/* */
/* */
/* */
-/* (C) 2001 Ullrich von Bassewitz */
+/* (C) 2001-2002 Ullrich von Bassewitz */
/* Wacholderweg 14 */
/* D-70597 Stuttgart */
/* EMail: uz@cc65.org */
+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 */
/*****************************************************************************/
/* 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_GetEntry (S, I+1)) {
+ if (E->AM == AM65_BRA &&
+ E->JumpTo &&
+ E->JumpTo->Owner == CS_GetNextEntry (S, I)) {
/* Delete the dead jump */
CS_DelEntry (S, I);
/*****************************************************************************/
-/* Remove dead code */
+/* Remove dead code */
/*****************************************************************************/
while (I < CS_GetEntryCount (S)) {
CodeEntry* N;
+ CodeLabel* LN;
/* 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
+ * no labels attached, or if the label is just used so that the insn
+ * can jump to itself.
*/
- if ((E->Info & OF_DEAD) != 0 &&
- (N = CS_GetNextEntry (S, I)) != 0 &&
- !CE_HasLabel (N)) {
+ 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);
((E->Info & OF_CBRA) != 0 &&
GetBranchCond (E->OPC) == GetBranchCond (N->OPC))) {
- /* This is a jump cascade and we may jump to the final target.
- * Insert a new instruction, then remove the old one
+ /* 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 = NewCodeEntry (E->OPC, E->AM, N->Arg, N->JumpTo, E->LI);
+ 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);
+
+ }
/* Insert it behind E */
CS_InsertEntry (S, X, I+1);
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 */
/* Walk over the entries */
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
/* Get next entry */
- E2 = CS_GetEntry (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 = CS_GetEntryIndex (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 = CS_GetEntry (S, TI-1);
/* Get the entry preceeding the jump */
E1 = CS_GetEntry (S, I);
/*****************************************************************************/
-/* Remove unused loads and stores */
+/* Remove unused loads and stores */
/*****************************************************************************/
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 &&
- (N->Info & OF_FBRA) == 0) {
+ 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_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_DEX:
+ case OP65_INX:
+ case OP65_LDX:
case OP65_TAX: R = REG_X; break;
- case OP65_DEY:
- case OP65_INY:
+ case OP65_DEY:
+ case OP65_INY:
case OP65_LDY:
case OP65_TAY: R = REG_Y; break;
default: goto NextEntry; /* OOPS */
if ((GetRegInfo (S, I+1, R) & R) == 0) {
/* Register value is not used, remove the load */
- CS_DelEntry (S, I);
+ CS_DelEntry (S, I);
- /* Remember, we had changes */
- ++Changes;
+ /* Remember, we had changes */
+ ++Changes;
}
}
switch (E->OPC) {
case OP65_LDA:
- if (In->RegA >= 0 && /* Value of A is known */
+ 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 */
- (N->Info & OF_FBRA) == 0) { /* Which is not a cond branch */
+ !CE_UseLoadFlags (N)) { /* Which does not use the flags */
Delete = 1;
}
break;
case OP65_LDX:
- if (In->RegX >= 0 && /* Value of X is known */
+ 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 */
- (N->Info & OF_FBRA) == 0) { /* Which is not a cond branch */
+ !CE_UseLoadFlags (N)) { /* Which does not use the flags */
Delete = 1;
}
break;
case OP65_LDY:
- if (In->RegY >= 0 && /* Value of Y is known */
+ 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 */
- (N->Info & OF_FBRA) == 0) { /* Which is not a cond branch */
+ !CE_UseLoadFlags (N)) { /* Which does not use the flags */
Delete = 1;
}
break;
* location does already contain the value to be stored,
* remove the store.
*/
- if (In->RegA >= 0 && /* Value of A is known */
+ if (RegValIsKnown (In->RegA) && /* Value of A is known */
E->AM == AM65_ZP && /* Store into zp */
- (((E->Chg & REG_SREG_LO) != 0 && /* Store into sreg */
- In->RegA == In->SRegLo) || /* Value identical */
- ((E->Chg & REG_SREG_HI) != 0 && /* Store into sreg+1 */
- In->RegA == In->SRegHi))) { /* Value identical */
+ In->RegA == RegVal (E->Chg, In)) { /* Value identical */
+
Delete = 1;
}
break;
* location does already contain the value to be stored,
* remove the store.
*/
- if (In->RegX >= 0 && /* Value of A is known */
+ if (RegValIsKnown (In->RegX) && /* Value of A is known */
E->AM == AM65_ZP && /* Store into zp */
- (((E->Chg & REG_SREG_LO) != 0 && /* Store into sreg */
- In->RegX == In->SRegLo) || /* Value identical */
- ((E->Chg & REG_SREG_HI) != 0 && /* Store into sreg+1 */
- In->RegX == In->SRegHi))) { /* Value identical */
+ In->RegX == RegVal (E->Chg, In)) { /* Value identical */
+
Delete = 1;
/* If the value in the X register is known and the same as
* later. STX does support the zeropage,y addressing mode,
* so be sure to check for that.
*/
- } else if (In->RegX >= 0 &&
+ } else if (RegValIsKnown (In->RegX) &&
In->RegX == In->RegA &&
E->AM != AM65_ABSY &&
E->AM != AM65_ZPY) {
* location does already contain the value to be stored,
* remove the store.
*/
- if (In->RegX >= 0 && /* Value of A is known */
+ if (RegValIsKnown (In->RegY) && /* Value of Y is known */
E->AM == AM65_ZP && /* Store into zp */
- (((E->Chg & REG_SREG_LO) != 0 && /* Store into sreg */
- In->RegX == In->SRegLo) || /* Value identical */
- ((E->Chg & REG_SREG_HI) != 0 && /* Store into sreg+1 */
- In->RegX == In->SRegHi))) { /* Value identical */
+ 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
+ * replacement by X, but check for invalid addressing modes
* in this case.
*/
- } else if (In->RegY >= 0) {
+ } else if (RegValIsKnown (In->RegY)) {
if (In->RegY == In->RegA) {
- CE_ReplaceOPC (E, OP65_STA);
+ CE_ReplaceOPC (E, OP65_STA);
} else if (In->RegY == In->RegX &&
- E->AM != AM65_ABSX &&
- E->AM != AM65_ZPX) {
+ 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 (In->RegA >= 0 &&
+ if (RegValIsKnown (In->RegA) &&
In->RegA == In->RegX &&
(N = CS_GetNextEntry (S, I)) != 0 &&
- (N->Info & OF_FBRA) == 0) {
+ !CE_UseLoadFlags (N)) {
/* Value is identical and not followed by a branch */
Delete = 1;
}
break;
case OP65_TAY:
- if (In->RegA >= 0 &&
- In->RegA == In->RegY &&
+ if (RegValIsKnown (In->RegA) &&
+ In->RegA == In->RegY &&
(N = CS_GetNextEntry (S, I)) != 0 &&
- (N->Info & OF_FBRA) == 0) {
+ !CE_UseLoadFlags (N)) {
/* Value is identical and not followed by a branch */
Delete = 1;
}
break;
case OP65_TXA:
- if (In->RegX >= 0 &&
- In->RegX == In->RegA &&
+ if (RegValIsKnown (In->RegX) &&
+ In->RegX == In->RegA &&
(N = CS_GetNextEntry (S, I)) != 0 &&
- (N->Info & OF_FBRA) == 0) {
+ !CE_UseLoadFlags (N)) {
/* Value is identical and not followed by a branch */
Delete = 1;
}
break;
case OP65_TYA:
- if (In->RegY >= 0 &&
- In->RegY == In->RegA &&
+ if (RegValIsKnown (In->RegY) &&
+ In->RegY == In->RegA &&
(N = CS_GetNextEntry (S, I)) != 0 &&
- (N->Info & OF_FBRA) == 0) {
+ !CE_UseLoadFlags (N)) {
/* Value is identical and not followed by a branch */
Delete = 1;
}
(E->OPC == OP65_STY && N->OPC == OP65_LDY)) &&
strcmp (E->Arg, N->Arg) == 0 &&
(X = CS_GetNextEntry (S, I+1)) != 0 &&
- (X->Info & OF_FBRA) == 0) {
+ !CE_UseLoadFlags (X)) {
/* Register has already the correct value, remove the load */
CS_DelEntry (S, I+1);
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+1))) {
+ (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
if ((X = CS_GetNextEntry (S, I+1)) == 0) {
goto NextEntry;
}
- if ((X->Info & OF_FBRA) != 0) {
- if (I == 0) {
+ 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;
- }
- }
+ goto NextEntry;
+ }
+ }
- /* Remove both transfers */
- CS_DelEntry (S, I+1);
- CS_DelEntry (S, I);
+ /* Remove both transfers */
+ CS_DelEntry (S, I+1);
+ CS_DelEntry (S, I);
- /* Remember, we had changes */
- ++Changes;
+ /* Remember, we had changes */
+ ++Changes;
}
}
+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 */
/*****************************************************************************/
/* 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 = CS_GetEntryCount (S);
/* Walk over the entries */
- I = 0;
- while (I < Count) {
+ unsigned I = 0;
+ while (I < CS_GetEntryCount (S)) {
/* Get next entry */
CodeEntry* E = CS_GetEntry (S, I);
projects / cc65 / blobdiff