442 lines
10 KiB
C
442 lines
10 KiB
C
/*
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* (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
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* See the copyright notice in the ACK home directory, in the file "Copyright".
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*/
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/* $Header$ */
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/* S E M A N T I C A N A L Y S I S -- C H A P T E R 7 RM */
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#include "lint.h"
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#include "nofloat.h"
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#include "debug.h"
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#include "nobitfield.h"
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#include "idf.h"
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#include "arith.h"
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#include "type.h"
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#include "struct.h"
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#include "label.h"
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#include "expr.h"
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#include "def.h"
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#include "Lpars.h"
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#include "assert.h"
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extern char options[];
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extern char *symbol2str();
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/* Most expression-handling routines have a pointer to a
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(struct type *) as first parameter. The object under the pointer
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gets updated in the process.
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*/
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ch7sel(expp, oper, idf)
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struct expr **expp;
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struct idf *idf;
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{
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/* The selector idf is applied to *expp; oper may be '.' or
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ARROW.
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*/
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register struct expr *exp;
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register struct type *tp;
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register struct sdef *sd;
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any2opnd(expp, oper);
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exp = *expp;
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tp = exp->ex_type;
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if (oper == ARROW) {
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if (tp->tp_fund == POINTER &&
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( tp->tp_up->tp_fund == STRUCT ||
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tp->tp_up->tp_fund == UNION)) /* normal case */
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tp = tp->tp_up;
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else { /* constructions like "12->selector" and
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"char c; c->selector"
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*/
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switch (tp->tp_fund) {
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case INT:
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case LONG:
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/* Allowed by RM 14.1 */
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ch7cast(expp, CAST, pa_type);
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sd = idf2sdef(idf, tp);
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tp = sd->sd_stype;
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break;
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case POINTER:
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break;
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default:
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expr_error(exp, "-> applied to %s",
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symbol2str(tp->tp_fund));
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case ERRONEOUS:
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exp->ex_type = error_type;
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return;
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}
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}
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} /* oper == ARROW */
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else { /* oper == '.' */
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/* filter out illegal expressions "non_lvalue.sel" */
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if (!exp->ex_lvalue) {
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expr_error(exp, "dot requires lvalue");
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return;
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}
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}
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exp = *expp;
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switch (tp->tp_fund) {
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case POINTER: /* for int *p; p->next = ... */
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case STRUCT:
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case UNION:
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break;
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case INT:
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case LONG:
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/* warning will be given by idf2sdef() */
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break;
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default:
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if (!is_anon_idf(idf))
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expr_error(exp, "selector %s applied to %s",
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idf->id_text, symbol2str(tp->tp_fund));
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case ERRONEOUS:
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exp->ex_type = error_type;
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return;
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}
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sd = idf2sdef(idf, tp);
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if (oper == '.') {
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/* there are 3 cases in which the selection can be
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performed compile-time:
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I: n.sel (n either an identifier or a constant)
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II: (e.s1).s2 (transformed into (e.(s1+s2)))
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III: (e->s1).s2 (transformed into (e->(s1+s2)))
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The code performing these conversions is
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extremely obscure.
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*/
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if (exp->ex_class == Value) {
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/* It is an object we know the address of; so
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we can calculate the address of the
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selected member
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*/
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exp->VL_VALUE += sd->sd_offset;
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exp->ex_type = sd->sd_type;
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if (exp->ex_type == error_type)
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exp->ex_flags |= EX_ERROR;
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}
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else
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if (exp->ex_class == Oper) {
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struct oper *op = &(exp->ex_object.ex_oper);
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if (op->op_oper == '.' || op->op_oper == ARROW) {
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ASSERT(is_cp_cst(op->op_right));
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op->op_right->VL_VALUE += sd->sd_offset;
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exp->ex_type = sd->sd_type;
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if (exp->ex_type == error_type)
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exp->ex_flags |= EX_ERROR;
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}
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else
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exp = new_oper(sd->sd_type, exp, '.',
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intexpr(sd->sd_offset, INT));
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}
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}
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else /* oper == ARROW */
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exp = new_oper(sd->sd_type,
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exp, oper, intexpr(sd->sd_offset, INT));
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exp->ex_lvalue = (sd->sd_type->tp_fund != ARRAY);
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*expp = exp;
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}
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ch7incr(expp, oper)
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struct expr **expp;
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{
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/* The monadic prefix/postfix incr/decr operator oper is
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applied to *expp.
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*/
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ch7asgn(expp, oper, intexpr((arith)1, INT));
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}
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ch7cast(expp, oper, tp)
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register struct expr **expp;
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register struct type *tp;
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{
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/* The expression *expp is cast to type tp; the cast is
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caused by the operator oper. If the cast has
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to be passed on to run time, its left operand will be an
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expression of class Type.
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*/
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register struct type *oldtp;
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if ((*expp)->ex_type->tp_fund == FUNCTION)
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function2pointer(*expp);
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if ((*expp)->ex_type->tp_fund == ARRAY)
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array2pointer(*expp);
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if ((*expp)->ex_class == String)
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string2pointer(*expp);
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oldtp = (*expp)->ex_type;
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#ifndef NOBITFIELD
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if (oldtp->tp_fund == FIELD) {
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field2arith(expp);
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ch7cast(expp, oper, tp);
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}
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else
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if (tp->tp_fund == FIELD) {
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ch7cast(expp, oper, tp->tp_up);
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}
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else
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#endif /* NOBITFIELD */
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if (oldtp == tp) {
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/* life is easy */
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}
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else
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if (tp->tp_fund == VOID) {
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/* Easy again */
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(*expp)->ex_type = void_type;
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}
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else
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if (is_arith_type(oldtp) && is_arith_type(tp)) {
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int oldi = is_integral_type(oldtp);
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int i = is_integral_type(tp);
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if (oldi && i) {
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if ( oper != CAST
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&& ( tp->tp_fund == ENUM
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|| oldtp->tp_fund == ENUM
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)
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) {
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expr_warning(*expp,
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"dubious %s on enum",
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symbol2str(oper));
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}
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#ifdef LINT
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if (oper == CAST)
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(*expp)->ex_type = tp;
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else
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int2int(expp, tp);
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#else /* LINT */
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int2int(expp, tp);
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#endif /* LINT */
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}
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#ifndef NOFLOAT
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else
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if (oldi && !i) {
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if (oldtp->tp_fund == ENUM && oper != CAST)
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expr_warning(*expp,
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"conversion of enum to %s\n",
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symbol2str(tp->tp_fund));
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#ifdef LINT
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if (oper == CAST)
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(*expp)->ex_type = tp;
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else
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int2float(expp, tp);
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#else /* LINT */
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int2float(expp, tp);
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#endif /* LINT */
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}
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else
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if (!oldi && i) {
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#ifdef LINT
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if (oper == CAST)
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(*expp)->ex_type = tp;
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else
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float2int(expp, tp);
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#else /* LINT */
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float2int(expp, tp);
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#endif /* LINT */
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}
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else {
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/* !oldi && !i */
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#ifdef LINT
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if (oper == CAST)
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(*expp)->ex_type = tp;
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else
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float2float(expp, tp);
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#else /* LINT */
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float2float(expp, tp);
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#endif /* LINT */
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}
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#else /* NOFLOAT */
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else {
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crash("(ch7cast) floats not implemented\n");
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/*NOTREACHED*/
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}
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#endif /* NOFLOAT */
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}
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else
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if (oldtp->tp_fund == POINTER && tp->tp_fund == POINTER) {
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if (oper != CAST)
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expr_warning(*expp, "incompatible pointers in %s",
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symbol2str(oper));
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#ifdef LINT
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if (oper != CAST)
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lint_ptr_conv(oldtp->tp_up->tp_fund, tp->tp_up->tp_fund);
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#endif /* LINT */
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(*expp)->ex_type = tp; /* free conversion */
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}
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else
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if (oldtp->tp_fund == POINTER && is_integral_type(tp)) {
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/* from pointer to integral */
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if (oper != CAST)
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expr_warning(*expp,
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"illegal conversion of pointer to %s",
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symbol2str(tp->tp_fund));
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if (oldtp->tp_size > tp->tp_size)
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expr_warning(*expp,
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"conversion of pointer to %s loses accuracy",
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symbol2str(tp->tp_fund));
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if (oldtp->tp_size != tp->tp_size)
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int2int(expp, tp);
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else
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(*expp)->ex_type = tp;
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}
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else
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if (tp->tp_fund == POINTER && is_integral_type(oldtp)) {
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/* from integral to pointer */
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switch (oper) {
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case CAST:
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break;
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case EQUAL:
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case NOTEQUAL:
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case ':':
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case '=':
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case RETURN:
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if (is_cp_cst(*expp) && (*expp)->VL_VALUE == (arith)0)
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break;
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default:
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expr_warning(*expp,
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"dubious conversion of %s to pointer",
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symbol2str(oldtp->tp_fund));
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break;
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}
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if (oldtp->tp_size > tp->tp_size)
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expr_warning(*expp,
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"conversion of %s to pointer loses accuracy",
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symbol2str(oldtp->tp_fund));
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if (oldtp->tp_size != tp->tp_size)
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int2int(expp, tp);
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else
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(*expp)->ex_type = tp;
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}
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else
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if (oldtp->tp_fund == ERRONEOUS) {
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/* we just won't look */
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(*expp)->ex_type = tp; /* brute force */
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}
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else
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if (oldtp->tp_size == tp->tp_size && oper == CAST) {
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expr_warning(*expp, "dubious conversion based on equal size");
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(*expp)->ex_type = tp; /* brute force */
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}
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else {
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if (oldtp->tp_fund != ERRONEOUS && tp->tp_fund != ERRONEOUS)
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expr_error(*expp, "cannot convert %s to %s",
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symbol2str(oldtp->tp_fund),
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symbol2str(tp->tp_fund)
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);
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(*expp)->ex_type = tp; /* brute force */
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}
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}
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ch7asgn(expp, oper, expr)
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struct expr **expp;
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struct expr *expr;
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{
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/* The assignment operators.
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"f op= e" should be interpreted as
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"f = (typeof f)((typeof (f op e))f op (typeof (f op e))e)"
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and not as "f = f op (typeof f)e".
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Consider, for example, (i == 10) i *= 0.9; (i == 9), where
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typeof i == int.
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The resulting expression tree becomes:
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op=
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/ \
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/ \
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f (typeof (f op e))e
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EVAL should however take care of evaluating (typeof (f op e))f
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*/
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register struct expr *exp = *expp;
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int fund = exp->ex_type->tp_fund;
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struct type *tp;
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/* We expect an lvalue */
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if (!exp->ex_lvalue) {
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expr_error(exp, "no lvalue in lhs of %s", symbol2str(oper));
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exp->ex_depth = 99; /* no direct store/load at EVAL() */
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/* what is 99 ??? DG */
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}
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if (oper == '=') {
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ch7cast(&expr, oper, exp->ex_type);
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tp = expr->ex_type;
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}
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else { /* turn e into e' where typeof(e') = typeof (f op e) */
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struct expr *extmp = intexpr((arith)0, INT);
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/* this is really $#@&*%$# ! */
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/* if you correct this, please correct lint_new_oper() too */
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extmp->ex_lvalue = 1;
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extmp->ex_type = exp->ex_type;
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ch7bin(&extmp, oper, expr);
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/* Note that ch7bin creates a tree of the expression
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((typeof (f op e))f op (typeof (f op e))e),
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where f ~ extmp and e ~ expr.
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We want to use (typeof (f op e))e.
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Ch7bin does not create a tree if both operands
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were illegal or constants!
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*/
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tp = extmp->ex_type; /* perform the arithmetic in type tp */
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if (extmp->ex_class == Oper) {
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expr = extmp->OP_RIGHT;
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extmp->OP_RIGHT = NILEXPR;
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free_expression(extmp);
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}
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else
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expr = extmp;
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}
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#ifndef NOBITFIELD
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if (fund == FIELD)
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exp = new_oper(exp->ex_type->tp_up, exp, oper, expr);
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else
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exp = new_oper(exp->ex_type, exp, oper, expr);
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#else /* NOBITFIELD */
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exp = new_oper(exp->ex_type, exp, oper, expr);
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#endif /* NOBITFIELD */
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exp->OP_TYPE = tp; /* for EVAL() */
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exp->ex_flags |= EX_SIDEEFFECTS;
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*expp = exp;
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}
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/* Some interesting (?) questions answered.
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*/
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int
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is_integral_type(tp)
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register struct type *tp;
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{
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switch (tp->tp_fund) {
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case CHAR:
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case SHORT:
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case INT:
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case LONG:
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case ENUM:
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return 1;
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#ifndef NOBITFIELD
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case FIELD:
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return is_integral_type(tp->tp_up);
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#endif /* NOBITFIELD */
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default:
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return 0;
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}
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}
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int
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is_arith_type(tp)
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register struct type *tp;
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{
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switch (tp->tp_fund) {
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case CHAR:
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case SHORT:
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case INT:
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case LONG:
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case ENUM:
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#ifndef NOFLOAT
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case FLOAT:
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case DOUBLE:
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#endif /* NOFLOAT */
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return 1;
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#ifndef NOBITFIELD
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case FIELD:
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return is_arith_type(tp->tp_up);
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#endif /* NOBITFIELD */
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default:
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return 0;
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}
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}
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