/* Macros to extract values from a shift type */
-#define SHIFT_COUNT(S) ((S) & SHIFT_MASK_COUNT)
-#define SHIFT_DIR(S) ((S) & SHIFT_MASK_DIR)
-#define SHIFT_MODE(S) ((S) & SHIFT_MASK_MODE)
-#define SHIFT_TYPE(S) ((S) & SHIFT_MASK_TYPE)
+#define SHIFT_COUNT(S) ((S) & SHIFT_MASK_COUNT)
+#define SHIFT_DIR(S) ((S) & SHIFT_MASK_DIR)
+#define SHIFT_MODE(S) ((S) & SHIFT_MASK_MODE)
+#define SHIFT_TYPE(S) ((S) & SHIFT_MASK_TYPE)
/*****************************************************************************/
-/* Optimize shifts */
+/* Optimize shifts */
/*****************************************************************************/
unsigned OptShift1 (CodeSeg* S)
/* A call to the shlaxN routine may get replaced by one or more asl insns
- * if the value of X is not used later. If X is used later, but it is zero
- * on entry and it's a shift by one, it may get replaced by:
- *
- * asl a
- * bcc L1
- * inx
- * L1:
- *
- */
+** if the value of X is not used later. If X is used later, but it is zero
+** on entry and it's a shift by one, it may get replaced by:
+**
+** asl a
+** bcc L1
+** inx
+** L1:
+*/
{
unsigned Changes = 0;
unsigned I;
while (I < CS_GetEntryCount (S)) {
unsigned Shift;
- unsigned Count;
CodeEntry* N;
CodeEntry* X;
CodeLabel* L;
- /* Get next entry */
- CodeEntry* E = CS_GetEntry (S, I);
+ /* Get next entry */
+ CodeEntry* E = CS_GetEntry (S, I);
- /* Check for the sequence */
- if (E->OPC == OP65_JSR &&
+ /* Check for the sequence */
+ if (E->OPC == OP65_JSR &&
(Shift = GetShift (E->Arg)) != SHIFT_NONE &&
- SHIFT_DIR (Shift) == SHIFT_DIR_LEFT &&
- (Count = SHIFT_COUNT (Shift)) > 0) {
+ SHIFT_DIR (Shift) == SHIFT_DIR_LEFT) {
+
+ unsigned Count = SHIFT_COUNT (Shift);
if (!RegXUsed (S, I+1)) {
- /* Insert shift insns */
- while (Count--) {
+ if (Count == SHIFT_COUNT_Y) {
+
+ CodeLabel* L;
+
+ if (S->CodeSizeFactor < 200) {
+ goto NextEntry;
+ }
+
+ /* Change into
+ **
+ ** L1: asl a
+ ** dey
+ ** bpl L1
+ ** ror a
+ */
+
+ /* asl a */
X = NewCodeEntry (OP65_ASL, AM65_ACC, "a", 0, E->LI);
CS_InsertEntry (S, X, I+1);
- }
+ L = CS_GenLabel (S, X);
- /* Delete the call to shlax */
- CS_DelEntry (S, I);
+ /* dey */
+ X = NewCodeEntry (OP65_DEY, AM65_IMP, 0, 0, E->LI);
+ CS_InsertEntry (S, X, I+2);
- /* Remember, we had changes */
- ++Changes;
+ /* bpl L1 */
+ X = NewCodeEntry (OP65_BPL, AM65_BRA, L->Name, L, E->LI);
+ CS_InsertEntry (S, X, I+3);
+
+ /* ror a */
+ X = NewCodeEntry (OP65_ROR, AM65_ACC, "a", 0, E->LI);
+ CS_InsertEntry (S, X, I+4);
+
+ } else {
+ /* Insert shift insns */
+ while (Count--) {
+ X = NewCodeEntry (OP65_ASL, AM65_ACC, "a", 0, E->LI);
+ CS_InsertEntry (S, X, I+1);
+ }
+ }
} else if (E->RI->In.RegX == 0 &&
Count == 1 &&
X = NewCodeEntry (OP65_INX, AM65_IMP, 0, 0, E->LI);
CS_InsertEntry (S, X, I+3);
- /* Delete the call to shlax */
- CS_DelEntry (S, I);
+ } else {
+
+ /* We won't handle this one */
+ goto NextEntry;
- /* Remember, we had changes */
- ++Changes;
}
- }
+ /* Delete the call to shlax */
+ CS_DelEntry (S, I);
- /* Next entry */
- ++I;
+ /* Remember, we had changes */
+ ++Changes;
+ }
+
+NextEntry:
+ /* Next entry */
+ ++I;
}
-unsigned OptShift2(CodeSeg* S)
-/* A call to the asrax1 routines may get replaced by something simpler, if
- * X is not used later:
- *
- * cmp #$80
- * ror a
- *
- */
+unsigned OptShift2 (CodeSeg* S)
+/* The sequence
+**
+** bpl L
+** dex
+** L: jsr asraxN
+**
+** might be replaced by N copies of
+**
+** cmp #$80
+** ror a
+**
+** if X is not used later (X is assumed to be zero on entry).
+** If the sequence is followed immediately by another
+**
+** jsr asraxN
+**
+** then their shifts are combined.
+*/
{
unsigned Changes = 0;
- unsigned I;
+ unsigned I = 0;
/* Walk over the entries */
- I = 0;
while (I < CS_GetEntryCount (S)) {
-
unsigned Shift;
- unsigned Count;
-
- /* Get next entry */
- CodeEntry* E = CS_GetEntry (S, I);
+ unsigned Count, Count2;
+ unsigned K;
+ CodeEntry* L[4];
+
+ /* Get next entry */
+ L[0] = CS_GetEntry (S, I);
+
+ /* Check for the sequence */
+ if ((L[0]->OPC == OP65_BPL || L[0]->OPC == OP65_BCC) &&
+ L[0]->JumpTo != 0 &&
+ CS_GetEntries (S, L+1, I+1, 3) &&
+ L[1]->OPC == OP65_DEX &&
+ L[0]->JumpTo->Owner == L[2] &&
+ !CS_RangeHasLabel (S, I, 2) &&
+ L[2]->OPC == OP65_JSR &&
+ SHIFT_TYPE (Shift = GetShift (L[2]->Arg)) == SHIFT_TYPE_ASR &&
+ (Count = SHIFT_COUNT (Shift)) > 0) {
- /* Check for the sequence */
- if (E->OPC == OP65_JSR &&
- (Shift = GetShift (E->Arg)) != SHIFT_NONE &&
- SHIFT_TYPE (Shift) == SHIFT_TYPE_ASR &&
- (Count = SHIFT_COUNT (Shift)) > 0 &&
- Count * 100 <= S->CodeSizeFactor &&
- !RegXUsed (S, I+1)) {
+ if (L[3]->OPC == OP65_JSR &&
+ SHIFT_TYPE (Shift = GetShift (L[3]->Arg)) == SHIFT_TYPE_ASR &&
+ (Count2 = SHIFT_COUNT (Shift)) > 0) {
- CodeEntry* X;
- unsigned J = I+1;
+ /* Found a second jsr asraxN */
+ Count += Count2;
+ K = 4;
+ } else {
+ K = 3;
+ }
+ if (Count * 100 <= S->CodeSizeFactor &&
+ !RegXUsed (S, I+K)) {
- /* Generate the replacement sequence */
- while (Count--) {
- /* cmp #$80 */
- X = NewCodeEntry (OP65_CMP, AM65_IMM, "$80", 0, E->LI);
- CS_InsertEntry (S, X, J++);
+ CodeEntry* X;
+ unsigned J = I+K;
- /* ror a */
- X = NewCodeEntry (OP65_ROR, AM65_ACC, "a", 0, E->LI);
- CS_InsertEntry (S, X, J++);
- }
+ /* Generate the replacement sequence */
+ do {
+ /* cmp #$80 */
+ X = NewCodeEntry (OP65_CMP, AM65_IMM, "$80", 0, L[2]->LI);
+ CS_InsertEntry (S, X, J++);
- /* Delete the call to asrax */
- CS_DelEntry (S, I);
+ /* ror a */
+ X = NewCodeEntry (OP65_ROR, AM65_ACC, "a", 0, L[2]->LI);
+ CS_InsertEntry (S, X, J++);
+ } while (--Count);
- /* Remember, we had changes */
- ++Changes;
- }
+ /* Remove the bpl/dex/jsr */
+ CS_DelEntries (S, I, K);
- /* Next entry */
- ++I;
+ /* Remember, we had changes */
+ ++Changes;
+ }
+ }
+ /* Next entry */
+ ++I;
}
/* Return the number of changes made */
unsigned OptShift3 (CodeSeg* S)
/* The sequence
- *
- * bcc L
- * inx
- * L: jsr shrax1
- *
- * may get replaced by
- *
- * ror a
- *
- * if X is zero on entry and unused later. For shift counts > 1, more
- *
- * shr a
- *
- * must be added.
- */
+**
+** bcc L
+** inx
+** L: jsr shrax1
+**
+** may get replaced by
+**
+** ror a
+**
+** if X is zero on entry. For shift counts > 1, more
+**
+** shr a
+**
+** must be added.
+*/
{
unsigned Changes = 0;
unsigned I;
unsigned Shift;
unsigned Count;
- CodeEntry* L[3];
+ CodeEntry* L[3];
- /* Get next entry */
- L[0] = CS_GetEntry (S, I);
+ /* Get next entry */
+ L[0] = CS_GetEntry (S, I);
- /* Check for the sequence */
- if ((L[0]->OPC == OP65_BCC || L[0]->OPC == OP65_JCC) &&
- L[0]->JumpTo != 0 &&
+ /* Check for the sequence */
+ if ((L[0]->OPC == OP65_BCC || L[0]->OPC == OP65_JCC) &&
+ L[0]->JumpTo != 0 &&
L[0]->RI->In.RegX == 0 &&
- CS_GetEntries (S, L+1, I+1, 2) &&
- L[1]->OPC == OP65_INX &&
- L[0]->JumpTo->Owner == L[2] &&
- !CS_RangeHasLabel (S, I, 2) &&
+ CS_GetEntries (S, L+1, I+1, 2) &&
+ L[1]->OPC == OP65_INX &&
+ L[0]->JumpTo->Owner == L[2] &&
+ !CS_RangeHasLabel (S, I, 2) &&
L[2]->OPC == OP65_JSR &&
(Shift = GetShift (L[2]->Arg)) != SHIFT_NONE &&
- SHIFT_TYPE (Shift) == SHIFT_TYPE_ASR &&
- (Count = SHIFT_COUNT (Shift)) > 0 &&
- !RegXUsed (S, I+3)) {
+ SHIFT_DIR (Shift) == SHIFT_DIR_RIGHT &&
+ (Count = SHIFT_COUNT (Shift)) > 0) {
/* Add the replacement insn instead */
CodeEntry* X = NewCodeEntry (OP65_ROR, AM65_ACC, "a", 0, L[2]->LI);
CS_InsertEntry (S, X, I+4);
}
- /* Remove the bcs/dex/jsr */
- CS_DelEntries (S, I, 3);
+ /* Remove the bcc/inx/jsr */
+ CS_DelEntries (S, I, 3);
- /* Remember, we had changes */
- ++Changes;
+ /* Remember, we had changes */
+ ++Changes;
- }
+ }
- /* Next entry */
- ++I;
+ /* Next entry */
+ ++I;
}
unsigned OptShift4 (CodeSeg* S)
/* Calls to the asraxN or shraxN routines may get replaced by one or more lsr
- * insns if the value of X is zero.
- */
+** insns if the value of X is zero.
+*/
{
unsigned Changes = 0;
unsigned I;
unsigned Shift;
unsigned Count;
- /* Get next entry */
- CodeEntry* E = CS_GetEntry (S, I);
+ /* Get next entry */
+ CodeEntry* E = CS_GetEntry (S, I);
- /* Check for the sequence */
- if (E->OPC == OP65_JSR &&
+ /* Check for the sequence */
+ if (E->OPC == OP65_JSR &&
(Shift = GetShift (E->Arg)) != SHIFT_NONE &&
SHIFT_DIR (Shift) == SHIFT_DIR_RIGHT &&
- E->RI->In.RegX == 0) {
+ E->RI->In.RegX == 0) {
CodeEntry* X;
Count = SHIFT_COUNT (Shift);
if (Count == SHIFT_COUNT_Y) {
- /* Generate:
- *
- * L1: lsr a
- * dey
- * bpl L1
- * rol a
- */
CodeLabel* L;
+ if (S->CodeSizeFactor < 200) {
+ /* Not acceptable */
+ goto NextEntry;
+ }
+
+ /* Generate:
+ **
+ ** L1: lsr a
+ ** dey
+ ** bpl L1
+ ** rol a
+ **
+ ** A negative shift count or one that is greater or equal than
+ ** the bit width of the left operand (which is promoted to
+ ** integer before the operation) causes undefined behaviour, so
+ ** above transformation is safe.
+ */
+
/* lsr a */
X = NewCodeEntry (OP65_LSR, AM65_ACC, "a", 0, E->LI);
CS_InsertEntry (S, X, I+1);
}
- /* Delete the call to shrax */
- CS_DelEntry (S, I);
+ /* Delete the call to shrax */
+ CS_DelEntry (S, I);
- /* Remember, we had changes */
- ++Changes;
+ /* Remember, we had changes */
+ ++Changes;
- }
+ }
- /* Next entry */
- ++I;
+NextEntry:
+ /* Next entry */
+ ++I;
}
unsigned OptShift5 (CodeSeg* S)
/* Search for the sequence
- *
- * lda xxx
- * ldx yyy
- * jsr aslax1/asrax1/shlax1/shrax1
- * sta aaa
- * stx bbb
- *
- * and replace it by
- *
- * lda xxx
- * asl a
- * sta aaa
- * lda yyy
- * rol a
- * sta bbb
- *
- * or similar, provided that a/x is not used later
- */
+**
+** lda xxx
+** ldx yyy
+** jsr aslax1/asrax1/shlax1/shrax1
+** sta aaa
+** stx bbb
+**
+** and replace it by
+**
+** lda xxx
+** asl a
+** sta aaa
+** lda yyy
+** rol a
+** sta bbb
+**
+** or similar, provided that a/x is not used later
+*/
{
unsigned Changes = 0;
while (I < CS_GetEntryCount (S)) {
unsigned ShiftType;
- CodeEntry* L[5];
+ CodeEntry* L[5];
- /* Get next entry */
- L[0] = CS_GetEntry (S, I);
+ /* Get next entry */
+ L[0] = CS_GetEntry (S, I);
- /* Check for the sequence */
- if (L[0]->OPC == OP65_LDA &&
+ /* Check for the sequence */
+ if (L[0]->OPC == OP65_LDA &&
(L[0]->AM == AM65_ABS || L[0]->AM == AM65_ZP) &&
- CS_GetEntries (S, L+1, I+1, 4) &&
+ CS_GetEntries (S, L+1, I+1, 4) &&
!CS_RangeHasLabel (S, I+1, 4) &&
L[1]->OPC == OP65_LDX &&
(L[1]->AM == AM65_ABS || L[1]->AM == AM65_ZP) &&
L[2]->OPC == OP65_JSR &&
(ShiftType = GetShift (L[2]->Arg)) != SHIFT_NONE &&
SHIFT_COUNT(ShiftType) == 1 &&
- L[3]->OPC == OP65_STA &&
+ L[3]->OPC == OP65_STA &&
(L[3]->AM == AM65_ABS || L[3]->AM == AM65_ZP) &&
L[4]->OPC == OP65_STX &&
(L[4]->AM == AM65_ABS || L[4]->AM == AM65_ZP) &&
}
- /* Remember, we had changes */
+ /* Remember, we had changes */
++Changes;
- }
+ }
- /* Next entry */
- ++I;
+ /* Next entry */
+ ++I;
}
CodeEntry* X;
unsigned IP;
- /* Get next entry */
- CodeEntry* E = CS_GetEntry (S, I);
+ /* Get next entry */
+ CodeEntry* E = CS_GetEntry (S, I);
- /* Check for a call to one of the shift routine */
- if (E->OPC == OP65_JSR &&
+ /* Check for a call to one of the shift routine */
+ if (E->OPC == OP65_JSR &&
(Shift = GetShift (E->Arg)) != SHIFT_NONE &&
SHIFT_DIR (Shift) == SHIFT_DIR_LEFT &&
(Count = SHIFT_COUNT (Shift)) > 0) {
/* Code is:
- *
- * stx tmp1
- * asl a
- * rol tmp1
- * (repeat ShiftCount-1 times)
- * ldx tmp1
- *
- * which makes 4 + 3 * ShiftCount bytes, compared to the original
- * 3 bytes for the subroutine call. However, in most cases, the
- * final load of the X register gets merged with some other insn
- * and replaces a txa, so for a shift count of 1, we get a factor
- * of 200, which matches nicely the CodeSizeFactor enabled with -Oi
- */
+ **
+ ** stx tmp1
+ ** asl a
+ ** rol tmp1
+ ** (repeat ShiftCount-1 times)
+ ** ldx tmp1
+ **
+ ** which makes 4 + 3 * ShiftCount bytes, compared to the original
+ ** 3 bytes for the subroutine call. However, in most cases, the
+ ** final load of the X register gets merged with some other insn
+ ** and replaces a txa, so for a shift count of 1, we get a factor
+ ** of 200, which matches nicely the CodeSizeFactor enabled with -Oi
+ */
if (Count > 1 || S->CodeSizeFactor > 200) {
unsigned Size = 4 + 3 * Count;
if ((Size * 100 / 3) > S->CodeSizeFactor) {
/* Remove the subroutine call */
CS_DelEntry (S, I);
- /* Remember, we had changes */
+ /* Remember, we had changes */
++Changes;
- }
+ }
NextEntry:
- /* Next entry */
- ++I;
+ /* Next entry */
+ ++I;
}
/* Return the number of changes made */
return Changes;
}
-
-
-
projects / cc65 / blobdiff