-/* Structure that holds the needed data */
+/* Flags for the functions */
+typedef enum {
+ STOP_NONE = 0x00, /* Nothing special */
+ STOP_A_UNUSED = 0x01, /* Call only if a unused later */
+ STOP_A_KNOWN = 0x02, /* Call only if A is known */
+ STOP_X_ZERO = 0x04 /* Call only if X is zero */
+} STOP_FLAGS;
+
+/* Structure forward decl */
typedef struct StackOpData StackOpData;
+
+/* Structure that describes an optimizer subfunction for a specific op */
+typedef unsigned (*OptFunc) (StackOpData* D);
+typedef struct OptFuncDesc OptFuncDesc;
+struct OptFuncDesc {
+ const char* Name; /* Name of the replaced runtime function */
+ OptFunc Func; /* Function pointer */
+ STOP_FLAGS Flags; /* Flags */
+};
+
+/* Structure that holds the needed data */
struct StackOpData {
- CodeSeg* Code; /* Pointer to code segment */
- unsigned Flags; /* Flags to remember things */
- unsigned PushIndex; /* Index of call to pushax in codeseg */
- unsigned OpIndex; /* Index of actual operation */
- CodeEntry* PrevEntry; /* Entry before the call to pushax */
- CodeEntry* PushEntry; /* Pointer to entry with call to pushax */
- CodeEntry* OpEntry; /* Pointer to entry with op */
- CodeEntry* NextEntry; /* Entry after the op */
- const char* ZPLo; /* Lo byte of zero page loc to use */
- const char* ZPHi; /* Hi byte of zero page loc to use */
- unsigned IP; /* Insertion point used by some routines */
+ CodeSeg* Code; /* Pointer to code segment */
+ unsigned Flags; /* Flags to remember things */
+
+ /* Pointer to optimizer subfunction description */
+ const OptFuncDesc* OptFunc;
+
+ /* ZP register usage inside the sequence */
+ unsigned UsedRegs;
+
+ /* Several indices if insns in the code segment */
+ int LoadAIndex; /* Index of load insns, -1 = invalid */
+ int LoadXIndex;
+ int LoadYIndex;
+ int PushIndex; /* Index of call to pushax in codeseg */
+ int OpIndex; /* Index of actual operation */
+
+ CodeEntry* PrevEntry; /* Entry before the call to pushax */
+ CodeEntry* PushEntry; /* Pointer to entry with call to pushax */
+ CodeEntry* OpEntry; /* Pointer to entry with op */
+ CodeEntry* NextEntry; /* Entry after the op */
+ const char* ZPLo; /* Lo byte of zero page loc to use */
+ const char* ZPHi; /* Hi byte of zero page loc to use */
+ unsigned IP; /* Insertion point used by some routines */
};
/* Flags returned by DirectOp */
-static unsigned AdjustStackOffset (CodeSeg* S, unsigned Start, unsigned Stop,
- unsigned Offs)
-/* Adjust the offset for all stack accesses in the range Start to Stop, both
- * inclusive. The function returns the number of instructions that have been
- * inserted.
+static void AdjustStackOffset (StackOpData* D, unsigned Offs)
+/* Adjust the offset for all stack accesses in the range PushIndex to OpIndex.
+ * OpIndex is adjusted according to the insertions.
*/
{
- /* Number of inserted instructions */
- unsigned Inserted = 0;
-
/* Walk over all entries */
- unsigned I = Start;
- while (I <= Stop) {
+ int I = D->PushIndex + 1;
+ while (I < D->OpIndex) {
- CodeEntry* E = CS_GetEntry (S, I);
+ CodeEntry* E = CS_GetEntry (D->Code, I);
int NeedCorrection = 0;
if ((E->Use & REG_SP) != 0) {
if (NeedCorrection) {
- CodeEntry* P;
-
- /* If the Y register value is needed later, we have to reload the
- * register after changing it.
- */
- int NeedY = RegYUsed (S, I+1);
- unsigned YVal = E->RI->In.RegY;
-
/* Get the code entry before this one. If it's a LDY, adjust the
* value.
*/
- P = CS_GetPrevEntry (S, I);
+ CodeEntry* P = CS_GetPrevEntry (D->Code, I);
if (P && P->OPC == OP65_LDY && CE_IsConstImm (P)) {
- /* The Y load is just before the stack access, adjust it */
- CE_SetNumArg (P, P->Num - Offs);
+ /* The Y load is just before the stack access, adjust it */
+ CE_SetNumArg (P, P->Num - Offs);
} else {
- /* Insert a new load instruction before the stack access */
- const char* Arg = MakeHexArg (YVal - Offs);
- CodeEntry* X = NewCodeEntry (OP65_LDY, AM65_IMM, Arg, 0, E->LI);
- CS_InsertEntry (S, X, I);
+ /* Insert a new load instruction before the stack access */
+ const char* Arg = MakeHexArg (E->RI->In.RegY - Offs);
+ CodeEntry* X = NewCodeEntry (OP65_LDY, AM65_IMM, Arg, 0, E->LI);
+ CS_InsertEntry (D->Code, X, I++);
/* One more inserted entries */
- ++Inserted;
- ++Stop;
-
- /* Be sure to skip the stack access for the next round */
- ++I;
+ ++D->OpIndex;
}
/* If we need the value of Y later, be sure to reload it */
- if (NeedY) {
- const char* Arg = MakeHexArg (YVal);
+ if (RegYUsed (D->Code, I+1)) {
+ const char* Arg = MakeHexArg (E->RI->In.RegY);
CodeEntry* X = NewCodeEntry (OP65_LDY, AM65_IMM, Arg, 0, E->LI);
- CS_InsertEntry (S, X, I+1);
+ CS_InsertEntry (D->Code, X, I+1);
/* One more inserted entries */
- ++Inserted;
- ++Stop;
+ ++D->OpIndex;
- /* Skip this instruction int the next round */
+ /* Skip this instruction in the next round */
++I;
}
}
/* Next entry */
++I;
}
-
- /* Return the number of inserted entries */
- return Inserted;
}
-static void InsertEntry (StackOpData* D, CodeEntry* E, unsigned Index)
+static void InsertEntry (StackOpData* D, CodeEntry* E, int Index)
/* Insert a new entry. Depending on Index, D->PushIndex and D->OpIndex will
* be adjusted by this function.
*/
-static void DelEntry (StackOpData* D, unsigned Index)
+static void DelEntry (StackOpData* D, int Index)
/* Delete an entry. Depending on Index, D->PushIndex and D->OpIndex will be
* adjusted by this function, and PushEntry/OpEntry may get invalidated.
*/
-/* Flags for the functions */
-typedef enum {
- STOP_NONE = 0x00, /* Nothing special */
- STOP_A_UNUSED = 0x01, /* Call only if a unused later */
- STOP_A_KNOWN = 0x02, /* Call only if A is known */
- STOP_X_ZERO = 0x04 /* Call only if X is zero */
-} STOP_FLAGS;
-
-
-typedef unsigned (*OptFunc) (StackOpData* D);
-typedef struct OptFuncDesc OptFuncDesc;
-struct OptFuncDesc {
- const char* Name; /* Name of the replaced runtime function */
- OptFunc Func; /* Function pointer */
- STOP_FLAGS Flags; /* Flags */
-};
-
static const OptFuncDesc FuncTable[] = {
{ "__bzero", Opt___bzero, STOP_X_ZERO | STOP_A_KNOWN },
{ "staspidx", Opt_staspidx, STOP_NONE },
+static void ResetStackOpData (StackOpData* Data)
+/* Reset the given data structure */
+{
+ Data->Flags = 0;
+ Data->OptFunc = 0;
+
+ Data->LoadAIndex = -1;
+ Data->LoadXIndex = -1;
+ Data->LoadYIndex = -1;
+ Data->PushIndex = -1;
+ Data->OpIndex = -1;
+
+ Data->UsedRegs = REG_NONE;
+}
+
+
+
+static int PreCondOk (StackOpData* D)
+/* Check if the preconditions for a call to the optimizer subfunction are
+ * satisfied. As a side effect, this function will also choose the zero page
+ * register to use.
+ */
+{
+ /* Check the flags */
+ if ((D->OptFunc->Flags & STOP_A_UNUSED) != 0 &&
+ RegAUsed (D->Code, D->OpIndex+1)) {
+ /* Cannot optimize */
+ return 0;
+ } else if ((D->OptFunc->Flags & STOP_A_KNOWN) != 0 &&
+ RegValIsUnknown (D->OpEntry->RI->In.RegA)) {
+ /* Cannot optimize */
+ return 0;
+ } else if ((D->OptFunc->Flags & STOP_X_ZERO) != 0 &&
+ D->OpEntry->RI->In.RegX != 0) {
+ /* Cannot optimize */
+ return 0;
+ }
+
+ /* Determine the zero page locations to use */
+ if ((D->UsedRegs & REG_SREG) == REG_NONE) {
+ D->ZPLo = "sreg";
+ D->ZPHi = "sreg+1";
+ } else if ((D->UsedRegs & REG_PTR1) == REG_NONE) {
+ D->ZPLo = "ptr1";
+ D->ZPHi = "ptr1+1";
+ } else if ((D->UsedRegs & REG_PTR2) == REG_NONE) {
+ D->ZPLo = "ptr2";
+ D->ZPHi = "ptr2+1";
+ } else {
+ /* No registers available */
+ return 0;
+ }
+
+ /* Determine if we have a basic block */
+ return CS_IsBasicBlock (D->Code, D->PushIndex, D->OpIndex);
+}
+
+
+
/*****************************************************************************/
/* Code */
/*****************************************************************************/
unsigned OptStackOps (CodeSeg* S)
/* Optimize operations that take operands via the stack */
{
- unsigned Changes = 0; /* Number of changes in one run */
- int InSeq = 0; /* Inside a sequence */
- unsigned Push = 0; /* Index of pushax */
- unsigned UsedRegs = 0; /* Zeropage registers used in sequence */
- unsigned I;
+ unsigned Changes = 0; /* Number of changes in one run */
+ StackOpData Data;
+ unsigned I;
+
+ enum {
+ Searching,
+ FoundPush,
+ FoundOp
+ } State = Searching;
/* Generate register info */
CS_GenRegInfo (S);
+ /* Clear Data */
+ Data.Code = S;
+ ResetStackOpData (&Data);
+
/* Look for a call to pushax followed by a call to some other function
* that takes it's first argument on the stack, and the second argument
* in the primary register.
I = 0;
while (I < CS_GetEntryCount (S)) {
- /* Get the next entry */
- CodeEntry* E = CS_GetEntry (S, I);
-
- /* Handling depends if we're inside a sequence or not */
- if (InSeq) {
-
- /* If we are using the stack, and we don't have "indirect Y"
- * addressing mode, or the value of Y is unknown, or less than
- * two, we cannot cope with this piece of code. Having an unknown
- * value of Y means that we cannot correct the stack offset, while
- * having an offset less than two means that the code works with
- * the value on stack which is to be removed.
- */
- if ((E->Use & REG_SP) != 0 &&
- (E->AM != AM65_ZP_INDY || RegValIsUnknown (E->RI->In.RegY) ||
- E->RI->In.RegY < 2)) {
-
- /* All this stuff is not allowed in a sequence */
- InSeq = 0;
-
- } else if (E->OPC == OP65_JSR) {
-
- /* Subroutine call: Check if this is one of our functions */
- const OptFuncDesc* F = FindFunc (E->Arg);
- if (F) {
-
- StackOpData Data;
- int PreCondOk = 1;
-
- /* Check the flags */
- if ((F->Flags & STOP_A_UNUSED) != 0 && RegAUsed (S, I+1)) {
- /* Cannot optimize */
- PreCondOk = 0;
- } else if ((F->Flags & STOP_A_KNOWN) != 0 && RegValIsUnknown (E->RI->In.RegA)) {
- /* Cannot optimize */
- PreCondOk = 0;
- } else if ((F->Flags & STOP_X_ZERO) != 0 && E->RI->In.RegX != 0) {
- /* Cannot optimize */
- PreCondOk = 0;
+ /* Get the next entry */
+ CodeEntry* E = CS_GetEntry (S, I);
+
+ /* Actions depend on state */
+ switch (State) {
+
+ case Searching:
+ /* While searching, track register load insns, so we can tell
+ * what is in a register once pushax is encountered.
+ */
+ if (CE_IsCallTo (E, "pushax")) {
+ Data.PushIndex = I;
+ State = FoundPush;
+ } else if (E->Info & OF_LOAD) {
+ if (E->Chg & REG_A) {
+ Data.LoadAIndex = I;
}
-
- /* Determine the zero page locations to use */
- if (PreCondOk) {
- UsedRegs |= GetRegInfo (S, I+1, REG_SREG | REG_PTR1 | REG_PTR2);
- if ((UsedRegs & REG_SREG) == REG_NONE) {
- /* SREG is available */
- Data.ZPLo = "sreg";
- Data.ZPHi = "sreg+1";
- } else if ((UsedRegs & REG_PTR1) == REG_NONE) {
- Data.ZPLo = "ptr1";
- Data.ZPHi = "ptr1+1";
- } else if ((UsedRegs & REG_PTR2) == REG_NONE) {
- Data.ZPLo = "ptr2";
- Data.ZPHi = "ptr2+1";
- } else {
- /* No registers available */
- PreCondOk = 0;
- }
- }
-
- /* Determine if we have a basic block */
- if (PreCondOk) {
- PreCondOk = CS_IsBasicBlock (S, Push, I);
+ if (E->Chg & REG_X) {
+ Data.LoadXIndex = I;
+ }
+ if (E->Chg & REG_Y) {
+ Data.LoadYIndex = I;
+ }
+ } else if (E->Info & OF_XFR) {
+ switch (E->OPC) {
+ case OP65_TAX: Data.LoadXIndex = Data.LoadAIndex; break;
+ case OP65_TAY: Data.LoadYIndex = Data.LoadAIndex; break;
+ case OP65_TXA: Data.LoadAIndex = Data.LoadXIndex; break;
+ case OP65_TYA: Data.LoadAIndex = Data.LoadYIndex; break;
+ default: break;
}
-
- /* If preconditions are ok, call the optimizer function */
- if (PreCondOk) {
-
- /* Adjust stack offsets */
- Data.OpIndex = I + AdjustStackOffset (S, Push, I, 2);
-
- /* Prepare the remainder of the data structure */
- Data.Code = S;
- Data.Flags = 0;
- Data.PushIndex = Push;
- Data.PrevEntry = CS_GetPrevEntry (S, Data.PushIndex);
- Data.PushEntry = CS_GetEntry (S, Data.PushIndex);
- Data.OpEntry = E;
- Data.NextEntry = CS_GetNextEntry (S, Data.OpIndex);
-
- /* Call the optimizer function */
- Changes += F->Func (&Data);
-
- /* Regenerate register info */
- CS_GenRegInfo (S);
- }
-
- /* End of sequence */
- InSeq = 0;
-
- } else if (strcmp (E->Arg, "pushax") == 0) {
- /* Restart the sequence */
- Push = I;
- UsedRegs = REG_NONE;
- } else if (HarmlessCall (E->Arg)) {
- /* Track zeropage register usage */
- UsedRegs |= (E->Use | E->Chg);
} else {
- /* A call to an unkown subroutine ends the sequence */
- InSeq = 0;
- }
-
- } else {
- /* Other stuff: Track zeropage register usage */
- UsedRegs |= (E->Use | E->Chg);
- }
+ if (E->Chg & REG_A) {
+ Data.LoadAIndex = -1;
+ }
+ if (E->Chg & REG_X) {
+ Data.LoadXIndex = -1;
+ }
+ if (E->Chg & REG_Y) {
+ Data.LoadYIndex = -1;
+ }
+ }
+ break;
+
+ case FoundPush:
+ /* We' found a pushax before. Search for a stack op that may
+ * follow and in the meantime, track zeropage usage and check
+ * for code that will disable us from translating the sequence.
+ */
+ if (E->OPC == OP65_JSR) {
+
+ /* Subroutine call: Check if this is one of the functions,
+ * we're going to replace.
+ */
+ Data.OptFunc = FindFunc (E->Arg);
+ if (Data.OptFunc) {
+ /* Remember the op index and go on */
+ Data.OpIndex = I;
+ Data.OpEntry = E;
+ State = FoundOp;
+ break;
+ } else if (HarmlessCall (E->Arg)) {
+ /* Track zeropage register usage */
+ Data.UsedRegs |= (E->Use | E->Chg);
+ } else {
+ /* A call to an unkown subroutine: We need to start
+ * over after the last pushax. Note: This will also
+ * happen if we encounter a call to pushax!
+ */
+ I = Data.PushIndex;
+ ResetStackOpData (&Data);
+ State = Searching;
+ break;
+ }
- } else if (CE_IsCallTo (E, "pushax")) {
+ } else if ((E->Use & REG_SP) != 0 &&
+ (E->AM != AM65_ZP_INDY || RegValIsUnknown (E->RI->In.RegY) ||
+ E->RI->In.RegY < 2)) {
+
+ /* If we are using the stack, and we don't have "indirect Y"
+ * addressing mode, or the value of Y is unknown, or less
+ * than two, we cannot cope with this piece of code. Having
+ * an unknown value of Y means that we cannot correct the
+ * stack offset, while having an offset less than two means
+ * that the code works with the value on stack which is to
+ * be removed.
+ */
+ I = Data.PushIndex;
+ ResetStackOpData (&Data);
+ State = Searching;
+ break;
- /* This starts a sequence */
- Push = I;
- UsedRegs = REG_NONE;
- InSeq = 1;
+ } else {
+ /* Other stuff: Track zeropage register usage */
+ Data.UsedRegs |= (E->Use | E->Chg);
+ }
+ break;
+
+ case FoundOp:
+ /* Track zero page location usage beyond this point */
+ Data.UsedRegs |= GetRegInfo (S, I, REG_SREG | REG_PTR1 | REG_PTR2);
+
+ /* Check the preconditions. If they aren't ok, reset the insn
+ * pointer to the pushax and start over. We will loose part of
+ * load tracking but at least a/x has probably lost between
+ * pushax and here and will be tracked again when restarting.
+ */
+ if (!PreCondOk (&Data)) {
+ I = Data.PushIndex;
+ ResetStackOpData (&Data);
+ State = Searching;
+ break;
+ }
+
+ /* Preconditions are ok, so call the optimizer function */
+
+ /* Adjust stack offsets to account for the upcoming removal */
+ AdjustStackOffset (&Data, 2);
+
+ /* Prepare the remainder of the data structure */
+ Data.PrevEntry = CS_GetPrevEntry (S, Data.PushIndex);
+ Data.PushEntry = CS_GetEntry (S, Data.PushIndex);
+ Data.OpEntry = CS_GetEntry (S, Data.OpIndex);
+ Data.NextEntry = CS_GetNextEntry (S, Data.OpIndex);
+
+ /* Call the optimizer function */
+ Changes += Data.OptFunc->Func (&Data);
+
+ /* Regenerate register info */
+ CS_GenRegInfo (S);
+
+ /* Done */
+ ResetStackOpData (&Data);
+ State = Searching;
+ break;
}
projects / cc65 / commitdiff