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;
}
void GetFuncInfo (const char* Name, unsigned short* Use, unsigned short* Chg)
/* For the given function, lookup register information and store it into
** the given variables. If the function is unknown, assume it will use and
** load all registers.
*/
{
/* If the function name starts with an underline, it is an external
** function. Search for it in the symbol table. If the function does
** not start with an underline, it may be a runtime support function.
** Search for it in the list of builtin functions.
*/
if (Name[0] == '_') {
/* Search in the symbol table, skip the leading underscore */
SymEntry* E = FindGlobalSym (Name+1);
/* Did we find it in the top-level table? */
if (E && IsTypeFunc (E->Type)) {
FuncDesc* D = E->V.F.Func;
/* A variadic function will use the Y register (the parameter list
** size is passed there). A fastcall function will use the A or A/X
** registers. In all other cases, no registers are used. However,
** we assume that any function will destroy all registers.
*/
if ((D->Flags & FD_VARIADIC) != 0) {
*Use = REG_Y;
} else if (D->ParamCount > 0 &&
(AutoCDecl ?
IsQualFastcall (E->Type) :
!IsQualCDecl (E->Type))) {
/* Will use registers depending on the last param. */
switch (CheckedSizeOf (D->LastParam->Type)) {
case 1u:
*Use = REG_A;
break;
case 2u:
*Use = REG_AX;
break;
default:
*Use = REG_EAX;
}
} else {
/* Will not use any registers */
*Use = REG_NONE;
}
/* Will destroy all registers */
*Chg = REG_ALL;
/* Done */
return;
}
} else if (IsDigit (Name[0]) || Name[0] == '$') {
/* A call to a numeric address. Assume that anything gets used and
** destroyed. This is not a real problem, since numeric addresses
** are used mostly in inline assembly anyway.
*/
*Use = REG_ALL;
*Chg = REG_ALL;
return;
} else {
/* Search for the function in the list of builtin functions */
const FuncInfo* Info = bsearch (Name, FuncInfoTable, FuncInfoCount,
sizeof(FuncInfo), CompareFuncInfo);
/* Do we know the function? */
if (Info) {
/* Use the information we have */
*Use = Info->Use;
*Chg = Info->Chg;
} else {
/* It's an internal function we have no information for. If in
** debug mode, output an additional warning, so we have a chance
** to fix it. Otherwise assume that the internal function will
** use and change all registers.
*/
if (Debug) {
fprintf (stderr, "No info about internal function `%s'\n", Name);
}
*Use = REG_ALL;
*Chg = REG_ALL;
}
return;
}
/* Function not found - assume that the primary register is input, and all
** registers are changed
*/
*Use = REG_EAXY;
*Chg = REG_ALL;
}
void NewFunc (SymEntry* Func)
/* Parse argument declarations and function body. */
{
int C99MainFunc = 0;/* Flag for C99 main function returning int */
SymEntry* Param;
/* Get the function descriptor from the function entry */
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;
/* 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;
}
}
/* 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;
}
/* 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;
/* Now process statements in this block */
while (CurTok.Tok != TOK_RCURLY && CurTok.Tok != TOK_CEOF) {
Statement (0);
}
/* 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 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);
}
/* Output the function exit code label */
g_defcodelabel (F_GetRetLab (CurrentFunc));
/* Restore the register variables */
F_RestoreRegVars (CurrentFunc);
/* Generate the exit code */
g_leave ();
/* 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;
}
static void F_RestoreRegVars (Function* F)
/* Restore the register variables for the local function if there are any. */
{
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);
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;
}
/* Restore the accumulator if needed */
if (!F_HasVoidReturn (F)) {
g_restore (CF_CHAR | CF_FORCECHAR);
}
}
static void DoConversion (ExprDesc* Expr, const Type* NewType)
/* Emit code to convert the given expression to a new type. */
{
Type* OldType;
unsigned OldSize;
unsigned NewSize;
/* Remember the old type */
OldType = Expr->Type;
/* If we're converting to void, we're done. Note: This does also cover a
* conversion void -> void.
*/
if (IsTypeVoid (NewType)) {
ED_MakeRVal (Expr); /* Never an lvalue */
goto ExitPoint;
}
/* Don't allow casts from void to something else. */
if (IsTypeVoid (OldType)) {
Error ("Cannot convert from `void' to something else");
goto ExitPoint;
}
/* Get the sizes of the types. Since we've excluded void types, checking
* for known sizes makes sense here.
*/
OldSize = CheckedSizeOf (OldType);
NewSize = CheckedSizeOf (NewType);
/* lvalue? */
if (ED_IsLVal (Expr)) {
/* We have an lvalue. If the new size is smaller than the new one,
* we don't need to do anything. The compiler will generate code
* to load only the portion of the value that is actually needed.
* This works only on a little endian architecture, but that's
* what we support.
* If both sizes are equal, do also leave the value alone.
* If the new size is larger, we must convert the value.
*/
if (NewSize > OldSize) {
/* Load the value into the primary */
LoadExpr (CF_NONE, Expr);
/* Emit typecast code */
g_typecast (TypeOf (NewType), TypeOf (OldType) | CF_FORCECHAR);
/* Value is now in primary and an rvalue */
ED_MakeRValExpr (Expr);
}
} else if (ED_IsLocAbs (Expr)) {
/* A cast of a constant numeric value to another type. Be sure
* to handle sign extension correctly.
*/
/* Get the current and new size of the value */
unsigned OldBits = OldSize * 8;
unsigned NewBits = NewSize * 8;
/* Check if the new datatype will have a smaller range. If it
* has a larger range, things are ok, since the value is
* internally already represented by a long.
*/
if (NewBits <= OldBits) {
/* Cut the value to the new size */
Expr->IVal &= (0xFFFFFFFFUL >> (32 - NewBits));
/* If the new type is signed, sign extend the value */
if (IsSignSigned (NewType)) {
if (Expr->IVal & (0x01UL << (NewBits-1))) {
/* Beware: Use the safe shift routine here. */
Expr->IVal |= shl_l (~0UL, NewBits);
}
}
}
} else {
