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Added an optimization for signed shift right.

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git-svn-id: svn://svn.cc65.org/cc65/trunk@5657 b7a2c559-68d2-44c3-8de9-860c34a00d81
This commit is contained in:
uz 2012-05-09 18:00:27 +00:00
parent 914c6a0ad8
commit 7d62062bd2
1 changed files with 75 additions and 5 deletions
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80
src/cc65/codeopt.c
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@ -180,7 +180,75 @@ static unsigned OptShift1 (CodeSeg* S)
static unsigned OptShift2 (CodeSeg* S)
static 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 Changes = 0;
unsigned I;
/* Generate register info */
CS_GenRegInfo (S);
/* Walk over the entries */
I = 0;
while (I < CS_GetEntryCount (S)) {
unsigned Count;
/* Get next entry */
CodeEntry* E = CS_GetEntry (S, I);
/* Check for the sequence */
if (E->OPC == OP65_JSR &&
strncmp (E->Arg, "asrax", 5) == 0 &&
strlen (E->Arg) == 6 &&
IsDigit (E->Arg[5]) &&
(Count = (E->Arg[5] - '0')) >= 1 &&
Count * 100 <= S->CodeSizeFactor &&
!RegXUsed (S, I+1)) {
CodeEntry* X;
unsigned J = I+1;
/* Generate the replacement sequence */
while (Count--) {
/* cmp #$80 */
X = NewCodeEntry (OP65_CMP, AM65_IMM, "$80", 0, E->LI);
CS_InsertEntry (S, X, J++);
/* ror a */
X = NewCodeEntry (OP65_ROR, AM65_ACC, "a", 0, E->LI);
CS_InsertEntry (S, X, J++);
}
/* Delete the call to asrax */
CS_DelEntry (S, I);
/* Remember, we had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Free the register info */
CS_FreeRegInfo (S);
/* Return the number of changes made */
return Changes;
}
static unsigned OptShift3 (CodeSeg* S)
/* A call to the shraxN routine may get replaced by one or more lsr insns
* if the value of X is zero.
*/
@ -255,7 +323,7 @@ static unsigned GetShiftType (const char* Sub)
static unsigned OptShift3 (CodeSeg* S)
static unsigned OptShift4 (CodeSeg* S)
/* Search for the sequence
*
* lda xxx
@ -376,7 +444,7 @@ static unsigned OptShift3 (CodeSeg* S)
static unsigned OptShift4 (CodeSeg* S)
static unsigned OptShift5 (CodeSeg* S)
/* Inline the shift subroutines. */
{
unsigned Changes = 0;
@ -1415,8 +1483,9 @@ static OptFunc DOptPush2 = { OptPush2, "OptPush2", 50, 0,
static OptFunc DOptPushPop = { OptPushPop, "OptPushPop", 0, 0, 0, 0, 0, 0 };
static OptFunc DOptShift1 = { OptShift1, "OptShift1", 100, 0, 0, 0, 0, 0 };
static OptFunc DOptShift2 = { OptShift2, "OptShift2", 100, 0, 0, 0, 0, 0 };
static OptFunc DOptShift3 = { OptShift3, "OptShift3", 110, 0, 0, 0, 0, 0 };
static OptFunc DOptShift4 = { OptShift4, "OptShift4", 200, 0, 0, 0, 0, 0 };
static OptFunc DOptShift3 = { OptShift3, "OptShift3", 100, 0, 0, 0, 0, 0 };
static OptFunc DOptShift4 = { OptShift4, "OptShift4", 110, 0, 0, 0, 0, 0 };
static OptFunc DOptShift5 = { OptShift5, "OptShift5", 200, 0, 0, 0, 0, 0 };
static OptFunc DOptSize1 = { OptSize1, "OptSize1", 100, 0, 0, 0, 0, 0 };
static OptFunc DOptSize2 = { OptSize2, "OptSize2", 100, 0, 0, 0, 0, 0 };
static OptFunc DOptStackOps = { OptStackOps, "OptStackOps", 100, 0, 0, 0, 0, 0 };
@ -1510,6 +1579,7 @@ static OptFunc* OptFuncs[] = {
&DOptShift2,
&DOptShift3,
&DOptShift4,
&DOptShift5,
&DOptSize1,
&DOptSize2,
&DOptStackOps,