/*****************************************************************************/
/* */
-/* coptind.c */
+/* coptind.c */
/* */
-/* Environment independent low level optimizations */
+/* Environment independent low level optimizations */
/* */
/* */
/* */
/*****************************************************************************/
-/* Helper functions */
+/* Helper functions */
/*****************************************************************************/
-static int MemAccess (CodeSeg* S, unsigned From, unsigned To, const char* Arg)
-/* Checks a range of code entries if there are any memory accesses to Arg.
- * Note: This function is not 100% safe, because there is more than one way
- * to express a memory location ("foo" and "foo+0" comes to mind) and there
- * may be other accesses through pointers. For the code generated by cc65 and
- * for the purpose of the caller (OptPushPop) it is assumed to be safe enough
- * however.
- */
+static int MemAccess (CodeSeg* S, unsigned From, unsigned To, const CodeEntry* N)
+/* Checks a range of code entries if there are any memory accesses to N->Arg */
{
+ /* Get the length of the argument */
+ unsigned NLen = strlen (N->Arg);
+
+ /* What to check for? */
+ enum {
+ None = 0x00,
+ Base = 0x01, /* Check for location without "+1" */
+ Word = 0x02, /* Check for location with "+1" added */
+ } What = None;
+
+
+ /* If the argument of N is a zero page location that ends with "+1", we
+ ** must also check for word accesses to the location without +1.
+ */
+ if (N->AM == AM65_ZP && NLen > 2 && strcmp (N->Arg + NLen - 2, "+1") == 0) {
+ What |= Base;
+ }
+
+ /* If the argument is zero page indirect, we must also check for accesses
+ ** to "arg+1"
+ */
+ if (N->AM == AM65_ZP_INDY || N->AM == AM65_ZPX_IND || N->AM == AM65_ZP_IND) {
+ What |= Word;
+ }
+
/* Walk over all code entries */
while (From <= To) {
- /* Get the next entry */
- CodeEntry* E = CS_GetEntry (S, From);
+ /* Get the next entry */
+ CodeEntry* E = CS_GetEntry (S, From);
+
+ /* Check if there is an argument and if this argument equals Arg in
+ ** some variants.
+ */
+ if (E->Arg[0] != '\0') {
- /* For simplicity, we just check if there is an argument and if this
- * argument equals Arg.
- */
- if (E->Arg && strcmp (E->Arg, Arg) == 0) {
- /* Found an access */
- return 1;
+ unsigned ELen;
+
+ if (strcmp (E->Arg, N->Arg) == 0) {
+ /* Found an access */
+ return 1;
+ }
+
+ ELen = strlen (E->Arg);
+ if ((What & Base) != 0) {
+ if (ELen == NLen - 2 && strncmp (E->Arg, N->Arg, NLen-2) == 0) {
+ /* Found an access */
+ return 1;
+ }
+ }
+
+ if ((What & Word) != 0) {
+ if (ELen == NLen + 2 && strncmp (E->Arg, N->Arg, NLen) == 0 &&
+ E->Arg[NLen] == '+' && E->Arg[NLen+1] == '1') {
+ /* Found an access */
+ return 1;
+ }
+ }
}
/* Next entry */
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.
- */
+** 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;
- }
+ /* 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;
- }
+ /* Backward branch */
+ unsigned J = TI;
+ while (J < From) {
+ CodeEntry* N = CS_GetEntry (S, J++);
+ Distance -= N->Size;
+ }
}
/* Return the calculated distance */
/* Return the contents of the given zeropage register */
{
if ((Use & REG_TMP1) != 0) {
- return RC->Tmp1;
+ return RC->Tmp1;
} else if ((Use & REG_PTR1_LO) != 0) {
- return RC->Ptr1Lo;
+ return RC->Ptr1Lo;
} else if ((Use & REG_PTR1_HI) != 0) {
- return RC->Ptr1Hi;
+ return RC->Ptr1Hi;
} else if ((Use & REG_SREG_LO) != 0) {
- return RC->SRegLo;
+ return RC->SRegLo;
} else if ((Use & REG_SREG_HI) != 0) {
- return RC->SRegHi;
+ return RC->SRegHi;
} else {
- return UNKNOWN_REGVAL;
+ return UNKNOWN_REGVAL;
}
}
/* Return the contents of the given register */
{
if ((Use & REG_A) != 0) {
- return RC->RegA;
+ return RC->RegA;
} else if ((Use & REG_X) != 0) {
- return RC->RegX;
+ return RC->RegX;
} else if ((Use & REG_Y) != 0) {
- return RC->RegY;
+ return RC->RegY;
} else {
return ZPRegVal (Use, RC);
}
/*****************************************************************************/
-/* Replace jumps to RTS by RTS */
+/* Replace jumps to RTS by RTS */
/*****************************************************************************/
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
- /* Get the next entry */
- CodeEntry* E = CS_GetEntry (S, I);
+ /* 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) {
+ /* 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);
+ /* 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);
+ /* Delete the jump */
+ CS_DelEntry (S, I);
- /* Remember, we had changes */
- ++Changes;
+ /* Remember, we had changes */
+ ++Changes;
- }
+ }
- /* Next entry */
- ++I;
+ /* Next entry */
+ ++I;
}
unsigned OptRTSJumps2 (CodeSeg* S)
-/* Replace long conditional jumps to RTS */
+/* Replace long conditional jumps to RTS or to a final target */
{
unsigned Changes = 0;
/* Walk over all entries minus the last one */
unsigned I = 0;
- while (I < CS_GetEntryCount (S)) {
+ while (I < CS_GetEntryCount (S) - 1) {
- CodeEntry* N;
+ /* Get the next entry */
+ CodeEntry* E = CS_GetEntry (S, I);
- /* Get the next entry */
- CodeEntry* E = CS_GetEntry (S, I);
+ /* Check if it's an conditional 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 */
- /* 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;
+ /* Get the jump target and the next entry. There's always a next
+ ** entry, because we don't cover the last entry in the loop.
+ */
+ CodeEntry* X = 0;
+ CodeEntry* T = E->JumpTo->Owner;
+ CodeEntry* N = CS_GetNextEntry (S, I);
+
+ /* Check if it's a jump to an RTS insn */
+ if (T->OPC == OP65_RTS) {
- /* 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);
+ /* It's a jump to RTS. Create a conditional branch around an
+ ** RTS insn.
+ */
+ X = NewCodeEntry (OP65_RTS, AM65_IMP, 0, 0, T->LI);
- /* Get the new branch opcode */
- NewBranch = MakeShortBranch (GetInverseBranch (E->OPC));
+ } else if (T->OPC == OP65_JMP && T->JumpTo == 0) {
- /* Get the label attached to N, create a new one if needed */
- LN = CS_GenLabel (S, N);
+ /* It's a jump to a label outside the function. Create a
+ ** conditional branch around a jump to the external label.
+ */
+ X = NewCodeEntry (OP65_JMP, AM65_ABS, T->Arg, T->JumpTo, T->LI);
- /* Generate the branch */
- X = NewCodeEntry (NewBranch, AM65_BRA, LN->Name, LN, E->LI);
- CS_InsertEntry (S, X, I+1);
+ }
+
+ /* If we have a replacement insn, insert it */
+ if (X) {
- /* Delete the long branch */
- CS_DelEntry (S, I);
+ CodeLabel* LN;
+ opc_t NewBranch;
- /* Remember, we had changes */
- ++Changes;
+ /* Insert the new insn */
+ CS_InsertEntry (S, X, I+1);
- }
+ /* Create a conditional branch with the inverse condition
+ ** around the replacement insn
+ */
- /* Next entry */
- ++I;
+ /* 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;
}
/*****************************************************************************/
-/* Remove dead jumps */
+/* Remove dead jumps */
/*****************************************************************************/
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
- /* Get the next entry */
- CodeEntry* E = CS_GetEntry (S, I);
+ /* Get the next entry */
+ 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 == AM65_BRA &&
- E->JumpTo &&
- E->JumpTo->Owner == CS_GetNextEntry (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 == AM65_BRA &&
+ E->JumpTo &&
+ E->JumpTo->Owner == CS_GetNextEntry (S, I)) {
- /* Delete the dead jump */
- CS_DelEntry (S, I);
+ /* Delete the dead jump */
+ CS_DelEntry (S, I);
- /* Remember, we had changes */
- ++Changes;
+ /* Remember, we had changes */
+ ++Changes;
- } else {
+ } else {
- /* Next entry */
- ++I;
+ /* Next entry */
+ ++I;
- }
+ }
}
/* Return the number of changes made */
/*****************************************************************************/
-/* Remove dead code */
+/* Remove dead code */
/*****************************************************************************/
unsigned OptDeadCode (CodeSeg* S)
/* Remove dead code (code that follows an unconditional jump or an rts/rti
- * and has no label)
- */
+** and has no label)
+*/
{
unsigned Changes = 0;
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
- CodeEntry* N;
+ CodeEntry* N;
CodeLabel* LN;
- /* Get this entry */
- CodeEntry* E = CS_GetEntry (S, I);
+ /* Get this entry */
+ CodeEntry* E = CS_GetEntry (S, I);
- /* Check if it's an unconditional branch, and if the next entry has
- * no labels attached, or if the label is just used so that the insn
- * can jump to itself.
- */
- 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 */
+ /* Check if it's an unconditional branch, and if the next entry has
+ ** no labels attached, or if the label is just used so that the insn
+ ** can jump to itself.
+ */
+ 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 */
- CS_DelEntry (S, I+1);
+ /* Delete the next entry */
+ CS_DelEntry (S, I+1);
- /* Remember, we had changes */
- ++Changes;
+ /* Remember, we had changes */
+ ++Changes;
- } else {
+ } else {
- /* Next entry */
- ++I;
+ /* Next entry */
+ ++I;
- }
+ }
}
/* Return the number of changes made */
/*****************************************************************************/
-/* Optimize jump cascades */
+/* Optimize jump cascades */
/*****************************************************************************/
unsigned OptJumpCascades (CodeSeg* S)
/* Optimize jump cascades (jumps to jumps). In such a case, the jump is
- * replaced by a jump to the final location. This will in some cases produce
- * worse code, because some jump targets are no longer reachable by short
- * branches, but this is quite rare, so there are more advantages than
- * disadvantages.
- */
+** replaced by a jump to the final location. This will in some cases produce
+** worse code, because some jump targets are no longer reachable by short
+** branches, but this is quite rare, so there are more advantages than
+** disadvantages.
+*/
{
unsigned Changes = 0;
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
- CodeEntry* N;
- CodeLabel* OldLabel;
-
- /* Get this entry */
- CodeEntry* E = CS_GetEntry (S, I);
-
- /* 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 &&
- (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
- * conditional branch checking the same condition as the first one.
- */
- if ((N->Info & OF_UBRA) != 0 ||
- ((E->Info & OF_CBRA) != 0 &&
- GetBranchCond (E->OPC) == GetBranchCond (N->OPC))) {
-
- /* 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.
- */
- CodeEntry* X;
+ CodeEntry* N;
+ CodeLabel* OldLabel;
+
+ /* Get this entry */
+ CodeEntry* E = CS_GetEntry (S, I);
+
+ /* Check:
+ ** - if it's a branch,
+ ** - if it has a jump label,
+ ** - if this jump label is not attached to the instruction itself,
+ ** - if the target instruction is itself a branch,
+ ** - if either the first branch is unconditional or the target of
+ ** the second branch is internal to the function.
+ ** The latter condition will avoid conditional branches to targets
+ ** outside of the function (usually incspx), which won't simplify the
+ ** code, since conditional far branches are emulated by a short branch
+ ** around a jump.
+ */
+ if ((E->Info & OF_BRA) != 0 &&
+ (OldLabel = E->JumpTo) != 0 &&
+ (N = OldLabel->Owner) != E &&
+ (N->Info & OF_BRA) != 0 &&
+ ((E->Info & OF_CBRA) == 0 ||
+ N->JumpTo != 0)) {
+
+ /* Check if we can use the final target label. That is the case,
+ ** if the target branch is an absolute branch; or, if it is a
+ ** conditional branch checking the same condition as the first one.
+ */
+ if ((N->Info & OF_UBRA) != 0 ||
+ ((E->Info & OF_CBRA) != 0 &&
+ GetBranchCond (E->OPC) == GetBranchCond (N->OPC))) {
+
+ /* 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.
+ */
+ 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.
- */
+ ** by a jump to itself.
+ */
CodeLabel* LE = CS_GenLabel (S, E);
X = NewCodeEntry (E->OPC, E->AM, LE->Name, LE, E->LI);
}
- /* Insert it behind E */
- CS_InsertEntry (S, X, I+1);
+ /* Insert it behind E */
+ CS_InsertEntry (S, X, I+1);
- /* Remove E */
- CS_DelEntry (S, I);
+ /* Remove E */
+ CS_DelEntry (S, I);
- /* Remember, we had changes */
- ++Changes;
+ /* Remember, we had changes */
+ ++Changes;
- /* Check if both are conditional branches, and the condition of
- * the second is the inverse of that of the first. In this case,
- * the second branch will never be taken, and we may jump directly
- * to the instruction behind this one.
- */
- } else if ((E->Info & OF_CBRA) != 0 && (N->Info & OF_CBRA) != 0) {
+ /* Check if both are conditional branches, and the condition of
+ ** the second is the inverse of that of the first. In this case,
+ ** the second branch will never be taken, and we may jump directly
+ ** to the instruction behind this one.
+ */
+ } else if ((E->Info & OF_CBRA) != 0 && (N->Info & OF_CBRA) != 0) {
- 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. 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;
- }
+ /* 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 = CS_GenLabel (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 */
- CS_MoveLabelRef (S, E, LX);
+ /* Move the reference from E to the new label */
+ CS_MoveLabelRef (S, E, LX);
- /* Remember, we had changes */
- ++Changes;
- }
- }
+ /* Remember, we had changes */
+ ++Changes;
+ }
+ }
NextEntry:
- /* Next entry */
- ++I;
+ /* Next entry */
+ ++I;
}
/*****************************************************************************/
-/* Optimize jsr/rts */
+/* Optimize jsr/rts */
/*****************************************************************************/
unsigned OptRTS (CodeSeg* S)
/* Optimize subroutine calls followed by an RTS. The subroutine call will get
- * replaced by a jump. Don't bother to delete the RTS if it does not have a
- * label, the dead code elimination should take care of it.
- */
+** replaced by a jump. Don't bother to delete the RTS if it does not have a
+** label, the dead code elimination should take care of it.
+*/
{
unsigned Changes = 0;
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
- CodeEntry* N;
+ CodeEntry* N;
- /* Get this entry */
- CodeEntry* E = CS_GetEntry (S, I);
+ /* Get this entry */
+ CodeEntry* E = CS_GetEntry (S, I);
- /* Check if it's a subroutine call and if the following insn is RTS */
- if (E->OPC == OP65_JSR &&
- (N = CS_GetNextEntry (S, I)) != 0 &&
- N->OPC == OP65_RTS) {
+ /* Check if it's a subroutine call and if the following insn is 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 = AM65_BRA;
- CE_ReplaceOPC (E, OP65_JMP);
+ /* Change the jsr to a jmp and use the additional info for a jump */
+ E->AM = AM65_BRA;
+ CE_ReplaceOPC (E, OP65_JMP);
- /* Remember, we had changes */
- ++Changes;
+ /* Remember, we had changes */
+ ++Changes;
- }
+ }
- /* Next entry */
- ++I;
+ /* Next entry */
+ ++I;
}
/*****************************************************************************/
-/* Optimize jump targets */
+/* Optimize jump targets */
/*****************************************************************************/
unsigned OptJumpTarget1 (CodeSeg* S)
/* If the instruction preceeding an unconditional branch is the same as the
- * instruction preceeding the jump target, the jump target may be moved
- * one entry back. This is a size optimization, since the instruction before
- * the branch gets removed.
- */
+** instruction preceeding the jump target, the jump target may be moved
+** one entry back. This is a size optimization, since the instruction before
+** the branch gets removed.
+*/
{
unsigned Changes = 0;
- CodeEntry* E1; /* Entry 1 */
- CodeEntry* E2; /* Entry 2 */
- CodeEntry* T1; /* Jump target entry 1 */
- CodeLabel* TL1; /* Target label 1 */
+ CodeEntry* E1; /* Entry 1 */
+ CodeEntry* E2; /* Entry 2 */
+ CodeEntry* T1; /* Jump target entry 1 */
+ CodeLabel* TL1; /* Target label 1 */
/* Walk over the entries */
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
- /* Get next entry */
- E2 = CS_GetNextEntry (S, I);
-
- /* 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;
- }
-
- /* Get the entry preceeding the jump */
- E1 = CS_GetEntry (S, I);
-
- /* Check if both preceeding instructions are identical */
- if (!CodeEntriesAreEqual (E1, T1)) {
- /* Not equal, try next */
+ /* Get next entry */
+ E2 = CS_GetNextEntry (S, I);
+
+ /* Check if we have a jump or branch without a label attached, and
+ ** a jump target, which is not attached to the jump itself
+ */
+ if (E2 != 0 &&
+ (E2->Info & OF_UBRA) != 0 &&
+ !CE_HasLabel (E2) &&
+ 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;
- }
+ }
- /* Get the label for the instruction preceeding the jump target.
- * This routine will create a new label if the instruction does
- * not already have one.
- */
- TL1 = CS_GenLabel (S, T1);
+ /* The entry preceeding the branch target may not be the branch
+ ** insn.
+ */
+ if (T1 == E2) {
+ goto NextEntry;
+ }
+
+ /* Get the entry preceeding the jump */
+ E1 = CS_GetEntry (S, I);
+
+ /* Check if both preceeding instructions are identical */
+ if (!CodeEntriesAreEqual (E1, T1)) {
+ /* Not equal, try next */
+ goto NextEntry;
+ }
- /* Change the jump target to point to this new label */
- CS_MoveLabelRef (S, E2, TL1);
+ /* Get the label for the instruction preceeding the jump target.
+ ** This routine will create a new label if the instruction does
+ ** not already have one.
+ */
+ TL1 = CS_GenLabel (S, T1);
- /* If the instruction preceeding the jump has labels attached,
- * move references to this label to the new label.
- */
- if (CE_HasLabel (E1)) {
- CS_MoveLabels (S, E1, T1);
- }
+ /* Change the jump target to point to this new label */
+ CS_MoveLabelRef (S, E2, TL1);
- /* Remove the entry preceeding the jump */
- CS_DelEntry (S, I);
+ /* If the instruction preceeding the jump has labels attached,
+ ** move references to this label to the new label.
+ */
+ if (CE_HasLabel (E1)) {
+ CS_MoveLabels (S, E1, T1);
+ }
+
+ /* Remove the entry preceeding the jump */
+ CS_DelEntry (S, I);
- /* Remember, we had changes */
- ++Changes;
+ /* Remember, we had changes */
+ ++Changes;
- } else {
+ } else {
NextEntry:
/* Next entry */
++I;
unsigned OptJumpTarget2 (CodeSeg* S)
/* If a bcs jumps to a sec insn or a bcc jumps to clc, skip this insn, since
- * it's job is already done.
- */
+** it's job is already done.
+*/
{
unsigned Changes = 0;
/* New jump label */
CodeLabel* L;
- /* Get next entry */
- CodeEntry* E = CS_GetEntry (S, I);
+ /* Get next entry */
+ CodeEntry* E = CS_GetEntry (S, I);
/* Check if this is a bcc insn */
if (E->OPC == OP65_BCC || E->OPC == OP65_JCC) {
}
/* Get the owner insn of the jump target and check if it's the one, we
- * will skip if present.
- */
+ ** will skip if present.
+ */
T = E->JumpTo->Owner;
if (T->OPC != OPC) {
goto NextEntry;
}
/* Get the label for the instruction following the jump target.
- * This routine will create a new label if the instruction does
- * not already have one.
- */
+ ** This routine will create a new label if the instruction does
+ ** not already have one.
+ */
L = CS_GenLabel (S, N);
/* Change the jump target to point to this new label */
+unsigned OptJumpTarget3 (CodeSeg* S)
+/* Jumps to load instructions of a register, that do already have the matching
+** register contents may skip the load instruction, since it's job is already
+** done.
+*/
+{
+ unsigned Changes = 0;
+ unsigned I;
+
+ /* Walk over the entries */
+ I = 0;
+ while (I < CS_GetEntryCount (S)) {
+
+ CodeEntry* N;
+
+ /* Get next entry */
+ CodeEntry* E = CS_GetEntry (S, I);
+
+ /* Check if this is a load insn with a label and the next insn is not
+ ** a conditional branch that needs the flags from the load.
+ */
+ if ((E->Info & OF_LOAD) != 0 &&
+ CE_IsConstImm (E) &&
+ CE_HasLabel (E) &&
+ (N = CS_GetNextEntry (S, I)) != 0 &&
+ !CE_UseLoadFlags (N)) {
+
+ unsigned J;
+ int K;
+
+ /* New jump label */
+ CodeLabel* LN = 0;
+
+ /* Walk over all insn that jump here */
+ for (J = 0; J < CE_GetLabelCount (E); ++J) {
+
+ /* Get the label */
+ CodeLabel* L = CE_GetLabel (E, J);
+
+ /* Loop over all insn that reference this label. Since we may
+ ** eventually remove a reference in the loop, we must loop
+ ** from end down to start.
+ */
+ for (K = CL_GetRefCount (L) - 1; K >= 0; --K) {
+
+ /* Get the entry that jumps here */
+ CodeEntry* Jump = CL_GetRef (L, K);
+
+ /* Get the register info from this insn */
+ short Val = RegVal (E->Chg, &Jump->RI->Out2);
+
+ /* Check if the outgoing value is the one thats's loaded */
+ if (Val == (unsigned char) E->Num) {
+
+ /* OK, skip the insn. First, generate a label for the
+ ** next insn after E.
+ */
+ if (LN == 0) {
+ LN = CS_GenLabel (S, N);
+ }
+
+ /* Change the jump target to point to this new label */
+ CS_MoveLabelRef (S, Jump, LN);
+
+ /* Remember that we had changes */
+ ++Changes;
+ }
+ }
+ }
+
+ }
+
+ /* Next entry */
+ ++I;
+ }
+
+ /* Return the number of changes made */
+ return Changes;
+}
+
+
+
/*****************************************************************************/
-/* Optimize conditional branches */
+/* Optimize conditional branches */
/*****************************************************************************/
unsigned OptCondBranches1 (CodeSeg* S)
/* Performs several optimization steps:
- *
- * - If an immidiate load of a register is followed by a conditional jump that
- * is never taken because the load of the register sets the flags in such a
- * manner, remove the conditional branch.
- * - If the conditional branch is always taken because of the register load,
- * replace it by a jmp.
- * - If a conditional branch jumps around an unconditional branch, remove the
- * conditional branch and make the jump a conditional branch with the
- * inverse condition of the first one.
- */
+**
+** - If an immediate load of a register is followed by a conditional jump that
+** is never taken because the load of the register sets the flags in such a
+** manner, remove the conditional branch.
+** - If the conditional branch is always taken because of the register load,
+** replace it by a jmp.
+** - If a conditional branch jumps around an unconditional branch, remove the
+** conditional branch and make the jump a conditional branch with the
+** inverse condition of the first one.
+*/
{
unsigned Changes = 0;
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
- CodeEntry* N;
- CodeLabel* L;
+ CodeEntry* N;
+ CodeLabel* L;
- /* Get next entry */
- CodeEntry* E = CS_GetEntry (S, I);
+ /* Get next entry */
+ 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 == 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 */
+ /* Check if it's a register load */
+ 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);
+ /* 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) ||
- (BC == BC_PL && (E->Num & 0x80) != 0) ||
- (BC == BC_MI && (E->Num & 0x80) == 0)) {
+ /* Check the argument against the branch condition */
+ 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 */
- CS_DelEntry (S, I+1);
+ /* Remove the conditional branch */
+ CS_DelEntry (S, I+1);
- /* Remember, we had changes */
- ++Changes;
+ /* Remember, we had changes */
+ ++Changes;
- } 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)) {
+ } 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 */
- CE_ReplaceOPC (N, OP65_JMP);
+ /* The branch is always taken, replace it by a jump */
+ CE_ReplaceOPC (N, OP65_JMP);
- /* Remember, we had changes */
- ++Changes;
- }
+ /* 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 = 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 */
+ 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.
- */
- CE_ReplaceOPC (N, GetInverseBranch (E->OPC));
+ /* Replace the jump by a conditional branch with the inverse branch
+ ** condition than the branch around it.
+ */
+ CE_ReplaceOPC (N, GetInverseBranch (E->OPC));
- /* Remove the conditional branch */
- CS_DelEntry (S, I);
+ /* Remove the conditional branch */
+ CS_DelEntry (S, I);
- /* Remember, we had changes */
- ++Changes;
+ /* Remember, we had changes */
+ ++Changes;
- }
+ }
- /* Next entry */
- ++I;
+ /* Next entry */
+ ++I;
}
unsigned OptCondBranches2 (CodeSeg* S)
/* If on entry to a "rol a" instruction the accu is zero, and a beq/bne follows,
- * we can remove the rol and branch on the state of the carry.
- */
+** we can remove the rol and branch on the state of the carry flag.
+*/
{
unsigned Changes = 0;
-
- /* Generate register info for this step */
- CS_GenRegInfo (S);
+ unsigned I;
/* Walk over the entries */
- unsigned I = 0;
+ I = 0;
while (I < CS_GetEntryCount (S)) {
- CodeEntry* N;
+ CodeEntry* N;
- /* Get next entry */
- CodeEntry* E = CS_GetEntry (S, I);
+ /* Get next entry */
+ CodeEntry* E = CS_GetEntry (S, I);
- /* Check if it's a rol insn with A in accu and a branch follows */
- if (E->OPC == OP65_ROL &&
+ /* Check if it's a rol insn with A in accu and a branch follows */
+ if (E->OPC == OP65_ROL &&
E->AM == AM65_ACC &&
E->RI->In.RegA == 0 &&
!CE_HasLabel (E) &&
(N->Info & OF_ZBRA) != 0 &&
!RegAUsed (S, I+1)) {
- /* Replace the branch condition */
- switch (GetBranchCond (N->OPC)) {
+ /* Replace the branch condition */
+ switch (GetBranchCond (N->OPC)) {
case BC_EQ: CE_ReplaceOPC (N, OP65_JCC); break;
case BC_NE: CE_ReplaceOPC (N, OP65_JCS); break;
default: Internal ("Unknown branch condition in OptCondBranches2");
/* Remember, we had changes */
++Changes;
+ }
- }
-
- /* Next entry */
- ++I;
-
+ /* Next entry */
+ ++I;
}
- /* Free register info */
- CS_FreeRegInfo (S);
-
/* Return the number of changes made */
return Changes;
}
/*****************************************************************************/
-/* Remove unused loads and stores */
+/* Remove unused loads and stores */
/*****************************************************************************/
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
- CodeEntry* N;
-
- /* Get next entry */
- CodeEntry* E = CS_GetEntry (S, I);
-
- /* 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 or transfer it is */
- unsigned R;
- switch (E->OPC) {
- 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) & R) == 0) {
-
- /* Register value is not used, remove the load */
- CS_DelEntry (S, I);
-
- /* Remember, we had changes. Account the deleted entry in I. */
- ++Changes;
- --I;
-
- }
- }
+ CodeEntry* N;
+
+ /* Get next entry */
+ CodeEntry* E = CS_GetEntry (S, I);
+
+ /* 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 or transfer it is */
+ unsigned R;
+ switch (E->OPC) {
+ 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) & R) == 0) {
+
+ /* Register value is not used, remove the load */
+ CS_DelEntry (S, I);
+
+ /* Remember, we had changes. Account the deleted entry in I. */
+ ++Changes;
+ --I;
+
+ }
+ }
NextEntry:
- /* Next entry */
- ++I;
+ /* Next entry */
+ ++I;
}
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
- /* Get next entry */
- CodeEntry* E = CS_GetEntry (S, I);
+ /* 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 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;
+ /* 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) {
+ /* 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);
+ /* Register value is not used, remove the load */
+ CS_DelEntry (S, I);
- /* Remember, we had changes */
- ++Changes;
+ /* Remember, we had changes */
+ ++Changes;
/* Continue with next insn */
continue;
- }
- }
+ }
+ }
- /* Next entry */
- ++I;
+ /* Next entry */
+ ++I;
}
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_IsKnownImm (E, In->RegA) && /* Value to be loaded is known */
- (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_IsKnownImm (E, In->RegX) && /* Value to be loaded is known */
- (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_IsKnownImm (E, In->RegY) && /* Value to be loaded is known */
- (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 == ZPRegVal (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 == ZPRegVal (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 == ZPRegVal (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 ((CPUIsets[CPU] & CPU_ISET_65SC02) != 0 && E->AM == AM65_ZP) {
- if (ZPRegVal (E->Chg, In) == 0) {
+ 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_IsKnownImm (E, In->RegA) && /* Value to be loaded is known */
+ (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_IsKnownImm (E, In->RegX) && /* Value to be loaded is known */
+ (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_IsKnownImm (E, In->RegY) && /* Value to be loaded is known */
+ (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 == ZPRegVal (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 == ZPRegVal (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 == ZPRegVal (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 ((CPUIsets[CPU] & CPU_ISET_65SC02) != 0 && E->AM == AM65_ZP) {
+ if (ZPRegVal (E->Chg, In) == 0) {
Delete = 1;
}
- }
- break;
+ }
+ break;
- case OP65_TAX:
+ 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:
+ 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:
+ 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:
+ 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;
+ 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;
+ default:
+ break;
- }
+ }
- /* Delete the entry if requested */
- if (Delete) {
+ /* Delete the entry if requested */
+ if (Delete) {
- /* Register value is not used, remove the load */
- CS_DelEntry (S, I);
+ /* Register value is not used, remove the load */
+ CS_DelEntry (S, I);
- /* Remember, we had changes */
- ++Changes;
+ /* Remember, we had changes */
+ ++Changes;
- } else {
+ } else {
- /* Next entry */
- ++I;
+ /* Next entry */
+ ++I;
- }
+ }
}
- /* Free register info */
- CS_FreeRegInfo (S);
-
/* Return the number of changes made */
return Changes;
}
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 &&
+ 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);
+ /* Register has already the correct value, remove the load */
+ CS_DelEntry (S, I+1);
- /* Remember, we had changes */
- ++Changes;
+ /* Remember, we had changes */
+ ++Changes;
- }
+ }
- /* Next entry */
- ++I;
+ /* Next entry */
+ ++I;
}
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 we have two transfer instructions */
- 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;
- }
+ CodeEntry* N;
+ CodeEntry* X;
+ CodeEntry* P;
+
+ /* Get next entry */
+ CodeEntry* E = CS_GetEntry (S, I);
+
+ /* Check if we have two transfer instructions */
+ 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;
- }
- }
+ 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;
+ /* Next entry */
+ ++I;
}
unsigned OptTransfers2 (CodeSeg* S)
/* Replace loads followed by a register transfer by a load with the second
- * register if possible.
- */
+** register if possible.
+*/
{
unsigned Changes = 0;
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
- CodeEntry* N;
+ CodeEntry* N;
- /* Get next entry */
- CodeEntry* E = CS_GetEntry (S, I);
+ /* Get next entry */
+ CodeEntry* E = CS_GetEntry (S, I);
- /* Check if we have a load followed by a transfer where the loaded
- * register is not used later.
- */
- if ((E->Info & OF_LOAD) != 0 &&
- (N = CS_GetNextEntry (S, I)) != 0 &&
- !CE_HasLabel (N) &&
- (N->Info & OF_XFR) != 0 &&
+ /* Check if we have a load followed by a transfer where the loaded
+ ** register is not used later.
+ */
+ if ((E->Info & OF_LOAD) != 0 &&
+ (N = CS_GetNextEntry (S, I)) != 0 &&
+ !CE_HasLabel (N) &&
+ (N->Info & OF_XFR) != 0 &&
GetRegInfo (S, I+2, E->Chg) != E->Chg) {
CodeEntry* X = 0;
X = NewCodeEntry (OP65_LDA, E->AM, E->Arg, 0, N->LI);
} else if (E->OPC == OP65_LDX && N->OPC == OP65_TXA) {
/* LDX/TXA. LDA doesn't support zp,y, so we must map it to
- * abs,y instead.
- */
+ ** abs,y instead.
+ */
am_t AM = (E->AM == AM65_ZPY)? AM65_ABSY : E->AM;
X = NewCodeEntry (OP65_LDA, AM, E->Arg, 0, N->LI);
}
++Changes;
--I; /* Correct for one entry less */
}
- }
+ }
- /* Next entry */
- ++I;
+ /* Next entry */
+ ++I;
}
/* Return the number of changes made */
unsigned OptTransfers3 (CodeSeg* S)
/* Replace a register transfer followed by a store of the second register by a
- * store of the first register if this is possible.
- */
+** store of the first register if this is possible.
+*/
{
unsigned Changes = 0;
unsigned UsedRegs = REG_NONE; /* Track used registers */
} State = Initialize;
/* Walk over the entries. Look for a xfer instruction that is followed by
- * a store later, where the value of the register is not used later.
- */
+ ** a store later, where the value of the register is not used later.
+ */
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
- /* Get next entry */
- CodeEntry* E = CS_GetEntry (S, I);
+ /* Get next entry */
+ CodeEntry* E = CS_GetEntry (S, I);
switch (State) {
case FoundXfer:
/* If we find a conditional jump, abort the sequence, since
- * handling them makes things really complicated.
- */
+ ** handling them makes things really complicated.
+ */
if (E->Info & OF_CBRA) {
/* Switch back to searching */
} else if ((E->Use & XferEntry->Chg) != 0) {
/* It it's a store instruction, and the block is a basic
- * block, proceed. Otherwise restart
- */
+ ** block, proceed. Otherwise restart
+ */
if ((E->Info & OF_STORE) != 0 &&
CS_IsBasicBlock (S, Xfer, I)) {
Store = I;
} else if (E->Chg & XferEntry->Chg) {
/* We *may* add code here to remove the transfer, but I'm
- * currently not sure about the consequences, so I won't
- * do that and bail out instead.
- */
+ ** currently not sure about the consequences, so I won't
+ ** do that and bail out instead.
+ */
I = Xfer;
State = Initialize;
case FoundStore:
/* We are at the instruction behind the store. If the register
- * isn't used later, and we have an address mode match, we can
- * replace the transfer by a store and remove the store here.
- */
+ ** isn't used later, and we have an address mode match, we can
+ ** replace the transfer by a store and remove the store here.
+ */
if ((GetRegInfo (S, I, XferEntry->Chg) & XferEntry->Chg) == 0 &&
(StoreEntry->AM == AM65_ABS ||
StoreEntry->AM == AM65_ZP) &&
(StoreEntry->AM != AM65_ZP ||
(StoreEntry->Chg & UsedRegs) == 0) &&
- !MemAccess (S, Xfer+1, Store-1, StoreEntry->Arg)) {
+ !MemAccess (S, Xfer+1, Store-1, StoreEntry)) {
/* Generate the replacement store insn */
CodeEntry* X = 0;
}
- /* Next entry */
- ++I;
+ /* Next entry */
+ ++I;
}
/* Return the number of changes made */
unsigned OptTransfers4 (CodeSeg* S)
/* Replace a load of a register followed by a transfer insn of the same register
- * by a load of the second register if possible.
- */
+** by a load of the second register if possible.
+*/
{
unsigned Changes = 0;
unsigned Load = 0; /* Index of load insn */
} State = Search;
/* Walk over the entries. Look for a load instruction that is followed by
- * a load later.
- */
+ ** a load later.
+ */
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
- /* Get next entry */
- CodeEntry* E = CS_GetEntry (S, I);
+ /* Get next entry */
+ CodeEntry* E = CS_GetEntry (S, I);
switch (State) {
case FoundLoad:
/* If we find a conditional jump, abort the sequence, since
- * handling them makes things really complicated.
- */
+ ** handling them makes things really complicated.
+ */
if (E->Info & OF_CBRA) {
/* Switch back to searching */
} else if ((E->Use & LoadEntry->Chg) != 0) {
/* It it's a xfer instruction, and the block is a basic
- * block, proceed. Otherwise restart
- */
+ ** block, proceed. Otherwise restart
+ */
if ((E->Info & OF_XFR) != 0 &&
CS_IsBasicBlock (S, Load, I)) {
Xfer = I;
} else if (E->Chg & LoadEntry->Chg) {
/* We *may* add code here to remove the load, but I'm
- * currently not sure about the consequences, so I won't
- * do that and bail out instead.
- */
+ ** currently not sure about the consequences, so I won't
+ ** do that and bail out instead.
+ */
I = Load;
State = Search;
}
case FoundXfer:
/* We are at the instruction behind the xfer. If the register
- * isn't used later, and we have an address mode match, we can
- * replace the transfer by a load and remove the initial load.
- */
+ ** isn't used later, and we have an address mode match, we can
+ ** replace the transfer by a load and remove the initial load.
+ */
if ((GetRegInfo (S, I, LoadEntry->Chg) & LoadEntry->Chg) == 0 &&
(LoadEntry->AM == AM65_ABS ||
LoadEntry->AM == AM65_ZP ||
LoadEntry->AM == AM65_IMM) &&
- !MemAccess (S, Load+1, Xfer-1, LoadEntry->Arg)) {
+ !MemAccess (S, Load+1, Xfer-1, LoadEntry)) {
/* Generate the replacement load insn */
CodeEntry* X = 0;
}
- /* Next entry */
- ++I;
+ /* Next entry */
+ ++I;
}
/* Return the number of changes made */
unsigned Changes = 0;
unsigned Push = 0; /* Index of push insn */
unsigned Pop = 0; /* Index of pop insn */
+ unsigned ChgA = 0; /* Flag for A changed */
enum {
Searching,
FoundPush,
} 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.
- */
+ ** 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)) {
CodeEntry* X;
- /* Get next entry */
- CodeEntry* E = CS_GetEntry (S, I);
+ /* Get next entry */
+ CodeEntry* E = CS_GetEntry (S, I);
switch (State) {
if (E->OPC == OP65_PHA) {
/* Found start of sequence */
Push = I;
+ ChgA = 0;
State = FoundPush;
}
break;
if (E->OPC == OP65_PHA) {
/* Inner push/pop, restart */
Push = I;
+ ChgA = 0;
} else if (E->OPC == OP65_PLA) {
/* Found a matching pop */
Pop = I;
/* Check that the block between Push and Pop is a basic
- * block (one entry, one exit). Otherwise ignore it.
- */
+ ** block (one entry, one exit). Otherwise ignore it.
+ */
if (CS_IsBasicBlock (S, Push, Pop)) {
State = FoundPop;
} else {
/* Go into searching mode again */
State = Searching;
}
+ } else if (E->Chg & REG_A) {
+ ChgA = 1;
}
break;
case FoundPop:
/* We're at the instruction after the PLA.
- * Check for the following conditions:
- * - If this instruction is a store of A, and A is not used
- * later, we may replace the PHA by the store and remove
- * pla if several other conditions are met.
- * - If this instruction is not a conditional branch, and A
- * is unused later, we may remove PHA and PLA.
- */
- if (E->OPC == OP65_STA &&
- !RegAUsed (S, I+1) &&
- !MemAccess (S, Push+1, Pop-1, E->Arg)) {
+ ** Check for the following conditions:
+ ** - If this instruction is a store of A that doesn't use
+ ** another register, if the instruction does not have a
+ ** label, and A is not used later, we may replace the PHA
+ ** by the store and remove pla if several other conditions
+ ** are met.
+ ** - If this instruction is not a conditional branch, and A
+ ** is either unused later, or not changed by the code
+ ** between push and pop, we may remove PHA and PLA.
+ */
+ if (E->OPC == OP65_STA &&
+ (E->AM == AM65_ABS || E->AM == AM65_ZP) &&
+ !CE_HasLabel (E) &&
+ !RegAUsed (S, I+1) &&
+ !MemAccess (S, Push+1, Pop-1, E)) {
/* Insert a STA after the PHA */
X = NewCodeEntry (E->OPC, E->AM, E->Arg, E->JumpTo, E->LI);
++Changes;
} else if ((E->Info & OF_CBRA) == 0 &&
- !RegAUsed (S, I)) {
+ (!RegAUsed (S, I) || !ChgA)) {
/* We can remove the PHA and PLA instructions */
CS_DelEntry (S, Pop);
}
- /* Next entry */
- ++I;
+ /* Next entry */
+ ++I;
}
/* Return the number of changes made */
unsigned OptPrecalc (CodeSeg* S)
/* Replace immediate operations with the accu where the current contents are
- * known by a load of the final value.
- */
+** known by a load of the final value.
+*/
{
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);
+ /* Get next entry */
+ CodeEntry* E = CS_GetEntry (S, I);
- /* Get a pointer to the output registers of the insn */
- const RegContents* Out = &E->RI->Out;
+ /* Get pointers to the input and output registers of the insn */
+ const RegContents* Out = &E->RI->Out;
+ const RegContents* In = &E->RI->In;
/* Argument for LDn and flag */
const char* Arg = 0;
}
break;
- case OP65_ADC:
- case OP65_ASL:
case OP65_EOR:
- case OP65_LSR:
- case OP65_SBC:
if (RegValIsKnown (Out->RegA)) {
/* Accu op zp with known contents */
Arg = MakeHexArg (Out->RegA);
}
break;
+ case OP65_ADC:
+ case OP65_SBC:
+ /* If this is an operation with an immediate operand of zero,
+ ** and the register is zero, the operation won't give us any
+ ** results we don't already have (including the flags), so
+ ** remove it. Something like this is generated as a result of
+ ** a compare where parts of the values are known to be zero.
+ ** The only situation where we need to leave things as they are
+ ** is when V flag is being tested in the next instruction,
+ ** because ADC/SBC #0 always clears it.
+ */
+ if (In->RegA == 0 && CE_IsKnownImm (E, 0x00) &&
+ (E = CS_GetEntry (S, I + 1)) &&
+ E->OPC != OP65_BVC &&
+ E->OPC != OP65_BVS ) {
+ /* 0-0 or 0+0 -> remove */
+ CS_DelEntry (S, I);
+ ++Changes;
+ }
+ break;
+
case OP65_AND:
if (CE_IsKnownImm (E, 0xFF)) {
/* AND with 0xFF, remove */
CS_DelEntry (S, I);
++Changes;
+ } else if (CE_IsKnownImm (E, 0x00)) {
+ /* AND with 0x00, replace by lda #$00 */
+ Arg = MakeHexArg (0x00);
} else if (RegValIsKnown (Out->RegA)) {
/* Accu AND zp with known contents */
Arg = MakeHexArg (Out->RegA);
+ } else if (In->RegA == 0xFF) {
+ /* AND but A contains 0xFF - replace by lda */
+ CE_ReplaceOPC (E, OP65_LDA);
+ ++Changes;
}
break;
/* ORA with zero, remove */
CS_DelEntry (S, I);
++Changes;
+ } else if (CE_IsKnownImm (E, 0xFF)) {
+ /* ORA with 0xFF, replace by lda #$ff */
+ Arg = MakeHexArg (0xFF);
} else if (RegValIsKnown (Out->RegA)) {
/* Accu AND zp with known contents */
Arg = MakeHexArg (Out->RegA);
+ } else if (In->RegA == 0) {
+ /* ORA but A contains 0x00 - replace by lda */
+ CE_ReplaceOPC (E, OP65_LDA);
+ ++Changes;
}
break;
++Changes;
}
- /* Next entry */
- ++I;
+ /* Next entry */
+ ++I;
}
- /* Free register info */
- CS_FreeRegInfo (S);
-
/* Return the number of changes made */
return Changes;
}
/*****************************************************************************/
-/* Optimize branch types */
+/* Optimize branch types */
/*****************************************************************************/
-
+
unsigned OptBranchDist (CodeSeg* S)
/* Change branches for the distance needed. */
{
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
- /* Get next entry */
- CodeEntry* E = CS_GetEntry (S, I);
+ /* Get next entry */
+ CodeEntry* E = CS_GetEntry (S, I);
- /* Check if it's a conditional branch to a local label. */
- if (E->Info & OF_CBRA) {
+ /* Check if it's a conditional branch to a local label. */
+ if (E->Info & OF_CBRA) {
- /* Is this a branch to a local symbol? */
- if (E->JumpTo != 0) {
+ /* Is this a branch to a local symbol? */
+ if (E->JumpTo != 0) {
- /* Check if the branch distance is short */
- int IsShort = IsShortDist (GetBranchDist (S, I, E->JumpTo->Owner));
+ /* 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 && !IsShort) {
- /* Short branch but long distance */
- CE_ReplaceOPC (E, MakeLongBranch (E->OPC));
- ++Changes;
- } else if ((E->Info & OF_LBRA) != 0 && IsShort) {
- /* Long branch but short distance */
- CE_ReplaceOPC (E, MakeShortBranch (E->OPC));
- ++Changes;
- }
+ /* Make the branch short/long according to distance */
+ if ((E->Info & OF_LBRA) == 0 && !IsShort) {
+ /* Short branch but long distance */
+ CE_ReplaceOPC (E, MakeLongBranch (E->OPC));
+ ++Changes;
+ } else if ((E->Info & OF_LBRA) != 0 && IsShort) {
+ /* Long branch but short distance */
+ CE_ReplaceOPC (E, MakeShortBranch (E->OPC));
+ ++Changes;
+ }
- } else if ((E->Info & OF_LBRA) == 0) {
+ } else if ((E->Info & OF_LBRA) == 0) {
- /* Short branch to external symbol - make it long */
- CE_ReplaceOPC (E, MakeLongBranch (E->OPC));
- ++Changes;
+ /* Short branch to external symbol - make it long */
+ CE_ReplaceOPC (E, MakeLongBranch (E->OPC));
+ ++Changes;
- }
+ }
- } else if ((CPUIsets[CPU] & CPU_ISET_65SC02) != 0 &&
- (E->Info & OF_UBRA) != 0 &&
- E->JumpTo != 0 &&
- IsShortDist (GetBranchDist (S, I, E->JumpTo->Owner))) {
+ } else if ((CPUIsets[CPU] & CPU_ISET_65SC02) != 0 &&
+ (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;
- }
+ /* The jump is short and may be replaced by a BRA on the 65C02 CPU */
+ CE_ReplaceOPC (E, OP65_BRA);
+ ++Changes;
+ }
- /* Next entry */
- ++I;
+ /* Next entry */
+ ++I;
}
+/*****************************************************************************/
+/* Optimize indirect loads */
+/*****************************************************************************/
+
+
+
+unsigned OptIndLoads1 (CodeSeg* S)
+/* Change
+**
+** lda (zp),y
+**
+** into
+**
+** lda (zp,x)
+**
+** provided that x and y are both zero.
+*/
+{
+ 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 it's what we're looking for */
+ if (E->OPC == OP65_LDA &&
+ E->AM == AM65_ZP_INDY &&
+ E->RI->In.RegY == 0 &&
+ E->RI->In.RegX == 0) {
+
+ /* Replace by the same insn with other addressing mode */
+ CodeEntry* X = NewCodeEntry (E->OPC, AM65_ZPX_IND, E->Arg, 0, E->LI);
+ CS_InsertEntry (S, X, I+1);
+
+ /* Remove the old insn */
+ CS_DelEntry (S, I);
+ ++Changes;
+ }
+
+ /* Next entry */
+ ++I;
+
+ }
+
+ /* Return the number of changes made */
+ return Changes;
+}
+
+
+
+unsigned OptIndLoads2 (CodeSeg* S)
+/* Change
+**
+** lda (zp,x)
+**
+** into
+**
+** lda (zp),y
+**
+** provided that x and y are both zero.
+*/
+{
+ 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 it's what we're looking for */
+ if (E->OPC == OP65_LDA &&
+ E->AM == AM65_ZPX_IND &&
+ E->RI->In.RegY == 0 &&
+ E->RI->In.RegX == 0) {
+
+ /* Replace by the same insn with other addressing mode */
+ CodeEntry* X = NewCodeEntry (E->OPC, AM65_ZP_INDY, E->Arg, 0, E->LI);
+ CS_InsertEntry (S, X, I+1);
+
+ /* Remove the old insn */
+ CS_DelEntry (S, I);
+ ++Changes;
+ }
+
+ /* Next entry */
+ ++I;
+
+ }
+
+ /* Return the number of changes made */
+ return Changes;
+}
projects / cc65 / blobdiff