108 lines
2.4 KiB
Plaintext
108 lines
2.4 KiB
Plaintext
/* PDP-11 desciptor table for ACK target optimizer */
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/* Tunable constants: */
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MAXOP 2;
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LABEL_STARTER 'I';
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OPC_TERMINATOR ' ';
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%%;
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/* useful addressing modes: */
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ZERO {strcmp(VAL,"$00") == 0 };
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ONE {strcmp(VAL,"$01") == 0 };
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CONST {VAL[0] == '$' }; /* constant */
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A,B {no_side_effects(VAL) };
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X,Y {TRUE };
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REG {is_register(VAL) }; /* register */
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SREG {is_scratchreg(VAL) }; /* scratch reg */
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M_ONE {strcmp(VAL,"$-1") == 0 }; /* -1 */
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LAB,L1,L2 {VAL[0] == 'I' }; /* label */
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%%;
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/* optimization patterns: */
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add ZERO,A {carry_dead(REST)} -> ;
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add ONE, X {carry_dead(REST)} -> inc X;
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sub ONE, X {carry_dead(REST)} -> dec X;
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mov A,A -> tst A;
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/* tst-elimination */
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tst (sp)+ : tst X -> mov X,(sp)+;
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tst (sp)+ : mov X,-(sp) -> mov X,(sp);
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mov A,X : tst A -> mov A,X;
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mov X,A : tst A -> mov X,A;
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/* register subsumption */
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mov REG,A : ANY A,X -> mov REG,A : ANY REG,X;
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mov REG,A : ANY *A -> mov REG,A : ANY *REG;
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mov REG,A : ANY *A,X -> mov REG,A : ANY *REG,X;
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mov REG,A : ANY X,*A -> mov REG,A : ANY X,*REG;
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/* compare with -1 */
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cmp SREG,M_ONE : jeq LAB -> inc SREG : jeq LAB;
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cmp SREG,M_ONE : jne LAB -> inc SREG : jne LAB;
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/* skip over jump */
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jeq L1 : jbr L2: labdef L1 -> jne L2 : labdef L1;
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jge L1 : jbr L2: labdef L1 -> jlt L2 : labdef L1;
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jgt L1 : jbr L2: labdef L1 -> jle L2 : labdef L1;
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jlt L1 : jbr L2: labdef L1 -> jge L2 : labdef L1;
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jle L1 : jbr L2: labdef L1 -> jgt L2 : labdef L1;
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jne L1 : jbr L2: labdef L1 -> jeq L2 : labdef L1;
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/* byte-test */
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clr SREG : bisb X,SREG : tst SREG : jeq LAB
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-> tstb X : jeq LAB;
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clr SREG : bisb X,SREG : tst SREG : jne LAB
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-> tstb X : jne LAB;
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%%;
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/* auxiliary routines: */
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int no_side_effects(s)
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register char *s;
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{
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for(;;) {
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switch(*s++) {
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case '\0': return TRUE;
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case '-': if (*s == '(') return FALSE; break;
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case ')': if (*s == '+') return FALSE; break;
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}
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}
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/* NOTREACHED */
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}
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int is_register(s)
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register char *s;
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{
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return *s++ == 'r' && *s >= '0' && *s <= '5';
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}
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int is_scratchreg(s)
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register char *s;
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{
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return *s++ == 'r' && (*s == '0' || *s == '1' || *s == '3');
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}
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int carry_dead(s)
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char *s;
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{
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switch(*s++) {
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case 'a': /* adc and adcb */
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return *s++ != 'd' || *s != 'c';
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case 'b': /* bcc, bcs, bhi, bhis, blo, blos */
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return *s != 'c' && *s != 'h' &&
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(*s++ != 'l' || *s != 'o');
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case 's': /* sbc and sbcb */
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return *s++ != 'b' || *s != 'c';
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default:
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return TRUE;
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}
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}
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