mirror of https://github.com/cc65/cc65.git
237 lines
7.1 KiB
C
237 lines
7.1 KiB
C
/*****************************************************************************/
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/* */
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/* coptunary.c */
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/* */
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/* Optimize bitwise unary sequences */
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/* */
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/* */
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/* */
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/* (C) 2001-2012, Ullrich von Bassewitz */
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/* Roemerstrasse 52 */
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/* D-70794 Filderstadt */
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/* EMail: uz@cc65.org */
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/* */
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/* */
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/* This software is provided 'as-is', without any expressed or implied */
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/* warranty. In no event will the authors be held liable for any damages */
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/* arising from the use of this software. */
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/* */
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/* Permission is granted to anyone to use this software for any purpose, */
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/* including commercial applications, and to alter it and redistribute it */
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/* freely, subject to the following restrictions: */
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/* */
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/* 1. The origin of this software must not be misrepresented; you must not */
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/* claim that you wrote the original software. If you use this software */
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/* in a product, an acknowledgment in the product documentation would be */
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/* appreciated but is not required. */
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/* 2. Altered source versions must be plainly marked as such, and must not */
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/* be misrepresented as being the original software. */
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/* 3. This notice may not be removed or altered from any source */
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/* distribution. */
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/* */
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/*****************************************************************************/
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/* cc65 */
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#include "codeent.h"
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#include "codeinfo.h"
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#include "coptbool.h"
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/*****************************************************************************/
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/* negax optimizations */
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/*****************************************************************************/
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unsigned OptNegAX1 (CodeSeg* S)
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/* Search for a call to negax and replace it by
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**
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** eor #$FF
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** clc
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** adc #$01
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**
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** if X isn't used later.
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*/
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{
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unsigned Changes = 0;
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unsigned I;
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/* Walk over the entries */
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I = 0;
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while (I < CS_GetEntryCount (S)) {
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/* Get next entry */
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CodeEntry* E = CS_GetEntry (S, I);
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/* Check if this is a call to negax, and if X isn't used later */
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if (CE_IsCallTo (E, "negax") && !RegXUsed (S, I+1)) {
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CodeEntry* X;
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/* Add replacement code behind */
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X = NewCodeEntry (OP65_EOR, AM65_IMM, "$FF", 0, E->LI);
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CS_InsertEntry (S, X, I+1);
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X = NewCodeEntry (OP65_CLC, AM65_IMP, 0, 0, E->LI);
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CS_InsertEntry (S, X, I+2);
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X = NewCodeEntry (OP65_ADC, AM65_IMM, "$01", 0, E->LI);
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CS_InsertEntry (S, X, I+3);
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/* Delete the call to negax */
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CS_DelEntry (S, I);
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/* Skip the generated code */
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I += 2;
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/* We had changes */
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++Changes;
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}
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/* Next entry */
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++I;
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}
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/* Return the number of changes made */
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return Changes;
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}
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unsigned OptNegAX2 (CodeSeg* S)
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/* Search for a call to negax and replace it by
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**
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** ldx #$FF
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** eor #$FF
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** clc
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** adc #$01
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** bcc L1
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** inx
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** L1:
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**
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** if X is known and zero on entry.
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*/
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{
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unsigned Changes = 0;
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unsigned I;
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/* Walk over the entries */
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I = 0;
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while (I < CS_GetEntryCount (S)) {
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CodeEntry* P;
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/* Get next entry */
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CodeEntry* E = CS_GetEntry (S, I);
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/* Check if this is a call to negax, and if X is known and zero */
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if (E->RI->In.RegX == 0 &&
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CE_IsCallTo (E, "negax") &&
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(P = CS_GetNextEntry (S, I)) != 0) {
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CodeEntry* X;
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CodeLabel* L;
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/* Add replacement code behind */
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/* ldx #$FF */
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X = NewCodeEntry (OP65_LDX, AM65_IMM, "$FF", 0, E->LI);
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CS_InsertEntry (S, X, I+1);
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/* eor #$FF */
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X = NewCodeEntry (OP65_EOR, AM65_IMM, "$FF", 0, E->LI);
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CS_InsertEntry (S, X, I+2);
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/* clc */
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X = NewCodeEntry (OP65_CLC, AM65_IMP, 0, 0, E->LI);
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CS_InsertEntry (S, X, I+3);
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/* adc #$01 */
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X = NewCodeEntry (OP65_ADC, AM65_IMM, "$01", 0, E->LI);
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CS_InsertEntry (S, X, I+4);
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/* Get the label attached to the insn following the call */
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L = CS_GenLabel (S, P);
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/* bcc L */
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X = NewCodeEntry (OP65_BCC, AM65_BRA, L->Name, L, E->LI);
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CS_InsertEntry (S, X, I+5);
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/* inx */
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X = NewCodeEntry (OP65_INX, AM65_IMP, 0, 0, E->LI);
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CS_InsertEntry (S, X, I+6);
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/* Delete the call to negax */
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CS_DelEntry (S, I);
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/* Skip the generated code */
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I += 5;
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/* We had changes */
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++Changes;
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}
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/* Next entry */
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++I;
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}
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/* Return the number of changes made */
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return Changes;
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}
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/*****************************************************************************/
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/* complax optimizations */
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/*****************************************************************************/
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unsigned OptComplAX1 (CodeSeg* S)
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/* Search for a call to complax and replace it by
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**
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** eor #$FF
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**
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** if X isn't used later.
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*/
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{
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unsigned Changes = 0;
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unsigned I;
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/* Walk over the entries */
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I = 0;
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while (I < CS_GetEntryCount (S)) {
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/* Get next entry */
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CodeEntry* E = CS_GetEntry (S, I);
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/* Check if this is a call to negax, and if X isn't used later */
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if (CE_IsCallTo (E, "complax") && !RegXUsed (S, I+1)) {
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CodeEntry* X;
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/* Add replacement code behind */
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X = NewCodeEntry (OP65_EOR, AM65_IMM, "$FF", 0, E->LI);
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CS_InsertEntry (S, X, I+1);
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/* Delete the call to negax */
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CS_DelEntry (S, I);
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/* We had changes */
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++Changes;
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}
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/* Next entry */
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++I;
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}
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/* Return the number of changes made */
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return Changes;
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}
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