1 /*****************************************************************************/
5 /* Parse the switch statement */
9 /* (C) 1998-2004 Ullrich von Bassewitz */
11 /* D-70794 Filderstadt */
12 /* EMail: uz@cc65.org */
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. */
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: */
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 */
32 /*****************************************************************************/
58 /*****************************************************************************/
60 /*****************************************************************************/
64 void SwitchStatement (void)
65 /* Handle a switch statement for chars with a cmp cascade for the selector */
67 Collection* Nodes; /* CaseNode tree */
68 ExprDesc SwitchExpr; /* Switch statement expression */
69 ExprDesc CaseExpr; /* Case label expression */
70 type SwitchExprType; /* Basic switch expression type */
71 CodeMark CaseCodeStart; /* Start of code marker */
72 unsigned Depth; /* Number of bytes the selector type has */
73 unsigned ExitLabel; /* Exit label */
74 unsigned CaseLabel; /* Label for case */
75 unsigned DefaultLabel; /* Label for the default branch */
76 unsigned SwitchCodeLabel; /* Label for the switch code */
77 long Val; /* Case label value */
78 int HaveBreak = 0; /* True if the last statement had a break */
81 /* Eat the "switch" token */
84 /* Read the switch expression and load it into the primary. It must have
88 Expression0 (&SwitchExpr);
89 if (!IsClassInt (SwitchExpr.Type)) {
90 Error ("Switch quantity is not an integer");
91 /* To avoid any compiler errors, make the expression a valid int */
92 ED_MakeConstAbsInt (&SwitchExpr, 1);
94 /* Load the expression into the primary register */
97 /* Add a jump to the switch code. This jump is usually unnecessary,
98 * because the switch code will moved up just behind the switch
99 * expression. However, in rare cases, there's a label at the end of
100 * the switch expression. This label will not get moved, so the code
101 * jumps around the switch code, and after moving the switch code,
102 * things look really weird. If we add a jump here, we will never have
103 * a label attached to the current code position, and the jump itself
104 * will get removed by the optimizer if it is unnecessary.
106 SwitchCodeLabel = GetLocalLabel ();
107 g_jump (SwitchCodeLabel);
109 /* Remember the current code position. We will move the switch code
110 * to this position later.
112 GetCodePos (&CaseCodeStart);
114 /* Opening curly brace */
117 /* Get the unqualified type of the switch expression */
118 SwitchExprType = UnqualifiedType (SwitchExpr.Type[0]);
120 /* Get the number of bytes the selector type has */
121 Depth = SizeOf (SwitchExpr.Type);
122 CHECK (Depth == 1 || Depth == 2 || Depth == 4);
124 /* Get the exit label for the switch statement */
125 ExitLabel = GetLocalLabel ();
127 /* Create a loop so we may use break. */
128 AddLoop (ExitLabel, 0);
130 /* Create the collection for the case node tree */
131 Nodes = NewCollection ();
133 /* Clear the label for the default branch */
136 /* Parse the labels */
137 while (CurTok.Tok != TOK_RCURLY) {
139 while (CurTok.Tok == TOK_CASE || CurTok.Tok == TOK_DEFAULT) {
141 /* Parse the selector */
142 if (CurTok.Tok == TOK_CASE) {
144 /* Skip the "case" token */
147 /* Read the selector expression */
148 ConstAbsIntExpr (hie1, &CaseExpr);
150 /* Check the range of the expression */
152 switch (SwitchExprType) {
156 if (Val < -128 || Val > 127) {
157 Error ("Range error");
162 if (Val < 0 || Val > 255) {
163 Error ("Range error");
169 if (Val < -32768 || Val > 32767) {
170 Error ("Range error");
176 if (Val < 0 || Val > 65535) {
177 Error ("Range error");
186 Internal ("Invalid type: %04X", SwitchExprType);
189 /* Insert the case selector into the selector table */
190 CaseLabel = InsertCaseValue (Nodes, Val, Depth);
192 /* Define this label */
193 g_defcodelabel (CaseLabel);
203 /* Check if we do already have a default branch */
204 if (DefaultLabel == 0) {
206 /* Generate and emit the default label */
207 DefaultLabel = GetLocalLabel ();
208 g_defcodelabel (DefaultLabel);
211 /* We had the default label already */
212 Error ("Duplicate `default' case");
222 /* Parse statements */
223 if (CurTok.Tok != TOK_RCURLY) {
224 HaveBreak = Statement (0);
228 /* Check if we had any labels */
229 if (CollCount (Nodes) == 0 && DefaultLabel == 0) {
231 Warning ("No case labels");
235 CodeMark SwitchCodeStart, SwitchCodeEnd;
237 /* If the last statement did not have a break, we may have an open
238 * label (maybe from an if or similar). Emitting code and then moving
239 * this code to the top will also move the label to the top which is
240 * wrong. So if the last statement did not have a break (which would
241 * carry the label), add a jump to the exit. If it is useless, the
242 * optimizer will remove it later.
248 /* Remember the current position */
249 GetCodePos (&SwitchCodeStart);
251 /* Output the switch code label */
252 g_defcodelabel (SwitchCodeLabel);
255 g_switch (Nodes, DefaultLabel? DefaultLabel : ExitLabel, Depth);
257 /* Move the code to the front */
258 GetCodePos (&SwitchCodeEnd);
259 MoveCode (&SwitchCodeStart, &SwitchCodeEnd, &CaseCodeStart);
263 /* Define the exit label */
264 g_defcodelabel (ExitLabel);
266 /* Eat the closing curly brace */
269 /* Free the case value tree */
270 FreeCaseNodeColl (Nodes);