6502/cc65
1
0
Fork 0
mirror of https://github.com/cc65/cc65.git synced 2024-11-19 06:31:31 +00:00
Code Issues Projects Releases Wiki Activity

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

Browse Source
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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

44
src/cc65/coptshift.c
View File

@ -320,6 +320,11 @@ unsigned OptShift2 (CodeSeg* S)
** ror a ** ror a
** **
** if X is not used later (X is assumed to be zero on entry). ** 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 Changes = 0;
@ -327,10 +332,10 @@ unsigned OptShift2 (CodeSeg* S)
/* Walk over the entries */ /* Walk over the entries */
while (I < CS_GetEntryCount (S)) { while (I < CS_GetEntryCount (S)) {
unsigned Shift; unsigned Shift;
unsigned Count; unsigned Count, Count2;
CodeEntry* L[3]; unsigned K;
CodeEntry* L[4];
/* Get next entry */ /* Get next entry */
L[0] = CS_GetEntry (S, I); L[0] = CS_GetEntry (S, I);
@ -338,40 +343,51 @@ unsigned OptShift2 (CodeSeg* S)
/* Check for the sequence */ /* Check for the sequence */
if (L[0]->OPC == OP65_BPL && if (L[0]->OPC == OP65_BPL &&
L[0]->JumpTo != 0 && 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[1]->OPC == OP65_DEX &&
L[0]->JumpTo->Owner == L[2] && L[0]->JumpTo->Owner == L[2] &&
!CS_RangeHasLabel (S, I, 2) && !CS_RangeHasLabel (S, I, 2) &&
L[2]->OPC == OP65_JSR && L[2]->OPC == OP65_JSR &&
SHIFT_TYPE (Shift = GetShift (L[2]->Arg)) == SHIFT_TYPE_ASR && SHIFT_TYPE (Shift = GetShift (L[2]->Arg)) == SHIFT_TYPE_ASR &&
(Count = SHIFT_COUNT (Shift)) > 0 && (Count = SHIFT_COUNT (Shift)) > 0) {
Count * 100 <= S->CodeSizeFactor &&
!RegXUsed (S, I+3)) { if (L[3]->OPC == OP65_JSR &&
SHIFT_TYPE (Shift = GetShift (L[3]->Arg)) == SHIFT_TYPE_ASR &&
(Count2 = SHIFT_COUNT (Shift)) > 0) {
/* Found a second jsr asraxN */
Count += Count2;
K = 4;
} else {
K = 3;
}
if (Count * 100 <= S->CodeSizeFactor &&
!RegXUsed (S, I+K)) {
CodeEntry* X; CodeEntry* X;
unsigned J = I+2; unsigned J = I+K;
/* Generate the replacement sequence */ /* Generate the replacement sequence */
while (Count--) { do {
/* cmp #$80 */ /* cmp #$80 */
X = NewCodeEntry (OP65_CMP, AM65_IMM, "$80", 0, L[2]->LI); X = NewCodeEntry (OP65_CMP, AM65_IMM, "$80", 0, L[2]->LI);
CS_InsertEntry (S, X, ++J); CS_InsertEntry (S, X, J++);
/* ror a */ /* ror a */
X = NewCodeEntry (OP65_ROR, AM65_ACC, "a", 0, L[2]->LI); X = NewCodeEntry (OP65_ROR, AM65_ACC, "a", 0, L[2]->LI);
CS_InsertEntry (S, X, ++J); CS_InsertEntry (S, X, J++);
} } while (--Count);
/* Remove the bpl/dex/jsr */ /* Remove the bpl/dex/jsr */
CS_DelEntries (S, I, 3); CS_DelEntries (S, I, K);
/* Remember, we had changes */ /* Remember, we had changes */
++Changes; ++Changes;
} }
}
/* Next entry */ /* Next entry */
++I; ++I;
} }
/* Return the number of changes made */ /* Return the number of changes made */