Working on optimizations

[cc65] / src / cc65 / codeopt.c

diff --git a/src/cc65/codeopt.c b/src/cc65/codeopt.c
index 36798b78ee006a8c580f30d944101c46c08533ef..d249b9958f1d1bc2e9dd4212465a933517708cb2 100644 (file)
--- a/src/cc65/codeopt.c
+++ b/src/cc65/codeopt.c
@@ -790,6 +790,7 @@ static unsigned OptPtrLoad1 (CodeSeg* S)
 static unsigned OptPtrLoad2 (CodeSeg* S)
 /* Search for the sequence:
  *
+ *      clc
  *      adc            xxx
  *      tay
  *      txa
@@ -801,6 +802,7 @@ static unsigned OptPtrLoad2 (CodeSeg* S)
  *
  * and replace it by:
  *
+ *      clc
  *      adc            xxx
  *      sta     ptr1
  *      txa
@@ -817,52 +819,67 @@ static unsigned OptPtrLoad2 (CodeSeg* S)
     unsigned I = 0;
     while (I < CS_GetEntryCount (S)) {
 
-       CodeEntry* L[8];
+       CodeEntry* L[9];
 
        /* Get next entry */
                L[0] = CS_GetEntry (S, I);
 
        /* Check for the sequence */
-               if (L[0]->OPC == OP65_ADC               &&
-                   CS_GetEntries (S, L+1, I+1, 7)      &&
-                   L[1]->OPC == OP65_TAY               &&
-           !CE_HasLabel (L[1])                 &&
-           L[2]->OPC == OP65_TXA               &&
-           !CE_HasLabel (L[2])                 &&
-           L[3]->OPC == OP65_ADC               &&
+               if (L[0]->OPC == OP65_CLC               &&
+                   CS_GetEntries (S, L+1, I+1, 8)      &&
+           L[1]->OPC == OP65_ADC               &&
+           !CE_HasLabel (L[1])                 &&
+                   L[2]->OPC == OP65_TAY               &&
+           !CE_HasLabel (L[2])                 &&
+           L[3]->OPC == OP65_TXA               &&
            !CE_HasLabel (L[3])                 &&
-           L[4]->OPC == OP65_TAX               &&
+           L[4]->OPC == OP65_ADC               &&
            !CE_HasLabel (L[4])                 &&
-           L[5]->OPC == OP65_TYA               &&
+           L[5]->OPC == OP65_TAX               &&
            !CE_HasLabel (L[5])                 &&
-           L[6]->OPC == OP65_LDY               &&
+           L[6]->OPC == OP65_TYA               &&
            !CE_HasLabel (L[6])                 &&
-                   CE_IsCall (L[7], "ldauidx")         &&
-           !CE_HasLabel (L[7])) {
+           L[7]->OPC == OP65_LDY               &&
+           !CE_HasLabel (L[7])                 &&
+                   CE_IsCall (L[8], "ldauidx")         &&
+           !CE_HasLabel (L[8])) {
 
            CodeEntry* X;
+           CodeEntry* P;
 
                    /* Store the low byte and remove the TAY instead */
-           X = NewCodeEntry (OP65_STA, AM65_ZP, "ptr1", 0, L[0]->LI);
-           CS_InsertEntry (S, X, I+1);
-           CS_DelEntry (S, I+2);
+           X = NewCodeEntry (OP65_STA, AM65_ZP, "ptr1", 0, L[1]->LI);
+           CS_InsertEntry (S, X, I+2);
+           CS_DelEntry (S, I+3);
 
            /* Store the high byte */
-           X = NewCodeEntry (OP65_STA, AM65_ZP, "ptr1+1", 0, L[3]->LI);
-           CS_InsertEntry (S, X, I+4);
+           X = NewCodeEntry (OP65_STA, AM65_ZP, "ptr1+1", 0, L[4]->LI);
+           CS_InsertEntry (S, X, I+5);
+
+           /* If the instruction before the adc is a ldx, replace the
+            * txa by and lda with the same location of the ldx.
+            */
+           if ((P = CS_GetPrevEntry (S, I)) != 0 &&
+               P->OPC == OP65_LDX                &&
+               !CE_HasLabel (P)) {
+
+               X = NewCodeEntry (OP65_LDA, P->AM, P->Arg, 0, P->LI);
+               CS_InsertEntry (S, X, I+4);
+               CS_DelEntry (S, I+3);
+           }
 
            /* Delete more transfer insns */
+           CS_DelEntry (S, I+7);
            CS_DelEntry (S, I+6);
-           CS_DelEntry (S, I+5);
 
            /* Delete the call to ldauidx */
-           CS_DelEntry (S, I+6);
+           CS_DelEntry (S, I+7);
 
            /* Load high and low byte */
-           X = NewCodeEntry (OP65_LDX, AM65_IMM, "$00", 0, L[6]->LI);
-           CS_InsertEntry (S, X, I+6);
-           X = NewCodeEntry (OP65_LDA, AM65_ZP_INDY, "ptr1", 0, L[6]->LI);
+           X = NewCodeEntry (OP65_LDX, AM65_IMM, "$00", 0, L[7]->LI);
            CS_InsertEntry (S, X, I+7);
+           X = NewCodeEntry (OP65_LDA, AM65_ZP_INDY, "ptr1", 0, L[7]->LI);
+           CS_InsertEntry (S, X, I+8);
 
            /* Remember, we had changes */
            ++Changes;
@@ -1381,7 +1398,7 @@ static unsigned OptDecouple (CodeSeg* S)
 
 
 /*****************************************************************************/
-/*                            Size optimization                             */
+/*                            Size optimization                             */
 /*****************************************************************************/
 
 
@@ -1424,7 +1441,7 @@ static unsigned OptSize (CodeSeg* S)
                            X = NewCodeEntry (OP65_DEA, AM65_IMP, 0, 0, E->LI);
                        } else if (Val == ((E->RI->In.RegA + 1) & 0xFF)) {
                            X = NewCodeEntry (OP65_INA, AM65_IMP, 0, 0, E->LI);
-                       }
+                       }
                    }
                }
                break;