346 lines
6.7 KiB
C
346 lines
6.7 KiB
C
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/* R E G I S T E R A L L O C A T I O N
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*
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* R A _ I T E M S . C
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*/
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#include "../share/types.h"
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#include "../share/debug.h"
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#include "../share/def.h"
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#include "../share/global.h"
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#include "../share/lset.h"
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#include "../share/aux.h"
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#include "../share/alloc.h"
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#include "../../../h/em_mnem.h"
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#include "../../../h/em_spec.h"
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#include "../../../h/em_pseu.h"
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#include "../../../h/em_reg.h"
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#include "ra.h"
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#include "ra_aux.h"
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#include "ra_items.h"
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#include "itemtab.h"
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/* Maps EM mnemonics onto item types, e.g. op_lol -> LOCALVAR, op_ldc->DCONST,
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* generated from em_mmen.h and itemtab.src files.
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*/
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#define SMALL_CONSTANT(c) (c >= 0 && c <= 8)
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/* prevent small constants from being put in a register */
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clean_tab(items)
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item_p items[];
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{
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int t;
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for (t = 0; t < NRITEMTYPES;t++) {
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items[t] = (item_p) 0;
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}
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}
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short item_type(l)
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line_p l;
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{
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int instr = INSTR(l);
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int t;
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if (instr < sp_fmnem || instr > sp_lmnem) return NO_ITEM;
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t = itemtab[instr - sp_fmnem].id_type;
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if (t == CONST && SMALL_CONSTANT(off_set(l))) return NO_ITEM;
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return t;
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}
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bool is_item(l)
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line_p l;
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{
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return item_type(l) != NO_ITEM;
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}
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item_p item_of(off,items)
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offset off;
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item_p items[];
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{
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register item_p x;
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for (x = items[LOCALVAR]; x != (item_p) 0; x = x->it_next) {
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if (off == x->i_t.it_off) {
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if (!x->it_desirable) break;
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/* don't put this item in reg */
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return x;
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}
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}
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return (item_p) 0;
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}
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fill_item(item,l)
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item_p item;
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line_p l;
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{
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item->it_type = item_type(l);
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switch(item->it_type) {
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case GLOBL_ADDR:
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item->i_t.it_obj = OBJ(l);
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break;
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case PROC_ADDR:
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item->i_t.it_proc = PROC(l);
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break;
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default:
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item->i_t.it_off = off_set(l);
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}
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}
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STATIC bool desirable(l)
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line_p l;
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{
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/* See if it is really desirable to put the item of line l
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* in a register. We do not put an item in a register if it
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* is used as 'address of array descriptor' of an array
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* instruction.
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*/
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if (l->l_next != (line_p) 0) {
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switch(INSTR(l->l_next)) {
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case op_aar:
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case op_lar:
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case op_sar:
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return FALSE;
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}
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}
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return TRUE;
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}
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STATIC int cmp_items(a,b)
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item_p a,b;
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{
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/* This routine defines the <, = and > relations between items,
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* used to sort them for fast lookup.
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*/
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offset n1,n2;
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switch(a->it_type) {
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case GLOBL_ADDR:
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assert(b->it_type == GLOBL_ADDR);
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n1 = (offset) a->i_t.it_obj->o_id;
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n2 = (offset) b->i_t.it_obj->o_id;
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break;
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case PROC_ADDR:
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assert(b->it_type == PROC_ADDR);
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n1 = (offset) a->i_t.it_proc->p_id;
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n2 = (offset) b->i_t.it_proc->p_id;
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break;
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default:
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n1 = a->i_t.it_off;
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n2 = b->i_t.it_off;
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}
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return (n1 == n2 ? 0 : (n1 > n2 ? 1 : -1));
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}
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bool same_item(a,b)
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item_p a,b;
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{
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return cmp_items(a,b) == 0;
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}
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STATIC bool lt_item(a,b)
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item_p a,b;
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{
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return cmp_items(a,b) == -1;
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}
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/* build_itemlist()
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*
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* Build a list of all items used in the current procedure. An item
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* is anything that can be put in a register (a local variable, a constant,
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* the address of a local or global variable).
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* For each type of item we use a sorted list containing all items of
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* that type found so far.
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* A local variable is only considered to be an item if there is a
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* register message for it (indicating it is never accessed indirectly).
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* For each item, we keep track of all places where it is used
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* (either fetched or stored into). The usage of a local variable is also
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* considered to be a usage of its address.
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*/
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STATIC item_p items[NRITEMTYPES]; /* items[i] points to the list of type i */
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STATIC short reg_type(item)
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item_p item;
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{
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/* See which type of register the item should best be assigned to */
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switch(item->it_type) {
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case LOCALVAR:
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return regv_type(item->i_t.it_off);
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/* use type mentioned in reg. message for local */
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case LOCAL_ADDR:
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case GLOBL_ADDR:
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case PROC_ADDR:
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return reg_pointer;
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case CONST:
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case DCONST:
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return reg_any;
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default: assert(FALSE);
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}
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/* NOTREACHED */
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}
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STATIC short item_size(item)
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item_p item;
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{
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/* Determine the size of the item (in bytes) */
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switch(item->it_type) {
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case LOCALVAR:
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return regv_size(item->i_t.it_off);
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/* use size mentioned in reg. message for local */
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case LOCAL_ADDR:
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case GLOBL_ADDR:
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case PROC_ADDR:
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return ps; /* pointer size */
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case CONST:
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return ws; /* word size */
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case DCONST:
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return 2 * ws; /* 2 * word size */
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default: assert(FALSE);
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}
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/* NOTREACHED */
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}
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STATIC init_item(a,b)
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item_p a,b;
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{
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a->it_type = b->it_type;
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switch(a->it_type) {
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case GLOBL_ADDR:
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a->i_t.it_obj = b->i_t.it_obj;
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break;
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case PROC_ADDR:
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a->i_t.it_proc = b->i_t.it_proc;
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break;
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default:
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a->i_t.it_off = b->i_t.it_off;
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}
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a->it_usage = Lempty_set();
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a->it_regtype = reg_type(b);
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a->it_size = item_size(b);
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a->it_desirable = b->it_desirable;
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}
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STATIC add_item(item,t,items)
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item_p item;
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time_p t;
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item_p items[];
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{
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/* See if there was already a list element for item. In any
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* case record the fact that item is used at 't'.
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*/
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register item_p x, *q;
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q = &items[item->it_type]; /* each type has its own list */
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for (x = *q; x != (item_p) 0; x = *q) {
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if (same_item(x,item)) {
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/* found */
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if (!item->it_desirable) {
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x->it_desirable = FALSE;
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}
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Ladd(t,&x->it_usage);
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return; /* done */
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}
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if (lt_item(item,x)) break;
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q = &x->it_next;
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}
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/* not found, allocate new item; q points to it_next field of
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* the item after which the new item should be put.
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*/
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x = newitem();
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x->it_next = *q;
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*q = x;
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init_item(x,item);
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Ladd(t,&x->it_usage);
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}
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STATIC add_usage(l,b,items)
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line_p l;
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bblock_p b;
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item_p items[];
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{
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/* An item is used at line l. Add it to the list of items.
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* A local variable is only considered to be an item, if
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* there is a register message for it; else its address
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* is also considered to be an item.
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*/
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struct item thisitem;
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fill_item(&thisitem,l); /* fill in some fields */
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if (!desirable(l)) {
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thisitem.it_desirable = FALSE; /* don't put item in reg. */
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}
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if (thisitem.it_type == LOCALVAR && !is_regvar(thisitem.i_t.it_off)) {
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/* Use address of local instead of local itself */
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thisitem.it_type = LOCAL_ADDR;
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thisitem.it_regtype = reg_pointer;
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}
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add_item(&thisitem,cons_time(l,b),items);
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}
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build_itemlist(p,items,nrinstr_out)
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proc_p p;
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item_p items[];
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int *nrinstr_out;
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{
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/* Make a list of all items used in procedure p.
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* An item is anything that can be put in a register,
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* such as a local variable, a constant etc.
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* As a side effect, determine the number of instructions of p.
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*/
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register line_p l;
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register bblock_p b;
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register cnt= 0;
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clean_tab(items);
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for (b = p->p_start; b != (bblock_p) 0; b = b->b_next) {
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for (l = b->b_start; l != (line_p) 0; l = l->l_next) {
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if (is_item(l)) {
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add_usage(l,b,items);
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}
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cnt++;
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}
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}
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*nrinstr_out = cnt;
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}
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