Initial revision

diff --git a/mach/pdp/top/table b/mach/pdp/top/table
new file mode 100644 (file)
index 0000000..2b4e433
--- /dev/null
+++ b/mach/pdp/top/table
@@ -0,0 +1,104 @@
+/* PDP-11 desciptor table for ACK target optimizer */
+
+/* Tunable constants: */
+
+MAXOP          2;
+LABEL_STARTER  'I';
+OPC_TERMINATOR ' ';
+
+%%;
+
+/* useful addressing modes: */
+
+ZERO           {strcmp(VAL,"$00") == 0                 };
+ONE            {strcmp(VAL,"$01") == 0                 };
+CONST          {VAL[0] == '$'                          };      /* constant */
+A,B            {no_side_effects(VAL)                   };
+X,Y            {TRUE                                   };
+REG            {is_register(VAL)                       };      /* register */
+SREG           {is_scratchreg(VAL)                     };      /* scratch reg */
+M_ONE          {strcmp(VAL,"$037777777777") == 0       };      /* -1   */
+LAB,L1,L2      {VAL[0] == 'I'                          };      /* label */
+
+%%;
+
+/* optimization patterns: */
+
+add ZERO,A  {carry_dead(REST)} ->      ;
+add ONE, X  {carry_dead(REST)} ->      inc X;
+sub ONE, X  {carry_dead(REST)} ->      dec X;
+
+/* tst-elimination */
+tst (sp)+ : tst X              ->      mov X,(sp)+;
+tst (sp)+ : mov X,-(sp)        ->      mov X,(sp);
+mov A,X : tst A                        ->      mov A,X;
+
+/* register subsumption */
+mov REG,A : ANY A,X            ->      mov REG,A : ANY REG,X;
+mov REG,A : ANY *A             ->      mov REG,A : ANY *REG;
+mov REG,A : ANY *A,X           ->      mov REG,A : ANY *REG,X;
+mov REG,A : ANY X,*A           ->      mov REG,A : ANY X,*REG;
+
+/* compare with -1 */
+cmp SREG,M_ONE : jeq LAB       ->      inc SREG : jeq LAB;
+cmp SREG,M_ONE : jne LAB       ->      inc SREG : jne LAB;
+
+/* skip over jump */
+jeq L1 : jbr L2: labdef L1     ->      jne L2 : labdef L1;
+jge L1 : jbr L2: labdef L1     ->      jlt L2 : labdef L1;
+jgt L1 : jbr L2: labdef L1     ->      jle L2 : labdef L1;
+jlt L1 : jbr L2: labdef L1     ->      jge L2 : labdef L1;
+jle L1 : jbr L2: labdef L1     ->      jgt L2 : labdef L1;
+jne L1 : jbr L2: labdef L1     ->      jeq L2 : labdef L1;
+
+/* byte-test */
+clr SREG : bisb X,SREG : tst SREG : jeq LAB
+                               ->      tstb X : jeq LAB;
+clr SREG : bisb X,SREG : tst SREG : jne LAB
+                               ->      tstb X : jne LAB;
+
+%%;
+
+/* auxiliary routines: */
+
+int no_side_effects(s)
+       register char *s;
+{
+
+       for(;;) {
+               switch(*s++) {
+                       case '\0': return TRUE;
+                       case '-':  if (*s == '(') return FALSE; break;
+                       case ')':  if (*s == '+') return FALSE; break;
+               }
+       }
+       /* NOTREACHED */
+}
+
+int is_register(s)
+       register char *s;
+{
+       return *s++ == 'r' && *s >= '0' && *s <= '5';
+}
+
+int is_scratchreg(s)
+       register char *s;
+{
+       return *s++ == 'r' && (*s == '0' || *s == '1' || *s == '3');
+}
+
+int carry_dead(s)
+       char *s;
+{
+       switch(*s++) {
+               case 'a':       /* adc and adcb */
+                       return *s++ != 'd' || *s != 'c';
+               case 'b':       /* bcc, bcs, bhi, bhis, blo, blos */
+                       return *s != 'c' && *s != 'h' &&
+                               (*s++ != 'l' || *s != 'o');
+               case 's':       /* sbc and sbcb */
+                       return *s++ != 'b' || *s != 'c';
+               default:
+                       return TRUE;
+       }
+}