/*****************************************************************************/
/* */
-/* function.c */
+/* function.c */
/* */
-/* Parse function entry/body/exit */
+/* Parse function entry/body/exit */
/* */
/* */
/* */
-/* (C) 2000 Ullrich von Bassewitz */
-/* Wacholderweg 14 */
-/* D-70597 Stuttgart */
-/* EMail: uz@musoftware.de */
+/* (C) 2000-2012, Ullrich von Bassewitz */
+/* Roemerstrasse 52 */
+/* D-70794 Filderstadt */
+/* EMail: uz@cc65.org */
/* */
/* */
/* This software is provided 'as-is', without any expressed or implied */
+/* common */
+#include "check.h"
+#include "xmalloc.h"
+
+/* cc65 */
#include "asmcode.h"
#include "asmlabel.h"
#include "codegen.h"
#include "error.h"
#include "funcdesc.h"
+#include "global.h"
#include "litpool.h"
#include "locals.h"
-#include "mem.h"
#include "scanner.h"
+#include "stackptr.h"
+#include "standard.h"
#include "stmt.h"
#include "symtab.h"
#include "function.h"
/*****************************************************************************/
-/* Data */
+/* Data */
/*****************************************************************************/
+/* Enumeration for function flags */
+typedef enum {
+ FF_NONE = 0x0000,
+ FF_HAS_RETURN = 0x0001, /* Function has a return statement */
+ FF_IS_MAIN = 0x0002, /* This is the main function */
+ FF_VOID_RETURN = 0x0004, /* Function returning void */
+} funcflags_t;
+
/* Structure that holds all data needed for function activation */
struct Function {
- struct SymEntry* FuncEntry; /* Symbol table entry */
- type* ReturnType; /* Function return type */
- struct FuncDesc* Desc; /* Function descriptor */
- CodeMark EntryCode; /* Backpatch addr for entry code */
- unsigned LocalMax; /* Total space for locals */
- unsigned LocalSize; /* Current space for locals */
- unsigned RetLab; /* Return code label */
+ struct SymEntry* FuncEntry; /* Symbol table entry */
+ Type* ReturnType; /* Function return type */
+ FuncDesc* Desc; /* Function descriptor */
+ int Reserved; /* Reserved local space */
+ unsigned RetLab; /* Return code label */
+ int TopLevelSP; /* SP at function top level */
+ unsigned RegOffs; /* Register variable space offset */
+ funcflags_t Flags; /* Function flags */
};
/* Pointer to current function */
/*****************************************************************************/
-/* code */
+/* Subroutines working with struct Function */
/*****************************************************************************/
/* Create a new function activation structure and return it */
{
/* Allocate a new structure */
- Function* F = xmalloc (sizeof (Function));
+ Function* F = (Function*) xmalloc (sizeof (Function));
/* Initialize the fields */
F->FuncEntry = Sym;
- F->ReturnType = Sym->Type + 1 + DECODE_SIZE;
- F->Desc = DecodePtr (Sym->Type + 1);
- F->EntryCode = GetCodePos ();
- F->LocalMax = 0;
- F->LocalSize = 0;
- F->RetLab = GetLabel ();
+ F->ReturnType = GetFuncReturn (Sym->Type);
+ F->Desc = GetFuncDesc (Sym->Type);
+ F->Reserved = 0;
+ F->RetLab = GetLocalLabel ();
+ F->TopLevelSP = 0;
+ F->RegOffs = RegisterSpace;
+ F->Flags = IsTypeVoid (F->ReturnType) ? FF_VOID_RETURN : FF_NONE;
/* Return the new structure */
return F;
-const char* GetFuncName (const Function* F)
+const char* F_GetFuncName (const Function* F)
/* Return the name of the current function */
{
return F->FuncEntry->Name;
-unsigned GetParamSize (const Function* F)
+unsigned F_GetParamCount (const Function* F)
+/* Return the parameter count for the current function */
+{
+ return F->Desc->ParamCount;
+}
+
+
+
+unsigned F_GetParamSize (const Function* F)
/* Return the parameter size for the current function */
{
return F->Desc->ParamSize;
-type* GetReturnType (Function* F)
+Type* F_GetReturnType (Function* F)
/* Get the return type for the function */
{
return F->ReturnType;
-int HasVoidReturn (const Function* F)
+int F_HasVoidReturn (const Function* F)
/* Return true if the function does not have a return value */
{
- return IsVoid (F->ReturnType);
+ return (F->Flags & FF_VOID_RETURN) != 0;
+}
+
+
+
+void F_ReturnFound (Function* F)
+/* Mark the function as having a return statement */
+{
+ F->Flags |= FF_HAS_RETURN;
+}
+
+
+
+int F_HasReturn (const Function* F)
+/* Return true if the function contains a return statement*/
+{
+ return (F->Flags & FF_HAS_RETURN) != 0;
+}
+
+
+
+int F_IsMainFunc (const Function* F)
+/* Return true if this is the main function */
+{
+ return (F->Flags & FF_IS_MAIN) != 0;
+}
+
+
+
+int F_IsVariadic (const Function* F)
+/* Return true if this is a variadic function */
+{
+ return (F->Desc->Flags & FD_VARIADIC) != 0;
+}
+
+
+
+int F_IsOldStyle (const Function* F)
+/* Return true if this is an old style (K&R) function */
+{
+ return (F->Desc->Flags & FD_OLDSTYLE) != 0;
+}
+
+
+
+int F_HasOldStyleIntRet (const Function* F)
+/* Return true if this is an old style (K&R) function with an implicit int return */
+{
+ return (F->Desc->Flags & FD_OLDSTYLE_INTRET) != 0;
}
-unsigned GetRetLab (const Function* F)
+unsigned F_GetRetLab (const Function* F)
/* Return the return jump label */
{
return F->RetLab;
-unsigned AllocLocalSpace (Function* F, unsigned Size)
-/* Allocate space for the function locals, return stack offset */
+int F_GetTopLevelSP (const Function* F)
+/* Get the value of the stack pointer on function top level */
+{
+ return F->TopLevelSP;
+}
+
+
+
+int F_ReserveLocalSpace (Function* F, unsigned Size)
+/* Reserve (but don't allocate) the given local space and return the stack
+ * offset.
+ */
+{
+ F->Reserved += Size;
+ return StackPtr - F->Reserved;
+}
+
+
+
+int F_GetStackPtr (const Function* F)
+/* Return the current stack pointer including reserved (but not allocated)
+ * space on the stack.
+ */
+{
+ return StackPtr - F->Reserved;
+}
+
+
+
+void F_AllocLocalSpace (Function* F)
+/* Allocate any local space previously reserved. The function will do
+ * nothing if there is no reserved local space.
+ */
+{
+ if (F->Reserved > 0) {
+
+ /* Create space on the stack */
+ g_space (F->Reserved);
+
+ /* Correct the stack pointer */
+ StackPtr -= F->Reserved;
+
+ /* Nothing more reserved */
+ F->Reserved = 0;
+ }
+}
+
+
+
+int F_AllocRegVar (Function* F, const Type* Type)
+/* Allocate a register variable for the given variable type. If the allocation
+ * was successful, return the offset of the register variable in the register
+ * bank (zero page storage). If there is no register space left, return -1.
+ */
+{
+ /* Allow register variables only on top level and if enabled */
+ if (IS_Get (&EnableRegVars) && GetLexicalLevel () == LEX_LEVEL_FUNCTION) {
+
+ /* Get the size of the variable */
+ unsigned Size = CheckedSizeOf (Type);
+
+ /* Do we have space left? */
+ if (F->RegOffs >= Size) {
+ /* Space left. We allocate the variables from high to low addresses,
+ * so the adressing is compatible with the saved values on stack.
+ * This allows shorter code when saving/restoring the variables.
+ */
+ F->RegOffs -= Size;
+ return F->RegOffs;
+ }
+ }
+
+ /* No space left or no allocation */
+ return -1;
+}
+
+
+
+static void F_RestoreRegVars (Function* F)
+/* Restore the register variables for the local function if there are any. */
{
- /* Remember the current offset */
- unsigned Offs = F->LocalSize;
+ const SymEntry* Sym;
+
+ /* If we don't have register variables in this function, bail out early */
+ if (F->RegOffs == RegisterSpace) {
+ return;
+ }
+
+ /* Save the accumulator if needed */
+ if (!F_HasVoidReturn (F)) {
+ g_save (CF_CHAR | CF_FORCECHAR);
+ }
+
+ /* Get the first symbol from the function symbol table */
+ Sym = F->FuncEntry->V.F.Func->SymTab->SymHead;
+
+ /* Walk through all symbols checking for register variables */
+ while (Sym) {
+ if (SymIsRegVar (Sym)) {
+
+ /* Check for more than one variable */
+ int Offs = Sym->V.R.SaveOffs;
+ unsigned Bytes = CheckedSizeOf (Sym->Type);
- /* Add the size */
- F->LocalSize += Size;
- if (F->LocalSize > F->LocalMax) {
- F->LocalMax = F->LocalSize;
+ while (1) {
+
+ /* Find next register variable */
+ const SymEntry* NextSym = Sym->NextSym;
+ while (NextSym && !SymIsRegVar (NextSym)) {
+ NextSym = NextSym->NextSym;
+ }
+
+ /* If we have a next one, compare the stack offsets */
+ if (NextSym) {
+
+ /* We have a following register variable. Get the size */
+ int Size = CheckedSizeOf (NextSym->Type);
+
+ /* Adjacent variable? */
+ if (NextSym->V.R.SaveOffs + Size != Offs) {
+ /* No */
+ break;
+ }
+
+ /* Adjacent variable */
+ Bytes += Size;
+ Offs -= Size;
+ Sym = NextSym;
+
+ } else {
+ break;
+ }
+ }
+
+ /* Restore the memory range */
+ g_restore_regvars (Offs, Sym->V.R.RegOffs, Bytes);
+
+ }
+
+ /* Check next symbol */
+ Sym = Sym->NextSym;
}
- /* Return the offset */
- return Offs;
+ /* Restore the accumulator if needed */
+ if (!F_HasVoidReturn (F)) {
+ g_restore (CF_CHAR | CF_FORCECHAR);
+ }
}
-void FreeLocalSpace (Function* F, unsigned Size)
-/* Free space allocated for function locals */
+static void F_EmitDebugInfo (void)
+/* Emit debug infos for the current function */
{
- F->LocalSize -= Size;
+ if (DebugInfo) {
+ /* Get the current function */
+ const SymEntry* Sym = CurrentFunc->FuncEntry;
+
+ /* Output info for the function itself */
+ AddTextLine ("\t.dbg\tfunc, \"%s\", \"00\", %s, \"%s\"",
+ Sym->Name,
+ (Sym->Flags & SC_EXTERN)? "extern" : "static",
+ Sym->AsmName);
+ }
}
+/*****************************************************************************/
+/* code */
+/*****************************************************************************/
+
+
+
void NewFunc (SymEntry* Func)
/* Parse argument declarations and function body. */
{
- int isbrk;
+ int C99MainFunc = 0;/* Flag for C99 main function returning int */
+ SymEntry* Param;
/* Get the function descriptor from the function entry */
- FuncDesc* D = DecodePtr (Func->Type+1);
+ FuncDesc* D = Func->V.F.Func;
/* Allocate the function activation record for the function */
CurrentFunc = NewFunction (Func);
/* Reenter the lexical level */
ReenterFunctionLevel (D);
+ /* Check if the function header contains unnamed parameters. These are
+ * only allowed in cc65 mode.
+ */
+ if ((D->Flags & FD_UNNAMED_PARAMS) != 0 && (IS_Get (&Standard) != STD_CC65)) {
+ Error ("Parameter name omitted");
+ }
+
+ /* Declare two special functions symbols: __fixargs__ and __argsize__.
+ * The latter is different depending on the type of the function (variadic
+ * or not).
+ */
+ AddConstSym ("__fixargs__", type_uint, SC_DEF | SC_CONST, D->ParamSize);
+ if (D->Flags & FD_VARIADIC) {
+ /* Variadic function. The variable must be const. */
+ static const Type T[] = { TYPE(T_UCHAR | T_QUAL_CONST), TYPE(T_END) };
+ AddLocalSym ("__argsize__", T, SC_DEF | SC_REF | SC_AUTO, 0);
+ } else {
+ /* Non variadic */
+ AddConstSym ("__argsize__", type_uchar, SC_DEF | SC_CONST, D->ParamSize);
+ }
+
/* Function body now defined */
Func->Flags |= SC_DEF;
- /* C functions cannot currently have __fastcall__ calling conventions */
- if (IsFastCallFunc (Func->Type)) {
- Error (ERR_FASTCALL);
+ /* Special handling for main() */
+ if (strcmp (Func->Name, "main") == 0) {
+
+ /* Mark this as the main function */
+ CurrentFunc->Flags |= FF_IS_MAIN;
+
+ /* Main cannot be a fastcall function */
+ if (IsQualFastcall (Func->Type)) {
+ Error ("`main' cannot be declared as __fastcall__");
+ }
+
+ /* If cc65 extensions aren't enabled, don't allow a main function that
+ * doesn't return an int.
+ */
+ if (IS_Get (&Standard) != STD_CC65 && CurrentFunc->ReturnType[0].C != T_INT) {
+ Error ("`main' must always return an int");
+ }
+
+ /* Add a forced import of a symbol that is contained in the startup
+ * code. This will force the startup code to be linked in.
+ */
+ g_importstartup ();
+
+ /* If main() takes parameters, generate a forced import to a function
+ * that will setup these parameters. This way, programs that do not
+ * need the additional code will not get it.
+ */
+ if (D->ParamCount > 0 || (D->Flags & FD_VARIADIC) != 0) {
+ g_importmainargs ();
+ }
+
+ /* Determine if this is a main function in a C99 environment that
+ * returns an int.
+ */
+ if (IsTypeInt (F_GetReturnType (CurrentFunc)) &&
+ IS_Get (&Standard) == STD_C99) {
+ C99MainFunc = 1;
+ }
}
- /* Need a starting curly brace */
- if (curtok != LCURLY) {
- Error (ERR_LCURLY_EXPECTED);
+ /* Allocate code and data segments for this function */
+ Func->V.F.Seg = PushSegments (Func);
+
+ /* Allocate a new literal pool */
+ PushLiteralPool (Func);
+
+ /* If this is a fastcall function, push the last parameter onto the stack */
+ if (IsQualFastcall (Func->Type) && D->ParamCount > 0) {
+
+ unsigned Flags;
+
+ /* Fastcall functions may never have an ellipsis or the compiler is buggy */
+ CHECK ((D->Flags & FD_VARIADIC) == 0);
+
+ /* Generate the push */
+ if (IsTypeFunc (D->LastParam->Type)) {
+ /* Pointer to function */
+ Flags = CF_PTR;
+ } else {
+ Flags = TypeOf (D->LastParam->Type) | CF_FORCECHAR;
+ }
+ g_push (Flags, 0);
+ }
+
+ /* Generate function entry code if needed */
+ g_enter (TypeOf (Func->Type), F_GetParamSize (CurrentFunc));
+
+ /* If stack checking code is requested, emit a call to the helper routine */
+ if (IS_Get (&CheckStack)) {
+ g_stackcheck ();
+ }
+
+ /* Setup the stack */
+ StackPtr = 0;
+
+ /* Walk through the parameter list and allocate register variable space
+ * for parameters declared as register. Generate code to swap the contents
+ * of the register bank with the save area on the stack.
+ */
+ Param = D->SymTab->SymHead;
+ while (Param && (Param->Flags & SC_PARAM) != 0) {
+
+ /* Check for a register variable */
+ if (SymIsRegVar (Param)) {
+
+ /* Allocate space */
+ int Reg = F_AllocRegVar (CurrentFunc, Param->Type);
+
+ /* Could we allocate a register? */
+ if (Reg < 0) {
+ /* No register available: Convert parameter to auto */
+ CvtRegVarToAuto (Param);
+ } else {
+ /* Remember the register offset */
+ Param->V.R.RegOffs = Reg;
+
+ /* Generate swap code */
+ g_swap_regvars (Param->V.R.SaveOffs, Reg, CheckedSizeOf (Param->Type));
+ }
+ }
+
+ /* Next parameter */
+ Param = Param->NextSym;
}
- /* Setup register variables */
- InitRegVars ();
+ /* Need a starting curly brace */
+ ConsumeLCurly ();
+
+ /* Parse local variable declarations if any */
+ DeclareLocals ();
+
+ /* Remember the current stack pointer. All variables allocated elsewhere
+ * must be dropped when doing a return from an inner block.
+ */
+ CurrentFunc->TopLevelSP = StackPtr;
- /* Switch to the code segment and generate function entry code */
- g_usecode ();
- g_enter (TypeOf (Func->Type), Func->Name, GetParamSize (CurrentFunc));
+ /* Now process statements in this block */
+ while (CurTok.Tok != TOK_RCURLY && CurTok.Tok != TOK_CEOF) {
+ Statement (0);
+ }
- /* Parse the function body */
- oursp = 0;
- isbrk = compound ();
+ /* If this is not a void function, and not the main function in a C99
+ * environment returning int, output a warning if we didn't see a return
+ * statement.
+ */
+ if (!F_HasVoidReturn (CurrentFunc) && !F_HasReturn (CurrentFunc) && !C99MainFunc) {
+ Warning ("Control reaches end of non-void function");
+ }
- /* If the function did not end with an return statement, create exit code */
- if (!isbrk) {
-#if 0
- /* If the function has a return type, flag an error */
- if (!voidfunc) {
- Error (ERR_MUST_RETURN_VALUE);
- }
-#endif
- RestoreRegVars (0);
- g_leave (CF_NONE, 0);
+ /* If this is the main function in a C99 environment returning an int, let
+ * it always return zero. Note: Actual return statements jump to the return
+ * label defined below.
+ * The code is removed by the optimizer if unused.
+ */
+ if (C99MainFunc) {
+ g_getimmed (CF_INT | CF_CONST, 0, 0);
}
- /* Dump literal data created by the function */
- DumpLiteralPool ();
+ /* Output the function exit code label */
+ g_defcodelabel (F_GetRetLab (CurrentFunc));
+
+ /* Restore the register variables */
+ F_RestoreRegVars (CurrentFunc);
+
+ /* Generate the exit code */
+ g_leave ();
- /* Cleanup register variables */
- DoneRegVars ();
+ /* Emit references to imports/exports */
+ EmitExternals ();
+
+ /* Emit function debug info */
+ F_EmitDebugInfo ();
+ EmitDebugInfo ();
/* Leave the lexical level */
LeaveFunctionLevel ();
+ /* Eat the closing brace */
+ ConsumeRCurly ();
+
+ /* Restore the old literal pool, remembering the one for the function */
+ Func->V.F.LitPool = PopLiteralPool ();
+
+ /* Switch back to the old segments */
+ PopSegments ();
+
/* Reset the current function pointer */
FreeFunction (CurrentFunc);
CurrentFunc = 0;
}
-
-
-
projects / cc65 / blobdiff