ack/lang/cem/cemcom/switch.c

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/*
* (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
* See the copyright notice in the ACK home directory, in the file "Copyright".
*/
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/* $Id$ */
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/* S W I T C H - S T A T E M E N T A D M I N I S T R A T I O N */
#include "lint.h"
#include "nofloat.h"
#ifndef LINT
#include <em.h>
#else
#include "l_em.h"
#endif /* LINT */
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#include "debug.h"
#include "botch_free.h"
#include <alloc.h>
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#include "density.h"
#include "Lpars.h"
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#include "idf.h"
#include "label.h"
#include "arith.h"
#include "switch.h"
#include "code.h"
#include "assert.h"
#include "expr.h"
#include "type.h"
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#include "noRoption.h"
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extern char options[];
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int density = DENSITY;
compact(nr, low, up)
arith low, up;
{
/* Careful! up - low might not fit in an arith. And then,
the test "up-low < 0" might also not work to detect this
situation! Or is this just a bug in the M68020/M68000?
*/
arith diff = up - low;
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return (nr == 0 || (diff >= 0 && diff / nr <= (density - 1)));
}
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static struct switch_hdr *switch_stack = 0;
/* (EB 86.05.20) The following rules hold for switch statements:
- the expression E in "switch(E)" is cast to 'int' (RM 9.7)
- the expression E in "case E:" must be 'int' (RM 9.7)
- the values in the CSA/CSB tables are words (EM 7.4)
For simplicity, we suppose int_size == word_size.
*/
code_startswitch(expp)
struct expr **expp;
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{
/* Check the expression, stack a new case header and
fill in the necessary fields.
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*/
register label l_table = text_label();
register label l_break = text_label();
register struct switch_hdr *sh = new_switch_hdr();
int fund = any2arith(expp, SWITCH); /* INT, LONG or DOUBLE */
switch (fund) {
case LONG:
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#ifndef NOROPTION
if (options['R'])
warning("long in switch (cast to int)");
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#endif
int2int(expp, int_type);
break;
#ifndef NOFLOAT
case DOUBLE:
error("float/double in switch");
erroneous2int(expp);
break;
#endif /* NOFLOAT */
}
stack_stmt(l_break, NO_LABEL);
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sh->sh_break = l_break;
sh->sh_default = 0;
sh->sh_table = l_table;
sh->sh_nrofentries = 0;
sh->sh_type = (*expp)->ex_type; /* the expression switched */
sh->sh_lowerbd = sh->sh_upperbd = (arith)0; /* immaterial ??? */
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sh->sh_entries = (struct case_entry *) 0; /* case-entry list */
sh->sh_expr = *expp;
#ifdef LINT
code_expr(sh->sh_expr, RVAL, TRUE, NO_LABEL, NO_LABEL);
#endif
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sh->next = switch_stack; /* push onto switch-stack */
switch_stack = sh;
C_bra(l_table); /* goto start of switch_table */
}
code_endswitch()
{
register struct switch_hdr *sh = switch_stack;
register label tablabel;
register struct case_entry *ce;
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if (sh->sh_default == 0) /* no default occurred yet */
sh->sh_default = sh->sh_break;
C_bra(sh->sh_break); /* skip the switch table now */
C_df_ilb(sh->sh_table); /* switch table entry */
/* evaluate the switch expr. */
#ifndef LINT
code_expr(sh->sh_expr, RVAL, TRUE, NO_LABEL, NO_LABEL);
#endif
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tablabel = data_label(); /* the rom must have a label */
C_df_dlb(tablabel);
C_rom_ilb(sh->sh_default);
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if (compact(sh->sh_nrofentries, sh->sh_lowerbd, sh->sh_upperbd)) {
/* CSA */
register arith val;
C_rom_cst(sh->sh_lowerbd);
C_rom_cst(sh->sh_upperbd - sh->sh_lowerbd);
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ce = sh->sh_entries;
if (sh->sh_nrofentries)
for (val = sh->sh_lowerbd; val <= sh->sh_upperbd; val++) {
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ASSERT(ce);
if (val == ce->ce_value) {
C_rom_ilb(ce->ce_label);
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ce = ce->next;
}
else
C_rom_ilb(sh->sh_default);
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}
C_lae_dlb(tablabel, (arith)0); /* perform the switch */
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C_csa(sh->sh_type->tp_size);
}
else { /* CSB */
C_rom_cst((arith)sh->sh_nrofentries);
for (ce = sh->sh_entries; ce; ce = ce->next) {
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/* generate the entries: value + prog.label */
C_rom_cst(ce->ce_value);
C_rom_ilb(ce->ce_label);
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}
C_lae_dlb(tablabel, (arith)0); /* perform the switch */
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C_csb(sh->sh_type->tp_size);
}
C_df_ilb(sh->sh_break);
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switch_stack = sh->next; /* unstack the switch descriptor */
for (ce = sh->sh_entries; ce;) { /* free allocated switch structure */
register struct case_entry *tmp = ce->next;
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free_case_entry(ce);
ce = tmp;
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}
free_switch_hdr(sh);
unstack_stmt();
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}
code_case(expr)
struct expr *expr;
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{
register arith val;
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register struct case_entry *ce;
register struct switch_hdr *sh = switch_stack;
ASSERT(is_cp_cst(expr));
if (sh == 0) {
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error("case statement not in switch");
return;
}
if (expr->ex_flags & EX_ERROR) /* is probably 0 anyway */
return;
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ch7cast(&expr, CASE, sh->sh_type);
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ce = new_case_entry();
C_df_ilb(ce->ce_label = text_label());
ce->ce_value = val = expr->VL_VALUE;
if (sh->sh_entries == 0) { /* first case entry */
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ce->next = (struct case_entry *) 0;
sh->sh_entries = ce;
sh->sh_lowerbd = sh->sh_upperbd = val;
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sh->sh_nrofentries = 1;
}
else { /* second etc. case entry; put ce into proper place */
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register struct case_entry *c1 = sh->sh_entries, *c2 = 0;
if (val < sh->sh_lowerbd)
sh->sh_lowerbd = val;
else
if (val > sh->sh_upperbd)
sh->sh_upperbd = val;
while (c1 && c1->ce_value < ce->ce_value) {
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c2 = c1;
c1 = c1->next;
}
/* At this point three cases are possible:
1: c1 != 0 && c2 != 0: insert ce somewhere in the middle
2: c1 != 0 && c2 == 0: insert ce right after the head
3: c1 == 0 && c2 != 0: append ce to last element
The case c1 == 0 && c2 == 0 cannot occur, since
the list is guaranteed to be non-empty.
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*/
if (c1) {
if (c1->ce_value == ce->ce_value) {
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error("multiple case entry for value %ld",
ce->ce_value);
free_case_entry(ce);
return;
}
if (c2) {
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ce->next = c2->next;
c2->next = ce;
}
else {
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ce->next = sh->sh_entries;
sh->sh_entries = ce;
}
}
else {
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ASSERT(c2);
ce->next = (struct case_entry *) 0;
c2->next = ce;
}
(sh->sh_nrofentries)++;
}
}
code_default()
{
register struct switch_hdr *sh = switch_stack;
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if (sh == 0) {
error("default statement not in switch");
return;
}
if (sh->sh_default != 0) {
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error("multiple entry for default in switch");
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return;
}
C_df_ilb(sh->sh_default = text_label());
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}