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cc65/src/cc65/coptneg.c

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/*****************************************************************************/
/* */
/* coptneg.c */
/* */
/* Optimize negation sequences */
/* */
/* */
/* */
/* (C) 2001-2012, Ullrich von Bassewitz */
/* Roemerstrasse 52 */
/* D-70794 Filderstadt */
/* EMail: uz@cc65.org */
/* */
/* */
/* This software is provided 'as-is', without any expressed or implied */
/* warranty. In no event will the authors be held liable for any damages */
/* arising from the use of this software. */
/* */
/* Permission is granted to anyone to use this software for any purpose, */
/* including commercial applications, and to alter it and redistribute it */
/* freely, subject to the following restrictions: */
/* */
/* 1. The origin of this software must not be misrepresented; you must not */
/* claim that you wrote the original software. If you use this software */
/* in a product, an acknowledgment in the product documentation would be */
/* appreciated but is not required. */
/* 2. Altered source versions must be plainly marked as such, and must not */
/* be misrepresented as being the original software. */
/* 3. This notice may not be removed or altered from any source */
/* distribution. */
/* */
/*****************************************************************************/
/* cc65 */
#include "codeent.h"
#include "codeinfo.h"
#include "coptneg.h"
/*****************************************************************************/
/* bnega optimizations */
/*****************************************************************************/
unsigned OptBNegA1 (CodeSeg* S)
/* Check for
**
** ldx #$00
** lda ..
** jsr bnega
**
** Remove the ldx if the lda does not use it.
*/
{
unsigned Changes = 0;
/* Walk over the entries */
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
CodeEntry* L[2];
/* Get next entry */
CodeEntry* E = CS_GetEntry (S, I);
/* Check for a ldx */
if (E->OPC == OP65_LDX &&
E->AM == AM65_IMM &&
CE_HasNumArg (E) &&
E->Num == 0 &&
CS_GetEntries (S, L, I+1, 2) &&
L[0]->OPC == OP65_LDA &&
(L[0]->Use & REG_X) == 0 &&
!CE_HasLabel (L[0]) &&
CE_IsCallTo (L[1], "bnega") &&
!CE_HasLabel (L[1])) {
/* Remove the ldx instruction */
CS_DelEntry (S, I);
/* Remember, we had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
unsigned OptBNegA2 (CodeSeg* S)
/* Check for
**
** lda ..
** jsr bnega
** jeq/jne ..
**
** Adjust the conditional branch and remove the call to the subroutine.
*/
{
unsigned Changes = 0;
/* Walk over the entries */
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
CodeEntry* L[2];
/* Get next entry */
CodeEntry* E = CS_GetEntry (S, I);
/* Check for the sequence */
if ((E->OPC == OP65_ADC ||
E->OPC == OP65_AND ||
E->OPC == OP65_DEA ||
E->OPC == OP65_EOR ||
E->OPC == OP65_INA ||
E->OPC == OP65_LDA ||
E->OPC == OP65_ORA ||
E->OPC == OP65_PLA ||
E->OPC == OP65_SBC ||
E->OPC == OP65_TXA ||
E->OPC == OP65_TYA) &&
CS_GetEntries (S, L, I+1, 2) &&
CE_IsCallTo (L[0], "bnega") &&
!CE_HasLabel (L[0]) &&
(L[1]->Info & OF_ZBRA) != 0 &&
!CE_HasLabel (L[1])) {
/* Invert the branch */
CE_ReplaceOPC (L[1], GetInverseBranch (L[1]->OPC));
/* Delete the subroutine call */
CS_DelEntry (S, I+1);
/* Remember, we had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
/*****************************************************************************/
/* bnegax optimizations */
/*****************************************************************************/
unsigned OptBNegAX1 (CodeSeg* S)
/* On a call to bnegax, if X is zero, the result depends only on the value in
** A, so change the call to a call to bnega. This will get further optimized
** later if possible.
*/
{
unsigned Changes = 0;
unsigned I;
/* Walk over the entries */
I = 0;
while (I < CS_GetEntryCount (S)) {
/* Get next entry */
CodeEntry* E = CS_GetEntry (S, I);
/* Check if this is a call to bnegax, and if X is known and zero */
if (E->RI->In.RegX == 0 && CE_IsCallTo (E, "bnegax")) {
CodeEntry* X = NewCodeEntry (OP65_JSR, AM65_ABS, "bnega", 0, E->LI);
CS_InsertEntry (S, X, I+1);
CS_DelEntry (S, I);
/* We had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
unsigned OptBNegAX2 (CodeSeg* S)
/* Search for the sequence:
**
** ldy #xx
** jsr ldaxysp
** jsr bnegax
** jne/jeq ...
**
** and replace it by
**
** ldy #xx
** lda (sp),y
** dey
** ora (sp),y
** jeq/jne ...
*/
{
unsigned Changes = 0;
/* Walk over the entries */
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
CodeEntry* L[4];
/* Get next entry */
L[0] = CS_GetEntry (S, I);
/* Check for the sequence */
if (L[0]->OPC == OP65_LDY &&
CE_IsConstImm (L[0]) &&
!CS_RangeHasLabel (S, I+1, 3) &&
CS_GetEntries (S, L+1, I+1, 3) &&
CE_IsCallTo (L[1], "ldaxysp") &&
CE_IsCallTo (L[2], "bnegax") &&
(L[3]->Info & OF_ZBRA) != 0) {
CodeEntry* X;
/* lda (sp),y */
X = NewCodeEntry (OP65_LDA, AM65_ZP_INDY, "sp", 0, L[1]->LI);
CS_InsertEntry (S, X, I+1);
/* dey */
X = NewCodeEntry (OP65_DEY, AM65_IMP, 0, 0, L[1]->LI);
CS_InsertEntry (S, X, I+2);
/* ora (sp),y */
X = NewCodeEntry (OP65_ORA, AM65_ZP_INDY, "sp", 0, L[1]->LI);
CS_InsertEntry (S, X, I+3);
/* Invert the branch */
CE_ReplaceOPC (L[3], GetInverseBranch (L[3]->OPC));
/* Delete the entries no longer needed. */
CS_DelEntries (S, I+4, 2);
/* Remember, we had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
unsigned OptBNegAX3 (CodeSeg* S)
/* Search for the sequence:
**
** lda xx
** ldx yy
** jsr bnegax
** jne/jeq ...
**
** and replace it by
**
** lda xx
** ora xx+1
** jeq/jne ...
*/
{
unsigned Changes = 0;
/* Walk over the entries */
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
CodeEntry* L[3];
/* Get next entry */
CodeEntry* E = CS_GetEntry (S, I);
/* Check for the sequence */
if (E->OPC == OP65_LDA &&
CS_GetEntries (S, L, I+1, 3) &&
L[0]->OPC == OP65_LDX &&
!CE_HasLabel (L[0]) &&
CE_IsCallTo (L[1], "bnegax") &&
!CE_HasLabel (L[1]) &&
(L[2]->Info & OF_ZBRA) != 0 &&
!CE_HasLabel (L[2])) {
/* ldx --> ora */
CE_ReplaceOPC (L[0], OP65_ORA);
/* Invert the branch */
CE_ReplaceOPC (L[2], GetInverseBranch (L[2]->OPC));
/* Delete the subroutine call */
CS_DelEntry (S, I+2);
/* Remember, we had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
unsigned OptBNegAX4 (CodeSeg* S)
/* Search for the sequence:
**
** jsr xxx
** jsr bnega(x)
** jeq/jne ...
**
** and replace it by:
**
** jsr xxx
** <boolean test>
** jne/jeq ...
*/
{
unsigned Changes = 0;
/* Walk over the entries */
unsigned I = 0;
while (I < CS_GetEntryCount (S)) {
CodeEntry* L[2];
/* Get next entry */
CodeEntry* E = CS_GetEntry (S, I);
/* Check for the sequence */
if (E->OPC == OP65_JSR &&
CS_GetEntries (S, L, I+1, 2) &&
L[0]->OPC == OP65_JSR &&
strncmp (L[0]->Arg,"bnega",5) == 0 &&
!CE_HasLabel (L[0]) &&
(L[1]->Info & OF_ZBRA) != 0 &&
!CE_HasLabel (L[1])) {
CodeEntry* X;
/* Check if we're calling bnega or bnegax */
int ByteSized = (strcmp (L[0]->Arg, "bnega") == 0);
/* Insert apropriate test code */
if (ByteSized) {
/* Test bytes */
X = NewCodeEntry (OP65_TAX, AM65_IMP, 0, 0, L[0]->LI);
CS_InsertEntry (S, X, I+2);
} else {
/* Test words */
X = NewCodeEntry (OP65_STX, AM65_ZP, "tmp1", 0, L[0]->LI);
CS_InsertEntry (S, X, I+2);
X = NewCodeEntry (OP65_ORA, AM65_ZP, "tmp1", 0, L[0]->LI);
CS_InsertEntry (S, X, I+3);
}
/* Delete the subroutine call */
CS_DelEntry (S, I+1);
/* Invert the branch */
CE_ReplaceOPC (L[1], GetInverseBranch (L[1]->OPC));
/* Remember, we had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
/*****************************************************************************/
/* negax optimizations */
/*****************************************************************************/
unsigned OptNegAX1 (CodeSeg* S)
/* Search for a call to negax and replace it by
**
** eor #$FF
** clc
** adc #$01
**
** if X isn't used later.
*/
{
unsigned Changes = 0;
unsigned I;
/* Walk over the entries */
I = 0;
while (I < CS_GetEntryCount (S)) {
/* Get next entry */
CodeEntry* E = CS_GetEntry (S, I);
/* Check if this is a call to negax, and if X isn't used later */
if (CE_IsCallTo (E, "negax") && !RegXUsed (S, I+1)) {
CodeEntry* X;
/* Add replacement code behind */
X = NewCodeEntry (OP65_EOR, AM65_IMM, "$FF", 0, E->LI);
CS_InsertEntry (S, X, I+1);
X = NewCodeEntry (OP65_CLC, AM65_IMP, 0, 0, E->LI);
CS_InsertEntry (S, X, I+2);
X = NewCodeEntry (OP65_ADC, AM65_IMM, "$01", 0, E->LI);
CS_InsertEntry (S, X, I+3);
/* Delete the call to negax */
CS_DelEntry (S, I);
/* Skip the generated code */
I += 2;
/* We had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
unsigned OptNegAX2 (CodeSeg* S)
/* Search for a call to negax and replace it by
**
** ldx #$FF
** eor #$FF
** clc
** adc #$01
** bcc L1
** inx
** L1:
**
** if X is known and zero on entry.
*/
{
unsigned Changes = 0;
unsigned I;
/* Walk over the entries */
I = 0;
while (I < CS_GetEntryCount (S)) {
CodeEntry* P;
/* Get next entry */
CodeEntry* E = CS_GetEntry (S, I);
/* Check if this is a call to negax, and if X is known and zero */
if (E->RI->In.RegX == 0 &&
CE_IsCallTo (E, "negax") &&
(P = CS_GetNextEntry (S, I)) != 0) {
CodeEntry* X;
CodeLabel* L;
/* Add replacement code behind */
/* ldx #$FF */
X = NewCodeEntry (OP65_LDX, AM65_IMM, "$FF", 0, E->LI);
CS_InsertEntry (S, X, I+1);
/* eor #$FF */
X = NewCodeEntry (OP65_EOR, AM65_IMM, "$FF", 0, E->LI);
CS_InsertEntry (S, X, I+2);
/* clc */
X = NewCodeEntry (OP65_CLC, AM65_IMP, 0, 0, E->LI);
CS_InsertEntry (S, X, I+3);
/* adc #$01 */
X = NewCodeEntry (OP65_ADC, AM65_IMM, "$01", 0, E->LI);
CS_InsertEntry (S, X, I+4);
/* Get the label attached to the insn following the call */
L = CS_GenLabel (S, P);
/* bcc L */
X = NewCodeEntry (OP65_BCC, AM65_BRA, L->Name, L, E->LI);
CS_InsertEntry (S, X, I+5);
/* inx */
X = NewCodeEntry (OP65_INX, AM65_IMP, 0, 0, E->LI);
CS_InsertEntry (S, X, I+6);
/* Delete the call to negax */
CS_DelEntry (S, I);
/* Skip the generated code */
I += 5;
/* We had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
/*****************************************************************************/
/* complax optimizations */
/*****************************************************************************/
unsigned OptComplAX1 (CodeSeg* S)
/* Search for a call to complax and replace it by
**
** eor #$FF
**
** if X isn't used later.
*/
{
unsigned Changes = 0;
unsigned I;
/* Walk over the entries */
I = 0;
while (I < CS_GetEntryCount (S)) {
/* Get next entry */
CodeEntry* E = CS_GetEntry (S, I);
/* Check if this is a call to negax, and if X isn't used later */
if (CE_IsCallTo (E, "complax") && !RegXUsed (S, I+1)) {
CodeEntry* X;
/* Add replacement code behind */
X = NewCodeEntry (OP65_EOR, AM65_IMM, "$FF", 0, E->LI);
CS_InsertEntry (S, X, I+1);
/* Delete the call to negax */
CS_DelEntry (S, I);
/* We had changes */
++Changes;
}
/* Next entry */
++I;
}
/* Return the number of changes made */
return Changes;
}
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