added optimization for indexed 16-bit array load of form (array[i & 0x7f])

[cc65] / src / cc65 / coptptrload.c

diff --git a/src/cc65/coptptrload.c b/src/cc65/coptptrload.c
index 81682ab096cd37d0dfc158b757ab45842da1a52c..c508d56f492b67d6147736b69fb998df3b0903f7 100644 (file)
--- a/src/cc65/coptptrload.c
+++ b/src/cc65/coptptrload.c
@@ -1554,3 +1554,116 @@ unsigned OptPtrLoad18 (CodeSeg* S)
 
 
 
+unsigned OptPtrLoad19 (CodeSeg* S)
+/* Search for the sequence:
+**
+**     and     #mask           (any value < 128)
+**      jsr     aslax1/shlax1
+**      clc
+**      adc     #<(label+0)
+**      tay
+**      txa
+**      adc     #>(label+0)
+**      tax
+**      tya
+**      ldy     #$01
+**      jsr     ldaxidx
+**
+** and replace it by:
+**
+**     and     #mask           (remove if == 127)
+**     asl
+**     tay
+**     lda     label,y
+**     ldx     label+1,y
+*/
+{
+    unsigned Changes = 0;
+    unsigned I;
+
+    /* Walk over the entries */
+    I = 0;
+    while (I < CS_GetEntryCount (S)) {
+
+        CodeEntry* L[11];
+
+        /* Get next entry */
+        L[0] = CS_GetEntry (S, I);
+
+        /* Check for the sequence */
+        if (L[0]->OPC == OP65_AND                               &&
+            L[0]->AM == AM65_IMM                                &&
+            CE_HasNumArg (L[0]) && L[0]->Num <= 127             &&
+            CS_GetEntries (S, L+1, I+1, 10)                     &&
+            L[1]->OPC == OP65_JSR                               &&
+            (strcmp (L[1]->Arg, "aslax1") == 0          ||
+             strcmp (L[1]->Arg, "shlax1") == 0)                 &&
+            L[2]->OPC == OP65_CLC                               &&
+            L[3]->OPC == OP65_ADC                               &&
+            L[4]->OPC == OP65_TAY                               &&
+            L[5]->OPC == OP65_TXA                               &&
+            L[6]->OPC == OP65_ADC                               &&
+            L[7]->OPC == OP65_TAX                               &&
+            L[8]->OPC == OP65_TYA                               &&
+            L[9]->OPC == OP65_LDY                               &&
+            CE_IsKnownImm(L[9], 1)                              &&
+            strlen(L[3]->Arg) >= 3                              &&
+            L[3]->Arg[0] == '<'                                 &&
+            strlen(L[6]->Arg) >= 3                              &&
+            L[6]->Arg[0] == '>'                                 &&
+            !strcmp(L[3]->Arg+1, L[6]->Arg+1)                   &&
+            CE_IsCallTo (L[10], "ldaxidx")                      &&
+            !CS_RangeHasLabel (S, I+1, 10)) {
+
+            CodeEntry* X;
+            char* Label;
+            int Len = strlen(L[3]->Arg);
+
+            /* Track the insertion point */
+            unsigned IP = I + 11;
+
+            /* asl a */
+            X = NewCodeEntry (OP65_ASL, AM65_ACC, "a", 0, L[1]->LI);
+            CS_InsertEntry (S, X, IP++);
+
+            /* tay */
+            X = NewCodeEntry (OP65_TAY, AM65_IMP, 0, 0, L[1]->LI);
+            CS_InsertEntry (S, X, IP++);
+
+            /* lda label,y */
+            Label = memcpy (xmalloc (Len-2), L[3]->Arg+2, Len-3);
+            Label[Len-3] = '\0';
+            X = NewCodeEntry (OP65_LDA, AM65_ABSY, Label, 0, L[9]->LI);
+            CS_InsertEntry (S, X, IP++);
+            xfree (Label);
+
+            /* lda label+1,y */
+            Label = memcpy (xmalloc (Len), L[3]->Arg+2, Len-3);
+            strcpy(&Label[Len-3], "+1");
+            X = NewCodeEntry (OP65_LDX, AM65_ABSY, Label, 0, L[9]->LI);
+            CS_InsertEntry (S, X, IP++);
+            xfree (Label);
+
+            /* Remove the old code */
+            /* Remove the AND only if it's == 127, since ASL erases high bit */
+            if (L[0]->Num == 127)
+                CS_DelEntries (S, I, 11);
+            else
+                CS_DelEntries (S, I+1, 10);
+
+            /* Remember, we had changes */
+            ++Changes;
+
+        }
+
+        /* Next entry */
+        ++I;
+
+    }
+
+    /* Return the number of changes made */
+    return Changes;
+}
+
+
+