-/* Defines for the conditions in a compare */
-typedef enum {
- CMP_INV = -1,
- CMP_EQ,
- CMP_NE,
- CMP_GT,
- CMP_GE,
- CMP_LT,
- CMP_LE,
- CMP_UGT,
- CMP_UGE,
- CMP_ULT,
- CMP_ULE
-} cmp_t;
-
-/* Table with the compare suffixes */
-static const char CmpSuffixTab [][4] = {
- "eq", "ne", "gt", "ge", "lt", "le", "ugt", "uge", "ult", "ule"
-};
-
-/* Table used to invert a condition, indexed by condition */
-static const unsigned char CmpInvertTab [] = {
- CMP_NE, CMP_EQ,
- CMP_LE, CMP_LT, CMP_GE, CMP_GT,
- CMP_ULE, CMP_ULT, CMP_UGE, CMP_UGT
-};
-
-/* Table to show which compares are signed (use the N flag) */
-static const char CmpSignedTab [] = {
- 0, 0, 1, 1, 1, 1, 0, 0, 0, 0
-};
-
-
-
-/*****************************************************************************/
-/* Helper functions */
-/*****************************************************************************/
-
-
-
-static cmp_t FindCmpCond (const char* Code, unsigned CodeLen)
-/* Search for a compare condition by the given code using the given length */
-{
- unsigned I;
-
- /* Linear search */
- for (I = 0; I < sizeof (CmpSuffixTab) / sizeof (CmpSuffixTab [0]); ++I) {
- if (strncmp (Code, CmpSuffixTab [I], CodeLen) == 0) {
- /* Found */
- return I;
- }
- }
-
- /* Not found */
- return CMP_INV;
-}
-
-
-
-static cmp_t FindBoolCmpCond (const char* Name)
-/* Map a condition suffix to a code. Return the code or CMP_INV on failure */
-{
- /* Check for the correct subroutine name */
- if (strncmp (Name, "bool", 4) == 0) {
- /* Name is ok, search for the code in the table */
- return FindCmpCond (Name+4, strlen(Name)-4);
- } else {
- /* Not found */
- return CMP_INV;
- }
-}
-
-
-
-static cmp_t FindTosCmpCond (const char* Name)
-/* Check if this is a call to one of the TOS compare functions (tosgtax).
- * Return the condition code or CMP_INV on failure.
- */
-{
- unsigned Len = strlen (Name);
-
- /* Check for the correct subroutine name */
- if (strncmp (Name, "tos", 3) == 0 && strcmp (Name+Len-2, "ax") == 0) {
- /* Name is ok, search for the code in the table */
- return FindCmpCond (Name+3, Len-3-2);
- } else {
- /* Not found */
- return CMP_INV;
- }
-}
-
-
-
-static void ReplaceCmp (CodeSeg* S, unsigned I, cmp_t Cond)
-/* Helper function for the replacement of routines that return a boolean
- * followed by a conditional jump. Instead of the boolean value, the condition
- * codes are evaluated directly.
- * I is the index of the conditional branch, the sequence is already checked
- * to be correct.
- */
-{
- CodeEntry* N;
- CodeLabel* L;
-
- /* Get the entry */
- CodeEntry* E = CS_GetEntry (S, I);
-
- /* Replace the conditional branch */
- switch (Cond) {
-
- case CMP_EQ:
- CE_ReplaceOPC (E, OP65_JEQ);
- break;
-
- case CMP_NE:
- CE_ReplaceOPC (E, OP65_JNE);
- break;
-
- case CMP_GT:
- /* Replace by
- * beq @L
- * jpl Target
- * @L: ...
- */
- if ((N = CS_GetNextEntry (S, I)) == 0) {
- /* No such entry */
- Internal ("Invalid program flow");
- }
- L = CS_GenLabel (S, N);
- N = NewCodeEntry (OP65_BEQ, AM65_BRA, L->Name, L, E->LI);
- CS_InsertEntry (S, N, I);
- CE_ReplaceOPC (E, OP65_JPL);
- break;
-
- case CMP_GE:
- CE_ReplaceOPC (E, OP65_JPL);
- break;
-
- case CMP_LT:
- CE_ReplaceOPC (E, OP65_JMI);
- break;
-
- case CMP_LE:
- /* Replace by
- * jmi Target
- * jeq Target
- */
- CE_ReplaceOPC (E, OP65_JMI);
- L = E->JumpTo;
- N = NewCodeEntry (OP65_JEQ, AM65_BRA, L->Name, L, E->LI);
- CS_InsertEntry (S, N, I+1);
- break;
-
- case CMP_UGT:
- /* Replace by
- * beq @L
- * jcs Target
- * @L: ...
- */
- if ((N = CS_GetNextEntry (S, I)) == 0) {
- /* No such entry */
- Internal ("Invalid program flow");
- }
- L = CS_GenLabel (S, N);
- N = NewCodeEntry (OP65_BEQ, AM65_BRA, L->Name, L, E->LI);
- CS_InsertEntry (S, N, I);
- CE_ReplaceOPC (E, OP65_JCS);
- break;
-
- case CMP_UGE:
- CE_ReplaceOPC (E, OP65_JCS);
- break;
-
- case CMP_ULT:
- CE_ReplaceOPC (E, OP65_JCC);
- break;
-
- case CMP_ULE:
- /* Replace by
- * jcc Target
- * jeq Target
- */
- CE_ReplaceOPC (E, OP65_JCC);
- L = E->JumpTo;
- N = NewCodeEntry (OP65_JEQ, AM65_BRA, L->Name, L, E->LI);
- CS_InsertEntry (S, N, I+1);
- break;
-
- default:
- Internal ("Unknown jump condition: %d", Cond);
-
- }
-
-}
-
-
-
-static int IsCmpToZero (const CodeEntry* E)
-/* Check if the given instrcuction is a compare to zero instruction */
-{
- return (E->OPC == OP65_CMP &&
- E->AM == AM65_IMM &&
- (E->Flags & CEF_NUMARG) != 0 &&
- E->Num == 0);
-}
-
-
-
-static int IsSpLoad (const CodeEntry* E)
-/* Return true if this is the load of A from the stack */
-{
- return E->OPC == OP65_LDA && E->AM == AM65_ZP_INDY && strcmp (E->Arg, "sp") == 0;
-}
-
-
-
-static int IsLocalLoad16 (CodeSeg* S, unsigned Index,
- CodeEntry** L, unsigned Count)
-/* Check if a 16 bit load of a local variable follows:
- *
- * ldy #$xx
- * lda (sp),y
- * tax
- * dey
- * lda (sp),y
- *
- * If so, read Count entries following the first ldy into L and return true
- * if this is possible. Otherwise return false.
- */
-{
- /* Be sure we read enough entries for the check */
- CHECK (Count >= 5);
-
- /* Read the first entry */
- L[0] = CS_GetEntry (S, Index);
-
- /* Check for the sequence */
- return (L[0]->OPC == OP65_LDY &&
- L[0]->AM == AM65_IMM &&
- (L[0]->Flags & CEF_NUMARG) != 0 &&
- CS_GetEntries (S, L+1, Index+1, Count-1) &&
- IsSpLoad (L[1]) &&
- !CE_HasLabel (L[1]) &&
- L[2]->OPC == OP65_TAX &&
- !CE_HasLabel (L[2]) &&
- L[3]->OPC == OP65_DEY &&
- !CE_HasLabel (L[3]) &&
- IsSpLoad (L[4]) &&
- !CE_HasLabel (L[4]));
-}
-
-
-
-static int IsImmCmp16 (CodeSeg* S, CodeEntry** L)
-/* Check if the instructions at L are an immidiate compare of a/x:
- *
- *
- */
-{
- return (L[0]->OPC == OP65_CPX &&
- L[0]->AM == AM65_IMM &&
- (L[0]->Flags & CEF_NUMARG) != 0 &&
- !CE_HasLabel (L[0]) &&
- (L[1]->OPC == OP65_JNE || L[1]->OPC == OP65_BNE) &&
- L[1]->JumpTo != 0 &&
- !CE_HasLabel (L[1]) &&
- L[2]->OPC == OP65_CMP &&
- L[2]->AM == AM65_IMM &&
- (L[2]->Flags & CEF_NUMARG) != 0 &&
- (L[3]->Info & OF_ZBRA) != 0 &&
- L[3]->JumpTo != 0 &&
- (L[1]->JumpTo->Owner == L[3] || L[1]->JumpTo == L[3]->JumpTo));
-}
-
-
-
-/*****************************************************************************/
-/* Remove calls to the bool transformer subroutines */
-/*****************************************************************************/
-
-
-
-static unsigned OptBoolTransforms (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;
-}
-
-
-
-/*****************************************************************************/
-/* Optimize subtractions */
-/*****************************************************************************/
-
-
-
-static 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 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_GetEntries (S, L, I+1, 5) &&
- L[0]->OPC == OP65_SEC &&
- !CE_HasLabel (L[0]) &&
- L[1]->OPC == OP65_STA &&
- strcmp (L[1]->Arg, "tmp1") == 0 &&
- !CE_HasLabel (L[1]) &&
- L[2]->OPC == OP65_LDA &&
- !CE_HasLabel (L[2]) &&
- L[3]->OPC == OP65_SBC &&
- strcmp (L[3]->Arg, "tmp1") == 0 &&
- !CE_HasLabel (L[3]) &&
- L[4]->OPC == OP65_STA &&
- strcmp (L[4]->Arg, L[2]->Arg) == 0 &&
- !CE_HasLabel (L[4])) {
-
- /* 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;
-}
-
-
-
-/*****************************************************************************/
-/* Optimize additions */
-/*****************************************************************************/
-
-
-
-static unsigned OptAdd1 (CodeSeg* S)
-/* Search for the sequence
- *
- * jsr pushax
- * ldy xxx
- * ldx #$00
- * lda (sp),y
- * jsr tosaddax
- *
- * and replace it by:
- *
- * ldy xxx
- * clc
- * adc (sp),y
- * bcc L
- * inx
- * L:
- */
-{
- unsigned Changes = 0;
-
- /* Walk over the entries */
- unsigned I = 0;
- while (I < CS_GetEntryCount (S)) {
-
- CodeEntry* L[5];
-
- /* Get next entry */
- CodeEntry* E = CS_GetEntry (S, I);
-
- /* Check for the sequence */
- if (E->OPC == OP65_JSR &&
- strcmp (E->Arg, "pushax") == 0 &&
- CS_GetEntries (S, L, I+1, 5) &&
- L[0]->OPC == OP65_LDY &&
- !CE_HasLabel (L[0]) &&
- L[1]->OPC == OP65_LDX &&
- CE_KnownImm (L[1]) &&
- L[1]->Num == 0 &&
- !CE_HasLabel (L[1]) &&
- L[2]->OPC == OP65_LDA &&
- !CE_HasLabel (L[2]) &&
- L[3]->OPC == OP65_JSR &&
- strcmp (L[3]->Arg, "tosaddax") == 0 &&
- !CE_HasLabel (L[3])) {
-
- CodeEntry* X;
- CodeLabel* Label;
-
- /* Remove the call to pushax */
- CS_DelEntry (S, I);
-
- /* Add the clc . */
- X = NewCodeEntry (OP65_CLC, AM65_IMP, 0, 0, L[3]->LI);
- CS_InsertEntry (S, X, I+1);
-
- /* Remove the load */
- CS_DelEntry (S, I+3); /* lda */
- CS_DelEntry (S, I+2); /* ldx */
-
- /* Add the adc */
- X = NewCodeEntry (OP65_ADC, AM65_ZP_INDY, "sp", 0, L[3]->LI);
- CS_InsertEntry (S, X, I+2);
-
- /* Generate the branch label and the branch */
- Label = CS_GenLabel (S, L[4]);
- X = NewCodeEntry (OP65_BCC, AM65_BRA, Label->Name, Label, L[3]->LI);
- CS_InsertEntry (S, X, I+3);
-
- /* Generate the increment of the high byte */
- X = NewCodeEntry (OP65_INX, AM65_IMP, 0, 0, L[3]->LI);
- CS_InsertEntry (S, X, I+4);
-
- /* Delete the call to tosaddax */
- CS_DelEntry (S, I+5);
-
- /* Remember, we had changes */
- ++Changes;
-
- }
-
- /* Next entry */
- ++I;
-
- }
-
- /* Return the number of changes made */
- return Changes;
-}
-
-
-
-static unsigned OptAdd2 (CodeSeg* S)
-/* Search for the sequence
- *
- * ldy #xx
- * lda (sp),y
- * tax
- * dey
- * lda (sp),y
- * ldy #$yy
- * jsr addeqysp
- *
- * and replace it by:
- *
- * ldy #xx-1
- * lda (sp),y
- * ldy #yy
- * clc
- * adc (sp),y
- * sta (sp),y
- * ldy #xx
- * lda (sp),y
- * ldy #yy+1
- * adc (sp),y
- * sta (sp),y
- *
- * provided that a/x is not used later.
- */
-{
- unsigned Changes = 0;
-
- /* Walk over the entries */
- unsigned I = 0;
- while (I < CS_GetEntryCount (S)) {
-
- CodeEntry* L[7];
-
- /* Get next entry */
- L[0] = CS_GetEntry (S, I);
-
- /* Check for the sequence */
- if (L[0]->OPC == OP65_LDY &&
- CE_KnownImm (L[0]) &&
- CS_GetEntries (S, L+1, I+1, 6) &&
- L[1]->OPC == OP65_LDA &&
- L[1]->AM == AM65_ZP_INDY &&
- !CE_HasLabel (L[1]) &&
- L[2]->OPC == OP65_TAX &&
- !CE_HasLabel (L[2]) &&
- L[3]->OPC == OP65_DEY &&
- !CE_HasLabel (L[3]) &&
- L[4]->OPC == OP65_LDA &&
- L[4]->AM == AM65_ZP_INDY &&
- !CE_HasLabel (L[4]) &&
- L[5]->OPC == OP65_LDY &&
- CE_KnownImm (L[5]) &&
- !CE_HasLabel (L[5]) &&
- L[6]->OPC == OP65_JSR &&
- strcmp (L[6]->Arg, "addeqysp") == 0 &&
- !CE_HasLabel (L[6])) {
-
- char Buf [20];
- CodeEntry* X;
- int Offs;
-
-
- /* Create a replacement for the first LDY */
- Offs = (int) (L[0]->Num - 1);
- xsprintf (Buf, sizeof (Buf), "$%02X", Offs);
- X = NewCodeEntry (OP65_LDY, AM65_IMM, Buf, 0, L[0]->LI);
- CS_InsertEntry (S, X, I+1);
- CS_DelEntry (S, I);
-
- /* Load Y with the low offset of the target variable */
- X = NewCodeEntry (OP65_LDY, AM65_IMM, L[5]->Arg, 0, L[1]->LI);
- CS_InsertEntry (S, X, I+2);
-
- /* Add the CLC */
- X = NewCodeEntry (OP65_CLC, AM65_IMP, 0, 0, L[1]->LI);
- CS_InsertEntry (S, X, I+3);
-
- /* Remove the TAX/DEY sequence */
- CS_DelEntry (S, I+5); /* dey */
- CS_DelEntry (S, I+4); /* tax */
-
- /* Addition of the low byte */
- X = NewCodeEntry (OP65_ADC, AM65_ZP_INDY, "sp", 0, L[4]->LI);
- CS_InsertEntry (S, X, I+4);
- X = NewCodeEntry (OP65_STA, AM65_ZP_INDY, "sp", 0, L[4]->LI);
- CS_InsertEntry (S, X, I+5);
-
- /* LDY */
- xsprintf (Buf, sizeof (Buf), "$%02X", (Offs+1));
- X = NewCodeEntry (OP65_LDY, AM65_IMM, Buf, 0, L[4]->LI);
- CS_InsertEntry (S, X, I+6);
-
- /* Addition of the high byte */
- xsprintf (Buf, sizeof (Buf), "$%02X", (int)(L[5]->Num+1));
- X = NewCodeEntry (OP65_LDY, AM65_IMM, Buf, 0, L[5]->LI);
- CS_InsertEntry (S, X, I+8);
- X = NewCodeEntry (OP65_ADC, AM65_ZP_INDY, "sp", 0, L[6]->LI);
- CS_InsertEntry (S, X, I+9);
- X = NewCodeEntry (OP65_STA, AM65_ZP_INDY, "sp", 0, L[6]->LI);
- CS_InsertEntry (S, X, I+10);
-
- /* Delete the remaining stuff */
- CS_DelEntry (S, I+12);
- CS_DelEntry (S, I+11);
-
- /* Remember, we had changes */
- ++Changes;
-
- }
-
- /* Next entry */
- ++I;
-
- }
-
- /* Return the number of changes made */
- return Changes;
-}
-
-
-
-static unsigned OptAdd3 (CodeSeg* S)
-/* Search for the sequence
- *
- * adc ...
- * bcc L
- * inx
- * 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_ADC &&
- CS_GetEntries (S, L, I+1, 3) &&
- (L[0]->OPC == OP65_BCC || L[0]->OPC == OP65_JCC) &&
- L[0]->JumpTo != 0 &&
- !CE_HasLabel (L[0]) &&
- L[1]->OPC == OP65_INX &&
- !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;
-}
-
-
-
-/*****************************************************************************/
-/* Optimizations for compares */
-/*****************************************************************************/
-
-
-
-static unsigned OptCmp1 (CodeSeg* S)
-/* Search for the sequence
- *
- * stx xx
- * stx tmp1
- * ora tmp1
- *
- * and replace it by
- *
- * stx xx
- * ora xx
- */
-{
- 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_STX &&
- CS_GetEntries (S, L, I+1, 2) &&
- L[0]->OPC == OP65_STX &&
- strcmp (L[0]->Arg, "tmp1") == 0 &&
- !CE_HasLabel (L[0]) &&
- L[1]->OPC == OP65_ORA &&
- strcmp (L[1]->Arg, "tmp1") == 0 &&
- !CE_HasLabel (L[1])) {
-
- /* Remove the remaining instructions */
- CS_DelEntries (S, I+1, 2);
-
- /* Insert the ora instead */
- CS_InsertEntry (S, NewCodeEntry (OP65_ORA, E->AM, E->Arg, 0, E->LI), I+1);
-
- /* Remember, we had changes */
- ++Changes;
-
- }
-
- /* Next entry */
- ++I;
-
- }
-
- /* Return the number of changes made */
- return Changes;
-}
-
-
-
-static unsigned OptCmp2 (CodeSeg* S)
-/* Search for
- *
- * lda/and/ora/eor ...
- * cmp #$00
- * jeq/jne
- *
- * and remove the cmp.
- */
-{
- 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) &&
- IsCmpToZero (L[0]) &&
- !CE_HasLabel (L[0]) &&
- (L[1]->Info & OF_FBRA) != 0 &&
- !CE_HasLabel (L[1])) {
-
- /* Remove the compare */
- CS_DelEntry (S, I+1);
-
- /* Remember, we had changes */
- ++Changes;
-
- }
-
- /* Next entry */
- ++I;
-
- }
-
- /* Return the number of changes made */
- return Changes;
-}
-
-
-
-static unsigned OptCmp3 (CodeSeg* S)
-/* Search for
- *
- * lda x
- * ldx y
- * cpx #a
- * bne L1
- * cmp #b
- * jne/jeq L2
- *
- * If a is zero, we may remove the compare. If a and b are both zero, we may
- * replace it by the sequence
- *
- * lda x
- * ora x+1
- * jne/jeq ...
- *
- * L1 may be either the label at the branch instruction, or the target label
- * of this instruction.
- */
-{
- 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_GetEntries (S, L, I+1, 5) &&
- L[0]->OPC == OP65_LDX &&
- !CE_HasLabel (L[0]) &&
- IsImmCmp16 (S, L+1)) {
-
- if (L[1]->Num == 0 && L[3]->Num == 0) {
- /* The value is zero, we may use the simple code version. */
- CE_ReplaceOPC (L[0], OP65_ORA);
- CS_DelEntries (S, I+2, 3);
- } else {
- /* Move the lda instruction after the first branch. This will
- * improve speed, since the load is delayed after the first
- * test.
- */
- CS_MoveEntry (S, I, I+4);
-
- /* We will replace the ldx/cpx by lda/cmp */
- CE_ReplaceOPC (L[0], OP65_LDA);
- CE_ReplaceOPC (L[1], OP65_CMP);
-
- /* Beware: If the first LDA instruction had a label, we have
- * to move this label to the top of the sequence again.
- */
- if (CE_HasLabel (E)) {
- CS_MoveLabels (S, E, L[0]);
- }
-
- }
-
- ++Changes;
- }
-
- /* Next entry */
- ++I;
-
- }
-
- /* Return the number of changes made */
- return Changes;
-}
-
-
-
-static unsigned OptCmp4 (CodeSeg* S)
-/* Optimize compares of local variables:
- *
- * ldy #o
- * lda (sp),y
- * tax
- * dey
- * lda (sp),y
- * cpx #a
- * bne L1
- * cmp #b
- * jne/jeq L2
- */
-{
- unsigned Changes = 0;
-
- /* Walk over the entries */
- unsigned I = 0;
- while (I < CS_GetEntryCount (S)) {
-
- CodeEntry* L[9];
-
- /* Check for the sequence */
- if (IsLocalLoad16 (S, I, L, 9) && IsImmCmp16 (S, L+5)) {
-
- if (L[5]->Num == 0 && L[7]->Num == 0) {
-
- /* The value is zero, we may use the simple code version:
- * ldy #o
- * lda (sp),y
- * dey
- * ora (sp),y
- * jne/jeq ...
- */
- CE_ReplaceOPC (L[4], OP65_ORA);
- CS_DelEntries (S, I+5, 3); /* cpx/bne/cmp */
- CS_DelEntry (S, I+2); /* tax */
-
- } else {
-
- /* Change the code to just use the A register. Move the load
- * of the low byte after the first branch if possible:
- *
- * ldy #o
- * lda (sp),y
- * cmp #a
- * bne L1
- * dey
- * lda (sp),y
- * cmp #b
- * jne/jeq ...
- */
- CS_DelEntry (S, I+2); /* tax */
- CE_ReplaceOPC (L[5], OP65_CMP); /* cpx -> cmp */
- CS_MoveEntry (S, I+4, I+2); /* cmp */
- CS_MoveEntry (S, I+5, I+3); /* bne */
-
- }
-
- ++Changes;
- }