1 /*****************************************************************************/
5 /* Parse function entry/body/exit */
9 /* (C) 2000-2009, 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 /*****************************************************************************/
59 /*****************************************************************************/
61 /*****************************************************************************/
65 /* Enumeration for function flags */
68 FF_HAS_RETURN = 0x0001, /* Function has a return statement */
69 FF_IS_MAIN = 0x0002, /* This is the main function */
70 FF_VOID_RETURN = 0x0004, /* Function returning void */
73 /* Structure that holds all data needed for function activation */
75 struct SymEntry* FuncEntry; /* Symbol table entry */
76 Type* ReturnType; /* Function return type */
77 struct FuncDesc* Desc; /* Function descriptor */
78 int Reserved; /* Reserved local space */
79 unsigned RetLab; /* Return code label */
80 int TopLevelSP; /* SP at function top level */
81 unsigned RegOffs; /* Register variable space offset */
82 funcflags_t Flags; /* Function flags */
85 /* Pointer to current function */
86 Function* CurrentFunc = 0;
90 /*****************************************************************************/
91 /* Subroutines working with struct Function */
92 /*****************************************************************************/
96 static Function* NewFunction (struct SymEntry* Sym)
97 /* Create a new function activation structure and return it */
99 /* Allocate a new structure */
100 Function* F = (Function*) xmalloc (sizeof (Function));
102 /* Initialize the fields */
104 F->ReturnType = GetFuncReturn (Sym->Type);
105 F->Desc = GetFuncDesc (Sym->Type);
107 F->RetLab = GetLocalLabel ();
109 F->RegOffs = RegisterSpace;
110 F->Flags = IsTypeVoid (F->ReturnType) ? FF_VOID_RETURN : FF_NONE;
112 /* Return the new structure */
118 static void FreeFunction (Function* F)
119 /* Free a function activation structure */
126 const char* F_GetFuncName (const Function* F)
127 /* Return the name of the current function */
129 return F->FuncEntry->Name;
134 unsigned F_GetParamCount (const Function* F)
135 /* Return the parameter count for the current function */
137 return F->Desc->ParamCount;
142 unsigned F_GetParamSize (const Function* F)
143 /* Return the parameter size for the current function */
145 return F->Desc->ParamSize;
150 Type* F_GetReturnType (Function* F)
151 /* Get the return type for the function */
153 return F->ReturnType;
158 int F_HasVoidReturn (const Function* F)
159 /* Return true if the function does not have a return value */
161 return (F->Flags & FF_VOID_RETURN) != 0;
166 void F_ReturnFound (Function* F)
167 /* Mark the function as having a return statement */
169 F->Flags |= FF_HAS_RETURN;
174 int F_HasReturn (const Function* F)
175 /* Return true if the function contains a return statement*/
177 return (F->Flags & FF_HAS_RETURN) != 0;
182 int F_IsMainFunc (const Function* F)
183 /* Return true if this is the main function */
185 return (F->Flags & FF_IS_MAIN) != 0;
190 int F_IsVariadic (const Function* F)
191 /* Return true if this is a variadic function */
193 return (F->Desc->Flags & FD_VARIADIC) != 0;
198 int F_IsOldStyle (const Function* F)
199 /* Return true if this is an old style (K&R) function */
201 return (F->Desc->Flags & FD_OLDSTYLE) != 0;
206 int F_HasOldStyleIntRet (const Function* F)
207 /* Return true if this is an old style (K&R) function with an implicit int return */
209 return (F->Desc->Flags & FD_OLDSTYLE_INTRET) != 0;
214 unsigned F_GetRetLab (const Function* F)
215 /* Return the return jump label */
222 int F_GetTopLevelSP (const Function* F)
223 /* Get the value of the stack pointer on function top level */
225 return F->TopLevelSP;
230 int F_ReserveLocalSpace (Function* F, unsigned Size)
231 /* Reserve (but don't allocate) the given local space and return the stack
236 return StackPtr - F->Reserved;
241 void F_AllocLocalSpace (Function* F)
242 /* Allocate any local space previously reserved. The function will do
243 * nothing if there is no reserved local space.
246 if (F->Reserved > 0) {
248 /* Create space on the stack */
249 g_space (F->Reserved);
251 /* Correct the stack pointer */
252 StackPtr -= F->Reserved;
254 /* Nothing more reserved */
261 int F_AllocRegVar (Function* F, const Type* Type)
262 /* Allocate a register variable for the given variable type. If the allocation
263 * was successful, return the offset of the register variable in the register
264 * bank (zero page storage). If there is no register space left, return -1.
267 /* Allow register variables only on top level and if enabled */
268 if (IS_Get (&EnableRegVars) && GetLexicalLevel () == LEX_LEVEL_FUNCTION) {
270 /* Get the size of the variable */
271 unsigned Size = CheckedSizeOf (Type);
273 /* Do we have space left? */
274 if (F->RegOffs >= Size) {
275 /* Space left. We allocate the variables from high to low addresses,
276 * so the adressing is compatible with the saved values on stack.
277 * This allows shorter code when saving/restoring the variables.
284 /* No space left or no allocation */
290 static void F_RestoreRegVars (Function* F)
291 /* Restore the register variables for the local function if there are any. */
295 /* If we don't have register variables in this function, bail out early */
296 if (F->RegOffs == RegisterSpace) {
300 /* Save the accumulator if needed */
301 if (!F_HasVoidReturn (F)) {
302 g_save (CF_CHAR | CF_FORCECHAR);
305 /* Get the first symbol from the function symbol table */
306 Sym = F->FuncEntry->V.F.Func->SymTab->SymHead;
308 /* Walk through all symbols checking for register variables */
310 if (SymIsRegVar (Sym)) {
312 /* Check for more than one variable */
313 int Offs = Sym->V.R.SaveOffs;
314 unsigned Bytes = CheckedSizeOf (Sym->Type);
318 /* Find next register variable */
319 const SymEntry* NextSym = Sym->NextSym;
320 while (NextSym && !SymIsRegVar (NextSym)) {
321 NextSym = NextSym->NextSym;
324 /* If we have a next one, compare the stack offsets */
327 /* We have a following register variable. Get the size */
328 int Size = CheckedSizeOf (NextSym->Type);
330 /* Adjacent variable? */
331 if (NextSym->V.R.SaveOffs + Size != Offs) {
336 /* Adjacent variable */
346 /* Restore the memory range */
347 g_restore_regvars (Offs, Sym->V.R.RegOffs, Bytes);
351 /* Check next symbol */
355 /* Restore the accumulator if needed */
356 if (!F_HasVoidReturn (F)) {
357 g_restore (CF_CHAR | CF_FORCECHAR);
363 /*****************************************************************************/
365 /*****************************************************************************/
369 void NewFunc (SymEntry* Func)
370 /* Parse argument declarations and function body. */
374 /* Get the function descriptor from the function entry */
375 FuncDesc* D = Func->V.F.Func;
377 /* Allocate the function activation record for the function */
378 CurrentFunc = NewFunction (Func);
380 /* Reenter the lexical level */
381 ReenterFunctionLevel (D);
383 /* Check if the function header contains unnamed parameters. These are
384 * only allowed in cc65 mode.
386 if ((D->Flags & FD_UNNAMED_PARAMS) != 0 && (IS_Get (&Standard) != STD_CC65)) {
387 Error ("Parameter name omitted");
390 /* Declare two special functions symbols: __fixargs__ and __argsize__.
391 * The latter is different depending on the type of the function (variadic
394 AddConstSym ("__fixargs__", type_uint, SC_DEF | SC_CONST, D->ParamSize);
395 if (D->Flags & FD_VARIADIC) {
396 /* Variadic function. The variable must be const. */
397 static const Type T[] = { TYPE(T_UCHAR | T_QUAL_CONST), TYPE(T_END) };
398 AddLocalSym ("__argsize__", T, SC_DEF | SC_REF | SC_AUTO, 0);
401 AddConstSym ("__argsize__", type_uchar, SC_DEF | SC_CONST, D->ParamSize);
404 /* Function body now defined */
405 Func->Flags |= SC_DEF;
407 /* Special handling for main() */
408 if (strcmp (Func->Name, "main") == 0) {
410 /* Mark this as the main function */
411 CurrentFunc->Flags |= FF_IS_MAIN;
413 /* Main cannot be a fastcall function */
414 if (IsQualFastcall (Func->Type)) {
415 Error ("`main' cannot be declared as __fastcall__");
418 /* If cc65 extensions aren't enabled, don't allow a main function that
419 * doesn't return an int.
421 if (IS_Get (&Standard) != STD_CC65 && CurrentFunc->ReturnType[0].C != T_INT) {
422 Error ("`main' must always return an int");
425 /* Add a forced import of a symbol that is contained in the startup
426 * code. This will force the startup code to be linked in.
430 /* If main() takes parameters, generate a forced import to a function
431 * that will setup these parameters. This way, programs that do not
432 * need the additional code will not get it.
434 if (D->ParamCount > 0 || (D->Flags & FD_VARIADIC) != 0) {
439 /* Allocate code and data segments for this function */
440 Func->V.F.Seg = PushSegments (Func);
442 /* Allocate a new literal pool */
443 PushLiteralPool (Func);
445 /* If this is a fastcall function, push the last parameter onto the stack */
446 if (IsQualFastcall (Func->Type) && D->ParamCount > 0) {
450 /* Fastcall functions may never have an ellipsis or the compiler is buggy */
451 CHECK ((D->Flags & FD_VARIADIC) == 0);
453 /* Generate the push */
454 if (IsTypeFunc (D->LastParam->Type)) {
455 /* Pointer to function */
458 Flags = TypeOf (D->LastParam->Type) | CF_FORCECHAR;
463 /* Generate function entry code if needed */
464 g_enter (TypeOf (Func->Type), F_GetParamSize (CurrentFunc));
466 /* If stack checking code is requested, emit a call to the helper routine */
467 if (IS_Get (&CheckStack)) {
471 /* Setup the stack */
474 /* Walk through the parameter list and allocate register variable space
475 * for parameters declared as register. Generate code to swap the contents
476 * of the register bank with the save area on the stack.
478 Param = D->SymTab->SymHead;
479 while (Param && (Param->Flags & SC_PARAM) != 0) {
481 /* Check for a register variable */
482 if (SymIsRegVar (Param)) {
485 int Reg = F_AllocRegVar (CurrentFunc, Param->Type);
487 /* Could we allocate a register? */
489 /* No register available: Convert parameter to auto */
490 CvtRegVarToAuto (Param);
492 /* Remember the register offset */
493 Param->V.R.RegOffs = Reg;
495 /* Generate swap code */
496 g_swap_regvars (Param->V.R.SaveOffs, Reg, CheckedSizeOf (Param->Type));
501 Param = Param->NextSym;
504 /* Need a starting curly brace */
507 /* Parse local variable declarations if any */
510 /* Remember the current stack pointer. All variables allocated elsewhere
511 * must be dropped when doing a return from an inner block.
513 CurrentFunc->TopLevelSP = StackPtr;
515 /* Now process statements in this block */
516 while (CurTok.Tok != TOK_RCURLY && CurTok.Tok != TOK_CEOF) {
520 /* If this is not a void function, output a warning if we didn't see a
523 if (!F_HasVoidReturn (CurrentFunc) && !F_HasReturn (CurrentFunc)) {
524 Warning ("Control reaches end of non-void function");
527 /* Output the function exit code label */
528 g_defcodelabel (F_GetRetLab (CurrentFunc));
530 /* Restore the register variables */
531 F_RestoreRegVars (CurrentFunc);
533 /* Generate the exit code */
536 /* Emit references to imports/exports */
539 /* Leave the lexical level */
540 LeaveFunctionLevel ();
542 /* Eat the closing brace */
545 /* Dump the literal pool, the restore the old one */
549 /* Switch back to the old segments */
552 /* Reset the current function pointer */
553 FreeFunction (CurrentFunc);