mirror of https://github.com/cc65/cc65.git
154 lines
4.6 KiB
C
154 lines
4.6 KiB
C
/*****************************************************************************/
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/* */
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/* coptcmp.h */
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/* */
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/* Optimize compares */
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/* */
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/* */
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/* */
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/* (C) 2001-2009, 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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#ifndef COPTCMP_H
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#define COPTCMP_H
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/* cc65 */
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#include "codeseg.h"
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/*****************************************************************************/
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/* Optimizations for compares */
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/*****************************************************************************/
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unsigned OptCmp1 (CodeSeg* S);
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/* Search for the sequence
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**
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** ldx xx
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** stx tmp1
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** ora tmp1
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**
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** and replace it by
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**
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** ora xx
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*/
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unsigned OptCmp2 (CodeSeg* S);
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/* Search for the sequence
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**
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** stx xx
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** stx tmp1
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** ora tmp1
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**
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** and replace it by
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**
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** stx xx
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** ora xx
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*/
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unsigned OptCmp3 (CodeSeg* S);
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/* Search for
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**
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** lda/and/ora/eor ...
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** cmp #$00
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** jeq/jne
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** or
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** lda/and/ora/eor ...
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** cmp #$00
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** jsr boolxx
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**
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** and remove the cmp.
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*/
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unsigned OptCmp4 (CodeSeg* S);
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/* Search for
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**
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** lda x
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** ldx y
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** cpx #a
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** bne L1
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** cmp #b
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** jne/jeq L2
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**
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** If a is zero, we may remove the compare. If a and b are both zero, we may
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** replace it by the sequence
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**
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** lda x
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** ora x+1
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** jne/jeq ...
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**
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** L1 may be either the label at the branch instruction, or the target label
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** of this instruction.
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*/
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unsigned OptCmp5 (CodeSeg* S);
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/* Optimize compares of local variables:
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**
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** ldy #o
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** lda (sp),y
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** tax
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** dey
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** lda (sp),y
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** cpx #a
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** bne L1
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** cmp #b
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** jne/jeq L2
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*/
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unsigned OptCmp7 (CodeSeg* S);
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/* Search for a sequence ldx/txa/branch and remove the txa if A is not
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** used later.
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*/
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unsigned OptCmp8 (CodeSeg* S);
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/* Check for register compares where the contents of the register and therefore
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** the result of the compare is known.
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*/
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unsigned OptCmp9 (CodeSeg* S);
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/* Search for the sequence
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**
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** sbc xx
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** bvs/bvc L
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** eor #$80
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** L: asl a
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** bcc/bcs somewhere
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**
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** If A is not used later (which should be the case), we can branch on the N
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** flag instead of the carry flag and remove the asl.
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*/
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/* End of coptcmp.h */
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#endif
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