X-Git-Url: https://git.sur5r.net/?a=blobdiff_plain;f=src%2Fcc65%2Ffunction.c;h=c30e682a63eb17dd51ce5ade0a459844e5ed207b;hb=4a667ead00c10797fb57298b3dd33c2efc6c8d3f;hp=9ec1f52ab37a29906ee2189e03c59ea03f3c6bf2;hpb=4357bb47604774ded7900ed13d139c32cf854c0a;p=cc65 diff --git a/src/cc65/function.c b/src/cc65/function.c index 9ec1f52ab..c30e682a6 100644 --- a/src/cc65/function.c +++ b/src/cc65/function.c @@ -6,10 +6,10 @@ /* */ /* */ /* */ -/* (C) 2000 Ullrich von Bassewitz */ -/* Wacholderweg 14 */ -/* D-70597 Stuttgart */ -/* EMail: uz@musoftware.de */ +/* (C) 2000-2003 Ullrich von Bassewitz */ +/* Römerstrasse 52 */ +/* D-70794 Filderstadt */ +/* EMail: uz@cc65.org */ /* */ /* */ /* This software is provided 'as-is', without any expressed or implied */ @@ -47,6 +47,7 @@ #include "litpool.h" #include "locals.h" #include "scanner.h" +#include "segments.h" #include "stmt.h" #include "symtab.h" #include "function.h" @@ -61,12 +62,13 @@ /* 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 */ - int Reserved; /* Reserved local space */ + struct SymEntry* FuncEntry; /* Symbol table entry */ + type* ReturnType; /* Function return type */ + struct 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 */ }; /* Pointer to current function */ @@ -84,15 +86,16 @@ static Function* NewFunction (struct SymEntry* Sym) /* 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 = 0; + F->ReturnType = GetFuncReturn (Sym->Type); + F->Desc = (FuncDesc*) DecodePtr (Sym->Type + 1); F->Reserved = 0; - F->RetLab = GetLabel (); + F->RetLab = GetLocalLabel (); + F->TopLevelSP = 0; + F->RegOffs = RegisterSpace; /* Return the new structure */ return F; @@ -108,7 +111,7 @@ static void FreeFunction (Function* 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; @@ -116,7 +119,7 @@ const char* GetFuncName (const Function* F) -unsigned GetParamCount (const Function* F) +unsigned F_GetParamCount (const Function* F) /* Return the parameter count for the current function */ { return F->Desc->ParamCount; @@ -124,7 +127,7 @@ unsigned GetParamCount (const Function* F) -unsigned GetParamSize (const Function* F) +unsigned F_GetParamSize (const Function* F) /* Return the parameter size for the current function */ { return F->Desc->ParamSize; @@ -132,7 +135,7 @@ unsigned GetParamSize (const Function* F) -type* GetReturnType (Function* F) +type* F_GetReturnType (Function* F) /* Get the return type for the function */ { return F->ReturnType; @@ -140,7 +143,7 @@ type* GetReturnType (Function* F) -int HasVoidReturn (const Function* F) +int F_HasVoidReturn (const Function* F) /* Return true if the function does not have a return value */ { return IsTypeVoid (F->ReturnType); @@ -148,15 +151,31 @@ int HasVoidReturn (const Function* F) -void RememberEntry (Function* F) -/* Remember the current output position for local space creation later */ +int F_IsVariadic (const Function* F) +/* Return true if this is a variadic function */ { - F->EntryCode = GetCodePos (); + return (F->Desc->Flags & FD_VARIADIC) != 0; } -unsigned GetRetLab (const Function* F) +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 F_GetRetLab (const Function* F) /* Return the return jump label */ { return F->RetLab; @@ -164,7 +183,15 @@ unsigned GetRetLab (const Function* F) -int ReserveLocalSpace (Function* F, unsigned Size) +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. */ @@ -175,24 +202,123 @@ int ReserveLocalSpace (Function* F, unsigned Size) -void AllocLocalSpace (Function* F) +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) { - /* Switch to the code segment */ - g_usecode (); + /* Create space on the stack */ + g_space (F->Reserved); + + /* Correct the stack pointer */ + oursp -= F->Reserved; + + /* Nothing more reserved */ + F->Reserved = 0; + } +} - /* Create space on the stack */ - g_space (F->Reserved); - /* Correct the stack pointer */ - oursp -= 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 (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. */ +{ + 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); } } @@ -207,11 +333,11 @@ void AllocLocalSpace (Function* F) void NewFunc (SymEntry* Func) /* Parse argument declarations and function body. */ { - int isbrk; - unsigned Flags; + int HadReturn; + 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); @@ -219,81 +345,144 @@ void NewFunc (SymEntry* Func) /* Reenter the lexical level */ ReenterFunctionLevel (D); + /* 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 [] = { T_UCHAR | T_QUAL_CONST, 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; - /* Need a starting curly brace */ - if (curtok != TOK_LCURLY) { - Error ("`{' expected"); + /* Allocate code and data segments for this function */ + Func->V.F.Seg = PushSegments (Func); + + /* Special handling for main() */ + if (strcmp (Func->Name, "main") == 0) { + /* Main cannot be a fastcall function */ + if (IsFastCallFunc (Func->Type)) { + Error ("`main' cannot be declared as __fastcall__"); + } + + /* 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 (); + } } - /* Setup register variables */ - InitRegVars (); - - /* Switch to the code segment and define the function name label */ - g_usecode (); - g_defgloblabel (Func->Name); - /* If this is a fastcall function, push the last parameter onto the stack */ - if (IsFastCallFunc (Func->Type) && D->ParamCount > 0 && (D->Flags & FD_ELLIPSIS) == 0) { + if (IsFastCallFunc (Func->Type) && D->ParamCount > 0) { - unsigned Flags; + unsigned Flags; - /* Get a pointer to the last parameter entry */ - SymEntry* LastParam = D->SymTab->SymTail; + /* Fastcall functions may never have an ellipsis or the compiler is buggy */ + CHECK ((D->Flags & FD_VARIADIC) == 0); - /* Generate the push */ - if (IsTypeFunc (LastParam->Type)) { + /* Generate the push */ + if (IsTypeFunc (D->LastParam->Type)) { /* Pointer to function */ Flags = CF_PTR; } else { - Flags = TypeOf (LastParam->Type) | CF_FORCECHAR; + 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 (CheckStack) { - g_stackcheck (); + g_stackcheck (); } - /* Generate function entry code if needed */ - g_enter (TypeOf (Func->Type), GetParamSize (CurrentFunc)); + /* Setup the stack */ + oursp = 0; - /* Remember the current code position. This may be used later to create - * local variable space once we have created the function body itself. - * Currently this is not possible because the stack offsets of all locals - * have to be known in advance. + /* 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. */ - RememberEntry (CurrentFunc); + Param = D->SymTab->SymHead; + while (Param && (Param->Flags & SC_PARAM) != 0) { - /* Parse the function body */ - oursp = 0; - isbrk = compound (); - - /* 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 ("Function `%s' must return a value", Func->Name); - } -#endif - RestoreRegVars (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 (); - Flags = HasVoidReturn (CurrentFunc)? CF_NONE : CF_REG; - g_leave (Flags, 0); + /* Remember the current stack pointer. All variables allocated elsewhere + * must be dropped when doing a return from an inner block. + */ + CurrentFunc->TopLevelSP = oursp; + + /* Now process statements in this block */ + HadReturn = 0; + while (CurTok.Tok != TOK_RCURLY) { + if (CurTok.Tok != TOK_CEOF) { + HadReturn = Statement (0); + } else { + break; + } } - /* 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); - /* Cleanup register variables */ - DoneRegVars (); + /* Generate the exit code */ + g_leave (); + + /* Emit references to imports/exports */ + EmitExternals (); /* Leave the lexical level */ LeaveFunctionLevel (); + /* Eat the closing brace */ + ConsumeRCurly (); + + /* Switch back to the old segments */ + PopSegments (); + /* Reset the current function pointer */ FreeFunction (CurrentFunc); CurrentFunc = 0; @@ -301,4 +490,3 @@ void NewFunc (SymEntry* Func) -