1 | /*****************************************************************************/ |
2 | /* */ |
3 | /* coptcmp.h */ |
4 | /* */ |
5 | /* Optimize compares */ |
6 | /* */ |
7 | /* */ |
8 | /* */ |
9 | /* (C) 2001-2009, Ullrich von Bassewitz */ |
10 | /* Roemerstrasse 52 */ |
11 | /* D-70794 Filderstadt */ |
12 | /* EMail: uz@cc65.org */ |
13 | /* */ |
14 | /* */ |
15 | /* This software is provided 'as-is', without any expressed or implied */ |
16 | /* warranty. In no event will the authors be held liable for any damages */ |
17 | /* arising from the use of this software. */ |
18 | /* */ |
19 | /* Permission is granted to anyone to use this software for any purpose, */ |
20 | /* including commercial applications, and to alter it and redistribute it */ |
21 | /* freely, subject to the following restrictions: */ |
22 | /* */ |
23 | /* 1. The origin of this software must not be misrepresented; you must not */ |
24 | /* claim that you wrote the original software. If you use this software */ |
25 | /* in a product, an acknowledgment in the product documentation would be */ |
26 | /* appreciated but is not required. */ |
27 | /* 2. Altered source versions must be plainly marked as such, and must not */ |
28 | /* be misrepresented as being the original software. */ |
29 | /* 3. This notice may not be removed or altered from any source */ |
30 | /* distribution. */ |
31 | /* */ |
32 | /*****************************************************************************/ |
33 | |
34 | |
35 | |
36 | #ifndef COPTCMP_H |
37 | #define COPTCMP_H |
38 | |
39 | |
40 | |
41 | /* cc65 */ |
42 | #include "codeseg.h" |
43 | |
44 | |
45 | |
46 | /*****************************************************************************/ |
47 | /* Remove calls to the bool transformer subroutines */ |
48 | /*****************************************************************************/ |
49 | |
50 | |
51 | |
52 | unsigned OptBoolTrans (CodeSeg* S); |
53 | /* Try to remove the call to boolean transformer routines where the call is |
54 | ** not really needed. |
55 | */ |
56 | |
57 | |
58 | |
59 | /*****************************************************************************/ |
60 | /* Optimizations for compares */ |
61 | /*****************************************************************************/ |
62 | |
63 | |
64 | |
65 | unsigned OptCmp1 (CodeSeg* S); |
66 | /* Search for the sequence |
67 | ** |
68 | ** ldx xx |
69 | ** stx tmp1 |
70 | ** ora tmp1 |
71 | ** |
72 | ** and replace it by |
73 | ** |
74 | ** ora xx |
75 | */ |
76 | |
77 | unsigned OptCmp2 (CodeSeg* S); |
78 | /* Search for the sequence |
79 | ** |
80 | ** stx xx |
81 | ** stx tmp1 |
82 | ** ora tmp1 |
83 | ** |
84 | ** and replace it by |
85 | ** |
86 | ** stx xx |
87 | ** ora xx |
88 | */ |
89 | |
90 | unsigned OptCmp3 (CodeSeg* S); |
91 | /* Search for |
92 | ** |
93 | ** lda/and/ora/eor ... |
94 | ** cmp #$00 |
95 | ** jeq/jne |
96 | ** or |
97 | ** lda/and/ora/eor ... |
98 | ** cmp #$00 |
99 | ** jsr boolxx |
100 | ** |
101 | ** and remove the cmp. |
102 | */ |
103 | |
104 | unsigned OptCmp4 (CodeSeg* S); |
105 | /* Search for |
106 | ** |
107 | ** lda x |
108 | ** ldx y |
109 | ** cpx #a |
110 | ** bne L1 |
111 | ** cmp #b |
112 | ** jne/jeq L2 |
113 | ** |
114 | ** If a is zero, we may remove the compare. If a and b are both zero, we may |
115 | ** replace it by the sequence |
116 | ** |
117 | ** lda x |
118 | ** ora x+1 |
119 | ** jne/jeq ... |
120 | ** |
121 | ** L1 may be either the label at the branch instruction, or the target label |
122 | ** of this instruction. |
123 | */ |
124 | |
125 | unsigned OptCmp5 (CodeSeg* S); |
126 | /* Optimize compares of local variables: |
127 | ** |
128 | ** ldy #o |
129 | ** lda (sp),y |
130 | ** tax |
131 | ** dey |
132 | ** lda (sp),y |
133 | ** cpx #a |
134 | ** bne L1 |
135 | ** cmp #b |
136 | ** jne/jeq L2 |
137 | */ |
138 | |
139 | unsigned OptCmp6 (CodeSeg* S); |
140 | /* Search for calls to compare subroutines followed by a conditional branch |
141 | ** and replace them by cheaper versions, since the branch means that the |
142 | ** boolean value returned by these routines is not needed (we may also check |
143 | ** that explicitly, but for the current code generator it is always true). |
144 | */ |
145 | |
146 | unsigned OptCmp7 (CodeSeg* S); |
147 | /* Search for a sequence ldx/txa/branch and remove the txa if A is not |
148 | ** used later. |
149 | */ |
150 | |
151 | unsigned OptCmp8 (CodeSeg* S); |
152 | /* Check for register compares where the contents of the register and therefore |
153 | ** the result of the compare is known. |
154 | */ |
155 | |
156 | unsigned OptCmp9 (CodeSeg* S); |
157 | /* Search for the sequence |
158 | ** |
159 | ** sbc xx |
160 | ** bvs/bvc L |
161 | ** eor #$80 |
162 | ** L: asl a |
163 | ** bcc/bcs somewhere |
164 | ** |
165 | ** If A is not used later (which should be the case), we can branch on the N |
166 | ** flag instead of the carry flag and remove the asl. |
167 | */ |
168 | |
169 | |
170 | |
171 | /* End of coptcmp.h */ |
172 | |
173 | #endif |
174 | |