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/*
Crown Copyright (c) 1997
This TenDRA(r) Computer Program is subject to Copyright
owned by the United Kingdom Secretary of State for Defence
acting through the Defence Evaluation and Research Agency
(DERA). It is made available to Recipients with a
royalty-free licence for its use, reproduction, transfer
to other parties and amendment for any purpose not excluding
product development provided that any such use et cetera
shall be deemed to be acceptance of the following conditions:-
(1) Its Recipients shall ensure that this Notice is
reproduced upon any copies or amended versions of it;
(2) Any amended version of it shall be clearly marked to
show both the nature of and the organisation responsible
for the relevant amendment or amendments;
(3) Its onward transfer from a recipient to another
party shall be deemed to be that party's acceptance of
these conditions;
(4) DERA gives no warranty or assurance as to its
quality or suitability for any purpose and DERA accepts
no liability whatsoever in relation to any use to which
it may be put.
*/
/* $Id: weights.c,v 1.1.1.1 1998/01/17 15:56:01 release Exp $ */
#ifndef lint
static char vcid[] = "$Id: weights.c,v 1.1.1.1 1998/01/17 15:56:01 release Exp $";
#endif /* lint */
/*
weights.c
The main procedure here is weightsv which determines the
allocation of s regs. It considers which of those tags not
already allocated to a t reg by scan, are best put in an s
register. The same conditions as for t regs apply as to the
suitability of the tags for registers. Weights estimates the
usage of each tag and hence the amount that would be saved if
it were held in an s reg. Thus it computes break points for
register allocation for later use by reg_alloc. The type
weights consists of two arrays of integers. In the first array
each integer corresponds to a fixpnt reg and the second arrays'
integers correspond to floating point regs. At the end of a
call of weights on an ident exp the props field of the ident
may still contain inreg_bits or infreg_bits, set by scan, to
indicate that a t reg should be used. Otherwise number of ident
is set up to represent the break point for allocation. A similar
process occurs for proc parameters which have the break value
in the forweights field of the parapair of the corresponding
procrec. This value has three meanings:
1) The ident (or parameter) defines a fixpnt value and number
of ident (forweights of parpair) is an integer brk with the
interpretation that if there are at least brk fixpt s registers
unallocated at this point then one will be used for this tag
(parameter).
2) As 1 but for floating point values.
3) number of ident = 100 in which case allocate value on the
stack, (this is obviously always available for parameters).
*/
/*
$Log: weights.c,v $
* Revision 1.1.1.1 1998/01/17 15:56:01 release
* First version to be checked into rolling release.
*
* Revision 1.4 1996/02/19 09:25:40 john
* Added assertion
*
* Revision 1.3 1995/06/13 14:04:03 john
* Cosmetic change
*
* Revision 1.2 1995/05/16 10:56:50 john
* Changes for spec 3.1
*
* Revision 1.1.1.1 1995/03/23 10:39:26 john
* Entered into CVS
*
* Revision 1.4 1995/03/23 10:17:15 john
* Added sequence to tested cases
*
*/
#include "config.h"
#include <limits.h>
#include "common_types.h"
#include "exptypes.h"
#include "exp.h"
#include "expmacs.h"
#include "tags.h"
#include "procrectypes.h"
#include "procrecs.h"
#include "bitsmacs.h"
#include "maxminmacs.h"
#include "regable.h"
#include "shapemacs.h"
#include "special.h"
#include "weights.h"
weights zeroweights =
{{
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
},
{
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
}
};
weights weightsv PROTO_S ((double scale, exp e));
weights add_weights
PROTO_N ( ( w1,w2 ) )
PROTO_T ( weights *w1 X weights *w2 )
{
/* sum of weights*/
weights r;
long i;
for (i = 0; i < wfixno; ++i) {
(r.fix)[i] = (w1->fix)[i]+(w2->fix)[i];
};
for (i = 0; i < wfloatno; ++i) {
(r.floating)[i] = (w1->floating)[i]+(w2->floating)[i];
};
return (r);
}
/* loc is the usage count of a tag, ws is
the weights computed for the scope of
the tag and fix distinguishes between
fix and float. This computes the
weights for the declaration and a break
point for register allocation which
gives the number of available regs for
which it is worthwhile to allocate this
tag into a reg ("regged"). This proc is
the source of all non-zero weights. NB
loc may be negative since using a s-reg
will involve a dump and restore */
wp max_weights
PROTO_N ( ( loc, ws, fix ) )
PROTO_T ( double loc X weights * ws X bool fix )
{
long bk = wfixno + 1;
long i;
float *w = (ws -> fix);
/* w[i] = greatest usage of (i+1) inner fixed tags */
wp res;
float *pw = &(((res.wp_weights).fix)[0]);
if (fix) {
for (i = 0; i < wfixno; ++i) {
if (i == 0) {
if (loc > w[i]) {
/* this tag has higher usage than any inner one ... */
pw[i] = loc;
bk = i; /* ... so it's regged in pref to others */
}
else
pw[i] = w[i];
}
else {
if ((loc + w[i - 1]) > w[i]) {
/* this tag and i inner ones have higher usage than any other
(i+1) inner ones ... */
pw[i] = loc + w[i - 1];
if (i < bk)
bk = i;
/* ... so it and i inner ones are regged in preference to any
other (i+1) inner ones */
}
else
pw[i] = w[i];
};
};
res.fix_break = bk;
}
else {
for (i = 0; i < wfixno; ++i) {
pw[i] = w[i];
}
}
res.fix_break = bk;
bk = wfloatno + 1;
w = (ws -> floating);
pw = &(((res.wp_weights).floating)[0]);
if (!fix) { /* same algorithm for float regs as fixed
regs */
for (i = 0; i < wfloatno; ++i) {
if (i == 0) {
if (loc > w[i]) {
pw[i] = loc;
bk = i;
}
else
pw[i] = w[i];
}
else {
if ((loc + w[i - 1]) > w[i]) {
pw[i] = loc + w[i - 1];
if (i < bk)
bk = i;
}
else
pw[i] = w[i];
};
};
}
else {
for (i = 0; i < wfloatno; ++i) {
pw[i] = w[i];
}
}
res.float_break = bk;
return res;
}
weights mult_weights
PROTO_N ( ( m,ws ) )
PROTO_T ( double m X weights *ws )
{
/* multiply weights by scalar - non
overflowing */
weights res;
float *r = &(res.fix)[0];
float *w = ws -> fix;
long i;
for (i = 0; i < wfixno; ++i) {
r[i] = w[i] * m;
};
r = &(res.floating)[0];
w = ws -> floating;
for (i = 0; i < wfloatno; ++i) {
r[i] = w[i] * m;
};
return (res);
}
weights add_wlist
PROTO_N ( ( scale, re ) )
PROTO_T ( double scale X exp re )
{
weights w, w1;
exp r = re;
if (r == nilexp) {
return zeroweights;
}
else
if (last (r)) {
return (weightsv (scale, r));
}
else {
w = weightsv (scale, r);
Assert(r != bro(r));
do {
r = bro (r);
w1 = weightsv (scale, r);
w = add_weights (&w, &w1);
} while (!last (r));
return w;
}
}
/*
weightsv
This procedure estimates the usage of tags and parameters to
help determine whether they can advantageously be placed in
s registers. The parameter scale allows more importance to
be placed on usage inside 'for' loops for example. The
procedure reg_alloc in reg_alloc.c finally determines the
actual choice of s reg and recodes the number field of an ident.
*/
weights weightsv
PROTO_N ( ( scale, e ) )
PROTO_T ( double scale X exp e )
{
unsigned char n;
tailrecurse:
n = name (e);
switch (n) {
case name_tag:
{
exp s = son (e);
if (name (s) == ident_tag && !isglob (s)) {
if (is_floating(name(sh(e))) && name(sh(e)) != shrealhd) {
fno(s) += scale*2.0;
} else fno (s) += scale;
}
/* usage of tag stored in number of son of load_name (decl) */
return zeroweights;
}
case ident_tag:
{
if (son (e) != nilexp) {
weights wdef;
weights wbody;
long noe = no (e) /* set by scan */ ;
if ((name (son (e)) == clear_tag) || (props (e) & defer_bit)) {
wdef = zeroweights;
fno(e)= 0.0;
}
else {
/* maybe needs a store to initialise */
if (is_floating(name(sh(son(e)))) && name(sh(son(e))) != shrealhd) {
fno(e) = scale*2.0;
} else fno (e) = scale;
wdef = weightsv (scale, son (e));
}
/* weights for initialisation of dec */
wbody = weightsv (scale, bro (son (e)));
/* weights of body of scan */
if (props (e) & defer_bit) {/* declaration will be treated
transparently in code production */
exp t = son (e);
exp s;
if (name (t) == val_tag || name(t) == real_tag) {
return wbody;
}
while (name (t) != name_tag) {
t = son (t);
}
s = son (t);
if (name (s) == ident_tag && !isglob (t)){
fno (s) = fno (e); /* is this correct */
}
/* usage of tag stored in number of son of
load_name (decl) */
return wbody;
} /* end deferred */
if ((props (e) & inreg_bits) == 0 && fixregable (e)) {
wp p;
p = max_weights (fno (e) - 2.0*scale , &wbody, 1);
/* usage decreased by 2 because of dump and
restore of s-reg
*/
no (e) = p.fix_break;
return (add_weights (&wdef, &p.wp_weights));
}
else if ((props (e) & infreg_bits) == 0 && floatregable (e)) {
wp p;
p = max_weights (fno (e) - 2 * scale, &wbody, 0);
/* usage decreased by 4(on mips) because of dump
and restore of double s-reg */
no (e) = p.float_break;
return (add_weights (&wdef, &p.wp_weights));
}
else {
no (e) = noe /* restore to value given by scan */ ;
return add_weights (&wdef, &wbody);
}
}
else
return zeroweights;
};
case rep_tag: {
e = bro (son (e));
goto tailrecurse;
}
case case_tag: {
e = son (e);
goto tailrecurse;
};
case labst_tag: {
scale = fno(e);
e = bro (son (e));
goto tailrecurse;
}
case val_tag:{
return zeroweights;
};
case ncopies_tag: {
scale = no(e)*scale;
e = son(e);
goto tailrecurse;
}
case seq_tag: {
exp l = son(son(e));
exp r = bro(son(e));
weights w,w1;
w = weightsv(scale,l);
while(!last(l)){
l = bro(l);
w1 = weightsv(scale,l);
w = add_weights(&w,&w1);
}
w1 = weightsv(scale,r);
w = add_weights(&w,&w1);
return w;
}
default: {
if (son (e) == nilexp || n == env_offset_tag ||
n == general_env_offset_tag) {
return zeroweights;
}
if (last (son (e))) {
e = son (e);
goto tailrecurse;
}
return (add_wlist (scale, son (e)));
}
}
}