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118 lines
2.2 KiB
Groff
118 lines
2.2 KiB
Groff
/*
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Copyright 1982
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Alcyon Corporation
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8716 Production Ave.
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San Diego, Ca. 92121
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@(#)sucomp.c 1.3 11/2/83
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*/
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#include "cgen.h"
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#include "cskel.h"
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/* sucomp - Sethy-Ullman expression complexity measure computation*/
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/* This is a heuristic computation of the Sethy-Ullman numbers*/
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/* for expressions. This gives an approximation of the complexity*/
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/* of the expression. The code generation scheme works best if*/
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/* the most complex expressions are done first.*/
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sucomp(tp,nregs,flag) /* returns - none*/
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struct tnode *tp; /* pointer to tree*/
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int nregs; /* number of registers left*/
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int flag; /* 1=>set values in tree, 0=>return*/
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{
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register short su, sur, op, i;
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register struct tnode *ltp, *rtp;
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nregs = DREG(nregs);
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if( BINOP(op=tp->t_op) ) {
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ltp = tp->t_left;
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rtp = tp->t_right;
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}
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else if( UNARYOP(op) )
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ltp = tp->t_left;
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switch( op ) {
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case CLONG:
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if( tp->t_lvalue >= 0x8000L || tp->t_lvalue <= 0xffff8000L ) {
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su = SU_ADDR;
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break;
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}
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i = tp->t_lvalue;
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case CINT:
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if( op == CINT )
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i = tp->t_value;
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if( i == 0 )
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su = SU_ZERO;
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else if( i == 1 )
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su = SU_ONE;
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else if( i >= 1 && i <= QUICKVAL )
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su = SU_SMALL;
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else if( i >= -128 && i <= 127 )
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su = SU_QUICK;
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else
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su = SU_CONST;
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break;
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case COMMA:
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su = sucomp(rtp,nregs,flag);
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i = sucomp(ltp,nregs,flag);
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su = MAX(su,i);
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su = MAX(su,SU_EASY);
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break;
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case ADDR:
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su = sucomp(ltp,nregs,flag);
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break;
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case CFLOAT:
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case DCLONG:
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case AUTOINC:
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case AUTODEC:
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su = SU_ADDR;
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break;
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case SYMBOL:
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if( tp->t_sc != REGISTER )
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su = SU_ADDR;
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else if( ISDREG(tp->t_reg) )
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su = SU_REG;
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else
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su = SU_AREG;
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break;
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case LDIV:
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case LMOD:
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case LMULT:
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case CALL:
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sucomp(rtp,nregs,flag);
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case NACALL:
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sucomp(ltp,nregs,flag);
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su = SU_VHARD; /*very hard*/
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break;
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default:
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su = sucomp(ltp,nregs,flag);
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if( BINOP(op) ) {
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if( su <= SU_ADDR ) {
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i = sucomp(rtp,nregs,flag);
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su = MAX(su,i);
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}
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else {
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sur = sucomp(rtp,nregs+1,flag);
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if( sur > SU_ADDR && nregs > HICREG )
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su = MAX(su,SU_HARD);
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}
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su = MAX(SU_EASY,su);
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}
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else if( su <= SU_XREG )
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su = MAX(SU_EASY,su);
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if( ISFLOAT(tp->t_type) )
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su = SU_VHARD;
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break;
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}
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if( flag )
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tp->t_su = su;
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return(su);
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}
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