1 /*****************************************************************************/
5 /* Parse function entry/body/exit */
9 /* (C) 2000-2011, 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 /*****************************************************************************/
58 /*****************************************************************************/
60 /*****************************************************************************/
64 /* Enumeration for function flags */
67 FF_HAS_RETURN = 0x0001, /* Function has a return statement */
68 FF_IS_MAIN = 0x0002, /* This is the main function */
69 FF_VOID_RETURN = 0x0004, /* Function returning void */
72 /* Structure that holds all data needed for function activation */
74 struct SymEntry* FuncEntry; /* Symbol table entry */
75 Type* ReturnType; /* Function return type */
76 FuncDesc* Desc; /* Function descriptor */
77 int Reserved; /* Reserved local space */
78 unsigned RetLab; /* Return code label */
79 int TopLevelSP; /* SP at function top level */
80 unsigned RegOffs; /* Register variable space offset */
81 funcflags_t Flags; /* Function flags */
84 /* Pointer to current function */
85 Function* CurrentFunc = 0;
89 /*****************************************************************************/
90 /* Subroutines working with struct Function */
91 /*****************************************************************************/
95 static Function* NewFunction (struct SymEntry* Sym)
96 /* Create a new function activation structure and return it */
98 /* Allocate a new structure */
99 Function* F = (Function*) xmalloc (sizeof (Function));
101 /* Initialize the fields */
103 F->ReturnType = GetFuncReturn (Sym->Type);
104 F->Desc = GetFuncDesc (Sym->Type);
106 F->RetLab = GetLocalLabel ();
108 F->RegOffs = RegisterSpace;
109 F->Flags = IsTypeVoid (F->ReturnType) ? FF_VOID_RETURN : FF_NONE;
111 /* Return the new structure */
117 static void FreeFunction (Function* F)
118 /* Free a function activation structure */
125 const char* F_GetFuncName (const Function* F)
126 /* Return the name of the current function */
128 return F->FuncEntry->Name;
133 unsigned F_GetParamCount (const Function* F)
134 /* Return the parameter count for the current function */
136 return F->Desc->ParamCount;
141 unsigned F_GetParamSize (const Function* F)
142 /* Return the parameter size for the current function */
144 return F->Desc->ParamSize;
149 Type* F_GetReturnType (Function* F)
150 /* Get the return type for the function */
152 return F->ReturnType;
157 int F_HasVoidReturn (const Function* F)
158 /* Return true if the function does not have a return value */
160 return (F->Flags & FF_VOID_RETURN) != 0;
165 void F_ReturnFound (Function* F)
166 /* Mark the function as having a return statement */
168 F->Flags |= FF_HAS_RETURN;
173 int F_HasReturn (const Function* F)
174 /* Return true if the function contains a return statement*/
176 return (F->Flags & FF_HAS_RETURN) != 0;
181 int F_IsMainFunc (const Function* F)
182 /* Return true if this is the main function */
184 return (F->Flags & FF_IS_MAIN) != 0;
189 int F_IsVariadic (const Function* F)
190 /* Return true if this is a variadic function */
192 return (F->Desc->Flags & FD_VARIADIC) != 0;
197 int F_IsOldStyle (const Function* F)
198 /* Return true if this is an old style (K&R) function */
200 return (F->Desc->Flags & FD_OLDSTYLE) != 0;
205 int F_HasOldStyleIntRet (const Function* F)
206 /* Return true if this is an old style (K&R) function with an implicit int return */
208 return (F->Desc->Flags & FD_OLDSTYLE_INTRET) != 0;
213 unsigned F_GetRetLab (const Function* F)
214 /* Return the return jump label */
221 int F_GetTopLevelSP (const Function* F)
222 /* Get the value of the stack pointer on function top level */
224 return F->TopLevelSP;
229 int F_ReserveLocalSpace (Function* F, unsigned Size)
230 /* Reserve (but don't allocate) the given local space and return the stack
235 return StackPtr - F->Reserved;
240 void F_AllocLocalSpace (Function* F)
241 /* Allocate any local space previously reserved. The function will do
242 * nothing if there is no reserved local space.
245 if (F->Reserved > 0) {
247 /* Create space on the stack */
248 g_space (F->Reserved);
250 /* Correct the stack pointer */
251 StackPtr -= F->Reserved;
253 /* Nothing more reserved */
260 int F_AllocRegVar (Function* F, const Type* Type)
261 /* Allocate a register variable for the given variable type. If the allocation
262 * was successful, return the offset of the register variable in the register
263 * bank (zero page storage). If there is no register space left, return -1.
266 /* Allow register variables only on top level and if enabled */
267 if (IS_Get (&EnableRegVars) && GetLexicalLevel () == LEX_LEVEL_FUNCTION) {
269 /* Get the size of the variable */
270 unsigned Size = CheckedSizeOf (Type);
272 /* Do we have space left? */
273 if (F->RegOffs >= Size) {
274 /* Space left. We allocate the variables from high to low addresses,
275 * so the adressing is compatible with the saved values on stack.
276 * This allows shorter code when saving/restoring the variables.
283 /* No space left or no allocation */
289 static void F_RestoreRegVars (Function* F)
290 /* Restore the register variables for the local function if there are any. */
294 /* If we don't have register variables in this function, bail out early */
295 if (F->RegOffs == RegisterSpace) {
299 /* Save the accumulator if needed */
300 if (!F_HasVoidReturn (F)) {
301 g_save (CF_CHAR | CF_FORCECHAR);
304 /* Get the first symbol from the function symbol table */
305 Sym = F->FuncEntry->V.F.Func->SymTab->SymHead;
307 /* Walk through all symbols checking for register variables */
309 if (SymIsRegVar (Sym)) {
311 /* Check for more than one variable */
312 int Offs = Sym->V.R.SaveOffs;
313 unsigned Bytes = CheckedSizeOf (Sym->Type);
317 /* Find next register variable */
318 const SymEntry* NextSym = Sym->NextSym;
319 while (NextSym && !SymIsRegVar (NextSym)) {
320 NextSym = NextSym->NextSym;
323 /* If we have a next one, compare the stack offsets */
326 /* We have a following register variable. Get the size */
327 int Size = CheckedSizeOf (NextSym->Type);
329 /* Adjacent variable? */
330 if (NextSym->V.R.SaveOffs + Size != Offs) {
335 /* Adjacent variable */
345 /* Restore the memory range */
346 g_restore_regvars (Offs, Sym->V.R.RegOffs, Bytes);
350 /* Check next symbol */
354 /* Restore the accumulator if needed */
355 if (!F_HasVoidReturn (F)) {
356 g_restore (CF_CHAR | CF_FORCECHAR);
362 static void EmitDebugInfo (void)
363 /* Emit debug infos for the current function */
365 /* Fetch stuff for the current fuction */
366 const SymEntry* Sym = CurrentFunc->FuncEntry;
367 const FuncDesc* Desc = CurrentFunc->Desc;
368 const SymTable* Tab = Desc->SymTab;
370 /* Output info for the function itself */
371 AddTextLine ("\t.dbg\tfunc, \"%s\", \"\", %s, \"%s\"",
373 (Sym->Flags & SC_EXTERN)? "extern" : "static",
376 /* Output info for locals */
379 if ((Sym->Flags & (SC_CONST|SC_TYPE)) == 0) {
380 if (Sym->Flags & SC_AUTO) {
381 AddTextLine ("\t.dbg\tsym, \"%s\", \"\", auto, %d",
382 Sym->Name, Sym->V.Offs);
383 } else if (Sym->Flags & SC_REGISTER) {
384 AddTextLine ("\t.dbg\tsym, \"%s\", \"\", register, \"regbank\", %d",
385 Sym->Name, Sym->V.R.RegOffs);
388 AddTextLine ("\t.dbg\tsym, \"%s\", \"\", %s, \"%s\"",
390 (Sym->Flags & SC_EXTERN)? "extern" : "static",
400 /*****************************************************************************/
402 /*****************************************************************************/
406 void NewFunc (SymEntry* Func)
407 /* Parse argument declarations and function body. */
409 int C99MainFunc = 0;/* Flag for C99 main function returning int */
412 /* Get the function descriptor from the function entry */
413 FuncDesc* D = Func->V.F.Func;
415 /* Allocate the function activation record for the function */
416 CurrentFunc = NewFunction (Func);
418 /* Reenter the lexical level */
419 ReenterFunctionLevel (D);
421 /* Check if the function header contains unnamed parameters. These are
422 * only allowed in cc65 mode.
424 if ((D->Flags & FD_UNNAMED_PARAMS) != 0 && (IS_Get (&Standard) != STD_CC65)) {
425 Error ("Parameter name omitted");
428 /* Declare two special functions symbols: __fixargs__ and __argsize__.
429 * The latter is different depending on the type of the function (variadic
432 AddConstSym ("__fixargs__", type_uint, SC_DEF | SC_CONST, D->ParamSize);
433 if (D->Flags & FD_VARIADIC) {
434 /* Variadic function. The variable must be const. */
435 static const Type T[] = { TYPE(T_UCHAR | T_QUAL_CONST), TYPE(T_END) };
436 AddLocalSym ("__argsize__", T, SC_DEF | SC_REF | SC_AUTO, 0);
439 AddConstSym ("__argsize__", type_uchar, SC_DEF | SC_CONST, D->ParamSize);
442 /* Function body now defined */
443 Func->Flags |= SC_DEF;
445 /* Special handling for main() */
446 if (strcmp (Func->Name, "main") == 0) {
448 /* Mark this as the main function */
449 CurrentFunc->Flags |= FF_IS_MAIN;
451 /* Main cannot be a fastcall function */
452 if (IsQualFastcall (Func->Type)) {
453 Error ("`main' cannot be declared as __fastcall__");
456 /* If cc65 extensions aren't enabled, don't allow a main function that
457 * doesn't return an int.
459 if (IS_Get (&Standard) != STD_CC65 && CurrentFunc->ReturnType[0].C != T_INT) {
460 Error ("`main' must always return an int");
463 /* Add a forced import of a symbol that is contained in the startup
464 * code. This will force the startup code to be linked in.
468 /* If main() takes parameters, generate a forced import to a function
469 * that will setup these parameters. This way, programs that do not
470 * need the additional code will not get it.
472 if (D->ParamCount > 0 || (D->Flags & FD_VARIADIC) != 0) {
476 /* Determine if this is a main function in a C99 environment that
479 if (IsTypeInt (F_GetReturnType (CurrentFunc)) &&
480 IS_Get (&Standard) == STD_C99) {
485 /* Allocate code and data segments for this function */
486 Func->V.F.Seg = PushSegments (Func);
488 /* Allocate a new literal pool */
489 PushLiteralPool (Func);
491 /* If this is a fastcall function, push the last parameter onto the stack */
492 if (IsQualFastcall (Func->Type) && D->ParamCount > 0) {
496 /* Fastcall functions may never have an ellipsis or the compiler is buggy */
497 CHECK ((D->Flags & FD_VARIADIC) == 0);
499 /* Generate the push */
500 if (IsTypeFunc (D->LastParam->Type)) {
501 /* Pointer to function */
504 Flags = TypeOf (D->LastParam->Type) | CF_FORCECHAR;
509 /* Generate function entry code if needed */
510 g_enter (TypeOf (Func->Type), F_GetParamSize (CurrentFunc));
512 /* If stack checking code is requested, emit a call to the helper routine */
513 if (IS_Get (&CheckStack)) {
517 /* Setup the stack */
520 /* Walk through the parameter list and allocate register variable space
521 * for parameters declared as register. Generate code to swap the contents
522 * of the register bank with the save area on the stack.
524 Param = D->SymTab->SymHead;
525 while (Param && (Param->Flags & SC_PARAM) != 0) {
527 /* Check for a register variable */
528 if (SymIsRegVar (Param)) {
531 int Reg = F_AllocRegVar (CurrentFunc, Param->Type);
533 /* Could we allocate a register? */
535 /* No register available: Convert parameter to auto */
536 CvtRegVarToAuto (Param);
538 /* Remember the register offset */
539 Param->V.R.RegOffs = Reg;
541 /* Generate swap code */
542 g_swap_regvars (Param->V.R.SaveOffs, Reg, CheckedSizeOf (Param->Type));
547 Param = Param->NextSym;
550 /* Need a starting curly brace */
553 /* Parse local variable declarations if any */
556 /* Remember the current stack pointer. All variables allocated elsewhere
557 * must be dropped when doing a return from an inner block.
559 CurrentFunc->TopLevelSP = StackPtr;
561 /* Now process statements in this block */
562 while (CurTok.Tok != TOK_RCURLY && CurTok.Tok != TOK_CEOF) {
566 /* If this is not a void function, and not the main function in a C99
567 * environment returning int, output a warning if we didn't see a return
570 if (!F_HasVoidReturn (CurrentFunc) && !F_HasReturn (CurrentFunc) && !C99MainFunc) {
571 Warning ("Control reaches end of non-void function");
574 /* If this is the main function in a C99 environment returning an int, let
575 * it always return zero. Note: Actual return statements jump to the return
576 * label defined below.
577 * The code is removed by the optimizer if unused.
580 g_getimmed (CF_INT | CF_CONST, 0, 0);
583 /* Output the function exit code label */
584 g_defcodelabel (F_GetRetLab (CurrentFunc));
586 /* Restore the register variables */
587 F_RestoreRegVars (CurrentFunc);
589 /* Generate the exit code */
592 /* Emit references to imports/exports */
595 /* Emit function debug info */
598 /* Leave the lexical level */
599 LeaveFunctionLevel ();
601 /* Eat the closing brace */
604 /* Restore the old literal pool, remembering the one for the function */
605 Func->V.F.LitPool = PopLiteralPool ();
607 /* Switch back to the old segments */
610 /* Reset the current function pointer */
611 FreeFunction (CurrentFunc);