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Extend OPtShift3 to shift counts larger than 1.

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git-svn-id: svn://svn.cc65.org/cc65/trunk@5713 b7a2c559-68d2-44c3-8de9-860c34a00d81
This commit is contained in:
uz 2012-06-11 17:58:32 +00:00
parent 22078ba924
commit c66185259b
1 changed files with 15 additions and 2 deletions
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17
src/cc65/codeopt.c
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@ -261,7 +261,11 @@ static unsigned OptShift3 (CodeSeg* S)
*
* ror a
*
* if X is zero on entry and unused later.
* if X is zero on entry and unused later. For shift counts > 1, more
*
* shr a
*
* must be added.
*/
{
unsigned Changes = 0;
@ -287,12 +291,21 @@ static unsigned OptShift3 (CodeSeg* S)
L[1]->OPC == OP65_INX &&
L[0]->JumpTo->Owner == L[2] &&
!CS_RangeHasLabel (S, I, 2) &&
CE_IsCallTo (L[2], "shrax1") &&
L[2]->OPC == OP65_JSR &&
strlen (L[2]->Arg) == 6 &&
memcmp (L[2]->Arg, "shrax", 5) == 0 &&
IsDigit (L[2]->Arg[5]) &&
!RegXUsed (S, I+3)) {
unsigned ShiftCount = (L[2]->Arg[5] - '0');
/* Add the replacement insn instead */
CodeEntry* X = NewCodeEntry (OP65_ROR, AM65_ACC, "a", 0, L[2]->LI);
CS_InsertEntry (S, X, I+3);
while (--ShiftCount) {
X = NewCodeEntry (OP65_LSR, AM65_ACC, "a", 0, L[2]->LI);
CS_InsertEntry (S, X, I+4);
}
/* Remove the bcs/dex/jsr */
CS_DelEntries (S, I, 3);