unsigned OptCmp7 (CodeSeg* S)
/* Search for a sequence ldx/txa/branch and remove the txa if A is not
* used later.
*/
{
unsigned Changes = 0;
/* Walk over the entries */
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
CodeEntry* L[2];
/* Get next entry */
CodeEntry* E = CS_GetEntry (S, I);
/* Check for the sequence */
if ((E->OPC == OP65_LDX) &&
CS_GetEntries (S, L, I+1, 2) &&
L[0]->OPC == OP65_TXA &&
!CE_HasLabel (L[0]) &&
(L[1]->Info & OF_FBRA) != 0 &&
!CE_HasLabel (L[1]) &&
!RegAUsed (S, I+3)) {
/* Remove the txa */
CS_DelEntry (S, I+1);
/* Remember, we had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
unsigned Opt65C02BitOps (CodeSeg* S)
/* Use special bit op instructions of the C02 */
{
unsigned Changes = 0;
unsigned I;
/* Generate register info for this step */
CS_GenRegInfo (S);
/* Walk over the entries */
I = 0;
while (I < CS_GetEntryCount (S)) {
CodeEntry* L[3];
/* Get next entry */
L[0] = CS_GetEntry (S, I);
/* Check for the sequence */
if (L[0]->OPC == OP65_LDA &&
(L[0]->AM == AM65_ZP || L[0]->AM == AM65_ABS) &&
!CS_RangeHasLabel (S, I+1, 2) &&
CS_GetEntries (S, L+1, I+1, 2) &&
(L[1]->OPC == OP65_AND || L[1]->OPC == OP65_ORA) &&
CE_IsConstImm (L[1]) &&
L[2]->OPC == OP65_STA &&
L[2]->AM == L[0]->AM &&
strcmp (L[2]->Arg, L[0]->Arg) == 0 &&
!RegAUsed (S, I+3)) {
char Buf[32];
CodeEntry* X;
/* Use TRB for AND and TSB for ORA */
if (L[1]->OPC == OP65_AND) {
/* LDA #XX */
sprintf (Buf, "$%02X", (int) ((~L[1]->Num) & 0xFF));
X = NewCodeEntry (OP65_LDA, AM65_IMM, Buf, 0, L[1]->LI);
CS_InsertEntry (S, X, I+3);
/* TRB */
X = NewCodeEntry (OP65_TRB, L[0]->AM, L[0]->Arg, 0, L[0]->LI);
CS_InsertEntry (S, X, I+4);
} else {
/* LDA #XX */
sprintf (Buf, "$%02X", (int) L[1]->Num);
X = NewCodeEntry (OP65_LDA, AM65_IMM, Buf, 0, L[1]->LI);
CS_InsertEntry (S, X, I+3);
/* TSB */
X = NewCodeEntry (OP65_TSB, L[0]->AM, L[0]->Arg, 0, L[0]->LI);
CS_InsertEntry (S, X, I+4);
}
/* Delete the old stuff */
CS_DelEntries (S, I, 3);
/* We had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Free register info */
CS_FreeRegInfo (S);
/* Return the number of changes made */
return Changes;
}
unsigned OptCmp9 (CodeSeg* S)
/* Search for the sequence
*
* sbc xx
* bvs/bvc L
* eor #$80
* L: asl a
* bcc/bcs somewhere
*
* If A is not used later (which should be the case), we can branch on the N
* flag instead of the carry flag and remove the asl.
*/
{
unsigned Changes = 0;
unsigned I;
/* Walk over the entries */
I = 0;
while (I < CS_GetEntryCount (S)) {
CodeEntry* L[5];
/* Get next entry */
L[0] = CS_GetEntry (S, I);
/* Check for the sequence */
if (L[0]->OPC == OP65_SBC &&
CS_GetEntries (S, L+1, I+1, 4) &&
(L[1]->OPC == OP65_BVC ||
L[1]->OPC == OP65_BVS) &&
L[1]->JumpTo != 0 &&
L[1]->JumpTo->Owner == L[3] &&
L[2]->OPC == OP65_EOR &&
CE_IsKnownImm (L[2], 0x80) &&
L[3]->OPC == OP65_ASL &&
L[3]->AM == AM65_ACC &&
(L[4]->OPC == OP65_BCC ||
L[4]->OPC == OP65_BCS ||
L[4]->OPC == OP65_JCC ||
L[4]->OPC == OP65_JCS) &&
!CE_HasLabel (L[4]) &&
!RegAUsed (S, I+4)) {
/* Replace the branch condition */
switch (GetBranchCond (L[4]->OPC)) {
case BC_CC: CE_ReplaceOPC (L[4], OP65_JPL); break;
case BC_CS: CE_ReplaceOPC (L[4], OP65_JMI); break;
default: Internal ("Unknown branch condition in OptCmp9");
}
/* Delete the asl insn */
CS_DelEntry (S, I+3);
/* Next sequence is somewhat ahead (if any) */
I += 3;
/* Remember, we had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
