)	{
			case POINTER:
			case ARRAY:
				break;
			case ERRONEOUS:
				return;
			default:
				expr_error(*expp,
					"indexing an object of type %s",
					symbol2str((*expp)->ex_type->tp_fund));
				return;
			}
			break;
		}
		ch7bin(expp, '+', expr);
		ch7mon('*', expp);
		break;

	case '(':				/* RM 7.1 */
		if (	(*expp)->ex_type->tp_fund == POINTER &&
			(*expp)->ex_type->tp_up->tp_fund == FUNCTION
		)	{
#ifndef NOROPTION
			if (options['R'])
				warning("function pointer called");
#endif /* NOROPTION */
			ch7mon('*', expp);
		}
		switch ((*expp)->ex_type->tp_fund)	{
		case FUNCTION:
			*expp = new_oper((*expp)->ex_type->tp_up,
					*expp, '(', expr);
			break;
		default:		/* uncallable */
			expr_error(*expp, "calling an object of type %s",
				symbol2str((*expp)->ex_type->tp_fund));
		case ERRONEOUS:		/* uncallable but no message */
			/* leave the expression; it may still serve */
			free_expression(expr);	/* there go the parameters */
			break;
		}
		(*expp)->ex_flags |= EX_SIDEEFFECTS;
		break;

	case PARCOMMA:				/* RM 7.1 */
		if ((*expp)->ex_type->tp_fund == FUNCTION)
			function2pointer(*expp);
		*expp = new_oper(expr->ex_type, *expp, PARCOMMA, expr);
		break;

	case '%':
	case MODAB:
	case ANDAB:
	case XORAB:
	case ORAB:
		opnd2integral(expp, oper);
		opnd2integral(&expr, oper);
		/* Fall through */
	case '/':
	case DIVAB:
	case TIMESAB:
		arithbalance(expp, oper, &expr);
		non_commutative_binop(expp, oper, expr);
		if (oper != '/' && oper != '%') {
			(*expp)->ex_flags |= EX_SIDEEFFECTS;
		}
		break;

	case '&':
	case '^':
	case '|':
		opnd2integral(expp, oper);
		opnd2integral(&expr, oper);
		/* Fall through */
	case '*':
		arithbalance(expp, oper, &expr);
		commutative_binop(expp, oper, expr);
		break;

	case '+':
		if (expr->ex_type->tp_fund == POINTER)	{ /* swap operands */
			struct expr *etmp = expr;
			expr = *expp;
			*expp = etmp;
		}
		/*FALLTHROUGH*/
	case PLUSAB:
	case POSTINCR:
	case PLUSPLUS:
		if ((*expp)->ex_type->tp_fund == POINTER)	{
			pointer_arithmetic(expp, oper, &expr);
			if (expr->ex_type->tp_size != (*expp)->ex_type->tp_size)
				ch7cast(&expr, CAST, (*expp)->ex_type);
			pointer_binary(expp, oper, expr);
		}
		else	{
			arithbalance(expp, oper, &expr);
			if (oper == '+')
				commutative_binop(expp, oper, expr);
			else
				non_commutative_binop(expp, oper, expr);
		}
		if (oper != '+') {
			(*expp)->ex_flags |= EX_SIDEEFFECTS;
		}
		break;

	case '-':
	case MINAB:
	case POSTDECR:
	case MINMIN:
		if ((*expp)->ex_type->tp_fund == POINTER)	{
			if (expr->ex_type->tp_fund == POINTER)
				pntminuspnt(expp, oper, expr);
			else {
				pointer_arithmetic(expp, oper, &expr);
				pointer_binary(expp, oper, expr);
			}
		}
		else	{
			arithbalance(expp, oper, &expr);
			non_commutative_binop(expp, oper, expr);
		}
		if (oper != '-') {
			(*expp)->ex_flags |= EX_SIDEEFFECTS;
		}
		break;

	case LEFT:
	case RIGHT:
	case LEFTAB:
	case RIGHTAB:
		opnd2integral(expp, oper);
		opnd2integral(&expr, oper);
		arithbalance(expp, oper, &expr); /* ch. 7.5 */
		ch7cast(&expr, oper, int_type); /* cvt. rightop to int */
		non_commutative_binop(expp, oper, expr);
		if (oper != LEFT && oper != RIGHT) {
			(*expp)->ex_flags |= EX_SIDEEFFECTS;
		}
		break;

	case '<':
	case '>':
	case LESSEQ:
	case GREATEREQ:
	case EQUAL:
	case NOTEQUAL:
		relbalance(expp, oper, &expr);
		if (oper == EQUAL || oper == NOTEQUAL) {
			commutative_binop(expp, oper, expr);
		}
		else	non_commutative_binop(expp, oper, expr);
		(*expp)->ex_type = int_type;
		break;

	case AND:
	case OR:
		opnd2test(expp, oper);
		opnd2test(&expr, oper);
		if (is_cp_cst(*expp))	{
			register struct expr *ex = *expp;

			/* the following condition is a short-hand for
				((oper == AND) && o1) || ((oper == OR) && !o1)
				where o1 == (*expp)->VL_VALUE;
				and ((oper == AND) || (oper == OR))
			*/
			if ((oper == AND) == (ex->VL_VALUE != (arith)0))
				*expp = expr;
			else {
				ex->ex_flags |= expr->ex_flags;
				free_expression(expr);
				*expp = intexpr((arith)((oper == AND) ? 0 : 1),
						INT);
			}
			(*expp)->ex_flags |= ex->ex_flags;
			free_expression(ex);
		}
		else
		if (is_cp_cst(expr))	{
			/* Note!!!: the following condition is a short-hand for
				((oper == AND) && o2) || ((oper == OR) && !o2)
				where o2 == expr->VL_VALUE
				and ((oper == AND) || (oper == OR))
			*/
			if ((oper == AND) == (expr->VL_VALUE != (arith)0)) {
				(*expp)->ex_flags |= expr->ex_flags;
				free_expression(expr);
			}
			else {
				if (oper == OR)
					expr->VL_VALUE = (arith)1;
				ch7bin(expp, ',', expr);
			}
		}
		else
			*expp = new_oper(int_type, *expp, oper, expr);
		(*expp)->ex_flags |= EX_LOGICAL;
		break;

	case ':':
		if (	is_struct_or_union((*expp)->ex_type->tp_fund)
		||	is_struct_or_union(expr->ex_type->tp_fund)
		)	{
			if ((*expp)->ex_type != expr->ex_type)
				expr_error(*expp, "illegal balance");
		}
		else
			relbalance(expp, oper, &expr);
#ifdef	LINT
		if (	(is_cp_cst(*expp) && is_cp_cst(expr))
		&&	(*expp)->VL_VALUE == expr->VL_VALUE
		) {
			hwarning("operands of : are constant and equal");
		}
#endif	/* LINT */
		*expp = new_oper((*expp)->ex_type, *expp, oper, expr);
		break;

	case '?':
		opnd2logical(expp, oper);
		if (is_cp_cst(*expp)) {
#ifdef	LINT
			hwarning("condition in ?: expression is constant");
#endif	/* LINT */
			*expp = (*expp)->VL_VALUE ?
				expr->OP_LEFT : expr->OP_RIGHT;
		}
		else {
			*expp = new_oper(expr->ex_type, *expp, oper, expr);
		}
		break;

	case ',':
		if (is_cp_cst(*expp)) {
#ifdef	LINT
			hwarning("constant expression ignored");
#endif	/* LINT */
			*expp = expr;
		}
		else {
			*expp = new_oper(expr->ex_type, *expp, oper, expr);
		}
		(*expp)->ex_flags |= EX_COMMA;
		break;
	}
}

pntminuspnt(expp, oper, expr)
	register struct expr **expp, *expr;
{
	/*	Subtracting two pointers is so complicated it merits a
		routine of its own.
	*/
	struct type *up_type = (*expp)->ex_type->tp_up;

	if (up_type != expr->ex_type->tp_up)	{
		expr_error(*expp, "subtracting incompatible pointers");
		free_expression(expr);
		erroneous2int(expp);
		return;
	}
	/*	we hope the optimizer will eliminate the load-time
		pointer subtraction
	*/
	*expp = new_oper((*expp)->ex_type, *expp, oper, expr);
	ch7cast(expp, CAST, pa_type);	/* ptr-ptr: result has pa_type	*/
	ch7bin(expp, '/',
		intexpr(size_of_type(up_type, "object"), pa_type->tp_fund));
	ch7cast(expp, CAST, int_type);	/* result will be an integer expr */
}

mk_binop(expp, oper, expr, commutative)
	struct expr **expp;
	register struct expr *expr;
{
	/*	Constructs in *expp the operation indicated by the operands.
		"commutative" indicates whether "oper" is a commutative
		operator.
	*/
	register struct expr *ex = *expp;

	if (is_cp_cst(expr) && is_cp_cst(ex))
		cstbin(expp, oper, expr);
	else	{
		*expp = (commutative &&
			  ( expr->ex_depth > ex->ex_depth ||
			    (expr->ex_flags & EX_SIDEEFFECTS) ||
			    is_cp_cst(ex))) ?
				new_oper(ex->ex_type, expr, oper, ex) :
				new_oper(ex->ex_type, ex, oper, expr);
	}
}

pointer_arithmetic(expp1, oper, expp2)
	register struct expr **expp1, **expp2;
{
	/*	prepares the integral expression expp2 in order to
		apply it to the pointer expression expp1
	*/
#ifndef NOFLOAT
	if (any2arith(expp2, oper) == DOUBLE)	{
		expr_error(*expp2,
			"illegal combination of float and pointer");
		erroneous2int(expp2);
	}
#endif /* NOFLOAT */
	ch7bin( expp2, '*',
		intexpr(size_of_type((*expp1)->ex_type->tp_up, "object"),
			pa_type->tp_fund)
	);
}

pointer_binary(expp, oper, expr)
	register struct expr **expp, *expr;
{
	/*	constructs the pointer arithmetic expression out of
		a pointer expression, a binary operator and an integral
		expression.
	*/
	if (is_ld_cst(expr) && is_ld_cst(*expp))
		cstbin(expp, oper, expr);
	else
		*expp = new_oper((*expp)->ex_type, *expp, oper, expr);
}