/* */
/* */
/* */
-/* (C) 2001 Ullrich von Bassewitz */
+/* (C) 2001-2002 Ullrich von Bassewitz */
/* Wacholderweg 14 */
/* D-70597 Stuttgart */
/* EMail: uz@cc65.org */
-#include <string.h>
+/* common */
+#include "cpu.h"
/* cc65 */
#include "codeent.h"
+/*****************************************************************************/
+/* Helper functions */
+/*****************************************************************************/
+
+
+
+static int GetBranchDist (CodeSeg* S, unsigned From, CodeEntry* To)
+/* Get the branch distance between the two entries and return it. The distance
+ * will be negative for backward jumps and positive for forward jumps.
+ */
+{
+ /* Get the index of the branch target */
+ unsigned TI = CS_GetEntryIndex (S, To);
+
+ /* Determine the branch distance */
+ int Distance = 0;
+ if (TI >= From) {
+ /* Forward branch, do not count the current insn */
+ unsigned J = From+1;
+ while (J < TI) {
+ CodeEntry* N = CS_GetEntry (S, J++);
+ Distance += N->Size;
+ }
+ } else {
+ /* Backward branch */
+ unsigned J = TI;
+ while (J < From) {
+ CodeEntry* N = CS_GetEntry (S, J++);
+ Distance -= N->Size;
+ }
+ }
+
+ /* Return the calculated distance */
+ return Distance;
+}
+
+
+
+static int IsShortDist (int Distance)
+/* Return true if the given distance is a short branch distance */
+{
+ return (Distance >= -125 && Distance <= 125);
+}
+
+
+
+static short RegVal (unsigned short Use, const RegContents* RC)
+/* Return the contents of the given register */
+{
+ if ((Use & REG_A) != 0) {
+ return RC->RegA;
+ } else if ((Use & REG_X) != 0) {
+ return RC->RegX;
+ } else if ((Use & REG_Y) != 0) {
+ return RC->RegY;
+ } else if ((Use & REG_TMP1) != 0) {
+ return RC->Tmp1;
+ } else if ((Use & REG_SREG_LO) != 0) {
+ return RC->SRegLo;
+ } else if ((Use & REG_SREG_HI) != 0) {
+ return RC->SRegHi;
+ } else {
+ return UNKNOWN_REGVAL;
+ }
+}
+
+
+
+/*****************************************************************************/
+/* Replace jumps to RTS by RTS */
+/*****************************************************************************/
+
+
+
+unsigned OptRTSJumps1 (CodeSeg* S)
+/* Replace jumps to RTS by RTS */
+{
+ unsigned Changes = 0;
+
+ /* Walk over all entries minus the last one */
+ unsigned I = 0;
+ while (I < CS_GetEntryCount (S)) {
+
+ /* Get the next entry */
+ CodeEntry* E = CS_GetEntry (S, I);
+
+ /* Check if it's an unconditional branch to a local target */
+ if ((E->Info & OF_UBRA) != 0 &&
+ E->JumpTo != 0 &&
+ E->JumpTo->Owner->OPC == OP65_RTS) {
+
+ /* Insert an RTS instruction */
+ CodeEntry* X = NewCodeEntry (OP65_RTS, AM65_IMP, 0, 0, E->LI);
+ CS_InsertEntry (S, X, I+1);
+
+ /* Delete the jump */
+ CS_DelEntry (S, I);
+
+ /* Remember, we had changes */
+ ++Changes;
+
+ }
+
+ /* Next entry */
+ ++I;
+
+ }
+
+ /* Return the number of changes made */
+ return Changes;
+}
+
+
+
+unsigned OptRTSJumps2 (CodeSeg* S)
+/* Replace long conditional jumps to RTS */
+{
+ unsigned Changes = 0;
+
+ /* Walk over all entries minus the last one */
+ unsigned I = 0;
+ while (I < CS_GetEntryCount (S)) {
+
+ CodeEntry* N;
+
+ /* Get the next entry */
+ CodeEntry* E = CS_GetEntry (S, I);
+
+ /* Check if it's an unconditional branch to a local target */
+ if ((E->Info & OF_CBRA) != 0 && /* Conditional branch */
+ (E->Info & OF_LBRA) != 0 && /* Long branch */
+ E->JumpTo != 0 && /* Local label */
+ E->JumpTo->Owner->OPC == OP65_RTS && /* Target is an RTS */
+ (N = CS_GetNextEntry (S, I)) != 0) { /* There is a next entry */
+
+ CodeEntry* X;
+ CodeLabel* LN;
+ opc_t NewBranch;
+
+ /* We will create a jump around an RTS instead of the long branch */
+ X = NewCodeEntry (OP65_RTS, AM65_IMP, 0, 0, E->JumpTo->Owner->LI);
+ CS_InsertEntry (S, X, I+1);
+
+ /* Get the new branch opcode */
+ NewBranch = MakeShortBranch (GetInverseBranch (E->OPC));
+
+ /* Get the label attached to N, create a new one if needed */
+ LN = CS_GenLabel (S, N);
+
+ /* Generate the branch */
+ X = NewCodeEntry (NewBranch, AM65_BRA, LN->Name, LN, E->LI);
+ CS_InsertEntry (S, X, I+1);
+
+ /* Delete the long branch */
+ CS_DelEntry (S, I);
+
+ /* Remember, we had changes */
+ ++Changes;
+
+ }
+
+ /* Next entry */
+ ++I;
+
+ }
+
+ /* Return the number of changes made */
+ return Changes;
+}
+
+
+
/*****************************************************************************/
/* Remove dead jumps */
/*****************************************************************************/
/* Remove dead jumps (jumps to the next instruction) */
{
unsigned Changes = 0;
- CodeEntry* E;
- unsigned I;
-
- /* Get the number of entries, bail out if we have less than two entries */
- unsigned Count = GetCodeEntryCount (S);
- if (Count < 2) {
- return 0;
- }
/* Walk over all entries minus the last one */
- I = 0;
- while (I < Count-1) {
+ unsigned I = 0;
+ while (I < CS_GetEntryCount (S)) {
/* Get the next entry */
- E = GetCodeEntry (S, I);
+ CodeEntry* E = CS_GetEntry (S, I);
/* Check if it's a branch, if it has a local target, and if the target
* is the next instruction.
*/
- if (E->AM == AM_BRA && E->JumpTo && E->JumpTo->Owner == GetCodeEntry (S, I+1)) {
+ if (E->AM == AM65_BRA &&
+ E->JumpTo &&
+ E->JumpTo->Owner == CS_GetNextEntry (S, I)) {
/* Delete the dead jump */
- DelCodeEntry (S, I);
-
- /* Keep the number of entries updated */
- --Count;
+ CS_DelEntry (S, I);
/* Remember, we had changes */
++Changes;
/*****************************************************************************/
-/* Remove dead code */
+/* Remove dead code */
/*****************************************************************************/
*/
{
unsigned Changes = 0;
- unsigned I;
- /* Get the number of entries, bail out if we have less than two entries */
- unsigned Count = GetCodeEntryCount (S);
- if (Count < 2) {
- return 0;
- }
+ /* Walk over all entries */
+ unsigned I = 0;
+ while (I < CS_GetEntryCount (S)) {
- /* Walk over all entries minus the last one */
- I = 0;
- while (I < Count-1) {
+ CodeEntry* N;
+ CodeLabel* LN;
/* Get this entry */
- CodeEntry* E = GetCodeEntry (S, I);
+ CodeEntry* E = CS_GetEntry (S, I);
/* Check if it's an unconditional branch, and if the next entry has
- * no labels attached
+ * no labels attached, or if the label is just used so that the insn
+ * can jump to itself.
*/
- if ((E->Info & OF_DEAD) != 0 && !CodeEntryHasLabel (GetCodeEntry (S, I+1))) {
+ if ((E->Info & OF_DEAD) != 0 && /* Dead code follows */
+ (N = CS_GetNextEntry (S, I)) != 0 && /* Has next entry */
+ (!CE_HasLabel (N) || /* Don't has a label */
+ ((N->Info & OF_UBRA) != 0 && /* Uncond branch */
+ (LN = N->JumpTo) != 0 && /* Jumps to known label */
+ LN->Owner == N && /* Attached to insn */
+ CL_GetRefCount (LN) == 1))) { /* Only reference */
/* Delete the next entry */
- DelCodeEntry (S, I+1);
-
- /* Keep the number of entries updated */
- --Count;
+ CS_DelEntry (S, I+1);
/* Remember, we had changes */
++Changes;
*/
{
unsigned Changes = 0;
- unsigned I;
-
- /* Get the number of entries, bail out if we have no entries */
- unsigned Count = GetCodeEntryCount (S);
- if (Count == 0) {
- return 0;
- }
/* Walk over all entries */
- I = 0;
- while (I < Count) {
+ unsigned I = 0;
+ while (I < CS_GetEntryCount (S)) {
+
+ CodeEntry* N;
+ CodeLabel* OldLabel;
/* Get this entry */
- CodeEntry* E = GetCodeEntry (S, I);
+ CodeEntry* E = CS_GetEntry (S, I);
- /* Check if it's a branch, if it has a jump label, and if this jump
- * label is not attached to the instruction itself.
+ /* Check if it's a branch, if it has a jump label, if this jump
+ * label is not attached to the instruction itself, and if the
+ * target instruction is itself a branch.
*/
- if ((E->Info & OF_BRA) != 0 && E->JumpTo != 0 && E->JumpTo->Owner != E) {
-
- /* Get the label this insn is branching to */
- CodeLabel* OldLabel = E->JumpTo;
-
- /* Get the entry we're branching to */
- CodeEntry* N = OldLabel->Owner;
-
- /* If the entry we're branching to is not itself a branch, it is
- * not what we're searching for.
- */
- if ((N->Info & OF_BRA) == 0) {
- goto NextEntry;
- }
+ if ((E->Info & OF_BRA) != 0 &&
+ (OldLabel = E->JumpTo) != 0 &&
+ (N = OldLabel->Owner) != E &&
+ (N->Info & OF_BRA) != 0) {
/* Check if we can use the final target label. This is the case,
* if the target branch is an absolut branch, or if it is a
*/
if ((N->Info & OF_UBRA) != 0 ||
((E->Info & OF_CBRA) != 0 &&
- GetBranchCond (E->OPC) == GetBranchCond (N->OPC))) {
+ GetBranchCond (E->OPC) == GetBranchCond (N->OPC))) {
- /* This is a jump cascade and we may jump to the final target.
- * If we have a label, move the reference to this label. If
- * we don't have a label, use the argument instead.
+ /* This is a jump cascade and we may jump to the final target,
+ * provided that the other insn does not jump to itself. If
+ * this is the case, we can also jump to ourselves, otherwise
+ * insert a jump to the new instruction and remove the old one.
*/
- if (N->JumpTo) {
- /* Move the reference to the new insn */
- MoveCodeLabelRef (S, E, N->JumpTo);
- } else {
- /* Remove the reference to the old label */
- RemoveCodeLabelRef (S, E);
- }
+ CodeEntry* X;
+ CodeLabel* LN = N->JumpTo;
+
+ if (LN != 0 && LN->Owner == N) {
+
+ /* We found a jump to a jump to itself. Replace our jump
+ * by a jump to itself.
+ */
+ CodeLabel* LE = CS_GenLabel (S, E);
+ X = NewCodeEntry (E->OPC, E->AM, LE->Name, LE, E->LI);
+
+ } else {
+
+ /* Jump to the final jump target */
+ X = NewCodeEntry (E->OPC, E->AM, N->Arg, N->JumpTo, E->LI);
- /* Use the new argument */
- CodeEntrySetArg (E, N->Arg);
+ }
- /* Use the usage information from the new instruction */
- E->Use = N->Use;
- E->Chg = N->Chg;
+ /* Insert it behind E */
+ CS_InsertEntry (S, X, I+1);
+
+ /* Remove E */
+ CS_DelEntry (S, I);
/* Remember, we had changes */
++Changes;
*/
if ((E->Info & OF_CBRA) != 0 && (N->Info & OF_CBRA) != 0) {
- unsigned NI; /* Index of N */
- CodeEntry* X; /* Instruction behind N */
- CodeLabel* LX; /* Label attached to X */
+ CodeEntry* X; /* Instruction behind N */
+ CodeLabel* LX; /* Label attached to X */
- /* Get the branch conditions of both branches */
- bc_t BC1 = GetBranchCond (E->OPC);
- bc_t BC2 = GetBranchCond (N->OPC);
+ /* Get the branch conditions of both branches */
+ bc_t BC1 = GetBranchCond (E->OPC);
+ bc_t BC2 = GetBranchCond (N->OPC);
- /* Check the branch conditions */
- if (BC1 != GetInverseCond (BC2)) {
- /* Condition not met */
- goto NextEntry;
- }
+ /* Check the branch conditions */
+ if (BC1 != GetInverseCond (BC2)) {
+ /* Condition not met */
+ goto NextEntry;
+ }
- /* We may jump behind this conditional branch. This means that
- * N may not be the last entry.
- */
- NI = GetCodeEntryIndex (S, N);
- if (NI >= Count-1) {
- /* N is last entry */
- goto NextEntry;
- }
-
- /* Get the pointer to the next instruction */
- X = GetCodeEntry (S, NI+1);
+ /* We may jump behind this conditional branch. Get the
+ * pointer to the next instruction
+ */
+ if ((X = CS_GetNextEntry (S, CS_GetEntryIndex (S, N))) == 0) {
+ /* N is the last entry, bail out */
+ goto NextEntry;
+ }
- /* Get the label attached to X, create a new one if needed */
- LX = GenCodeLabel (S, X);
+ /* Get the label attached to X, create a new one if needed */
+ LX = CS_GenLabel (S, X);
- /* Move the reference from E to the new label */
- MoveCodeLabelRef (S, E, LX);
+ /* Move the reference from E to the new label */
+ CS_MoveLabelRef (S, E, LX);
/* Remember, we had changes */
++Changes;
*/
{
unsigned Changes = 0;
- unsigned I;
-
- /* Get the number of entries, bail out if we have less than 2 entries */
- unsigned Count = GetCodeEntryCount (S);
- if (Count < 2) {
- return 0;
- }
/* Walk over all entries minus the last one */
- I = 0;
- while (I < Count-1) {
+ unsigned I = 0;
+ while (I < CS_GetEntryCount (S)) {
CodeEntry* N;
/* Get this entry */
- CodeEntry* E = GetCodeEntry (S, I);
+ CodeEntry* E = CS_GetEntry (S, I);
/* Check if it's a subroutine call and if the following insn is RTS */
- if (E->OPC == OPC_JSR &&
- (N = GetNextCodeEntry (S, I)) != 0 &&
- N->OPC == OPC_RTS) {
+ if (E->OPC == OP65_JSR &&
+ (N = CS_GetNextEntry (S, I)) != 0 &&
+ N->OPC == OP65_RTS) {
/* Change the jsr to a jmp and use the additional info for a jump */
- E->AM = AM_BRA;
- ReplaceOPC (E, OPC_JMP);
+ E->AM = AM65_BRA;
+ CE_ReplaceOPC (E, OP65_JMP);
/* Remember, we had changes */
++Changes;
CodeEntry* E1; /* Entry 1 */
CodeEntry* E2; /* Entry 2 */
CodeEntry* T1; /* Jump target entry 1 */
- CodeEntry* T2; /* Jump target entry 2 */
CodeLabel* TL1; /* Target label 1 */
- unsigned TI; /* Target index */
- unsigned I;
-
- /* Get the number of entries, bail out if we have not enough */
- unsigned Count = GetCodeEntryCount (S);
- if (Count < 3) {
- return 0;
- }
/* Walk over the entries */
- I = 0;
- while (I < Count-1) {
+ unsigned I = 0;
+ while (I < CS_GetEntryCount (S)) {
/* Get next entry */
- E2 = GetCodeEntry (S, I+1);
+ E2 = CS_GetNextEntry (S, I);
- /* Check if we have a jump or branch, and a matching label */
- if ((E2->Info & OF_UBRA) != 0 && E2->JumpTo) {
-
- /* Get the target instruction for the label */
- T2 = E2->JumpTo->Owner;
-
- /* Get the entry preceeding this one (if possible) */
- TI = GetCodeEntryIndex (S, T2);
- if (TI == 0) {
- /* There is no entry before this one */
+ /* Check if we have a jump or branch, and a matching label, which
+ * is not attached to the jump itself
+ */
+ if (E2 != 0 &&
+ (E2->Info & OF_UBRA) != 0 &&
+ E2->JumpTo &&
+ E2->JumpTo->Owner != E2) {
+
+ /* Get the entry preceeding the branch target */
+ T1 = CS_GetPrevEntry (S, CS_GetEntryIndex (S, E2->JumpTo->Owner));
+ if (T1 == 0) {
+ /* There is no such entry */
goto NextEntry;
}
- T1 = GetCodeEntry (S, TI-1);
/* Get the entry preceeding the jump */
- E1 = GetCodeEntry (S, I);
+ E1 = CS_GetEntry (S, I);
/* Check if both preceeding instructions are identical */
if (!CodeEntriesAreEqual (E1, T1)) {
* This routine will create a new label if the instruction does
* not already have one.
*/
- TL1 = GenCodeLabel (S, T1);
+ TL1 = CS_GenLabel (S, T1);
/* Change the jump target to point to this new label */
- MoveCodeLabelRef (S, E2, TL1);
+ CS_MoveLabelRef (S, E2, TL1);
/* If the instruction preceeding the jump has labels attached,
* move references to this label to the new label.
*/
- if (CodeEntryHasLabel (E1)) {
- MoveCodeLabels (S, E1, T1);
+ if (CE_HasLabel (E1)) {
+ CS_MoveLabels (S, E1, T1);
}
/* Remove the entry preceeding the jump */
- DelCodeEntry (S, I);
- --Count;
+ CS_DelEntry (S, I);
/* Remember, we had changes */
++Changes;
/*****************************************************************************/
-/* Optimize conditional branches */
+/* Optimize conditional branches */
/*****************************************************************************/
*/
{
unsigned Changes = 0;
- unsigned I;
-
- /* Get the number of entries, bail out if we have not enough */
- unsigned Count = GetCodeEntryCount (S);
- if (Count < 2) {
- return 0;
- }
/* Walk over the entries */
- I = 0;
- while (I < Count-1) {
+ unsigned I = 0;
+ while (I < CS_GetEntryCount (S)) {
CodeEntry* N;
CodeLabel* L;
/* Get next entry */
- CodeEntry* E = GetCodeEntry (S, I);
+ CodeEntry* E = CS_GetEntry (S, I);
/* Check if it's a register load */
- if ((E->Info & OF_LOAD) != 0 && /* It's a load instruction */
- E->AM == AM_IMM && /* ..with immidiate addressing */
- (E->Flags & CEF_NUMARG) != 0 && /* ..and a numeric argument. */
- (N = GetNextCodeEntry (S, I)) != 0 && /* There is a following entry */
- (N->Info & OF_CBRA) != 0 && /* ..which is a conditional branch */
- !CodeEntryHasLabel (N)) { /* ..and does not have a label */
+ if ((E->Info & OF_LOAD) != 0 && /* It's a load instruction */
+ E->AM == AM65_IMM && /* ..with immidiate addressing */
+ (E->Flags & CEF_NUMARG) != 0 && /* ..and a numeric argument. */
+ (N = CS_GetNextEntry (S, I)) != 0 && /* There is a following entry */
+ (N->Info & OF_CBRA) != 0 && /* ..which is a conditional branch */
+ !CE_HasLabel (N)) { /* ..and does not have a label */
/* Get the branch condition */
bc_t BC = GetBranchCond (N->OPC);
/* Check the argument against the branch condition */
- if ((BC == BC_EQ && E->Num != 0) ||
- (BC == BC_NE && E->Num == 0) ||
+ if ((BC == BC_EQ && E->Num != 0) ||
+ (BC == BC_NE && E->Num == 0) ||
(BC == BC_PL && (E->Num & 0x80) != 0) ||
(BC == BC_MI && (E->Num & 0x80) == 0)) {
/* Remove the conditional branch */
- DelCodeEntry (S, I+1);
- --Count;
+ CS_DelEntry (S, I+1);
/* Remember, we had changes */
++Changes;
- } else if ((BC == BC_EQ && E->Num == 0) ||
- (BC == BC_NE && E->Num != 0) ||
+ } else if ((BC == BC_EQ && E->Num == 0) ||
+ (BC == BC_NE && E->Num != 0) ||
(BC == BC_PL && (E->Num & 0x80) == 0) ||
(BC == BC_MI && (E->Num & 0x80) != 0)) {
/* The branch is always taken, replace it by a jump */
- ReplaceOPC (N, OPC_JMP);
+ CE_ReplaceOPC (N, OP65_JMP);
/* Remember, we had changes */
++Changes;
}
- if ((E->Info & OF_CBRA) != 0 && /* It's a conditional branch */
- (L = E->JumpTo) != 0 && /* ..referencing a local label */
- (N = GetNextCodeEntry (S, I)) != 0 && /* There is a following entry */
- (N->Info & OF_UBRA) != 0 && /* ..which is an uncond branch, */
- !CodeEntryHasLabel (N) && /* ..has no label attached */
- L->Owner == GetNextCodeEntry (S, I+1)) {/* ..and jump target follows */
+ if ((E->Info & OF_CBRA) != 0 && /* It's a conditional branch */
+ (L = E->JumpTo) != 0 && /* ..referencing a local label */
+ (N = CS_GetNextEntry (S, I)) != 0 && /* There is a following entry */
+ (N->Info & OF_UBRA) != 0 && /* ..which is an uncond branch, */
+ !CE_HasLabel (N) && /* ..has no label attached */
+ L->Owner == CS_GetNextEntry (S, I+1)) {/* ..and jump target follows */
/* Replace the jump by a conditional branch with the inverse branch
* condition than the branch around it.
*/
- ReplaceOPC (N, GetInverseBranch (E->OPC));
+ CE_ReplaceOPC (N, GetInverseBranch (E->OPC));
/* Remove the conditional branch */
- DelCodeEntry (S, I);
- --Count;
+ CS_DelEntry (S, I);
/* Remember, we had changes */
++Changes;
/*****************************************************************************/
-/* Remove unused loads */
+/* Remove unused loads and stores */
/*****************************************************************************/
/* Remove loads of registers where the value loaded is not used later. */
{
unsigned Changes = 0;
- unsigned I;
-
- /* Get the number of entries, bail out if we have not enough */
- unsigned Count = GetCodeEntryCount (S);
- if (Count < 2) {
- return 0;
- }
/* Walk over the entries */
- I = 0;
- while (I < Count-1) {
-
- /* Get next entry */
- CodeEntry* E = GetCodeEntry (S, I);
+ unsigned I = 0;
+ while (I < CS_GetEntryCount (S)) {
- /* Check if it's a register load */
- if ((E->Info & OF_LOAD) != 0) {
+ CodeEntry* N;
- unsigned char R;
+ /* Get next entry */
+ CodeEntry* E = CS_GetEntry (S, I);
- /* Get the next instruction, it must not be a conditional branch */
- CodeEntry* N = GetCodeEntry (S, I+1);
- if ((N->Info & OF_CBRA) != 0) {
- goto NextEntry;
- }
+ /* Check if it's a register load or transfer insn */
+ if ((E->Info & (OF_LOAD | OF_XFR | OF_REG_INCDEC)) != 0 &&
+ (N = CS_GetNextEntry (S, I)) != 0 &&
+ !CE_UseLoadFlags (N)) {
- /* Check which sort of load it is */
+ /* Check which sort of load or transfer it is */
+ unsigned R;
switch (E->OPC) {
- case OPC_LDA: R = REG_A; break;
- case OPC_LDX: R = REG_X; break;
- case OPC_LDY: R = REG_Y; break;
- default: goto NextEntry; /* OOPS */
+ case OP65_DEA:
+ case OP65_INA:
+ case OP65_LDA:
+ case OP65_TXA:
+ case OP65_TYA: R = REG_A; break;
+ case OP65_DEX:
+ case OP65_INX:
+ case OP65_LDX:
+ case OP65_TAX: R = REG_X; break;
+ case OP65_DEY:
+ case OP65_INY:
+ case OP65_LDY:
+ case OP65_TAY: R = REG_Y; break;
+ default: goto NextEntry; /* OOPS */
}
/* Get register usage and check if the register value is used later */
- if ((GetRegInfo (S, I+1) & R) == 0) {
+ if ((GetRegInfo (S, I+1, R) & R) == 0) {
- /* Register value is not used, remove the load */
- DelCodeEntry (S, I);
- --Count;
+ /* Register value is not used, remove the load */
+ CS_DelEntry (S, I);
/* Remember, we had changes */
++Changes;
}
}
+NextEntry:
+ /* Next entry */
+ ++I;
+
+ }
+
+ /* Return the number of changes made */
+ return Changes;
+}
+
+
+
+unsigned OptUnusedStores (CodeSeg* S)
+/* Remove stores into zero page registers that aren't used later */
+{
+ unsigned Changes = 0;
+
+ /* Walk over the entries */
+ unsigned I = 0;
+ while (I < CS_GetEntryCount (S)) {
+
+ /* Get next entry */
+ CodeEntry* E = CS_GetEntry (S, I);
+
+ /* Check if it's a register load or transfer insn */
+ if ((E->Info & OF_STORE) != 0 &&
+ E->AM == AM65_ZP &&
+ (E->Chg & REG_ZP) != 0) {
+
+ /* Check for the zero page location. We know that there cannot be
+ * more than one zero page location involved in the store.
+ */
+ unsigned R = E->Chg & REG_ZP;
+
+ /* Get register usage and check if the register value is used later */
+ if ((GetRegInfo (S, I+1, R) & R) == 0) {
+
+ /* Register value is not used, remove the load */
+ CS_DelEntry (S, I);
+
+ /* Remember, we had changes */
+ ++Changes;
+
+ }
+ }
+
+ /* Next entry */
+ ++I;
+
+ }
+
+ /* Return the number of changes made */
+ return Changes;
+}
+
+
+
+unsigned OptDupLoads (CodeSeg* S)
+/* Remove loads of registers where the value loaded is already in the register. */
+{
+ 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* N;
+
+ /* Get next entry */
+ CodeEntry* E = CS_GetEntry (S, I);
+
+ /* Assume we won't delete the entry */
+ int Delete = 0;
+
+ /* Get a pointer to the input registers of the insn */
+ const RegContents* In = &E->RI->In;
+
+ /* Handle the different instructions */
+ switch (E->OPC) {
+
+ case OP65_LDA:
+ if (RegValIsKnown (In->RegA) && /* Value of A is known */
+ CE_KnownImm (E) && /* Value to be loaded is known */
+ In->RegA == (long) E->Num && /* Both are equal */
+ (N = CS_GetNextEntry (S, I)) != 0 && /* There is a next entry */
+ !CE_UseLoadFlags (N)) { /* Which does not use the flags */
+ Delete = 1;
+ }
+ break;
+
+ case OP65_LDX:
+ if (RegValIsKnown (In->RegX) && /* Value of X is known */
+ CE_KnownImm (E) && /* Value to be loaded is known */
+ In->RegX == (long) E->Num && /* Both are equal */
+ (N = CS_GetNextEntry (S, I)) != 0 && /* There is a next entry */
+ !CE_UseLoadFlags (N)) { /* Which does not use the flags */
+ Delete = 1;
+ }
+ break;
+
+ case OP65_LDY:
+ if (RegValIsKnown (In->RegY) && /* Value of Y is known */
+ CE_KnownImm (E) && /* Value to be loaded is known */
+ In->RegY == (long) E->Num && /* Both are equal */
+ (N = CS_GetNextEntry (S, I)) != 0 && /* There is a next entry */
+ !CE_UseLoadFlags (N)) { /* Which does not use the flags */
+ Delete = 1;
+ }
+ break;
+
+ case OP65_STA:
+ /* If we store into a known zero page location, and this
+ * location does already contain the value to be stored,
+ * remove the store.
+ */
+ if (RegValIsKnown (In->RegA) && /* Value of A is known */
+ E->AM == AM65_ZP && /* Store into zp */
+ In->RegA == RegVal (E->Chg, In)) { /* Value identical */
+
+ Delete = 1;
+ }
+ break;
+
+ case OP65_STX:
+ /* If we store into a known zero page location, and this
+ * location does already contain the value to be stored,
+ * remove the store.
+ */
+ if (RegValIsKnown (In->RegX) && /* Value of A is known */
+ E->AM == AM65_ZP && /* Store into zp */
+ In->RegX == RegVal (E->Chg, In)) { /* Value identical */
+
+ Delete = 1;
+
+ /* If the value in the X register is known and the same as
+ * that in the A register, replace the store by a STA. The
+ * optimizer will then remove the load instruction for X
+ * later. STX does support the zeropage,y addressing mode,
+ * so be sure to check for that.
+ */
+ } else if (RegValIsKnown (In->RegX) &&
+ In->RegX == In->RegA &&
+ E->AM != AM65_ABSY &&
+ E->AM != AM65_ZPY) {
+ /* Use the A register instead */
+ CE_ReplaceOPC (E, OP65_STA);
+ }
+ break;
+
+ case OP65_STY:
+ /* If we store into a known zero page location, and this
+ * location does already contain the value to be stored,
+ * remove the store.
+ */
+ if (RegValIsKnown (In->RegY) && /* Value of Y is known */
+ E->AM == AM65_ZP && /* Store into zp */
+ In->RegY == RegVal (E->Chg, In)) { /* Value identical */
+
+ Delete = 1;
+
+ /* If the value in the Y register is known and the same as
+ * that in the A register, replace the store by a STA. The
+ * optimizer will then remove the load instruction for Y
+ * later. If replacement by A is not possible try a
+ * replacement by X, but check for invalid addressing modes
+ * in this case.
+ */
+ } else if (RegValIsKnown (In->RegY)) {
+ if (In->RegY == In->RegA) {
+ CE_ReplaceOPC (E, OP65_STA);
+ } else if (In->RegY == In->RegX &&
+ E->AM != AM65_ABSX &&
+ E->AM != AM65_ZPX) {
+ CE_ReplaceOPC (E, OP65_STX);
+ }
+ }
+ break;
+
+ case OP65_STZ:
+ /* If we store into a known zero page location, and this
+ * location does already contain the value to be stored,
+ * remove the store.
+ */
+ if (CPU >= CPU_65C02 && E->AM == AM65_ZP) {
+ if (RegVal (E->Chg, In) == 0) {
+ Delete = 1;
+ }
+ }
+ break;
+
+ case OP65_TAX:
+ if (RegValIsKnown (In->RegA) &&
+ In->RegA == In->RegX &&
+ (N = CS_GetNextEntry (S, I)) != 0 &&
+ !CE_UseLoadFlags (N)) {
+ /* Value is identical and not followed by a branch */
+ Delete = 1;
+ }
+ break;
+
+ case OP65_TAY:
+ if (RegValIsKnown (In->RegA) &&
+ In->RegA == In->RegY &&
+ (N = CS_GetNextEntry (S, I)) != 0 &&
+ !CE_UseLoadFlags (N)) {
+ /* Value is identical and not followed by a branch */
+ Delete = 1;
+ }
+ break;
+
+ case OP65_TXA:
+ if (RegValIsKnown (In->RegX) &&
+ In->RegX == In->RegA &&
+ (N = CS_GetNextEntry (S, I)) != 0 &&
+ !CE_UseLoadFlags (N)) {
+ /* Value is identical and not followed by a branch */
+ Delete = 1;
+ }
+ break;
+
+ case OP65_TYA:
+ if (RegValIsKnown (In->RegY) &&
+ In->RegY == In->RegA &&
+ (N = CS_GetNextEntry (S, I)) != 0 &&
+ !CE_UseLoadFlags (N)) {
+ /* Value is identical and not followed by a branch */
+ Delete = 1;
+ }
+ break;
+
+ default:
+ break;
+
+ }
+
+ /* Delete the entry if requested */
+ if (Delete) {
+
+ /* Register value is not used, remove the load */
+ CS_DelEntry (S, I);
+
+ /* Remember, we had changes */
+ ++Changes;
+
+ } else {
+
+ /* Next entry */
+ ++I;
+
+ }
+
+ }
+
+ /* Free register info */
+ CS_FreeRegInfo (S);
+
+ /* Return the number of changes made */
+ return Changes;
+}
+
+
+
+unsigned OptStoreLoad (CodeSeg* S)
+/* Remove a store followed by a load from the same location. */
+{
+ unsigned Changes = 0;
+
+ /* Walk over the entries */
+ unsigned I = 0;
+ while (I < CS_GetEntryCount (S)) {
+
+ CodeEntry* N;
+ CodeEntry* X;
+
+ /* Get next entry */
+ CodeEntry* E = CS_GetEntry (S, I);
+
+ /* Check if it is a store instruction followed by a load from the
+ * same address which is itself not followed by a conditional branch.
+ */
+ if ((E->Info & OF_STORE) != 0 &&
+ (N = CS_GetNextEntry (S, I)) != 0 &&
+ !CE_HasLabel (N) &&
+ E->AM == N->AM &&
+ ((E->OPC == OP65_STA && N->OPC == OP65_LDA) ||
+ (E->OPC == OP65_STX && N->OPC == OP65_LDX) ||
+ (E->OPC == OP65_STY && N->OPC == OP65_LDY)) &&
+ strcmp (E->Arg, N->Arg) == 0 &&
+ (X = CS_GetNextEntry (S, I+1)) != 0 &&
+ !CE_UseLoadFlags (X)) {
+
+ /* Register has already the correct value, remove the load */
+ CS_DelEntry (S, I+1);
+
+ /* Remember, we had changes */
+ ++Changes;
+
+ }
+
+ /* Next entry */
+ ++I;
+
+ }
+
+ /* Return the number of changes made */
+ return Changes;
+}
+
+
+
+unsigned OptTransfers (CodeSeg* S)
+/* Remove transfers from one register to another and back */
+{
+ unsigned Changes = 0;
+
+ /* Walk over the entries */
+ unsigned I = 0;
+ while (I < CS_GetEntryCount (S)) {
+
+ CodeEntry* N;
+ CodeEntry* X;
+ CodeEntry* P;
+
+ /* Get next entry */
+ CodeEntry* E = CS_GetEntry (S, I);
+
+ /* Check if it is a store instruction followed by a load from the
+ * same address which is itself not followed by a conditional branch.
+ */
+ if ((E->Info & OF_XFR) != 0 &&
+ (N = CS_GetNextEntry (S, I)) != 0 &&
+ !CE_HasLabel (N) &&
+ (N->Info & OF_XFR) != 0) {
+
+ /* Check if it's a transfer and back */
+ if ((E->OPC == OP65_TAX && N->OPC == OP65_TXA && !RegXUsed (S, I+2)) ||
+ (E->OPC == OP65_TAY && N->OPC == OP65_TYA && !RegYUsed (S, I+2)) ||
+ (E->OPC == OP65_TXA && N->OPC == OP65_TAX && !RegAUsed (S, I+2)) ||
+ (E->OPC == OP65_TYA && N->OPC == OP65_TAY && !RegAUsed (S, I+2))) {
+
+ /* If the next insn is a conditional branch, check if the insn
+ * preceeding the first xfr will set the flags right, otherwise we
+ * may not remove the sequence.
+ */
+ if ((X = CS_GetNextEntry (S, I+1)) == 0) {
+ goto NextEntry;
+ }
+ if (CE_UseLoadFlags (X)) {
+ if (I == 0) {
+ /* No preceeding entry */
+ goto NextEntry;
+ }
+ P = CS_GetEntry (S, I-1);
+ if ((P->Info & OF_SETF) == 0) {
+ /* Does not set the flags */
+ goto NextEntry;
+ }
+ }
+
+ /* Remove both transfers */
+ CS_DelEntry (S, I+1);
+ CS_DelEntry (S, I);
+
+ /* Remember, we had changes */
+ ++Changes;
+ }
+ }
+
NextEntry:
/* Next entry */
++I;
+unsigned OptPushPop (CodeSeg* S)
+/* Remove a PHA/PLA sequence were A is not used later */
+{
+ unsigned Changes = 0;
+ unsigned Push = 0; /* Index of push insn */
+ unsigned Pop = 0; /* Index of pop insn */
+ enum {
+ Searching,
+ FoundPush,
+ FoundPop
+ } State = Searching;
+
+ /* Walk over the entries. Look for a push instruction that is followed by
+ * a pop later, where the pop is not followed by an conditional branch,
+ * and where the value of the A register is not used later on.
+ * Look out for the following problems:
+ *
+ * - There may be another PHA/PLA inside the sequence: Restart it.
+ * - If the PLA has a label, all jumps to this label must be inside
+ * the sequence, otherwise we cannot remove the PHA/PLA.
+ */
+ unsigned I = 0;
+ while (I < CS_GetEntryCount (S)) {
+
+ /* Get next entry */
+ CodeEntry* E = CS_GetEntry (S, I);
+
+ switch (State) {
+
+ case Searching:
+ if (E->OPC == OP65_PHA) {
+ /* Found start of sequence */
+ Push = I;
+ State = FoundPush;
+ }
+ break;
+
+ case FoundPush:
+ if (E->OPC == OP65_PHA) {
+ /* Inner push/pop, restart */
+ Push = I;
+ } else if (E->OPC == OP65_PLA) {
+ /* Found a matching pop */
+ Pop = I;
+ State = FoundPop;
+ }
+ break;
+
+ case FoundPop:
+ /* Next insn, just check if it is no conditional branch and
+ * that A is not used later. Check also that the range we have
+ * found now is a basic block, which means that the PHA is the
+ * only entrance and the PLA the only exit.
+ */
+ if ((E->Info & OF_CBRA) == 0 &&
+ !RegAUsed (S, I) &&
+ CS_IsBasicBlock (S, Push, Pop)) {
+ /* We can remove the PHA and PLA instructions */
+ CS_DelEntry (S, Pop);
+ CS_DelEntry (S, Push);
+ /* Correct I so we continue with the next insn */
+ I -= 2;
+ /* Remember we had changes */
+ ++Changes;
+ }
+ /* Go into search mode again */
+ State = Searching;
+ break;
+
+ }
+
+ /* Next entry */
+ ++I;
+ }
+
+ /* Return the number of changes made */
+ return Changes;
+}
+
+
+
/*****************************************************************************/
-/* Optimize branch types */
+/* Optimize branch types */
/*****************************************************************************/
/* Change branches for the distance needed. */
{
unsigned Changes = 0;
- unsigned I;
-
- /* Get the number of entries, bail out if we have not enough */
- unsigned Count = GetCodeEntryCount (S);
/* Walk over the entries */
- I = 0;
- while (I < Count) {
+ unsigned I = 0;
+ while (I < CS_GetEntryCount (S)) {
/* Get next entry */
- CodeEntry* E = GetCodeEntry (S, I);
+ CodeEntry* E = CS_GetEntry (S, I);
/* Check if it's a conditional branch to a local label. */
- if ((E->Info & OF_CBRA) != 0) {
+ if (E->Info & OF_CBRA) {
/* Is this a branch to a local symbol? */
if (E->JumpTo != 0) {
- /* Get the index of the branch target */
- unsigned TI = GetCodeEntryIndex (S, E->JumpTo->Owner);
-
- /* Determine the branch distance */
- int Distance = 0;
- if (TI >= I) {
- /* Forward branch */
- unsigned J = I;
- while (J < TI) {
- CodeEntry* N = GetCodeEntry (S, J++);
- Distance += N->Size;
- }
- } else {
- /* Backward branch */
- unsigned J = TI;
- while (J < I) {
- CodeEntry* N = GetCodeEntry (S, J++);
- Distance += N->Size;
- }
- }
+ /* Check if the branch distance is short */
+ int IsShort = IsShortDist (GetBranchDist (S, I, E->JumpTo->Owner));
/* Make the branch short/long according to distance */
- if ((E->Info & OF_LBRA) == 0 && Distance > 120) {
+ if ((E->Info & OF_LBRA) == 0 && !IsShort) {
/* Short branch but long distance */
- ReplaceOPC (E, MakeLongBranch (E->OPC));
+ CE_ReplaceOPC (E, MakeLongBranch (E->OPC));
++Changes;
- } else if ((E->Info & OF_LBRA) != 0 && Distance < 120) {
+ } else if ((E->Info & OF_LBRA) != 0 && IsShort) {
/* Long branch but short distance */
- ReplaceOPC (E, MakeShortBranch (E->OPC));
+ CE_ReplaceOPC (E, MakeShortBranch (E->OPC));
++Changes;
}
} else if ((E->Info & OF_LBRA) == 0) {
/* Short branch to external symbol - make it long */
- ReplaceOPC (E, MakeLongBranch (E->OPC));
+ CE_ReplaceOPC (E, MakeLongBranch (E->OPC));
++Changes;
}
+
+ } else if (CPU == CPU_65C02 &&
+ (E->Info & OF_UBRA) != 0 &&
+ E->JumpTo != 0 &&
+ IsShortDist (GetBranchDist (S, I, E->JumpTo->Owner))) {
+
+ /* The jump is short and may be replaced by a BRA on the 65C02 CPU */
+ CE_ReplaceOPC (E, OP65_BRA);
+ ++Changes;
}
/* Next entry */
-
-
-
-
projects / cc65 / blobdiff