79 lines
2.2 KiB
C
79 lines
2.2 KiB
C
/* $Header$ */
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/*
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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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/* 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 _ L I F E T I M E . 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 "ra_lifet.h"
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#define MSG_OFF(l) aoff(ARG(l),1)
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#define is_livemsg(l) (INSTR(l) == ps_mes && aoff(ARG(l),0) == ms_liv)
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#define is_deadmsg(l) (INSTR(l) == ps_mes && aoff(ARG(l),0) == ms_ded)
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build_lifetimes(items)
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item_p items[];
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{
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/* compute the it_lives attribute of every item; this is
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* a list of intervals during which the item is live,
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* i.e. its current value may be used.
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* We traverse the EM text of the current procedure in
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* lexical order. If we encounter a live-message, we store
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* the number ('time') of the current instruction in the
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* it_lastlive attribute of the concerning item. If we see
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* a dead-message for that item, we know that the item is
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* live in between these two pseudo's. If the first message
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* appearing in the procedure is a dead-message, the item
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* is live from time 0 (start of procedure) till now. (Note
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* that it_lastlive is initially 0!).
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* The lifetime ends on the last instruction before the
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* dead-message that is not a live -or dead message.
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*/
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register line_p l;
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register short now;
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item_p item;
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short last_code;
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last_code = 0;
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for (now = 0; now < nrinstrs; now++) {
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l = instrmap[now];
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if (is_livemsg(l)) {
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item = item_of(MSG_OFF(l),items);
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/* A local variable that is never used is NOT an
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* item; yet, there may be a register message for it...
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*/
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if(item != (item_p) 0) {
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item->it_lastlive = last_code + 1;
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}
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} else {
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if (is_deadmsg(l)) {
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item = item_of(MSG_OFF(l),items);
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if (item != (item_p) 0) {
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add_interval(item->it_lastlive,
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last_code, &item->it_lives);
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}
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} else {
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last_code = now;
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}
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}
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}
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}
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