Blame | Last modification | View Log | RSS feed
/*
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.
*/
/*
VERSION INFORMATION
===================
--------------------------------------------------------------------------
$Header: /u/g/release/CVSROOT/Source/src/installers/sparc/common/is_worth.c,v 1.1.1.1 1998/01/17 15:55:54 release Exp $
--------------------------------------------------------------------------
$Log: is_worth.c,v $
* Revision 1.1.1.1 1998/01/17 15:55:54 release
* First version to be checked into rolling release.
*
* Revision 1.2 1995/12/15 11:12:14 john
* Change for 64 bit values
*
* Revision 1.1.1.1 1995/03/13 10:18:40 john
* Entered into CVS
*
* Revision 1.4 1994/07/07 16:11:33 djch
* Jul94 tape
*
* Revision 1.3 1994/06/22 09:50:43 djch
* added check for val_tag to avoid derefing father if nil - jmf may not have
* connected the bro field, and we read it to get operator name.
*
* Revision 1.2 1994/05/13 12:33:17 djch
* Incorporates improvements from expt version
* Added bracket to make structure clearer
*
* Revision 1.1 1994/05/03 14:49:39 djch
* Initial revision
*
* Revision 1.5 94/02/21 16:11:11 16:11:11 ra (Robert Andrews)
* is_worth now returns an int, not a bool.
*
* Revision 1.4 93/11/19 16:29:18 16:29:18 ra (Robert Andrews)
* Never remove constant multiplicand from loops - it introduces a call
* when we could get away with shifts and adds.
*
* Revision 1.3 93/08/27 11:29:07 11:29:07 ra (Robert Andrews)
* Added a couple of explicit integer casts.
*
* Revision 1.2 93/07/14 11:18:46 11:18:46 ra (Robert Andrews)
* Reformatted. Changed cont_tag case to deal with reff_0's (because
* remove_zero_offsets is 0 they are not being removed by check).
*
* Revision 1.1 93/06/24 14:58:31 14:58:31 ra (Robert Andrews)
* Initial revision
*
--------------------------------------------------------------------------
*/
#define SPARCTRANS_CODE
#include "config.h"
#include "common_types.h"
#include "tags.h"
#include "expmacs.h"
#include "exp.h"
#include "shapemacs.h"
#include "sparcins.h"
#include "is_worth.h"
/*
BOOLEAN VALUES
*/
#define true 1
#define false 0
/*
IS THE EXPRESSION c WORTH EXTRACTING FROM A LOOP?
This is called from mc_list.
*/
int is_worth
PROTO_N ( ( c ) )
PROTO_T ( exp c )
{
unsigned char cnam = name ( c ) ;
bool isflt = ( bool ) is_floating ( name ( sh ( c ) ) ) ;
if ( name ( sh ( c ) ) == ptrhd && al1 ( sh ( c ) ) == 1 ) {
/* Pointers to bits aren't */
return ( false ) ;
}
if ( cnam == real_tag ) {
/* Real constants are */
return ( true ) ;
}
if ( cnam == goto_tag ) {
/* Extracting gotos messes things up */
return ( false ) ;
}
if ( cnam == cont_tag ) {
exp s = son ( c ) ;
if ( isflt && ( name ( s ) != name_tag || isglob ( son ( s ) ) ) ) {
return ( true ) ;
}
if ( name ( s ) == reff_tag && no ( s ) == 0 ) s = son ( s ) ;
if ( name ( s ) == name_tag && isglob ( son ( s ) ) ) {
return ( true ) ;
}
if ( name ( s ) == cont_tag ) {
exp ss = son ( s ) ;
if ( name ( ss ) == reff_tag && no ( ss ) == 0 ) ss = son ( ss ) ;
if ( name ( ss ) == name_tag ) return ( true ) ;
}
return ( false ) ;
}
if ( cnam == val_tag ) {
/* It is sometimes worth extracting large integer constants */
exp dad ;
long n = no ( c ) ;
if ( n == 0 ) return ( false ) ;
if(name(sh(c)) == u64hd || name(sh(c)) == s64hd) return (false);
dad = father ( c ) ;
if (dad == nilexp)
{
if ( SIMM13_SIZE ( n ) ) return ( false ) ;
return ( true ) ;
}
switch ( name ( dad ) ) {
case and_tag : {
exp grandad = father ( dad ) ;
if ( (name ( grandad ) == test_tag && ( n & ( n - 1 ) ) == 0
&& ( props ( grandad ) == 5 || props ( grandad ) == 6 )
&& ( name ( bro ( son ( grandad ) ) ) == val_tag
&& no ( bro ( son ( grandad ) ) ) == 0 ))
|| ( name ( son ( grandad ) ) == val_tag
&& no ( son ( grandad ) ) == 0 ) ) {
/* a & 2^n == 0 is transformed into a shift */
return ( false ) ;
}
/* FALL THROUGH */
}
case or_tag :
case xor_tag :
case test_tag : {
/* Large or negative constants are worth extracting */
return ( ( int ) ( n < 0 || !SIMM13_SIZE ( n ) ) ) ;
}
case mult_tag :
case offset_mult_tag : {
#if 0
/* Is this necessarily true? */
if ( SIMM13_SIZE ( n ) ) return ( false ) ;
return ( ( int ) ( ( n & ( n - 1 ) ) != 0 &&
( n & ( n + 1 ) ) != 0 &&
( ( n - 1 ) & ( n - 2 ) ) != 0 ) ) ;
#endif
return ( false ) ;
}
case div1_tag :
case div2_tag :
case rem2_tag : {
#if 0
/* Is this necessarily true? */
if ( SIMM13_SIZE ( n ) ) return ( false ) ;
#endif
return ( ( int ) ( ( n & ( n - 1 ) ) != 0 ) ) ; /* LINT */
}
default : {
/* Extract large constants */
if ( SIMM13_SIZE ( n ) ) return ( false ) ;
return ( true ) ;
}
}
}
if ( is_o ( cnam ) || cnam == clear_tag ) return ( false ) ;
return ( true ) ;
}