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Another tiny code improvement for integer compares.

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git-svn-id: svn://svn.cc65.org/cc65/trunk@4071 b7a2c559-68d2-44c3-8de9-860c34a00d81
This commit is contained in:
uz 2009-08-29 11:31:28 +00:00
parent c741f06ac1
commit 82919fa2f8
3 changed files with 91 additions and 6 deletions
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3
src/cc65/codeopt.c
View File

@ -1097,6 +1097,7 @@ static OptFunc DOptCmp5 = { OptCmp5, "OptCmp5", 100, 0,
static OptFunc DOptCmp6 = { OptCmp6, "OptCmp6", 100, 0, 0, 0, 0, 0 };
static OptFunc DOptCmp7 = { OptCmp7, "OptCmp7", 85, 0, 0, 0, 0, 0 };
static OptFunc DOptCmp8 = { OptCmp8, "OptCmp8", 50, 0, 0, 0, 0, 0 };
static OptFunc DOptCmp9 = { OptCmp9, "OptCmp9", 85, 0, 0, 0, 0, 0 };
static OptFunc DOptCondBranches1= { OptCondBranches1,"OptCondBranches1", 80, 0, 0, 0, 0, 0 };
static OptFunc DOptCondBranches2= { OptCondBranches2,"OptCondBranches2", 0, 0, 0, 0, 0, 0 };
static OptFunc DOptDeadCode = { OptDeadCode, "OptDeadCode", 100, 0, 0, 0, 0, 0 };
@ -1182,6 +1183,7 @@ static OptFunc* OptFuncs[] = {
&DOptCmp6,
&DOptCmp7,
&DOptCmp8,
&DOptCmp9,
&DOptCondBranches1,
&DOptCondBranches2,
&DOptDeadCode,
@ -1572,6 +1574,7 @@ static unsigned RunOptGroup3 (CodeSeg* S)
C += RunOptFunc (S, &DOptCmp6, 1);
C += RunOptFunc (S, &DOptCmp7, 1);
C += RunOptFunc (S, &DOptCmp8, 1);
C += RunOptFunc (S, &DOptCmp9, 1);
C += RunOptFunc (S, &DOptTest1, 1);
C += RunOptFunc (S, &DOptLoad1, 1);
C += RunOptFunc (S, &DOptUnusedLoads, 1);

73
src/cc65/coptcmp.c
View File

@ -6,8 +6,8 @@
/* */
/* */
/* */
/* (C) 2001-2005, Ullrich von Bassewitz */
/* Römerstrasse 52 */
/* (C) 2001-2009, Ullrich von Bassewitz */
/* Roemerstrasse 52 */
/* D-70794 Filderstadt */
/* EMail: uz@cc65.org */
/* */
@ -920,4 +920,73 @@ NextEntry:
unsigned OptCmp9 (CodeSeg* S)
/* Search for the sequence
*
* sbc xx
* bvs/bvc L
* eor #$80
* L: asl a
* bcc/bcs somewhere
*
* If A is not used later (which should be the case), we can branch on the N
* flag instead of the carry flag and remove the asl.
*/
{
unsigned Changes = 0;
unsigned I;
/* Walk over the entries */
I = 0;
while (I < CS_GetEntryCount (S)) {
CodeEntry* L[5];
/* Get next entry */
L[0] = CS_GetEntry (S, I);
/* Check for the sequence */
if (L[0]->OPC == OP65_SBC &&
CS_GetEntries (S, L+1, I+1, 4) &&
(L[1]->OPC == OP65_BVC ||
L[1]->OPC == OP65_BVS) &&
L[1]->JumpTo != 0 &&
L[1]->JumpTo->Owner == L[3] &&
L[2]->OPC == OP65_EOR &&
CE_IsKnownImm (L[2], 0x80) &&
L[3]->OPC == OP65_ASL &&
L[3]->AM == AM65_ACC &&
(L[4]->OPC == OP65_BCC ||
L[4]->OPC == OP65_BCS ||
L[4]->OPC == OP65_JCC ||
L[4]->OPC == OP65_JCS) &&
!CE_HasLabel (L[4]) &&
!RegAUsed (S, I+4)) {
/* Replace the branch condition */
switch (GetBranchCond (L[4]->OPC)) {
case BC_CC: CE_ReplaceOPC (L[4], OP65_JPL); break;
case BC_CS: CE_ReplaceOPC (L[4], OP65_JMI); break;
default: Internal ("Unknown branch condition in OptCmp9");
}
/* Delete the asl insn */
CS_DelEntry (S, I+3);
/* Next sequence is somewhat ahead (if any) */
I += 3;
/* Remember, we had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}

21
src/cc65/coptcmp.h
View File

@ -6,10 +6,10 @@
/* */
/* */
/* */
/* (C) 2001-2004 Ullrich von Bassewitz */
/* Römerstrasse 52 */
/* D-70794 Filderstadt */
/* EMail: uz@cc65.org */
/* (C) 2001-2009, Ullrich von Bassewitz */
/* Roemerstrasse 52 */
/* D-70794 Filderstadt */
/* EMail: uz@cc65.org */
/* */
/* */
/* This software is provided 'as-is', without any expressed or implied */
@ -153,6 +153,19 @@ unsigned OptCmp8 (CodeSeg* S);
* the result of the compare is known.
*/
unsigned OptCmp9 (CodeSeg* S);
/* Search for the sequence
*
* sbc xx
* bvs/bvc L
* eor #$80
* L: asl a
* bcc/bcs somewhere
*
* If A is not used later (which should be the case), we can branch on the N
* flag instead of the carry flag and remove the asl.
*/
/* End of coptcmp.h */