cc65/src/cc65/locals.c

/*****************************************************************************/
/*                                                                           */
/*				   locals.c				     */
/*                                                                           */
/*		Local variable handling for the cc65 C compiler		     */
/*                                                                           */
/*                                                                           */
/*                                                                           */
/* (C) 2000-2003 Ullrich von Bassewitz                                       */
/*               R<>merstrasse 52                                             */
/*               D-70794 Filderstadt                                         */
/* EMail:        uz@cc65.org                                                 */
/*                                                                           */
/*                                                                           */
/* This software is provided 'as-is', without any expressed or implied       */
/* warranty.  In no event will the authors be held liable for any damages    */
/* arising from the use of this software.                                    */
/*                                                                           */
/* Permission is granted to anyone to use this software for any purpose,     */
/* including commercial applications, and to alter it and redistribute it    */
/* freely, subject to the following restrictions:                            */
/*                                                                           */
/* 1. The origin of this software must not be misrepresented; you must not   */
/*    claim that you wrote the original software. If you use this software   */
/*    in a product, an acknowledgment in the product documentation would be  */
/*    appreciated but is not required.                                       */
/* 2. Altered source versions must be plainly marked as such, and must not   */
/*    be misrepresented as being the original software.                      */
/* 3. This notice may not be removed or altered from any source              */
/*    distribution.                                                          */
/*                                                                           */
/*****************************************************************************/



/* common */
#include "xmalloc.h"
#include "xsprintf.h"

/* cc65 */
#include "anonname.h"
#include "asmlabel.h"
#include "codegen.h"
#include "declare.h"
#include "error.h"
#include "expr.h"
#include "function.h"
#include "global.h"
#include "locals.h"
#include "symtab.h"
#include "typeconv.h"



/*****************************************************************************/
/*		   		     Code		       		     */
/*****************************************************************************/



static unsigned ParseRegisterDecl (Declaration* Decl, unsigned* SC, int Reg)
/* Parse the declaration of a register variable. The function returns the
 * symbol data, which is the offset of the variable in the register bank.
 */
{
    unsigned InitLabel;

    /* Determine if this is a compound variable */
    int IsCompound = IsClassStruct (Decl->Type) || IsTypeArray (Decl->Type);

    /* Get the size of the variable */
    unsigned Size = SizeOf (Decl->Type);

    /* Save the current contents of the register variable on stack */
    F_AllocLocalSpace (CurrentFunc);
    g_save_regvars (Reg, Size);

    /* Check for an optional initialization */
    if (CurTok.Tok == TOK_ASSIGN) {

        ExprDesc lval;

        /* Skip the '=' */
        NextToken ();

        /* Special handling for compound types */
        if (IsCompound) {

            /* Switch to read only data */
            g_userodata ();

            /* Define a label for the initialization data */
            InitLabel = GetLocalLabel ();
            g_defdatalabel (InitLabel);

            /* Parse the initialization generating a memory image of the
             * data in the RODATA segment. The function does return the size
             * of the initialization data, which may be greater than the
             * actual size of the type, if the type is a structure with a
             * flexible array member that has been initialized. Since we must
             * know the size of the data in advance for register variables,
             * we cannot allow that here.
             */
            if (ParseInit (Decl->Type) != Size) {
                Error ("Cannot initialize flexible array members of storage class `register'");
            }

            /* Generate code to copy this data into the variable space */
            g_initregister (InitLabel, Reg, Size);

        } else {

            /* Parse the expression */
            int k = hie1 (InitExprDesc (&lval));

            /* Convert it to the target type */
            k = TypeConversion (&lval, k, Decl->Type);

            /* Load the value into the primary */
            ExprLoad (CF_NONE, k, &lval);

            /* Store the value into the variable */
            g_putstatic (CF_REGVAR | TypeOf (Decl->Type), Reg, 0);

        }

        /* Mark the variable as referenced */
        *SC |= SC_REF;
    }

    /* Cannot allocate a variable of zero size */
    if (Size == 0) {
        Error ("Variable `%s' has unknown size", Decl->Ident);
    }

    /* Return the symbol data */
    return Reg;
}



static unsigned ParseAutoDecl (Declaration* Decl, unsigned* SC)
/* Parse the declaration of an auto variable. The function returns the symbol
 * data, which is the offset for variables on the stack, and the label for
 * static variables.
 */
{
    unsigned Flags;
    unsigned SymData;
    unsigned InitLabel;

    /* Determine if this is a compound variable */
    int IsCompound = IsClassStruct (Decl->Type) || IsTypeArray (Decl->Type);

    /* Get the size of the variable */
    unsigned Size = SizeOf (Decl->Type);

    /* Check if this is a variable on the stack or in static memory */
    if (StaticLocals == 0) {

        /* Check for an optional initialization */
        if (CurTok.Tok == TOK_ASSIGN) {

            ExprDesc lval;

            /* Skip the '=' */
            NextToken ();

            /* Special handling for compound types */
            if (IsCompound) {

                /* Switch to read only data */
                g_userodata ();

                /* Define a label for the initialization data */
                InitLabel = GetLocalLabel ();
                g_defdatalabel (InitLabel);

                /* Parse the initialization generating a memory image of the
                 * data in the RODATA segment. The function will return the
                 * actual size of the initialization data, which may be
                 * greater than the size of the variable if it is a struct
                 * that contains a flexible array member and we're not in
                 * ANSI mode.
                 */
                Size = ParseInit (Decl->Type);

                /* Now reserve space for the variable on the stack */
                SymData = F_ReserveLocalSpace (CurrentFunc, Size);

                /* Next, allocate the space on the stack. This means that the
                 * variable is now located at offset 0 from the current sp.
                 */
                F_AllocLocalSpace (CurrentFunc);

                /* Generate code to copy the initialization data into the
                 * variable space
                 */
                g_initauto (InitLabel, Size);

            } else {

                int k;

                /* Allocate previously reserved local space */
                F_AllocLocalSpace (CurrentFunc);

                /* Setup the type flags for the assignment */
                Flags = (Size == SIZEOF_CHAR)? CF_FORCECHAR : CF_NONE;

                /* Parse the expression */
                k = hie1 (InitExprDesc (&lval));

                /* Convert it to the target type */
                k = TypeConversion (&lval, k, Decl->Type);

                /* If the value is not const, load it into the primary.
                 * Otherwise pass the information to the code generator.
                 */
                if (k != 0 || lval.Flags != E_MCONST) {
                    ExprLoad (CF_NONE, k, &lval);
                    k = 0;
                } else {
                    Flags |= CF_CONST;
                }

                /* Push the value */
                g_push (Flags | TypeOf (Decl->Type), lval.ConstVal);

            }

            /* Mark the variable as referenced */
            *SC |= SC_REF;

            /* Variable is located at the current SP */
            SymData = oursp;

        } else {
            /* Non-initialized local variable. Just keep track of
             * the space needed.
             */
            SymData = F_ReserveLocalSpace (CurrentFunc, Size);
        }

    } else {

        /* Static local variables. */
        *SC = (*SC & ~SC_AUTO) | SC_STATIC;

        /* Put them into the BSS */
        g_usebss ();

        /* Define the variable label */
        SymData = GetLocalLabel ();
        g_defdatalabel (SymData);

        /* Reserve space for the data */
        g_res (Size);

        /* Allow assignments */
        if (CurTok.Tok == TOK_ASSIGN) {

            ExprDesc lval;

            /* Skip the '=' */
            NextToken ();

            if (IsCompound) {

                /* Switch to read only data */
                g_userodata ();

                /* Define a label for the initialization data */
                InitLabel = GetLocalLabel ();
                g_defdatalabel (InitLabel);

                /* Parse the initialization generating a memory image of the
                 * data in the RODATA segment.
                 */
                ParseInit (Decl->Type);

                /* Generate code to copy this data into the variable space */
                g_initstatic (InitLabel, SymData, Size);

            } else {

                /* Parse the expression */
                int k = hie1 (InitExprDesc (&lval));

                /* Convert it to the target type */
                k = TypeConversion (&lval, k, Decl->Type);

                /* Load the value into the primary */
                ExprLoad (CF_NONE, k, &lval);

                /* Store the value into the variable */
                g_putstatic (TypeOf (Decl->Type), SymData, 0);
            }

            /* Mark the variable as referenced */
            *SC |= SC_REF;
        }
    }

    /* Cannot allocate a variable of zero size */
    if (Size == 0) {
        Error ("Variable `%s' has unknown size", Decl->Ident);
    }

    /* Return the symbol data */
    return SymData;
}



static unsigned ParseStaticDecl (Declaration* Decl, unsigned* SC)
/* Parse the declaration of a static variable. The function returns the symbol
 * data, which is the asm label of the variable.
 */
{
    unsigned SymData;

    /* Get the size of the variable */
    unsigned Size = SizeOf (Decl->Type);

    /* Static data */
    if (CurTok.Tok == TOK_ASSIGN) {

        /* Initialization ahead, switch to data segment */
        if (IsQualConst (Decl->Type)) {
            g_userodata ();
        } else {
            g_usedata ();
        }

        /* Define the variable label */
        SymData = GetLocalLabel ();
        g_defdatalabel (SymData);

        /* Skip the '=' */
        NextToken ();

        /* Allow initialization of static vars */
        ParseInit (Decl->Type);

        /* If the previous size has been unknown, it must be known now */
        if (Size == 0) {
            Size = SizeOf (Decl->Type);
        }

        /* Mark the variable as referenced */
        *SC |= SC_REF;

    } else {

        /* Uninitialized data, use BSS segment */
        g_usebss ();

        /* Define the variable label */
        SymData = GetLocalLabel ();
        g_defdatalabel (SymData);

        /* Reserve space for the data */
        g_res (Size);

    }

    /* Cannot allocate a variable of zero size */
    if (Size == 0) {
        Error ("Variable `%s' has unknown size", Decl->Ident);
    }

    /* Return the symbol data */
    return SymData;
}



static void ParseOneDecl (const DeclSpec* Spec)
/* Parse one variable declaration */
{
    unsigned    SC;      	/* Storage class for symbol */
    unsigned    SymData = 0;    /* Symbol data (offset, label name, ...) */
    Declaration Decl;	       	/* Declaration data structure */


    /* Remember the storage class for the new symbol */
    SC = Spec->StorageClass;

    /* Read the declaration */
    ParseDecl (Spec, &Decl, DM_NEED_IDENT);

    /* Set the correct storage class for functions */
    if (IsTypeFunc (Decl.Type)) {
    	/* Function prototypes are always external */
    	if ((SC & SC_EXTERN) == 0) {
       	    Warning ("Function must be extern");
    	}
       	SC |= SC_FUNC | SC_EXTERN;

    }

    /* If we don't have a name, this was flagged as an error earlier.
     * To avoid problems later, use an anonymous name here.
     */
    if (Decl.Ident[0] == '\0') {
       	AnonName (Decl.Ident, "param");
    }

    /* Handle anything that needs storage (no functions, no typdefs) */
    if ((SC & SC_FUNC) != SC_FUNC && (SC & SC_TYPEDEF) != SC_TYPEDEF) {

        /* If we have a register variable, try to allocate a register and
         * convert the declaration to "auto" if this is not possible.
         */
        int Reg = 0;    /* Initialize to avoid gcc complains */
        if ((SC & SC_REGISTER) != 0 && (Reg = F_AllocRegVar (CurrentFunc, Decl.Type)) < 0) {
            /* No space for this register variable, convert to auto */
            SC = (SC & ~SC_REGISTER) | SC_AUTO;
        }

        /* Check the variable type */
        if ((SC & SC_REGISTER) == SC_REGISTER) {
            /* Register variable */
            SymData = ParseRegisterDecl (&Decl, &SC, Reg);
       	} else if ((SC & SC_AUTO) == SC_AUTO) {
            /* Auto variable */
            SymData = ParseAutoDecl (&Decl, &SC);
       	} else if ((SC & SC_STATIC) == SC_STATIC) {
            /* Static variable */
            SymData = ParseStaticDecl (&Decl, &SC);
       	} else {
            Internal ("Invalid storage class in ParseOneDecl: %04X", SC);
        }
    }

    /* If the symbol is not marked as external, it will be defined now */
    if ((SC & SC_EXTERN) == 0) {
       	SC |= SC_DEF;
    }

    /* Add the symbol to the symbol table */
    AddLocalSym (Decl.Ident, Decl.Type, SC, SymData);
}



void DeclareLocals (void)
/* Declare local variables and types. */
{
    /* Remember the current stack pointer */
    int InitialStack = oursp;

    /* Loop until we don't find any more variables */
    while (1) {

	/* Check variable declarations. We need to distinguish between a
    	 * default int type and the end of variable declarations. So we
	 * will do the following: If there is no explicit storage class
	 * specifier *and* no explicit type given, *and* no type qualifiers
         * have been read, it is assumed that we have reached the end of
         * declarations.
	 */
	DeclSpec Spec;
	ParseDeclSpec (&Spec, SC_AUTO, T_INT);
       	if ((Spec.Flags & DS_DEF_STORAGE) != 0 &&       /* No storage spec */
            (Spec.Flags & DS_DEF_TYPE) != 0    &&       /* No type given */
            GetQualifier (Spec.Type) == T_QUAL_NONE) {  /* No type qualifier */
	    break;
	}

	/* Accept type only declarations */
	if (CurTok.Tok == TOK_SEMI) {
	    /* Type declaration only */
	    CheckEmptyDecl (&Spec);
	    NextToken ();
	    continue;
	}

      	/* Parse a comma separated variable list */
      	while (1) {

	    /* Parse one declaration */
	    ParseOneDecl (&Spec);

	    /* Check if there is more */
     	    if (CurTok.Tok == TOK_COMMA) {
		/* More to come */
		NextToken ();
	    } else {
		/* Done */
     	      	break;
	    }
       	}

	/* A semicolon must follow */
	ConsumeSemi ();
    }

    /* Be sure to allocate any reserved space for locals */
    F_AllocLocalSpace (CurrentFunc);

    /* In case we've allocated local variables in this block, emit a call to
     * the stack checking routine if stack checks are enabled.
     */
    if (CheckStack && InitialStack != oursp) {
       	g_cstackcheck ();
    }
}