455 lines
8.8 KiB
C
455 lines
8.8 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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/* $Id$ */
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/* Lint main routines */
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#include "lint.h"
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#ifdef LINT
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#include <alloc.h> /* for st_free */
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#include "debug.h"
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#include "interface.h"
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#include "assert.h"
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#ifdef ANSI
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#include <flt_arith.h>
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#endif /* ANSI */
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#include "arith.h" /* definition arith */
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#include "label.h" /* definition label */
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#include "expr.h"
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#include "idf.h"
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#include "def.h"
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#include "code.h" /* RVAL etc */
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#include "LLlex.h"
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#include "Lpars.h"
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#include "stack.h"
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#include "type.h"
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#include "level.h"
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#include "l_lint.h"
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#include "l_state.h"
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#include "l_outdef.h"
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extern char options[128];
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extern char *symbol2str();
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PRIVATE struct expr_state *expr2state();
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PRIVATE struct expr_state *value2state();
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PRIVATE struct expr_state *oper2state();
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PRIVATE expr_ignored();
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PRIVATE add_expr_state();
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PRIVATE referred_esp();
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PRIVATE free_expr_states();
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lint_init()
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{
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lint_init_comment();
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lint_init_stack();
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}
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lint_expr(expr, used)
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struct expr *expr;
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int used; /* USED or IGNORED */
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{
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register struct expr_state *esp;
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esp = expr2state(expr, RVAL, used);
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referred_esp(esp);
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free_expr_states(esp);
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}
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PRIVATE struct expr_state *
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expr2state(expr, val, used)
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register struct expr *expr;
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int val; /* RVAL or LVAL */
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int used; /* USED or IGNORED */
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{
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/* Main function to process an expression tree.
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* It returns a structure containing information about which variables
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* are set and which are used in the expression.
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* In addition it sets 'used' and 'set' fields of the corresponding
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* variables in the current state.
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* If the value of an operation without side-effects is not used,
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* a warning is given.
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*/
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if (used == IGNORED) {
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expr_ignored(expr);
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}
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switch (expr->ex_class) {
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case Value:
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return value2state(expr, val);
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case Oper:
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return oper2state(expr, val, used);
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default: /* String, Float, Type */
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return 0;
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}
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}
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PRIVATE struct expr_state *
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value2state(expr, val)
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struct expr *expr;
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int val; /* RVAL or LVAL */
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{
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switch (expr->VL_CLASS) {
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case Const:
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case Label:
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return 0;
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case Name:
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{
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register struct idf *idf = expr->VL_IDF;
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struct expr_state *esp = 0;
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if (!idf || !idf->id_def)
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return 0;
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if (val == RVAL && expr->ex_lvalue == 1) {
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/* value of identifier used */
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change_state(idf, USED);
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add_expr_state(expr->EX_VALUE, USED, &esp);
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}
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if (val == RVAL && expr->ex_lvalue == 0) {
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/* address of identifier used */
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add_expr_state(expr->EX_VALUE, REFERRED, &esp);
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}
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return esp;
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}
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default:
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NOTREACHED();
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/* NOTREACHED */
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}
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}
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/* Let's get this straight.
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An assignment is performed by elaborating the LHS and the RHS
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collaterally, to use the A68 terminology, and then serially do the
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actual assignment. This means:
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1. evaluate the LHS as an LVAL,
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2. evaluate the RHS as an RVAL,
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3. merge them checking for interference,
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4. set the result of the LHS to SET, if it is a named variable
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*/
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PRIVATE struct expr_state *
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oper2state(expr, val, used)
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struct expr *expr;
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int val; /* RVAL or LVAL */
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int used; /* USED or IGNORED */
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{
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register int oper = expr->OP_OPER;
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register struct expr *left = expr->OP_LEFT;
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register struct expr *right = expr->OP_RIGHT;
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struct expr_state *esp_l = 0;
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struct expr_state *esp_r = 0;
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switch (oper) {
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/* assignments */
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case '=':
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case PLUSAB:
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case MINAB:
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case TIMESAB:
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case DIVAB:
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case MODAB:
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case LEFTAB:
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case RIGHTAB:
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case ANDAB:
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case XORAB:
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case ORAB:
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/* evaluate the LHS, only once; see RM 7.14 */
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esp_l = expr2state(left, (oper == '=' ? LVAL : RVAL), USED);
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/* evaluate the RHS as an RVAL and merge */
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esp_r = expr2state(right, RVAL, USED);
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check_and_merge(expr, &esp_l, esp_r);
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/* set resulting variable, if any */
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if (ISNAME(left)) {
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change_state(left->VL_IDF, SET);
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add_expr_state(left->EX_VALUE, SET, &esp_l);
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}
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return esp_l;
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case POSTINCR:
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case POSTDECR:
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case PLUSPLUS:
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case MINMIN:
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esp_l = expr2state(left, RVAL, USED);
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/* set resulting variable, if any */
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if (ISNAME(left)) {
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change_state(left->VL_IDF, SET);
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add_expr_state(left->EX_VALUE, SET, &esp_l);
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}
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return esp_l;
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case '?':
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esp_l = expr2state(left, RVAL, USED);
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esp_r = expr2state(right->OP_LEFT, RVAL, USED);
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check_and_merge(expr, &esp_l, esp_r);
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esp_r = expr2state(right->OP_RIGHT, RVAL, USED);
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check_and_merge(expr, &esp_l, esp_r);
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return esp_l;
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case '(':
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if (right != 0) {
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/* function call with parameters */
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register struct expr *ex = right;
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while ( ex->ex_class == Oper
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&& ex->OP_OPER == PARCOMMA
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) {
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esp_r = expr2state(ex->OP_RIGHT, RVAL, USED);
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check_and_merge(expr, &esp_l, esp_r);
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ex = ex->OP_LEFT;
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}
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esp_r = expr2state(ex, RVAL, USED);
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check_and_merge(expr, &esp_l, esp_r);
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}
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if (ISNAME(left)) {
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fill_outcall(expr,
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expr->ex_type->tp_fund == VOID ?
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VOIDED : used
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);
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outcall();
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left->VL_IDF->id_def->df_used = 1;
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}
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else {
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esp_r = expr2state(left, RVAL, USED);
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check_and_merge(expr, &esp_l, esp_r);
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}
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referred_esp(esp_l);
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return esp_l;
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case '.':
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return expr2state(left, val, USED);
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case ARROW:
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return expr2state(left, RVAL, USED);
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case INT2INT:
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case INT2FLOAT:
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case FLOAT2INT:
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case FLOAT2FLOAT:
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return expr2state(right, RVAL, USED);
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/* monadic operators */
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case '-':
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case '*':
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if (left)
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goto dyadic;
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case '~':
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case '!':
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return expr2state(right, RVAL, USED);
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/* relational operators */
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case '<':
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case '>':
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case LESSEQ:
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case GREATEREQ:
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case EQUAL:
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case NOTEQUAL:
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goto dyadic;
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/* dyadic operators */
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dyadic:
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case '+':
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case '/':
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case '%':
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case ',':
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case LEFT:
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case RIGHT:
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case '&':
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case '|':
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case '^':
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case OR:
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case AND:
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esp_l = expr2state(left, RVAL,
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oper == ',' ? IGNORED : USED);
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esp_r = expr2state(right, RVAL,
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oper == ',' ? used : USED);
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check_and_merge(expr, &esp_l, esp_r);
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return esp_l;
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default:
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return 0; /* for initcomma */
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}
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}
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PRIVATE
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expr_ignored(expr)
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struct expr *expr;
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{
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switch (expr->ex_class) {
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int oper;
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case Oper:
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oper = expr->OP_OPER;
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switch (oper) {
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case '=':
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case TIMESAB:
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case DIVAB:
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case MODAB:
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case LEFTAB:
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case RIGHTAB:
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case ANDAB:
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case XORAB:
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case ORAB:
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case AND: /* doubtful but useful */
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case OR: /* doubtful but useful */
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case '(':
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case '?':
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case ',':
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oper = 0; /* ignore the ignoring */
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break;
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case PLUSAB:
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case MINAB:
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case POSTINCR:
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case POSTDECR:
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case PLUSPLUS:
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case MINMIN:
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oper = 0; /* ignore in priciple */
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/* may, however, hide the operator '*' */
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if ( /* operation on a pointer */
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expr->OP_TYPE->tp_fund == POINTER
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&& /* the result is dereferenced, e.g. *p++; */
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expr->ex_type == expr->OP_TYPE->tp_up
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) {
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oper = '*';
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}
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break;
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case '/':
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/* this is a specially weird case: the '/' may
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result from pointer subtraction
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*/
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if ( expr->OP_TYPE->tp_fund == INT
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&& expr->OP_LEFT->OP_OPER == '-'
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&& expr->OP_LEFT->OP_TYPE->tp_fund == POINTER
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) {
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oper = '-';
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}
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break;
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}
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if (oper) {
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hwarning("result of %s ignored", symbol2str(oper));
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}
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break;
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case Value:
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if (expr->VL_CLASS == Const) {
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hwarning("constant expression ignored");
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}
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else {
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hwarning("value ignored");
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}
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break;
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default: /* String Float */
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hwarning("constant ignored");
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break;
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}
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}
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PRIVATE
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add_expr_state(value, to_state, espp)
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struct value value;
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struct expr_state **espp;
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{
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register struct expr_state *esp = *espp;
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ASSERT(value.vl_class == Name);
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/* try to find the esp */
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while ( esp
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&& !( esp->es_idf == value.vl_data.vl_idf
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&& esp->es_offset == value.vl_value
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)
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) {
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esp = esp->next;
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}
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/* if not found, add it */
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if (!esp) {
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esp = new_expr_state();
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esp->es_idf = value.vl_data.vl_idf;
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esp->es_offset = value.vl_value;
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esp->next = *espp;
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*espp = esp;
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}
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/* set state */
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switch (to_state) {
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case USED:
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esp->es_used = 1;
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break;
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case REFERRED:
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esp->es_referred = 1;
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break;
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case SET:
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esp->es_set = 1;
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break;
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default:
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NOTREACHED();
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/* NOTREACHED */
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}
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}
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PRIVATE
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referred_esp(esp)
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struct expr_state *esp;
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{
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/* raises all REFERRED items to SET and USED status */
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while (esp) {
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if (esp->es_referred) {
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esp->es_set = 1;
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change_state(esp->es_idf, SET);
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esp->es_used = 1;
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change_state(esp->es_idf, USED);
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esp->es_referred = 0;
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}
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esp = esp->next;
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}
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}
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PRIVATE
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free_expr_states(esp)
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register struct expr_state *esp;
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{
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while (esp) {
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register struct expr_state *esp2 = esp;
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esp = esp->next;
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free_expr_state(esp2);
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}
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}
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#ifdef DEBUG
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print_esp(msg, esp)
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char *msg;
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struct expr_state *esp;
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{
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print("%s: <", msg);
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while (esp) {
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print(" %s[%d]%c%c%c ",
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esp->es_idf->id_text, esp->es_offset,
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(esp->es_used ? 'U' : ' '),
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(esp->es_referred ? 'R' : ' '),
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(esp->es_set ? 'S' : ' ')
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);
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esp = esp->next;
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}
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print(">\n");
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}
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#endif /* DEBUG */
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#endif /* LINT */
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