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Extended a signed char shift optimization, to handle shifts that are longer than 4 bits.

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This commit is contained in:
Greg King 2015-12-13 17:10:31 -05:00
parent 4716083f3f
commit 651b1b40ec
1 changed files with 39 additions and 23 deletions
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62
src/cc65/coptshift.c
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@ -320,6 +320,11 @@ unsigned OptShift2 (CodeSeg* S)
** 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;
@ -327,10 +332,10 @@ unsigned OptShift2 (CodeSeg* S)
/* Walk over the entries */
while (I < CS_GetEntryCount (S)) {
unsigned Shift;
unsigned Count;
CodeEntry* L[3];
unsigned Count, Count2;
unsigned K;
CodeEntry* L[4];
/* Get next entry */
L[0] = CS_GetEntry (S, I);
@ -338,40 +343,51 @@ unsigned OptShift2 (CodeSeg* S)
/* Check for the sequence */
if (L[0]->OPC == OP65_BPL &&
L[0]->JumpTo != 0 &&
CS_GetEntries (S, L+1, I+1, 2) &&
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 &&
Count * 100 <= S->CodeSizeFactor &&
!RegXUsed (S, I+3)) {
(Count = SHIFT_COUNT (Shift)) > 0) {
CodeEntry* X;
unsigned J = I+2;
if (L[3]->OPC == OP65_JSR &&
SHIFT_TYPE (Shift = GetShift (L[3]->Arg)) == SHIFT_TYPE_ASR &&
(Count2 = SHIFT_COUNT (Shift)) > 0) {
/* Generate the replacement sequence */
while (Count--) {
/* cmp #$80 */
X = NewCodeEntry (OP65_CMP, AM65_IMM, "$80", 0, L[2]->LI);
CS_InsertEntry (S, X, ++J);
/* ror a */
X = NewCodeEntry (OP65_ROR, AM65_ACC, "a", 0, L[2]->LI);
CS_InsertEntry (S, X, ++J);
/* Found a second jsr asraxN */
Count += Count2;
K = 4;
} else {
K = 3;
}
if (Count * 100 <= S->CodeSizeFactor &&
!RegXUsed (S, I+K)) {
/* Remove the bpl/dex/jsr */
CS_DelEntries (S, I, 3);
CodeEntry* X;
unsigned J = I+K;
/* Remember, we had changes */
++Changes;
/* Generate the replacement sequence */
do {
/* cmp #$80 */
X = NewCodeEntry (OP65_CMP, AM65_IMM, "$80", 0, L[2]->LI);
CS_InsertEntry (S, X, J++);
/* ror a */
X = NewCodeEntry (OP65_ROR, AM65_ACC, "a", 0, L[2]->LI);
CS_InsertEntry (S, X, J++);
} while (--Count);
/* Remove the bpl/dex/jsr */
CS_DelEntries (S, I, K);
/* Remember, we had changes */
++Changes;
}
}
/* Next entry */
++I;
}
/* Return the number of changes made */