1 | /*****************************************************************************/ |
2 | /* */ |
3 | /* testexpr.c */ |
4 | /* */ |
5 | /* Test an expression and jump */ |
6 | /* */ |
7 | /* */ |
8 | /* */ |
9 | /* (C) 2004 Ullrich von Bassewitz */ |
10 | /* Römerstraße 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 | /* cc65 */ |
37 | #include "codegen.h" |
38 | #include "error.h" |
39 | #include "expr.h" |
40 | #include "loadexpr.h" |
41 | #include "scanner.h" |
42 | #include "testexpr.h" |
43 | |
44 | |
45 | |
46 | /*****************************************************************************/ |
47 | /* Code */ |
48 | /*****************************************************************************/ |
49 | |
50 | |
51 | |
52 | unsigned Test (unsigned Label, int Invert) |
53 | /* Evaluate a boolean test expression and jump depending on the result of |
54 | ** the test and on Invert. The function returns one of the TESTEXPR_xx codes |
55 | ** defined above. If the jump is always true, a warning is output. |
56 | */ |
57 | { |
58 | ExprDesc Expr; |
59 | unsigned Result; |
60 | |
61 | /* Read a boolean expression */ |
62 | BoolExpr (hie0, &Expr); |
63 | |
64 | /* Check for a constant expression */ |
65 | if (ED_IsConstAbs (&Expr)) { |
66 | |
67 | /* Result is constant, so we know the outcome */ |
68 | Result = (Expr.IVal != 0); |
69 | |
70 | /* Constant rvalue */ |
71 | if (!Invert && Expr.IVal == 0) { |
72 | g_jump (Label); |
73 | Warning ("Unreachable code" ); |
74 | } else if (Invert && Expr.IVal != 0) { |
75 | g_jump (Label); |
76 | } |
77 | |
78 | } else { |
79 | |
80 | /* Result is unknown */ |
81 | Result = TESTEXPR_UNKNOWN; |
82 | |
83 | /* If the expr hasn't set condition codes, set the force-test flag */ |
84 | if (!ED_IsTested (&Expr)) { |
85 | ED_MarkForTest (&Expr); |
86 | } |
87 | |
88 | /* Load the value into the primary register */ |
89 | LoadExpr (CF_FORCECHAR, &Expr); |
90 | |
91 | /* Generate the jump */ |
92 | if (Invert) { |
93 | g_truejump (CF_NONE, Label); |
94 | } else { |
95 | g_falsejump (CF_NONE, Label); |
96 | } |
97 | } |
98 | |
99 | /* Return the result */ |
100 | return Result; |
101 | } |
102 | |
103 | |
104 | |
105 | unsigned TestInParens (unsigned Label, int Invert) |
106 | /* Evaluate a boolean test expression in parenthesis and jump depending on |
107 | ** the result of the test * and on Invert. The function returns one of the |
108 | ** TESTEXPR_xx codes defined above. If the jump is always true, a warning is |
109 | ** output. |
110 | */ |
111 | { |
112 | unsigned Result; |
113 | |
114 | /* Eat the parenthesis */ |
115 | ConsumeLParen (); |
116 | |
117 | /* Do the test */ |
118 | Result = Test (Label, Invert); |
119 | |
120 | /* Check for the closing brace */ |
121 | ConsumeRParen (); |
122 | |
123 | /* Return the result of the expression */ |
124 | return Result; |
125 | } |
126 | |