6502/cc65
1
0
Fork 0
mirror of https://github.com/cc65/cc65.git synced 2025-02-22 12:29:12 +00:00
Code Issues Projects Releases Wiki Activity

Fixed a signed char shift optimization so that it won't be used on signed int also.

Browse Source 
(It would lose significant bits from the high byte.)
This commit is contained in:
Greg King 2015-12-13 07:17:41 -05:00
parent 377f31d085
commit 4716083f3f
2 changed files with 43 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

46
src/cc65/coptshift.c
View File

@ -308,50 +308,62 @@ NextEntry:
unsigned OptShift2 (CodeSeg* S)
/* A call to the asrax1 routines may get replaced by something simpler, if
** X is not used later:
/* 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).
*/
{
unsigned Changes = 0;
unsigned I;
unsigned I = 0;
/* Walk over the entries */
I = 0;
while (I < CS_GetEntryCount (S)) {
unsigned Shift;
unsigned Count;
CodeEntry* L[3];
/* Get next entry */
CodeEntry* E = CS_GetEntry (S, I);
L[0] = CS_GetEntry (S, I);
/* Check for the sequence */
if (E->OPC == OP65_JSR &&
(Shift = GetShift (E->Arg)) != SHIFT_NONE &&
SHIFT_TYPE (Shift) == SHIFT_TYPE_ASR &&
if (L[0]->OPC == OP65_BPL &&
L[0]->JumpTo != 0 &&
CS_GetEntries (S, L+1, I+1, 2) &&
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+1)) {
!RegXUsed (S, I+3)) {
CodeEntry* X;
unsigned J = I+1;
unsigned J = I+2;
/* Generate the replacement sequence */
while (Count--) {
/* cmp #$80 */
X = NewCodeEntry (OP65_CMP, AM65_IMM, "$80", 0, E->LI);
CS_InsertEntry (S, X, J++);
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, E->LI);
CS_InsertEntry (S, X, J++);
X = NewCodeEntry (OP65_ROR, AM65_ACC, "a", 0, L[2]->LI);
CS_InsertEntry (S, X, ++J);
}
/* Delete the call to asrax */
CS_DelEntry (S, I);
/* Remove the bpl/dex/jsr */
CS_DelEntries (S, I, 3);
/* Remember, we had changes */
++Changes;
@ -421,7 +433,7 @@ unsigned OptShift3 (CodeSeg* S)
CS_InsertEntry (S, X, I+4);
}
/* Remove the bcs/dex/jsr */
/* Remove the bcc/inx/jsr */
CS_DelEntries (S, I, 3);
/* Remember, we had changes */

11
src/cc65/coptshift.h
View File

@ -61,11 +61,18 @@ unsigned OptShift1 (CodeSeg* S);
*/
unsigned OptShift2 (CodeSeg* S);
/* A call to the asrax1 routines may get replaced by something simpler, if
** X is not used later:
/* 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).
*/
unsigned OptShift3 (CodeSeg* S);