1 /*****************************************************************************/
5 /* Parse a statement */
9 /* (C) 1998-2009, Ullrich von Bassewitz */
10 /* Roemerstrasse 52 */
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 /*****************************************************************************/
68 /*****************************************************************************/
69 /* Helper functions */
70 /*****************************************************************************/
74 static void CheckLabelWithoutStatement (void)
75 /* Called from Statement() after a label definition. Will check for a
76 * following closing curly brace. This means that a label is not followed
77 * by a statement which is required by the standard. Output an error if so.
80 if (CurTok.Tok == TOK_RCURLY) {
81 Error ("Label at end of compound statement");
87 static void CheckTok (token_t Tok, const char* Msg, int* PendingToken)
88 /* Helper function for Statement. Will check for Tok and print Msg if not
89 * found. If PendingToken is NULL, it will the skip the token, otherwise
90 * it will store one to PendingToken.
93 if (CurTok.Tok != Tok) {
95 } else if (PendingToken) {
104 static void CheckSemi (int* PendingToken)
105 /* Helper function for Statement. Will check for a semicolon and print an
106 * error message if not found (plus some error recovery). If PendingToken is
107 * NULL, it will the skip the token, otherwise it will store one to
109 * This function is a special version of CheckTok with the addition of the
113 int HaveToken = (CurTok.Tok == TOK_SEMI);
115 Error ("`;' expected");
116 /* Try to be smart about errors */
117 if (CurTok.Tok == TOK_COLON || CurTok.Tok == TOK_COMMA) {
132 static void SkipPending (int PendingToken)
133 /* Skip the pending token if we have one */
142 /*****************************************************************************/
144 /*****************************************************************************/
148 static int IfStatement (void)
149 /* Handle an 'if' statement */
158 /* Generate a jump label and parse the condition */
159 Label1 = GetLocalLabel ();
160 TestResult = TestInParens (Label1, 0);
162 /* Parse the if body */
163 GotBreak = Statement (0);
165 /* Else clause present? */
166 if (CurTok.Tok != TOK_ELSE) {
168 g_defcodelabel (Label1);
170 /* Since there's no else clause, we're not sure, if the a break
171 * statement is really executed.
177 /* Generate a jump around the else branch */
178 unsigned Label2 = GetLocalLabel ();
184 /* If the if expression was always true, the code in the else branch
185 * is never executed. Output a warning if this is the case.
187 if (TestResult == TESTEXPR_TRUE) {
188 Warning ("Unreachable code");
191 /* Define the target for the first test */
192 g_defcodelabel (Label1);
194 /* Total break only if both branches had a break. */
195 GotBreak &= Statement (0);
197 /* Generate the label for the else clause */
198 g_defcodelabel (Label2);
207 static void DoStatement (void)
208 /* Handle the 'do' statement */
210 /* Get the loop control labels */
211 unsigned LoopLabel = GetLocalLabel ();
212 unsigned BreakLabel = GetLocalLabel ();
213 unsigned ContinueLabel = GetLocalLabel ();
215 /* Skip the while token */
218 /* Add the loop to the loop stack */
219 AddLoop (BreakLabel, ContinueLabel);
221 /* Define the loop label */
222 g_defcodelabel (LoopLabel);
224 /* Parse the loop body */
227 /* Output the label for a continue */
228 g_defcodelabel (ContinueLabel);
230 /* Parse the end condition */
231 Consume (TOK_WHILE, "`while' expected");
232 TestInParens (LoopLabel, 1);
235 /* Define the break label */
236 g_defcodelabel (BreakLabel);
238 /* Remove the loop from the loop stack */
244 static void WhileStatement (void)
245 /* Handle the 'while' statement */
248 CodeMark CondCodeStart; /* Start of condition evaluation code */
249 CodeMark CondCodeEnd; /* End of condition evaluation code */
250 CodeMark Here; /* "Here" location of code */
252 /* Get the loop control labels */
253 unsigned LoopLabel = GetLocalLabel ();
254 unsigned BreakLabel = GetLocalLabel ();
255 unsigned CondLabel = GetLocalLabel ();
257 /* Skip the while token */
260 /* Add the loop to the loop stack. In case of a while loop, the condition
261 * label is used for continue statements.
263 AddLoop (BreakLabel, CondLabel);
265 /* We will move the code that evaluates the while condition to the end of
266 * the loop, so generate a jump here.
270 /* Remember the current position */
271 GetCodePos (&CondCodeStart);
273 /* Emit the code position label */
274 g_defcodelabel (CondLabel);
276 /* Test the loop condition */
277 TestInParens (LoopLabel, 1);
279 /* Remember the end of the condition evaluation code */
280 GetCodePos (&CondCodeEnd);
282 /* Define the head label */
283 g_defcodelabel (LoopLabel);
286 Statement (&PendingToken);
288 /* Move the test code here */
290 MoveCode (&CondCodeStart, &CondCodeEnd, &Here);
293 g_defcodelabel (BreakLabel);
295 /* Eat remaining tokens that were delayed because of line info
298 SkipPending (PendingToken);
300 /* Remove the loop from the loop stack */
306 static void ReturnStatement (void)
307 /* Handle the 'return' statement */
312 if (CurTok.Tok != TOK_SEMI) {
314 /* Evaluate the return expression */
317 /* If we return something in a void function, print an error and
318 * ignore the value. Otherwise convert the value to the type of the
321 if (F_HasVoidReturn (CurrentFunc)) {
322 Error ("Returning a value in function with return type void");
324 /* Convert the return value to the type of the function result */
325 TypeConversion (&Expr, F_GetReturnType (CurrentFunc));
327 /* Load the value into the primary */
328 LoadExpr (CF_NONE, &Expr);
331 } else if (!F_HasVoidReturn (CurrentFunc) && !F_HasOldStyleIntRet (CurrentFunc)) {
332 Error ("Function `%s' must return a value", F_GetFuncName (CurrentFunc));
335 /* Mark the function as having a return statement */
336 F_ReturnFound (CurrentFunc);
338 /* Cleanup the stack in case we're inside a block with locals */
339 g_space (StackPtr - F_GetTopLevelSP (CurrentFunc));
341 /* Output a jump to the function exit code */
342 g_jump (F_GetRetLab (CurrentFunc));
347 static void BreakStatement (void)
348 /* Handle the 'break' statement */
355 /* Get the current loop descriptor */
358 /* Check if we are inside a loop */
360 /* Error: No current loop */
361 Error ("`break' statement not within loop or switch");
365 /* Correct the stack pointer if needed */
366 g_space (StackPtr - L->StackPtr);
368 /* Jump to the exit label of the loop */
369 g_jump (L->BreakLabel);
374 static void ContinueStatement (void)
375 /* Handle the 'continue' statement */
379 /* Skip the continue */
382 /* Get the current loop descriptor */
385 /* Search for a loop that has a continue label. */
387 if (L->ContinueLabel) {
394 /* Did we find it? */
396 Error ("`continue' statement not within a loop");
400 /* Correct the stackpointer if needed */
401 g_space (StackPtr - L->StackPtr);
403 /* Jump to next loop iteration */
404 g_jump (L->ContinueLabel);
409 static void ForStatement (void)
410 /* Handle a 'for' statement */
415 CodeMark IncExprStart;
419 /* Get several local labels needed later */
420 unsigned TestLabel = GetLocalLabel ();
421 unsigned BreakLabel = GetLocalLabel ();
422 unsigned IncLabel = GetLocalLabel ();
423 unsigned BodyLabel = GetLocalLabel ();
425 /* Skip the FOR token */
428 /* Add the loop to the loop stack. A continue jumps to the start of the
429 * the increment condition.
431 AddLoop (BreakLabel, IncLabel);
433 /* Skip the opening paren */
436 /* Parse the initializer expression */
437 if (CurTok.Tok != TOK_SEMI) {
438 Expression0 (&lval1);
442 /* Label for the test expressions */
443 g_defcodelabel (TestLabel);
445 /* Parse the test expression */
446 if (CurTok.Tok != TOK_SEMI) {
454 /* Remember the start of the increment expression */
455 GetCodePos (&IncExprStart);
457 /* Label for the increment expression */
458 g_defcodelabel (IncLabel);
460 /* Parse the increment expression */
461 HaveIncExpr = (CurTok.Tok != TOK_RPAREN);
463 Expression0 (&lval3);
466 /* Jump to the test */
469 /* Remember the end of the increment expression */
470 GetCodePos (&IncExprEnd);
472 /* Skip the closing paren */
476 g_defcodelabel (BodyLabel);
477 Statement (&PendingToken);
479 /* If we had an increment expression, move the code to the bottom of
480 * the loop. In this case we don't need to jump there at the end of
486 MoveCode (&IncExprStart, &IncExprEnd, &Here);
488 /* Jump back to the increment expression */
492 /* Skip a pending token if we have one */
493 SkipPending (PendingToken);
495 /* Declare the break label */
496 g_defcodelabel (BreakLabel);
498 /* Remove the loop from the loop stack */
504 static int CompoundStatement (void)
505 /* Compound statement. Allow any number of statements inside braces. The
506 * function returns true if the last statement was a break or return.
511 /* Remember the stack at block entry */
512 int OldStack = StackPtr;
514 /* Enter a new lexical level */
517 /* Parse local variable declarations if any */
520 /* Now process statements in this block */
522 while (CurTok.Tok != TOK_RCURLY) {
523 if (CurTok.Tok != TOK_CEOF) {
524 GotBreak = Statement (0);
530 /* Clean up the stack. */
532 g_space (StackPtr - OldStack);
536 /* Emit references to imports/exports for this block */
539 /* Leave the lexical level */
547 int Statement (int* PendingToken)
548 /* Statement parser. Returns 1 if the statement does a return/break, returns
549 * 0 otherwise. If the PendingToken pointer is not NULL, the function will
550 * not skip the terminating token of the statement (closing brace or
551 * semicolon), but store true if there is a pending token, and false if there
552 * is none. The token is always checked, so there is no need for the caller to
553 * check this token, it must be skipped, however. If the argument pointer is
554 * NULL, the function will skip the token.
561 /* Assume no pending token */
566 /* Check for a label. A label is always part of a statement, it does not
569 while (CurTok.Tok == TOK_IDENT && NextTok.Tok == TOK_COLON) {
570 /* Handle the label */
572 CheckLabelWithoutStatement ();
575 switch (CurTok.Tok) {
579 GotBreak = CompoundStatement ();
580 CheckTok (TOK_RCURLY, "`{' expected", PendingToken);
584 return IfStatement ();
600 CheckSemi (PendingToken);
605 CheckSemi (PendingToken);
609 ContinueStatement ();
610 CheckSemi (PendingToken);
619 CheckSemi (PendingToken);
624 CheckSemi (PendingToken);
633 CheckLabelWithoutStatement ();
638 CheckLabelWithoutStatement ();
642 /* Remember the current code position */
644 /* Actual statement */
645 ExprWithCheck (hie0, &Expr);
646 /* Load the result only if it is an lvalue and the type is
647 * marked as volatile. Otherwise the load is useless.
649 if (ED_IsLVal (&Expr) && IsQualVolatile (Expr.Type)) {
650 LoadExpr (CF_NONE, &Expr);
652 /* If the statement didn't generate code, and is not of type
653 * void, emit a warning.
656 if (CodeRangeIsEmpty (&Start, &End) && !IsTypeVoid (Expr.Type)) {
657 Warning ("Statement has no effect");
659 CheckSemi (PendingToken);