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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.
*/
/**********************************************************************
$Author: release $
$Date: 1998/01/17 15:56:07 $
$Revision: 1.1.1.1 $
$Log: weights.c,v $
* Revision 1.1.1.1 1998/01/17 15:56:07 release
* First version to be checked into rolling release.
*
* Revision 1.1 1995/04/13 09:08:06 currie
* Initial revision
*
***********************************************************************/
/******************************************************************
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).
******************************************************************/
/* ALTERATIONS
25/3/93 scale in labst_tag in weightsv is already evaluated
332: scale = fno(e)*scale -> scale = fno(e);
*/
#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 "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
}
};
/* NB scale, throughout, should be a float but mips cc V2.10 compiles calls and
proc body inconsistently !! */
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);
}
wp max_weights
PROTO_N ( (loc, ws, fix) )
PROTO_T ( double loc X weights * ws X bool fix )
{
/* 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 */
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 )
{/* sum of weights of list 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);
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);
}
/* 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) - 4 * scale, &wbody, 0);
/* usage decreased by 4 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)));
}
}
}