193 lines
4 KiB
C
193 lines
4 KiB
C
/* $Id$ */
|
|
/*
|
|
* (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
|
|
* See the copyright notice in the ACK home directory, in the file "Copyright".
|
|
*/
|
|
/* S T R E N G T H R E D U C T I O N
|
|
*
|
|
* S R _ C A N D . C
|
|
*/
|
|
|
|
|
|
#include <em_mnem.h>
|
|
#include <em_pseu.h>
|
|
#include "../share/types.h"
|
|
#include "../share/lset.h"
|
|
#include "../share/cset.h"
|
|
#include "../share/debug.h"
|
|
#include "../share/global.h"
|
|
#include "../share/map.h"
|
|
#include "../share/aux.h"
|
|
#include "sr.h"
|
|
#include "sr_aux.h"
|
|
#include "sr_cand.h"
|
|
|
|
|
|
/* A candidate induction variable of a loop (hereafter called candidate) is a
|
|
* local variable (of the current procedure) that is assigned a value
|
|
* precisely once within the loop. Furthermore, this assignment must
|
|
* take place in a firm block of the loop.
|
|
* We determine those locals that are assigned precisely once, within
|
|
* a firm block;
|
|
*
|
|
* We represent a local variable via an instruction that references it,
|
|
* e.g. LOL -6 represents the local variable at offset -6 with size=wordsize.
|
|
* We keep track of two sets:
|
|
* cand - the set of all candidate variables
|
|
* dismiss - a set of variables that may not be made a candidate
|
|
* (because they are assigned more than once, or because
|
|
* they are assigned outside a firm block).
|
|
* Only local variables for which a register message is given are considered.
|
|
*/
|
|
|
|
|
|
STATIC lset cand, /* set of candidates */
|
|
dism; /* set of dismissed variables */
|
|
|
|
|
|
#define ALL_LINES(lnp,list) lnp = list; lnp != (line_p) 0; lnp = lnp->l_next
|
|
|
|
|
|
|
|
STATIC un_cand(lnp)
|
|
line_p lnp;
|
|
{
|
|
/* remove the variable stored into by lnp from the list of
|
|
* candidates (if it was there anyway).
|
|
*/
|
|
|
|
Lindex i, next;
|
|
|
|
for (i = Lfirst(cand); i != (Lindex) 0; i = next) {
|
|
next = Lnext(i,cand);
|
|
if (same_local(lnp,Lelem(i))) {
|
|
OUTTRACE("remove candidate",0);
|
|
Lremove(Lelem(i), &cand);
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
STATIC bool is_cand(lnp)
|
|
line_p lnp;
|
|
{
|
|
/* see if the variable stored into by lnp is a candate */
|
|
|
|
Lindex i;
|
|
|
|
for (i = Lfirst(cand); i != (Lindex) 0; i = Lnext(i,cand)) {
|
|
if (same_local(lnp,Lelem(i))) {
|
|
return TRUE;
|
|
}
|
|
}
|
|
return FALSE;
|
|
}
|
|
|
|
|
|
STATIC make_cand(lnp)
|
|
line_p lnp;
|
|
{
|
|
/* make the variable stored into by lnp a candidate */
|
|
|
|
|
|
OUTTRACE("add a new candidate",0);
|
|
Ladd(lnp,&cand);
|
|
}
|
|
|
|
|
|
|
|
STATIC do_dismiss(lnp)
|
|
line_p lnp;
|
|
{
|
|
Ladd(lnp,&dism);
|
|
}
|
|
|
|
|
|
STATIC dismiss(lnp)
|
|
line_p lnp;
|
|
{
|
|
/* The variable referenced by lnp is turned definitely into
|
|
* a non-candidate.
|
|
*/
|
|
|
|
un_cand(lnp); /* remove it from the candidate set,
|
|
* if it was there in the first place.
|
|
*/
|
|
do_dismiss(lnp); /* add it to the set of dismissed variables */
|
|
}
|
|
|
|
|
|
STATIC bool not_dismissed(lnp)
|
|
line_p lnp;
|
|
{
|
|
Lindex i;
|
|
|
|
for (i = Lfirst(dism); i != (Lindex) 0; i = Lnext(i,dism)) {
|
|
if (same_local(Lelem(i),lnp)) {
|
|
return FALSE; /* variable was dismissed */
|
|
}
|
|
}
|
|
return TRUE;
|
|
}
|
|
|
|
|
|
STATIC void try_cand(lnp,b)
|
|
line_p lnp;
|
|
bblock_p b;
|
|
{
|
|
/* If the variable stored into by lnp was not already a candidate
|
|
* and was not dismissed, then it is made a candidate
|
|
* (unless the assignment takes places in a block that is not firm).
|
|
*/
|
|
|
|
if (!is_regvar(off_set(lnp))) return;
|
|
if (is_cand(lnp) || !IS_FIRM(b)) {
|
|
dismiss(lnp);
|
|
} else {
|
|
if (not_dismissed(lnp)) {
|
|
make_cand(lnp);
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
candidates(lp,cand_out,vars_out)
|
|
loop_p lp;
|
|
lset *cand_out, *vars_out;
|
|
{
|
|
/* Find the candidate induction variables.
|
|
*/
|
|
|
|
bblock_p b;
|
|
line_p lnp;
|
|
Lindex i;
|
|
|
|
OUTTRACE("find candidates of loop %d",lp->lp_id);
|
|
cand = Lempty_set();
|
|
dism = Lempty_set();
|
|
|
|
for (i = Lfirst(lp->LP_BLOCKS); i != (Lindex) 0;
|
|
i = Lnext(i,lp->LP_BLOCKS)) {
|
|
b = (bblock_p) Lelem(i);
|
|
for ( ALL_LINES(lnp, b->b_start)) {
|
|
OUTTRACE("inspect instruction %d",INSTR(lnp));
|
|
switch(INSTR(lnp)) {
|
|
case op_stl:
|
|
case op_inl:
|
|
case op_del:
|
|
OUTTRACE("it's a store local",0);
|
|
try_cand(lnp,b);
|
|
break;
|
|
case op_zrl:
|
|
OUTTRACE("it's a destroy local",0);
|
|
if (is_regvar(off_set(lnp))) {
|
|
dismiss(lnp);
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
*cand_out = cand;
|
|
*vars_out = dism;
|
|
}
|