6502/cc65
1
0
Fork 0
mirror of https://github.com/cc65/cc65.git synced 2024-12-25 02:29:52 +00:00
Code Issues Projects Releases Wiki Activity

Inline the left shift routines.

Browse Source 
git-svn-id: svn://svn.cc65.org/cc65/trunk@4041 b7a2c559-68d2-44c3-8de9-860c34a00d81
This commit is contained in:
uz 2009-08-19 13:20:28 +00:00
parent 57ef34f041
commit 8a0d80bbf0
1 changed files with 91 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

90
src/cc65/codeopt.c
View File

@ -374,6 +374,93 @@ static unsigned OptShift3 (CodeSeg* S)
static unsigned OptShift4 (CodeSeg* S)
/* Inline the shift subroutines. */
{
unsigned Changes = 0;
/* Walk over the entries */
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
CodeEntry* X;
unsigned IP;
/* Get next entry */
CodeEntry* E = CS_GetEntry (S, I);
/* Check for a call to one of the shift routine */
if (E->OPC == OP65_JSR &&
(strncmp (E->Arg, "shlax", 5) == 0 ||
strncmp (E->Arg, "aslax", 5) == 0) &&
strlen (E->Arg) == 6 &&
IsDigit (E->Arg[5])) {
/* Get number of shifts */
unsigned ShiftCount = (E->Arg[5] - '0');
/* Code is:
*
* stx tmp1
* asl a
* rol tmp1
* (repeat ShiftCount-1 times)
* ldx tmp1
*
* which makes 4 + 3 * ShiftCount bytes, compared to the original
* 3 bytes for the subroutine call. However, in most cases, the
* final load of the X register gets merged with some other insn
* and replaces a txa, so for a shift count of 1, we get a factor
* of 200, which matches nicely the CodeSizeFactor enabled with -Oi
*/
if (ShiftCount > 1 || S->CodeSizeFactor > 200) {
unsigned Size = 4 + 3 * ShiftCount;
if ((Size * 100 / 3) > S->CodeSizeFactor) {
/* Not acceptable */
goto NextEntry;
}
}
/* Inline the code. Insertion point is behind the subroutine call */
IP = (I + 1);
/* stx tmp1 */
X = NewCodeEntry (OP65_STX, AM65_ZP, "tmp1", 0, E->LI);
CS_InsertEntry (S, X, IP++);
while (ShiftCount--) {
/* asl a */
X = NewCodeEntry (OP65_ASL, AM65_ACC, "a", 0, E->LI);
CS_InsertEntry (S, X, IP++);
/* rol tmp1 */
X = NewCodeEntry (OP65_ROL, AM65_ZP, "tmp1", 0, E->LI);
CS_InsertEntry (S, X, IP++);
}
/* ldx tmp1 */
X = NewCodeEntry (OP65_LDX, AM65_ZP, "tmp1", 0, E->LI);
CS_InsertEntry (S, X, IP++);
/* Remove the subroutine call */
CS_DelEntry (S, I);
/* Remember, we had changes */
++Changes;
}
NextEntry:
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
/*****************************************************************************/
/* Optimize loads */
/*****************************************************************************/
@ -1051,6 +1138,7 @@ static OptFunc DOptPushPop = { OptPushPop, "OptPushPop", 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 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 };
@ -1134,6 +1222,7 @@ static OptFunc* OptFuncs[] = {
&DOptShift1,
&DOptShift2,
&DOptShift3,
&DOptShift4,
&DOptSize1,
&DOptSize2,
&DOptStackOps,
@ -1415,6 +1504,7 @@ static unsigned RunOptGroup1 (CodeSeg* S)
Changes += RunOptFunc (S, &DOptShift1, 1);
Changes += RunOptFunc (S, &DOptShift2, 1);
Changes += RunOptFunc (S, &DOptShift3, 1);
Changes += RunOptFunc (S, &DOptShift4, 1);
Changes += RunOptFunc (S, &DOptStore1, 1);
Changes += RunOptFunc (S, &DOptStore2, 5);
Changes += RunOptFunc (S, &DOptStore3, 5);