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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.
*/
/*
$Log: is_worth.c,v $
* Revision 1.1.1.1 1998/01/17 15:56:02 release
* First version to be checked into rolling release.
*
* Revision 1.2 1995/12/18 13:11:42 wfs
* Put hppatrans uder cvs control. Major Changes made since last release
* include:
* (i) PIC code generation.
* (ii) Profiling.
* (iii) Dynamic Initialization.
* (iv) Debugging of Exception Handling and Diagnostics.
*
* Revision 5.0 1995/08/25 13:42:58 wfs
* Preperation for August 25 Glue release
*
* Revision 3.4 1995/08/25 13:33:36 wfs
* *** empty log message ***
*
* Revision 3.4 1995/08/25 13:33:36 wfs
* *** empty log message ***
*
* Revision 3.1 95/04/10 16:26:58 16:26:58 wfs (William Simmonds)
* Apr95 tape version.
*
* Revision 3.0 95/03/30 11:17:55 11:17:55 wfs (William Simmonds)
* Mar95 tape version with CRCR95_178 bug fix.
*
* Revision 2.0 95/03/15 15:27:42 15:27:42 wfs (William Simmonds)
* spec 3.1 changes implemented, tests outstanding.
*
* Revision 1.2 95/01/17 17:25:20 17:25:20 wfs (William Simmonds)
* Changed name of an included header file
*
* Revision 1.1 95/01/11 13:10:17 13:10:17 wfs (William Simmonds)
* Initial revision
*
*/
#define HPPATRANS_CODE
#include "config.h"
#include "common_types.h"
#include "tags.h"
#include "expmacs.h"
#include "exp.h"
#include "shapemacs.h"
#include "hppains.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 0
if (cnam==name_tag && name(father(c))==addptr_tag && isglob(son(c)))
return(true);
#endif
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 0
if ( name ( sh ( c ) ) == ptrhd && isglob(son(c)) ) {
return ( true ) ;
}
#endif
if ( cnam == val_tag ) {
/* It is sometimes worth extracting large integer constants */
exp dad ;
long n = no ( c ) ;
if ( n==0 )
return (false) ;
if ( shape_size(sh(c))==64 )
return (false) ; /* Cannot put 64 bit integers in registers! */
dad = father ( c ) ;
if (dad==nilexp)
{
if (SIMM13(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 */
if (((n+1)&n) ==0)
return false;
}
case or_tag :
case xor_tag :
case test_tag : {
/* Large or negative constants are worth extracting */
return ( ( bool ) ( n<0 || !SIMM5( n ) ) ) ;
}
case mult_tag :
case offset_mult_tag : {
#if 0
/* Is this necessarily true? */
if ( SIMM13( n ) ) return ( false ) ;
return ( ( bool ) ( ( 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( n ) ) return ( false ) ;
#endif
return ( ( bool ) ( ( n & ( n - 1 ) ) != 0 ) ) ; /* LINT */
}
default : {
/* Extract large constants */
if ( SIMM13( n ) ) return ( false ) ;
return ( true ) ;
}
}
}
if ( is_o ( cnam ) || cnam == clear_tag ) return ( false ) ;
return ( true ) ;
}