mirror of https://github.com/cc65/cc65.git
183 lines
6.0 KiB
C
183 lines
6.0 KiB
C
/*****************************************************************************/
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/* */
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/* coptpush.c */
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/* */
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/* Optimize push 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 "coptpush.h"
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/*****************************************************************************/
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/* Code */
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/*****************************************************************************/
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unsigned OptPush1 (CodeSeg* S)
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/* Given a sequence
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**
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** jsr ldaxysp
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** jsr pushax
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**
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** If a/x are not used later, and Y is known, replace that by
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**
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** ldy #xx+2
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** jsr pushwysp
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** ldy #$00 ; present if later code expects Y = 0
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**
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** saving several cycles.
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*/
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{
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unsigned I;
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unsigned Changes = 0;
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unsigned R;
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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* L[2];
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/* Get next entry */
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L[0] = CS_GetEntry (S, I);
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/* Check for the sequence */
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if (CE_IsCallTo (L[0], "ldaxysp") &&
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RegValIsKnown (L[0]->RI->In.RegY) &&
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L[0]->RI->In.RegY < 0xFE &&
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(L[1] = CS_GetNextEntry (S, I)) != 0 &&
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!CE_HasLabel (L[1]) &&
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CE_IsCallTo (L[1], "pushax") &&
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((R = (GetRegInfo (S, I+2, REG_AXY))) & REG_AX) == 0) {
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/* Insert new code behind the pushax */
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const char* Arg;
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CodeEntry* X;
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/* ldy #xx+1 */
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Arg = MakeHexArg (L[0]->RI->In.RegY+2);
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X = NewCodeEntry (OP65_LDY, AM65_IMM, Arg, 0, L[0]->LI);
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CS_InsertEntry (S, X, I+2);
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/* jsr pushwysp */
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X = NewCodeEntry (OP65_JSR, AM65_ABS, "pushwysp", 0, L[1]->LI);
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CS_InsertEntry (S, X, I+3);
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/* pushax sets Y = 0 and following code might rely on this */
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if ((R & REG_Y) != 0) {
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/* ldy #0 */
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X = NewCodeEntry (OP65_LDY, AM65_IMM, MakeHexArg (0), 0, L[1]->LI);
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CS_InsertEntry (S, X, I+4);
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}
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/* Delete the old code */
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CS_DelEntries (S, I, 2);
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/* Remember, we had changes */
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++Changes;
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/* Skip the handled lines */
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if ((R & REG_Y) == 0) {
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++I;
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} else {
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I += 2;
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}
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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 OptPush2 (CodeSeg* S)
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/* A sequence
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**
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** jsr ldaxidx
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** jsr pushax
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**
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** may get replaced by
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**
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** jsr pushwidx
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*/
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{
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unsigned I;
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unsigned Changes = 0;
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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* L[2];
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/* Get next entry */
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L[0] = CS_GetEntry (S, I);
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/* Check for the sequence */
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if (CE_IsCallTo (L[0], "ldaxidx") &&
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(L[1] = CS_GetNextEntry (S, I)) != 0 &&
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!CE_HasLabel (L[1]) &&
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CE_IsCallTo (L[1], "pushax")) {
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/* Insert new code behind the pushax */
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CodeEntry* X;
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/* jsr pushwidx */
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X = NewCodeEntry (OP65_JSR, AM65_ABS, "pushwidx", 0, L[1]->LI);
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CS_InsertEntry (S, X, I+2);
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/* Delete the old code */
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CS_DelEntries (S, I, 2);
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/* Remember, 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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