unsigned OptBNegAX1 (CodeSeg* S)
/* On a call to bnegax, if X is zero, the result depends only on the value in
* A, so change the call to a call to bnega. This will get further optimized
* later if possible.
*/
{
unsigned Changes = 0;
unsigned I;
/* Walk over the entries */
I = 0;
while (I < CS_GetEntryCount (S)) {
/* Get next entry */
CodeEntry* E = CS_GetEntry (S, I);
/* Check if this is a call to bnegax, and if X is known and zero */
if (E->RI->In.RegX == 0 && CE_IsCallTo (E, "bnegax")) {
CodeEntry* X = NewCodeEntry (OP65_JSR, AM65_ABS, "bnega", 0, E->LI);
CS_InsertEntry (S, X, I+1);
CS_DelEntry (S, I);
/* We had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
void CS_MoveEntries (CodeSeg* S, unsigned Start, unsigned Count, unsigned NewPos)
/* Move a range of entries from one position to another. Start is the index
* of the first entry to move, Count is the number of entries and NewPos is
* the index of the target entry. The entry with the index Start will later
* have the index NewPos. All entries with indices NewPos and above are
* moved to higher indices. If the code block is moved to the end of the
* current code, and if pending labels exist, these labels will get attached
* to the first instruction of the moved block (the first one after the
* current code end)
*/
{
/* Transparently handle an empty range */
if (Count == 0) {
return;
}
/* If NewPos is at the end of the code segment, move any labels from the
* label pool to the first instruction of the moved range.
*/
if (NewPos == CS_GetEntryCount (S)) {
CS_MoveLabelsToEntry (S, CS_GetEntry (S, Start));
}
/* Move the code block to the destination */
CollMoveMultiple (&S->Entries, Start, Count, NewPos);
}
int CS_RangeHasLabel (CodeSeg* S, unsigned Start, unsigned Count)
/* Return true if any of the code entries in the given range has a label
* attached. If the code segment does not span the given range, check the
* possible span instead.
*/
{
unsigned EntryCount = CS_GetEntryCount(S);
/* Adjust count. We expect at least Start to be valid. */
CHECK (Start < EntryCount);
if (Start + Count > EntryCount) {
Count = EntryCount - Start;
}
/* Check each entry. Since we have validated the index above, we may
* use the unchecked access function in the loop which is faster.
*/
while (Count--) {
const CodeEntry* E = CollAtUnchecked (&S->Entries, Start++);
if (CE_HasLabel (E)) {
return 1;
}
}
/* No label in the complete range */
return 0;
}
unsigned GetRegInfo (struct CodeSeg* S, unsigned Index, unsigned Wanted)
/* Determine register usage information for the instructions starting at the
** given index.
*/
{
CodeEntry* E;
Collection Visited; /* Visited entries */
unsigned R;
/* Get the code entry for the given index */
if (Index >= CS_GetEntryCount (S)) {
/* There is no such code entry */
return REG_NONE;
}
E = CS_GetEntry (S, Index);
/* Initialize the data structure used to collection information */
InitCollection (&Visited);
/* Call the recursive subfunction */
R = GetRegInfo1 (S, E, Index, &Visited, REG_NONE, REG_NONE, Wanted);
/* Delete the line collection */
DoneCollection (&Visited);
/* Return the registers used */
return R;
}
unsigned OptCmp6 (CodeSeg* S)
/* Search for calls to compare subroutines followed by a conditional branch
* and replace them by cheaper versions, since the branch means that the
* boolean value returned by these routines is not needed (we may also check
* that explicitly, but for the current code generator it is always true).
*/
{
unsigned Changes = 0;
/* Walk over the entries */
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
CodeEntry* N;
cmp_t Cond;
/* Get next entry */
CodeEntry* E = CS_GetEntry (S, I);
/* Check for the sequence */
if (E->OPC == OP65_JSR &&
(Cond = FindTosCmpCond (E->Arg)) != CMP_INV &&
(N = CS_GetNextEntry (S, I)) != 0 &&
(N->Info & OF_ZBRA) != 0 &&
!CE_HasLabel (N)) {
/* The tos... functions will return a boolean value in a/x and
* the Z flag says if this value is zero or not. We will call
* a cheaper subroutine instead, one that does not return a
* boolean value but only valid flags. Note: jeq jumps if
* the condition is not met, jne jumps if the condition is met.
* Invert the code if we jump on condition not met.
*/
if (GetBranchCond (N->OPC) == BC_EQ) {
/* Jumps if condition false, invert condition */
Cond = CmpInvertTab [Cond];
}
/* Replace the subroutine call. */
E = NewCodeEntry (OP65_JSR, AM65_ABS, "tosicmp", 0, E->LI);
CS_InsertEntry (S, E, I+1);
CS_DelEntry (S, I);
/* Replace the conditional branch */
ReplaceCmp (S, I+1, Cond);
/* Remember, we had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
unsigned OptPush2 (CodeSeg* S)
/* A sequence
*
* jsr ldaxidx
* jsr pushax
*
* may get replaced by
*
* jsr pushwidx
*
*/
{
unsigned I;
unsigned Changes = 0;
/* Generate register info */
CS_GenRegInfo (S);
/* Walk over the entries */
I = 0;
while (I < CS_GetEntryCount (S)) {
CodeEntry* L[2];
/* Get next entry */
L[0] = CS_GetEntry (S, I);
/* Check for the sequence */
if (CE_IsCallTo (L[0], "ldaxidx") &&
(L[1] = CS_GetNextEntry (S, I)) != 0 &&
!CE_HasLabel (L[1]) &&
CE_IsCallTo (L[1], "pushax")) {
/* Insert new code behind the pushax */
CodeEntry* X;
/* jsr pushwidx */
X = NewCodeEntry (OP65_JSR, AM65_ABS, "pushwidx", 0, L[1]->LI);
CS_InsertEntry (S, X, I+2);
/* Delete the old code */
CS_DelEntries (S, I, 2);
/* Remember, we had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Free the register info */
CS_FreeRegInfo (S);
/* Return the number of changes made */
return Changes;
}
unsigned OptShift2(CodeSeg* S)
/* A call to the asrax1 routines may get replaced by something simpler, if
* X is not used later:
*
* cmp #$80
* ror a
*
*/
{
unsigned Changes = 0;
unsigned I;
/* Walk over the entries */
I = 0;
while (I < CS_GetEntryCount (S)) {
unsigned Shift;
unsigned Count;
/* Get next entry */
CodeEntry* E = CS_GetEntry (S, I);
/* Check for the sequence */
if (E->OPC == OP65_JSR &&
(Shift = GetShift (E->Arg)) != SHIFT_NONE &&
SHIFT_TYPE (Shift) == SHIFT_TYPE_ASR &&
(Count = SHIFT_COUNT (Shift)) > 0 &&
Count * 100 <= S->CodeSizeFactor &&
!RegXUsed (S, I+1)) {
CodeEntry* X;
unsigned J = I+1;
/* Generate the replacement sequence */
while (Count--) {
/* cmp #$80 */
X = NewCodeEntry (OP65_CMP, AM65_IMM, "$80", 0, E->LI);
CS_InsertEntry (S, X, J++);
/* ror a */
X = NewCodeEntry (OP65_ROR, AM65_ACC, "a", 0, E->LI);
CS_InsertEntry (S, X, J++);
}
/* Delete the call to asrax */
CS_DelEntry (S, I);
/* Remember, we had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
void CS_FreeRegInfo (CodeSeg* S)
/* Free register infos for all instructions */
{
unsigned I;
for (I = 0; I < CS_GetEntryCount (S); ++I) {
CE_FreeRegInfo (CS_GetEntry(S, I));
}
}
unsigned OptBNegA2 (CodeSeg* S)
/* Check for
*
* lda ..
* jsr bnega
* jeq/jne ..
*
* Adjust the conditional branch and remove the call to the subroutine.
*/
{
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_ADC ||
E->OPC == OP65_AND ||
E->OPC == OP65_DEA ||
E->OPC == OP65_EOR ||
E->OPC == OP65_INA ||
E->OPC == OP65_LDA ||
E->OPC == OP65_ORA ||
E->OPC == OP65_PLA ||
E->OPC == OP65_SBC ||
E->OPC == OP65_TXA ||
E->OPC == OP65_TYA) &&
CS_GetEntries (S, L, I+1, 2) &&
CE_IsCallTo (L[0], "bnega") &&
!CE_HasLabel (L[0]) &&
(L[1]->Info & OF_ZBRA) != 0 &&
!CE_HasLabel (L[1])) {
/* Invert the branch */
CE_ReplaceOPC (L[1], GetInverseBranch (L[1]->OPC));
/* Delete the subroutine call */
CS_DelEntry (S, I+1);
/* Remember, we had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
unsigned OptBNegAX3 (CodeSeg* S)
/* Search for the sequence:
*
* lda xx
* ldx yy
* jsr bnegax
* jne/jeq ...
*
* and replace it by
*
* lda xx
* ora xx+1
* jeq/jne ...
*/
{
unsigned Changes = 0;
/* Walk over the entries */
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
CodeEntry* L[3];
/* Get next entry */
CodeEntry* E = CS_GetEntry (S, I);
/* Check for the sequence */
if (E->OPC == OP65_LDA &&
CS_GetEntries (S, L, I+1, 3) &&
L[0]->OPC == OP65_LDX &&
!CE_HasLabel (L[0]) &&
CE_IsCallTo (L[1], "bnegax") &&
!CE_HasLabel (L[1]) &&
(L[2]->Info & OF_ZBRA) != 0 &&
!CE_HasLabel (L[2])) {
/* ldx --> ora */
CE_ReplaceOPC (L[0], OP65_ORA);
/* Invert the branch */
CE_ReplaceOPC (L[2], GetInverseBranch (L[2]->OPC));
/* Delete the subroutine call */
CS_DelEntry (S, I+2);
/* Remember, we had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
void CS_DelCodeAfter (CodeSeg* S, unsigned Last)
/* Delete all entries including the given one */
{
/* Get the number of entries in this segment */
unsigned Count = CS_GetEntryCount (S);
/* First pass: Delete all references to labels. If the reference count
* for a label drops to zero, delete it.
*/
unsigned C = Count;
while (Last < C--) {
/* Get the next entry */
CodeEntry* E = CS_GetEntry (S, C);
/* Check if this entry has a label reference */
if (E->JumpTo) {
/* If the label is a label in the label pool and this is the last
* reference to the label, remove the label from the pool.
*/
CodeLabel* L = E->JumpTo;
int Index = CollIndex (&S->Labels, L);
if (Index >= 0 && CollCount (&L->JumpFrom) == 1) {
/* Delete it from the pool */
CollDelete (&S->Labels, Index);
}
/* Remove the reference to the label */
CS_RemoveLabelRef (S, E);
}
}
/* Second pass: Delete the instructions. If a label attached to an
* instruction still has references, it must be references from outside
* the deleted area. Don't delete the label in this case, just make it
* ownerless and move it to the label pool.
*/
C = Count;
while (Last < C--) {
/* Get the next entry */
CodeEntry* E = CS_GetEntry (S, C);
/* Check if this entry has a label attached */
if (CE_HasLabel (E)) {
/* Move the labels to the pool and clear the owner pointer */
CS_MoveLabelsToPool (S, E);
}
/* Delete the pointer to the entry */
CollDelete (&S->Entries, C);
/* Delete the entry itself */
FreeCodeEntry (E);
}
}
unsigned OptCmp1 (CodeSeg* S)
/* Search for the sequence
*
* ldx xx
* stx tmp1
* ora tmp1
*
* and replace it by
*
* ora xx
*/
{
unsigned Changes = 0;
/* Walk over the entries */
unsigned 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_LDX &&
!CS_RangeHasLabel (S, I+1, 2) &&
CS_GetEntries (S, L+1, I+1, 2) &&
L[1]->OPC == OP65_STX &&
strcmp (L[1]->Arg, "tmp1") == 0 &&
L[2]->OPC == OP65_ORA &&
strcmp (L[2]->Arg, "tmp1") == 0) {
CodeEntry* X;
/* Insert the ora instead */
X = NewCodeEntry (OP65_ORA, L[0]->AM, L[0]->Arg, 0, L[0]->LI);
CS_InsertEntry (S, X, I);
/* Remove all other instructions */
CS_DelEntries (S, I+1, 3);
/* Remember, we had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
unsigned OptStore4 (CodeSeg* S)
/* Search for the sequence
**
** sta xx
** stx yy
** lda xx
** ldx yy
**
** and remove the useless load, provided that the next insn doesn't use flags
** from the load.
*/
{
unsigned Changes = 0;
/* Walk over the entries */
unsigned 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_STA &&
(L[0]->AM == AM65_ABS || L[0]->AM == AM65_ZP) &&
!CS_RangeHasLabel (S, I+1, 3) &&
CS_GetEntries (S, L+1, I+1, 4) &&
L[1]->OPC == OP65_STX &&
L[1]->AM == L[0]->AM &&
L[2]->OPC == OP65_LDA &&
L[2]->AM == L[0]->AM &&
L[3]->OPC == OP65_LDX &&
L[3]->AM == L[1]->AM &&
strcmp (L[0]->Arg, L[2]->Arg) == 0 &&
strcmp (L[1]->Arg, L[3]->Arg) == 0 &&
!CE_UseLoadFlags (L[4])) {
/* Register has already the correct value, remove the loads */
CS_DelEntries (S, I+2, 2);
/* Remember, we had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
unsigned OptBoolTrans (CodeSeg* S)
/* Try to remove the call to boolean transformer routines where the call is
* not really needed.
*/
{
unsigned Changes = 0;
/* Walk over the entries */
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
CodeEntry* N;
cmp_t Cond;
/* Get next entry */
CodeEntry* E = CS_GetEntry (S, I);
/* Check for a boolean transformer */
if (E->OPC == OP65_JSR &&
(Cond = FindBoolCmpCond (E->Arg)) != CMP_INV &&
(N = CS_GetNextEntry (S, I)) != 0 &&
(N->Info & OF_ZBRA) != 0) {
/* Make the boolean transformer unnecessary by changing the
* the conditional jump to evaluate the condition flags that
* are set after the compare directly. Note: jeq jumps if
* the condition is not met, jne jumps if the condition is met.
* Invert the code if we jump on condition not met.
*/
if (GetBranchCond (N->OPC) == BC_EQ) {
/* Jumps if condition false, invert condition */
Cond = CmpInvertTab [Cond];
}
/* Check if we can replace the code by something better */
ReplaceCmp (S, I+1, Cond);
/* Remove the call to the bool transformer */
CS_DelEntry (S, I);
/* Remember, we had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
void CS_DelEntry (CodeSeg* S, unsigned Index)
/* Delete an entry from the code segment. This includes moving any associated
* labels, removing references to labels and even removing the referenced labels
* if the reference count drops to zero.
* Note: Labels are moved forward if possible, that is, they are moved to the
* next insn (not the preceeding one).
*/
{
/* Get the code entry for the given index */
CodeEntry* E = CS_GetEntry (S, Index);
/* If the entry has a labels, we have to move this label to the next insn.
* If there is no next insn, move the label into the code segement label
* pool. The operation is further complicated by the fact that the next
* insn may already have a label. In that case change all reference to
* this label and delete the label instead of moving it.
*/
unsigned Count = CE_GetLabelCount (E);
if (Count > 0) {
/* The instruction has labels attached. Check if there is a next
* instruction.
*/
if (Index == CS_GetEntryCount (S)-1) {
/* No next instruction, move to the codeseg label pool */
CS_MoveLabelsToPool (S, E);
} else {
/* There is a next insn, get it */
CodeEntry* N = CS_GetEntry (S, Index+1);
/* Move labels to the next entry */
CS_MoveLabels (S, E, N);
}
}
/* If this insn references a label, remove the reference. And, if the
* the reference count for this label drops to zero, remove this label.
*/
if (E->JumpTo) {
/* Remove the reference */
CS_RemoveLabelRef (S, E);
}
/* Delete the pointer to the insn */
CollDelete (&S->Entries, Index);
/* Delete the instruction itself */
FreeCodeEntry (E);
}
unsigned OptNegAX1 (CodeSeg* S)
/* Search for a call to negax and replace it by
*
* eor #$FF
* clc
* adc #$01
*
* if X isn't used later.
*/
{
unsigned Changes = 0;
unsigned I;
/* Walk over the entries */
I = 0;
while (I < CS_GetEntryCount (S)) {
/* Get next entry */
CodeEntry* E = CS_GetEntry (S, I);
/* Check if this is a call to negax, and if X isn't used later */
if (CE_IsCallTo (E, "negax") && !RegXUsed (S, I+1)) {
CodeEntry* X;
/* Add replacement code behind */
X = NewCodeEntry (OP65_EOR, AM65_IMM, "$FF", 0, E->LI);
CS_InsertEntry (S, X, I+1);
X = NewCodeEntry (OP65_CLC, AM65_IMP, 0, 0, E->LI);
CS_InsertEntry (S, X, I+2);
X = NewCodeEntry (OP65_ADC, AM65_IMM, "$01", 0, E->LI);
CS_InsertEntry (S, X, I+3);
/* Delete the call to negax */
CS_DelEntry (S, I);
/* Skip the generated code */
I += 2;
/* We had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
unsigned OptSub3 (CodeSeg* S)
/* Search for a call to decaxn and replace it by an 8 bit sub if the X register
** is not used later.
*/
{
unsigned Changes = 0;
/* Walk over the entries */
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
CodeEntry* E;
/* Get next entry */
E = CS_GetEntry (S, I);
/* Check for the sequence */
if (E->OPC == OP65_JSR &&
strncmp (E->Arg, "decax", 5) == 0 &&
IsDigit (E->Arg[5]) &&
E->Arg[6] == '\0' &&
!RegXUsed (S, I+1)) {
CodeEntry* X;
const char* Arg;
/* Insert new code behind the sequence */
X = NewCodeEntry (OP65_SEC, AM65_IMP, 0, 0, E->LI);
CS_InsertEntry (S, X, I+1);
Arg = MakeHexArg (E->Arg[5] - '0');
X = NewCodeEntry (OP65_SBC, AM65_IMM, Arg, 0, E->LI);
CS_InsertEntry (S, X, I+2);
/* Delete the old code */
CS_DelEntry (S, I);
/* Remember, we had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
unsigned OptStore1 (CodeSeg* S)
/* Search for the sequence
**
** ldy #n
** jsr staxysp
** ldy #n+1
** jsr ldaxysp
**
** and remove the useless load.
*/
{
unsigned Changes = 0;
/* Walk over the entries */
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
CodeEntry* L[4];
/* Get next entry */
L[0] = CS_GetEntry (S, I);
/* Check for the sequence */
if (L[0]->OPC == OP65_LDY &&
CE_IsConstImm (L[0]) &&
L[0]->Num < 0xFF &&
!CS_RangeHasLabel (S, I+1, 3) &&
CS_GetEntries (S, L+1, I+1, 3) &&
CE_IsCallTo (L[1], "staxysp") &&
L[2]->OPC == OP65_LDY &&
CE_IsKnownImm (L[2], L[0]->Num + 1) &&
CE_IsCallTo (L[3], "ldaxysp")) {
/* Register has already the correct value, remove the loads */
CS_DelEntries (S, I+2, 2);
/* Remember, we had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
unsigned OptSub1 (CodeSeg* S)
/* Search for the sequence
**
** sbc ...
** bcs L
** dex
** L:
**
** and remove the handling of the high byte if X is not used later.
*/
{
unsigned Changes = 0;
/* Walk over the entries */
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
CodeEntry* L[3];
/* Get next entry */
CodeEntry* E = CS_GetEntry (S, I);
/* Check for the sequence */
if (E->OPC == OP65_SBC &&
CS_GetEntries (S, L, I+1, 3) &&
(L[0]->OPC == OP65_BCS || L[0]->OPC == OP65_JCS) &&
L[0]->JumpTo != 0 &&
!CE_HasLabel (L[0]) &&
L[1]->OPC == OP65_DEX &&
!CE_HasLabel (L[1]) &&
L[0]->JumpTo->Owner == L[2] &&
!RegXUsed (S, I+3)) {
/* Remove the bcs/dex */
CS_DelEntries (S, I+1, 2);
/* Remember, we had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
static unsigned OptLoad1 (CodeSeg* S)
/* Search for a call to ldaxysp where X is not used later and replace it by
** a load of just the A register.
*/
{
unsigned I;
unsigned Changes = 0;
/* Walk over the entries */
I = 0;
while (I < CS_GetEntryCount (S)) {
CodeEntry* E;
/* Get next entry */
E = CS_GetEntry (S, I);
/* Check for the sequence */
if (CE_IsCallTo (E, "ldaxysp") &&
RegValIsKnown (E->RI->In.RegY) &&
!RegXUsed (S, I+1)) {
CodeEntry* X;
/* Reload the Y register */
const char* Arg = MakeHexArg (E->RI->In.RegY - 1);
X = NewCodeEntry (OP65_LDY, AM65_IMM, Arg, 0, E->LI);
CS_InsertEntry (S, X, I+1);
/* Load from stack */
X = NewCodeEntry (OP65_LDA, AM65_ZP_INDY, "sp", 0, E->LI);
CS_InsertEntry (S, X, I+2);
/* Now remove the call to the subroutine */
CS_DelEntry (S, I);
/* Remember, we had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
unsigned OptBNegA1 (CodeSeg* S)
/* Check for
*
* ldx #$00
* lda ..
* jsr bnega
*
* Remove the ldx if the lda does not use it.
*/
{
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 a ldx */
if (E->OPC == OP65_LDX &&
E->AM == AM65_IMM &&
(E->Flags & CEF_NUMARG) != 0 &&
E->Num == 0 &&
CS_GetEntries (S, L, I+1, 2) &&
L[0]->OPC == OP65_LDA &&
(L[0]->Use & REG_X) == 0 &&
!CE_HasLabel (L[0]) &&
CE_IsCallTo (L[1], "bnega") &&
!CE_HasLabel (L[1])) {
/* Remove the ldx instruction */
CS_DelEntry (S, I);
/* Remember, we had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
unsigned Opt65C02Stores (CodeSeg* S)
/* Use STZ where possible */
{
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)) {
/* Get next entry */
CodeEntry* E = CS_GetEntry (S, I);
/* Check for a store with a register value of zero and an addressing
* mode available with STZ.
*/
if (((E->OPC == OP65_STA && E->RI->In.RegA == 0) ||
(E->OPC == OP65_STX && E->RI->In.RegX == 0) ||
(E->OPC == OP65_STY && E->RI->In.RegY == 0)) &&
(E->AM == AM65_ZP || E->AM == AM65_ABS ||
E->AM == AM65_ZPX || E->AM == AM65_ABSX)) {
/* Replace by STZ */
CodeEntry* X = NewCodeEntry (OP65_STZ, E->AM, E->Arg, 0, E->LI);
CS_InsertEntry (S, X, I+1);
/* Delete the old stuff */
CS_DelEntry (S, I);
/* We had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Free register info */
CS_FreeRegInfo (S);
/* Return the number of changes made */
return Changes;
}
unsigned Opt65C02Ind (CodeSeg* S)
/* Try to use the indirect addressing mode where possible */
{
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)) {
/* Get next entry */
CodeEntry* E = CS_GetEntry (S, I);
/* Check for addressing mode indirect indexed Y where Y is zero.
* Note: All opcodes that are available as (zp),y are also available
* as (zp), so we can ignore the actual opcode here.
*/
if (E->AM == AM65_ZP_INDY && E->RI->In.RegY == 0) {
/* Replace it by indirect addressing mode */
CodeEntry* X = NewCodeEntry (E->OPC, AM65_ZP_IND, E->Arg, 0, E->LI);
CS_InsertEntry (S, X, I+1);
CS_DelEntry (S, I);
/* We had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Free register info */
CS_FreeRegInfo (S);
/* Return the number of changes made */
return Changes;
}
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 OptTest2 (CodeSeg* S)
/* Search for an inc/dec operation followed by a load and a conditional
* branch based on the flags from the load. Remove the load if the insn
* isn't used later.
*/
{
unsigned Changes = 0;
/* Walk over the entries */
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
CodeEntry* L[3];
/* Get next entry */
L[0] = CS_GetEntry (S, I);
/* Check if it's the sequence we're searching for */
if ((L[0]->OPC == OP65_INC || L[0]->OPC == OP65_DEC) &&
CS_GetEntries (S, L+1, I+1, 2) &&
!CE_HasLabel (L[1]) &&
(L[1]->Info & OF_LOAD) != 0 &&
(L[2]->Info & OF_FBRA) != 0 &&
L[1]->AM == L[0]->AM &&
strcmp (L[0]->Arg, L[1]->Arg) == 0 &&
(GetRegInfo (S, I+2, L[1]->Chg) & L[1]->Chg) == 0) {
/* Remove the load */
CS_DelEntry (S, I+1);
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
static unsigned OptStackPtrOps (CodeSeg* S)
/* Merge adjacent calls to decsp into one. NOTE: This function won't merge all
** known cases!
*/
{
unsigned Changes = 0;
unsigned I;
/* Walk over the entries */
I = 0;
while (I < CS_GetEntryCount (S)) {
unsigned Dec1;
unsigned Dec2;
const CodeEntry* N;
/* Get the next entry */
const CodeEntry* E = CS_GetEntry (S, I);
/* Check for decspn or subysp */
if (E->OPC == OP65_JSR &&
(Dec1 = IsDecSP (E)) > 0 &&
(N = CS_GetNextEntry (S, I)) != 0 &&
(Dec2 = IsDecSP (N)) > 0 &&
(Dec1 += Dec2) <= 255 &&
!CE_HasLabel (N)) {
CodeEntry* X;
char Buf[20];
/* We can combine the two */
if (Dec1 <= 8) {
/* Insert a call to decsp */
xsprintf (Buf, sizeof (Buf), "decsp%u", Dec1);
X = NewCodeEntry (OP65_JSR, AM65_ABS, Buf, 0, N->LI);
CS_InsertEntry (S, X, I+2);
} else {
/* Insert a call to subysp */
const char* Arg = MakeHexArg (Dec1);
X = NewCodeEntry (OP65_LDY, AM65_IMM, Arg, 0, N->LI);
CS_InsertEntry (S, X, I+2);
X = NewCodeEntry (OP65_JSR, AM65_ABS, "subysp", 0, N->LI);
CS_InsertEntry (S, X, I+3);
}
/* Delete the old code */
CS_DelEntries (S, I, 2);
/* Regenerate register info */
CS_GenRegInfo (S);
/* Remember we had changes */
++Changes;
} else {
/* Next entry */
++I;
}
}
/* Return the number of changes made */
return Changes;
}
unsigned OptStore5 (CodeSeg* S)
/* Search for the sequence
**
** lda foo
** ldx bar
** sta something
** stx something-else
**
** and replace it by
**
** lda foo
** sta something
** lda bar
** sta something-else
**
** if X is not used later. This replacement doesn't save any cycles or bytes,
** but it keeps the value of X, which may be reused later.
*/
{
unsigned Changes = 0;
/* Walk over the entries */
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
CodeEntry* L[4];
/* Get next entry */
L[0] = CS_GetEntry (S, I);
/* Check for the sequence */
if (L[0]->OPC == OP65_LDA &&
!CS_RangeHasLabel (S, I+1, 3) &&
CS_GetEntries (S, L+1, I+1, 3) &&
L[1]->OPC == OP65_LDX &&
L[2]->OPC == OP65_STA &&
L[3]->OPC == OP65_STX &&
!RegXUsed (S, I+4)) {
CodeEntry* X;
/* Insert the code after the sequence */
X = NewCodeEntry (OP65_LDA, L[1]->AM, L[1]->Arg, 0, L[1]->LI);
CS_InsertEntry (S, X, I+4);
X = NewCodeEntry (OP65_STA, L[3]->AM, L[3]->Arg, 0, L[3]->LI);
CS_InsertEntry (S, X, I+5);
/* Delete the old code */
CS_DelEntry (S, I+3);
CS_DelEntry (S, I+1);
/* Remember, we had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
unsigned OptStore3 (CodeSeg* S)
/* Search for a call to steaxysp. If the eax register is not used later, and
** the value is constant, just use the A register and store directly into the
** stack.
*/
{
unsigned I;
unsigned Changes = 0;
/* Walk over the entries */
I = 0;
while (I < CS_GetEntryCount (S)) {
/* Get next entry */
CodeEntry* E = CS_GetEntry (S, I);
/* Get the input registers */
const RegInfo* RI = E->RI;
/* Check for the call */
if (CE_IsCallTo (E, "steaxysp") &&
RegValIsKnown (RI->In.RegA) &&
RegValIsKnown (RI->In.RegX) &&
RegValIsKnown (RI->In.RegY) &&
RegValIsKnown (RI->In.SRegLo) &&
RegValIsKnown (RI->In.SRegHi) &&
!RegEAXUsed (S, I+1)) {
/* Get the register values */
unsigned char A = (unsigned char) RI->In.RegA;
unsigned char X = (unsigned char) RI->In.RegX;
unsigned char Y = (unsigned char) RI->In.RegY;
unsigned char L = (unsigned char) RI->In.SRegLo;
unsigned char H = (unsigned char) RI->In.SRegHi;
/* Setup other variables */
unsigned Done = 0;
CodeEntry* N;
unsigned IP = I + 1; /* Insertion point */
/* Replace the store. We will not remove the loads, since this is
** too complex and will be done by other optimizer steps.
*/
N = NewCodeEntry (OP65_LDA, AM65_IMM, MakeHexArg (A), 0, E->LI);
CS_InsertEntry (S, N, IP++);
InsertStore (S, &IP, E->LI);
Done |= 0x01;
/* Check if we can store one of the other bytes */
if (A == X && (Done & 0x02) == 0) {
N = NewCodeEntry (OP65_LDY, AM65_IMM, MakeHexArg (Y+1), 0, E->LI);
CS_InsertEntry (S, N, IP++);
InsertStore (S, &IP, E->LI);
Done |= 0x02;
}
if (A == L && (Done & 0x04) == 0) {
N = NewCodeEntry (OP65_LDY, AM65_IMM, MakeHexArg (Y+2), 0, E->LI);
CS_InsertEntry (S, N, IP++);
InsertStore (S, &IP, E->LI);
Done |= 0x04;
}
if (A == H && (Done & 0x08) == 0) {
N = NewCodeEntry (OP65_LDY, AM65_IMM, MakeHexArg (Y+3), 0, E->LI);
CS_InsertEntry (S, N, IP++);
InsertStore (S, &IP, E->LI);
Done |= 0x08;
}
/* Store the second byte */
if ((Done & 0x02) == 0) {
N = NewCodeEntry (OP65_LDA, AM65_IMM, MakeHexArg (X), 0, E->LI);
CS_InsertEntry (S, N, IP++);
N = NewCodeEntry (OP65_LDY, AM65_IMM, MakeHexArg (Y+1), 0, E->LI);
CS_InsertEntry (S, N, IP++);
InsertStore (S, &IP, E->LI);
Done |= 0x02;
}
/* Check if we can store one of the other bytes */
if (X == L && (Done & 0x04) == 0) {
N = NewCodeEntry (OP65_LDY, AM65_IMM, MakeHexArg (Y+2), 0, E->LI);
CS_InsertEntry (S, N, IP++);
InsertStore (S, &IP, E->LI);
Done |= 0x04;
}
if (X == H && (Done & 0x08) == 0) {
N = NewCodeEntry (OP65_LDY, AM65_IMM, MakeHexArg (Y+3), 0, E->LI);
CS_InsertEntry (S, N, IP++);
InsertStore (S, &IP, E->LI);
Done |= 0x08;
}
/* Store the third byte */
if ((Done & 0x04) == 0) {
N = NewCodeEntry (OP65_LDA, AM65_IMM, MakeHexArg (L), 0, E->LI);
CS_InsertEntry (S, N, IP++);
N = NewCodeEntry (OP65_LDY, AM65_IMM, MakeHexArg (Y+2), 0, E->LI);
CS_InsertEntry (S, N, IP++);
InsertStore (S, &IP, E->LI);
Done |= 0x04;
}
/* Check if we can store one of the other bytes */
if (L == H && (Done & 0x08) == 0) {
N = NewCodeEntry (OP65_LDY, AM65_IMM, MakeHexArg (Y+3), 0, E->LI);
CS_InsertEntry (S, N, IP++);
InsertStore (S, &IP, E->LI);
Done |= 0x08;
}
/* Store the fourth byte */
if ((Done & 0x08) == 0) {
N = NewCodeEntry (OP65_LDA, AM65_IMM, MakeHexArg (H), 0, E->LI);
CS_InsertEntry (S, N, IP++);
N = NewCodeEntry (OP65_LDY, AM65_IMM, MakeHexArg (Y+3), 0, E->LI);
CS_InsertEntry (S, N, IP++);
InsertStore (S, &IP, E->LI);
Done |= 0x08;
}
/* Remove the call */
CS_DelEntry (S, I);
/* Remember, we had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
unsigned OptSub2 (CodeSeg* S)
/* Search for the sequence
**
** lda xx
** sec
** sta tmp1
** lda yy
** sbc tmp1
** sta yy
**
** and replace it by
**
** sec
** lda yy
** sbc xx
** sta yy
*/
{
unsigned Changes = 0;
/* Walk over the entries */
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
CodeEntry* L[5];
/* Get next entry */
CodeEntry* E = CS_GetEntry (S, I);
/* Check for the sequence */
if (E->OPC == OP65_LDA &&
!CS_RangeHasLabel (S, I+1, 5) &&
CS_GetEntries (S, L, I+1, 5) &&
L[0]->OPC == OP65_SEC &&
L[1]->OPC == OP65_STA &&
strcmp (L[1]->Arg, "tmp1") == 0 &&
L[2]->OPC == OP65_LDA &&
L[3]->OPC == OP65_SBC &&
strcmp (L[3]->Arg, "tmp1") == 0 &&
L[4]->OPC == OP65_STA &&
strcmp (L[4]->Arg, L[2]->Arg) == 0) {
/* Remove the store to tmp1 */
CS_DelEntry (S, I+2);
/* Remove the subtraction */
CS_DelEntry (S, I+3);
/* Move the lda to the position of the subtraction and change the
** op to SBC.
*/
CS_MoveEntry (S, I, I+3);
CE_ReplaceOPC (E, OP65_SBC);
/* If the sequence head had a label, move this label back to the
** head.
*/
if (CE_HasLabel (E)) {
CS_MoveLabels (S, E, L[0]);
}
/* 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;
}
