ack/lang/cem/cemcom.ansi/ch3bin.c

/*
 * (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
 * See the copyright notice in the ACK home directory, in the file "Copyright".
 */
/* $Id$ */
/* SEMANTIC ANALYSIS (CHAPTER 3.3)  --  BINARY OPERATORS */

#include	"parameters.h"
#include	<alloc.h>
#include	<flt_arith.h>
#include	"arith.h"
#include	"type.h"
#include	"struct.h"
#include	"label.h"
#include	"expr.h"
#include	"Lpars.h"
#include	"sizes.h"
#include    "ch3bin.h"
#include    "ch3mon.h"
#include    "ch3.h"
#include    "error.h"
#include    "cstoper.h"
#include    "fltcstoper.h"

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

void pntminuspnt();

/*	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.
*/

/*
 * Although the relational operators are generally not commutative, we can
 * switch the arguments if the operator is adapted (e.g. < becomes >)
 */
#define non_commutative_binop(expp, oper, expr)	mk_binop(expp, oper, expr, 0)
#define commutative_binop(expp, oper, expr)	mk_binop(expp, oper, expr, 1)
#define non_commutative_relop(expp, oper, expr)	mk_binop(expp, oper, expr, 1)

void ch3bin(register struct expr **expp, int oper, struct expr *expr)
{
	/*	apply binary operator oper between *expp and expr.
		NB: don't swap operands if op is one of the op= operators!!!
	*/
	register struct type *expp_tp;

	any2opnd(expp, oper);
	expp_tp = (*expp)->ex_type;
	/* expp_tp can never be ARRAY, since any2opnd() converts the type
	 * to pointer (except for SIZEOF and unary &).
	 */
	any2opnd(&expr, oper);
	switch (oper)	{
	case '[':				/* 3.3.2.1 */
		/* indexing follows the commutative laws */
		switch (expp_tp->tp_fund)	{
		case POINTER:
			break;
		case ERRONEOUS:
			return;
		default:		/* unindexable */
			switch (expr->ex_type->tp_fund)	{
			case POINTER:
				break;
			case ERRONEOUS:
				return;
			default:
				expr_error(*expp,
					"indexing an object of type %s",
					symbol2str(expp_tp->tp_fund));
				return;
			}
			break;
		}
		ch3bin(expp, '+', expr);
		ch3mon('*', expp);
		break;

	case '(':				/* 3.3.2.2 */
		if (expp_tp->tp_fund == POINTER
		    && expp_tp->tp_up->tp_fund == FUNCTION)	{
			ch3mon('*', expp);
			expp_tp = (*expp)->ex_type;
		}
		if (expp_tp->tp_fund != FUNCTION)	{
			expr_error(*expp, "call of non-function (%s)",
				symbol2str(expp_tp->tp_fund));
			/* leave the expression; it may still serve */
			free_expression(expr);	/* there go the parameters */
			*expp = new_oper(error_type,
					*expp, '(', (struct expr *)0);
		}
		else
			*expp = new_oper(expp_tp->tp_up, *expp, '(', expr);
		(*expp)->ex_flags |= EX_SIDEEFFECTS;
		break;

	case PARCOMMA:				/* 3.3.2.2 */
		*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);
		/* fallthrough */
	case '/':
	case DIVAB:
	case TIMESAB:
		arithbalance(expp, oper, &expr);
		non_commutative_binop(expp, oper, expr);
		break;

	case '&':
	case '^':
	case '|':
		opnd2integral(expp, oper);
		opnd2integral(&expr, oper);
		/* fallthrough */
	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;
			expp_tp = expr->ex_type;	/* both in registers */
			expr = *expp;
			*expp = etmp;
		}
		/* fallthrough */
	case PLUSAB:
	case POSTINCR:
	case PLUSPLUS:
		if (expp_tp->tp_fund == POINTER)	{
			pointer_arithmetic(expp, oper, &expr);
			if (expr->ex_type->tp_size != (*expp)->ex_type->tp_size)
				ch3cast(&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);
		}
		break;

	case '-':
	case MINAB:
	case POSTDECR:
	case MINMIN:
		if (expp_tp->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);
		}
		break;

	case LEFT:
	case RIGHT:
	case LEFTAB:
	case RIGHTAB:
		opnd2integral(expp, oper);
		opnd2integral(&expr, oper);
		arithbalance(expp, oper, &expr); /* ch. 3.3.7 */
		ch3cast(&expr, oper, int_type); /* cvt. rightop to int */
		non_commutative_binop(expp, oper, expr);
		break;

	case '<':
	case '>':
	case LESSEQ:
	case GREATEREQ:
	case EQUAL:
	case NOTEQUAL:
		relbalance(expp, oper, &expr);
		non_commutative_relop(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 != 0)) {
				*expp = expr;
			}
			else {
				ex->ex_flags |= expr->ex_flags;
				free_expression(expr);
				*expp = intexpr((arith)(oper != AND), INT);
			}
			(*expp)->ex_flags |= ex->ex_flags | EX_ILVALUE;
			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 != 0)) {
				(*expp)->ex_flags |= expr->ex_flags | EX_ILVALUE;
				free_expression(expr);
			}
			else {
				if (oper == OR)
					expr->VL_VALUE = 1;
				ch3bin(expp, ',', expr);
			}
		}
		else {
			*expp = new_oper(int_type, *expp, oper, expr);
		}
		(*expp)->ex_flags |= EX_LOGICAL;
		break;

	case ':':
		if (is_struct_or_union(expp_tp->tp_fund)
		    || is_struct_or_union(expr->ex_type->tp_fund))	{
			if (!equal_type(expp_tp, expr->ex_type, -1, 0))
				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 */
			if ((*expp)->VL_VALUE) {
				free_expression(*expp);
				free_expression(expr->OP_RIGHT);
				*expp = expr->OP_LEFT;
			}
			else {
				free_expression(*expp);
				free_expression(expr->OP_LEFT);
				*expp = expr->OP_RIGHT;
			}
			free_expr(expr);
			(*expp)->ex_flags |= EX_ILVALUE;
		}
		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 */
			free_expression(*expp);
			*expp = expr;
		}
		else {
			*expp = new_oper(expr->ex_type, *expp, oper, expr);
		}
		(*expp)->ex_flags |= EX_COMMA;
		break;
	}
}

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

	if (!equal_type(up_type, expr->ex_type->tp_up, -1, 0)) {
		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);
	ch3cast(expp, CAST, pa_type);	/* ptr-ptr: result has pa_type	*/
	ch3bin(expp, '/'
		, intexpr(size_of_type(up_type, symbol2str(up_type->tp_fund))
			    , pa_type->tp_fund));
	ch3cast(expp, CAST, pa_type);	/* result will be an integral expr */
					/* cast necessary ??? */
	if (int_size != pointer_size) (*expp)->ex_flags |= EX_PTRDIFF;
}

/*
 * The function arg_switched() returns the operator that should be used
 * when the arguments are switched.  This is special for some relational
 * operators.
 */
int arg_switched(int oper)
{
	switch (oper) {
	case '<':	return '>';
	case '>':	return '<';
	case LESSEQ:	return GREATEREQ;
	case GREATEREQ:	return LESSEQ;
	default:	return oper;
	}
}

void mk_binop(struct expr **expp, int oper, register struct expr *expr, int commutative)
{
	/*	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 if (is_fp_cst(expr) && is_fp_cst(ex))
		fltcstbin(expp, oper, expr);
	else {
		*expp = (commutative
			&& !(ex->ex_flags & EX_VOLATILE)
			&& (expr->ex_depth > ex->ex_depth
			    || ((expr->ex_flags & EX_SIDEEFFECTS)
				&& !(ex->ex_flags & EX_SIDEEFFECTS))
			    || is_cp_cst(ex)))
			? new_oper(ex->ex_type, expr, arg_switched(oper), ex)
			: new_oper(ex->ex_type, ex, oper, expr);
	}
}

void pointer_arithmetic(register struct expr **expp1, int oper, register struct expr **expp2)
{
	int typ;
	/*	prepares the integral expression expp2 in order to
		apply it to the pointer expression expp1
	*/
	if ((typ = any2arith(expp2, oper)) == FLOAT
	    || typ == DOUBLE
	    || typ == LNGDBL)	{
		expr_error(*expp2,
			"illegal combination of %s and pointer",
			symbol2str(typ));
		erroneous2int(expp2);
	}
	ch3bin( expp2, '*',
		intexpr(size_of_type((*expp1)->ex_type->tp_up, "object"),
			pa_type->tp_fund)
	);
}

void pointer_binary(register struct expr **expp, int oper, register struct expr *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);
}