mirror of https://github.com/cc65/cc65.git
171 lines
6.0 KiB
C
171 lines
6.0 KiB
C
/*****************************************************************************/
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/* */
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/* copttest.c */
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/* */
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/* Optimize test 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 "copttest.h"
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/*****************************************************************************/
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/* Optimize tests */
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/*****************************************************************************/
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unsigned OptTest1 (CodeSeg* S)
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/* Given a sequence
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**
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** stx xxx
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** ora xxx
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** beq/bne ...
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**
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** If X is zero, the sequence may be changed to
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**
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** cmp #$00
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** beq/bne ...
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**
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** which may be optimized further by another step.
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**
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** If A is zero, the sequence may be changed to
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**
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** txa
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** beq/bne ...
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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* L[3];
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/* Get next entry */
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L[0] = CS_GetEntry (S, I);
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/* Check if it's the sequence we're searching for */
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if (L[0]->OPC == OP65_STX &&
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CS_GetEntries (S, L+1, I+1, 2) &&
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!CE_HasLabel (L[1]) &&
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L[1]->OPC == OP65_ORA &&
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strcmp (L[0]->Arg, L[1]->Arg) == 0 &&
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!CE_HasLabel (L[2]) &&
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(L[2]->Info & OF_ZBRA) != 0) {
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/* Check if X is zero */
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if (L[0]->RI->In.RegX == 0) {
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/* Insert the compare */
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CodeEntry* N = NewCodeEntry (OP65_CMP, AM65_IMM, "$00", 0, L[0]->LI);
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CS_InsertEntry (S, N, I+2);
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/* Remove the two other insns */
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CS_DelEntry (S, I+1);
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CS_DelEntry (S, I);
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/* We had changes */
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++Changes;
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/* Check if A is zero */
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} else if (L[1]->RI->In.RegA == 0) {
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/* Insert the txa */
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CodeEntry* N = NewCodeEntry (OP65_TXA, AM65_IMP, 0, 0, L[1]->LI);
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CS_InsertEntry (S, N, I+2);
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/* Remove the two other insns */
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CS_DelEntry (S, I+1);
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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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}
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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 OptTest2 (CodeSeg* S)
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/* Search for an inc/dec operation followed by a load and a conditional
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** branch based on the flags from the load. Remove the load if the insn
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** isn't used later.
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*/
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{
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unsigned Changes = 0;
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/* Walk over the entries */
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unsigned I = 0;
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while (I < CS_GetEntryCount (S)) {
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CodeEntry* L[3];
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/* Get next entry */
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L[0] = CS_GetEntry (S, I);
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/* Check if it's the sequence we're searching for */
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if ((L[0]->OPC == OP65_INC || L[0]->OPC == OP65_DEC) &&
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CS_GetEntries (S, L+1, I+1, 2) &&
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!CE_HasLabel (L[1]) &&
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(L[1]->Info & OF_LOAD) != 0 &&
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(L[2]->Info & OF_FBRA) != 0 &&
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L[1]->AM == L[0]->AM &&
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strcmp (L[0]->Arg, L[1]->Arg) == 0 &&
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(GetRegInfo (S, I+2, L[1]->Chg & ~PSTATE_ZN) & L[1]->Chg & ~PSTATE_ZN) == 0) {
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/* Remove the load */
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CS_DelEntry (S, I+1);
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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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