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/*
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Crown Copyright (c) 1997
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This TenDRA(r) Computer Program is subject to Copyright
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owned by the United Kingdom Secretary of State for Defence
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acting through the Defence Evaluation and Research Agency
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(DERA). It is made available to Recipients with a
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royalty-free licence for its use, reproduction, transfer
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to other parties and amendment for any purpose not excluding
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product development provided that any such use et cetera
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shall be deemed to be acceptance of the following conditions:-
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(1) Its Recipients shall ensure that this Notice is
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reproduced upon any copies or amended versions of it;
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(2) Any amended version of it shall be clearly marked to
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show both the nature of and the organisation responsible
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for the relevant amendment or amendments;
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(3) Its onward transfer from a recipient to another
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party shall be deemed to be that party's acceptance of
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these conditions;
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(4) DERA gives no warranty or assurance as to its
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quality or suitability for any purpose and DERA accepts
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no liability whatsoever in relation to any use to which
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it may be put.
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*/
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/*
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$Log: is_worth.c,v $
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* Revision 1.1.1.1 1998/01/17 15:56:02 release
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* First version to be checked into rolling release.
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*
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* Revision 1.2 1995/12/18 13:11:42 wfs
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* Put hppatrans uder cvs control. Major Changes made since last release
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* include:
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* (i) PIC code generation.
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* (ii) Profiling.
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* (iii) Dynamic Initialization.
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* (iv) Debugging of Exception Handling and Diagnostics.
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*
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* Revision 5.0 1995/08/25 13:42:58 wfs
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* Preperation for August 25 Glue release
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*
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* Revision 3.4 1995/08/25 13:33:36 wfs
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* *** empty log message ***
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*
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* Revision 3.4 1995/08/25 13:33:36 wfs
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* *** empty log message ***
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*
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* Revision 3.1 95/04/10 16:26:58 16:26:58 wfs (William Simmonds)
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* Apr95 tape version.
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*
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* Revision 3.0 95/03/30 11:17:55 11:17:55 wfs (William Simmonds)
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* Mar95 tape version with CRCR95_178 bug fix.
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*
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* Revision 2.0 95/03/15 15:27:42 15:27:42 wfs (William Simmonds)
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* spec 3.1 changes implemented, tests outstanding.
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*
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* Revision 1.2 95/01/17 17:25:20 17:25:20 wfs (William Simmonds)
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* Changed name of an included header file
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*
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* Revision 1.1 95/01/11 13:10:17 13:10:17 wfs (William Simmonds)
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* Initial revision
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*
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*/
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#define HPPATRANS_CODE
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#include "config.h"
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#include "common_types.h"
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#include "tags.h"
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#include "expmacs.h"
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#include "exp.h"
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#include "shapemacs.h"
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#include "hppains.h"
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#include "is_worth.h"
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/*
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BOOLEAN VALUES
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*/
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#define true 1
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#define false 0
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/*
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IS THE EXPRESSION c WORTH EXTRACTING FROM A LOOP?
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This is called from mc_list.
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*/
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int is_worth
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PROTO_N ( ( c ) )
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PROTO_T ( exp c )
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{
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unsigned char cnam = name ( c ) ;
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bool isflt = ( bool ) is_floating ( name ( sh ( c ) ) ) ;
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if ( name ( sh ( c ) ) == ptrhd && al1 ( sh ( c ) ) == 1 ) {
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/* Pointers to bits aren't */
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return ( false ) ;
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}
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#if 0
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if (cnam==name_tag && name(father(c))==addptr_tag && isglob(son(c)))
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return(true);
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#endif
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if ( cnam == real_tag ) {
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/* Real constants are */
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return ( true ) ;
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}
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if ( cnam == goto_tag ) {
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/* Extracting gotos messes things up */
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return ( false ) ;
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}
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if ( cnam == cont_tag ) {
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exp s = son ( c ) ;
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if ( isflt && ( name ( s ) != name_tag || isglob ( son ( s ) ) ) ) {
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return ( true ) ;
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}
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if ( name ( s ) == reff_tag && no ( s ) == 0 ) s = son ( s ) ;
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if ( name ( s ) == name_tag && isglob ( son ( s ) ) ) {
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return ( true ) ;
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}
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if ( name ( s ) == cont_tag ) {
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exp ss = son ( s ) ;
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if ( name ( ss ) == reff_tag && no ( ss ) == 0 ) ss = son ( ss ) ;
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if ( name ( ss ) == name_tag ) return ( true ) ;
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}
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return ( false ) ;
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}
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#if 0
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if ( name ( sh ( c ) ) == ptrhd && isglob(son(c)) ) {
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return ( true ) ;
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}
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#endif
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if ( cnam == val_tag ) {
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/* It is sometimes worth extracting large integer constants */
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exp dad ;
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long n = no ( c ) ;
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if ( n==0 )
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return (false) ;
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if ( shape_size(sh(c))==64 )
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return (false) ; /* Cannot put 64 bit integers in registers! */
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dad = father ( c ) ;
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if (dad==nilexp)
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{
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if (SIMM13(n)) return (false);
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return (true);
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}
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switch ( name ( dad ) ) {
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case and_tag : {
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exp grandad = father ( dad ) ;
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if ( (name ( grandad ) == test_tag && ( n & ( n - 1 ) ) == 0
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&& ( props ( grandad ) == 5 || props ( grandad ) == 6 )
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&& ( name ( bro ( son ( grandad ) ) ) == val_tag
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&& no ( bro ( son ( grandad ) ) ) == 0 ))
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|| ( name ( son ( grandad ) ) == val_tag
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&& no ( son ( grandad ) ) == 0 ) ) {
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/* a & 2^n == 0 is transformed into a shift */
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return ( false ) ;
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}
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/* FALL THROUGH */
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if (((n+1)&n) ==0)
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return false;
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}
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case or_tag :
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case xor_tag :
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case test_tag : {
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/* Large or negative constants are worth extracting */
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return ( ( bool ) ( n<0 || !SIMM5( n ) ) ) ;
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}
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case mult_tag :
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case offset_mult_tag : {
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#if 0
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/* Is this necessarily true? */
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if ( SIMM13( n ) ) return ( false ) ;
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return ( ( bool ) ( ( n & ( n - 1 ) ) != 0 &&
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( n & ( n + 1 ) ) != 0 &&
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( ( n - 1 ) & ( n - 2 ) ) != 0 ) ) ;
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#endif
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return ( false ) ;
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}
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case div1_tag :
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case div2_tag :
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case rem2_tag : {
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#if 0
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/* Is this necessarily true? */
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if ( SIMM13( n ) ) return ( false ) ;
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#endif
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return ( ( bool ) ( ( n & ( n - 1 ) ) != 0 ) ) ; /* LINT */
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}
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default : {
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/* Extract large constants */
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if ( SIMM13( n ) ) return ( false ) ;
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return ( true ) ;
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}
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}
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}
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if ( is_o ( cnam ) || cnam == clear_tag ) return ( false ) ;
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return ( true ) ;
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}
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