mirror of
https://github.com/cc65/cc65.git
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298 lines
10 KiB
C
298 lines
10 KiB
C
/*****************************************************************************/
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/* */
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/* typeconv.c */
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/* */
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/* Handle type conversions */
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/* */
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/* */
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/* */
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/* (C) 2002-2008 Ullrich von Bassewitz */
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/* Roemerstrasse 52 */
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/* D-70794 Filderstadt */
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/* EMail: uz@cc65.org */
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/* */
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/* */
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/* This software is provided 'as-is', without any expressed or implied */
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/* warranty. In no event will the authors be held liable for any damages */
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/* arising from the use of this software. */
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/* */
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/* Permission is granted to anyone to use this software for any purpose, */
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/* including commercial applications, and to alter it and redistribute it */
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/* freely, subject to the following restrictions: */
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/* */
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/* 1. The origin of this software must not be misrepresented; you must not */
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/* claim that you wrote the original software. If you use this software */
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/* in a product, an acknowledgment in the product documentation would be */
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/* appreciated but is not required. */
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/* 2. Altered source versions must be plainly marked as such, and must not */
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/* be misrepresented as being the original software. */
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/* 3. This notice may not be removed or altered from any source */
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/* distribution. */
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/* */
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/*****************************************************************************/
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/* common */
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#include "shift.h"
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/* cc65 */
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#include "codegen.h"
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#include "datatype.h"
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#include "declare.h"
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#include "error.h"
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#include "expr.h"
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#include "loadexpr.h"
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#include "scanner.h"
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#include "typecmp.h"
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#include "typeconv.h"
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/*****************************************************************************/
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/* Code */
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/*****************************************************************************/
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static void DoConversion (ExprDesc* Expr, const Type* NewType)
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/* Emit code to convert the given expression to a new type. */
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{
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Type* OldType;
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unsigned OldSize;
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unsigned NewSize;
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/* Remember the old type */
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OldType = Expr->Type;
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/* If we're converting to void, we're done. Note: This does also cover a
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** conversion void -> void.
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*/
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if (IsTypeVoid (NewType)) {
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ED_MakeRVal (Expr); /* Never an lvalue */
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goto ExitPoint;
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}
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/* Don't allow casts from void to something else. */
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if (IsTypeVoid (OldType)) {
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Error ("Cannot convert from 'void' to something else");
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goto ExitPoint;
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}
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/* Get the sizes of the types. Since we've excluded void types, checking
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** for known sizes makes sense here.
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*/
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OldSize = CheckedSizeOf (OldType);
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NewSize = CheckedSizeOf (NewType);
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/* lvalue? */
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if (ED_IsLVal (Expr)) {
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/* We have an lvalue. If the new size is smaller than the old one,
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** we don't need to do anything. The compiler will generate code
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** to load only the portion of the value that is actually needed.
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** This works only on a little endian architecture, but that's
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** what we support.
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** If both sizes are equal, do also leave the value alone.
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** If the new size is larger, we must convert the value.
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*/
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if (NewSize > OldSize) {
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/* Load the value into the primary */
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LoadExpr (CF_NONE, Expr);
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/* Emit typecast code */
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g_typecast (TypeOf (NewType), TypeOf (OldType) | CF_FORCECHAR);
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/* Value is now in primary and an rvalue */
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ED_MakeRValExpr (Expr);
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}
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} else if (ED_IsLocAbs (Expr)) {
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/* A cast of a constant numeric value to another type. Be sure
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** to handle sign extension correctly.
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*/
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/* Get the current and new size of the value */
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unsigned OldBits = OldSize * 8;
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unsigned NewBits = NewSize * 8;
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/* Check if the new datatype will have a smaller range. If it
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** has a larger range, things are OK, since the value is
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** internally already represented by a long.
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*/
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if (NewBits <= OldBits) {
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/* Cut the value to the new size */
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Expr->IVal &= (0xFFFFFFFFUL >> (32 - NewBits));
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/* If the new type is signed, sign extend the value */
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if (IsSignSigned (NewType)) {
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if (Expr->IVal & (0x01UL << (NewBits-1))) {
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/* Beware: Use the safe shift routine here. */
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Expr->IVal |= shl_l (~0UL, NewBits);
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}
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}
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}
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} else {
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/* The value is not a constant. If the sizes of the types are
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** not equal, add conversion code. Be sure to convert chars
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** correctly.
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*/
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if (OldSize != NewSize) {
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/* Load the value into the primary */
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LoadExpr (CF_NONE, Expr);
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/* Emit typecast code. */
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g_typecast (TypeOf (NewType), TypeOf (OldType) | CF_FORCECHAR);
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/* Value is now a rvalue in the primary */
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ED_MakeRValExpr (Expr);
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}
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}
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ExitPoint:
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/* The expression has always the new type */
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ReplaceType (Expr, NewType);
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}
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void TypeConversion (ExprDesc* Expr, Type* NewType)
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/* Do an automatic conversion of the given expression to the new type. Output
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** warnings or errors where this automatic conversion is suspicious or
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** impossible.
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*/
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{
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#if 0
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/* Debugging */
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printf ("Expr:\n=======================================\n");
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PrintExprDesc (stdout, Expr);
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printf ("Type:\n=======================================\n");
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PrintType (stdout, NewType);
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printf ("\n");
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PrintRawType (stdout, NewType);
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#endif
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/* First, do some type checking */
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if (IsTypeVoid (NewType) || IsTypeVoid (Expr->Type)) {
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/* If one of the sides are of type void, output a more apropriate
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** error message.
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*/
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Error ("Illegal type");
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}
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/* If Expr is a function, convert it to pointer to function */
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if (IsTypeFunc(Expr->Type)) {
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Expr->Type = PointerTo (Expr->Type);
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}
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/* If both types are equal, no conversion is needed */
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if (TypeCmp (Expr->Type, NewType) >= TC_EQUAL) {
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/* We're already done */
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return;
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}
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/* Check for conversion problems */
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if (IsClassInt (NewType)) {
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/* Handle conversions to int type */
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if (IsClassPtr (Expr->Type)) {
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/* Pointer -> int conversion. Convert array to pointer */
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if (IsTypeArray (Expr->Type)) {
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Expr->Type = ArrayToPtr (Expr->Type);
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}
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Warning ("Converting pointer to integer without a cast");
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} else if (!IsClassInt (Expr->Type) && !IsClassFloat (Expr->Type)) {
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Error ("Incompatible types");
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}
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} else if (IsClassFloat (NewType)) {
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if (!IsClassFloat (Expr->Type) && !IsClassInt (Expr->Type)) {
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Error ("Incompatible types");
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}
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} else if (IsClassPtr (NewType)) {
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/* Handle conversions to pointer type */
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if (IsClassPtr (Expr->Type)) {
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/* Convert array to pointer */
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if (IsTypeArray (Expr->Type)) {
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Expr->Type = ArrayToPtr (Expr->Type);
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}
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/* Pointer to pointer assignment is valid, if:
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** - both point to the same types, or
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** - the rhs pointer is a void pointer, or
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** - the lhs pointer is a void pointer.
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*/
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if (!IsTypeVoid (Indirect (NewType)) && !IsTypeVoid (Indirect (Expr->Type))) {
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/* Compare the types */
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switch (TypeCmp (NewType, Expr->Type)) {
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case TC_INCOMPATIBLE:
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Error ("Incompatible pointer types at '%s'", (Expr->Sym? Expr->Sym->Name : "Unknown"));
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break;
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case TC_QUAL_DIFF:
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Error ("Pointer types differ in type qualifiers");
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break;
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default:
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/* Ok */
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break;
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}
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}
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} else if (IsClassInt (Expr->Type)) {
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/* Int to pointer assignment is valid only for constant zero */
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if (!ED_IsConstAbsInt (Expr) || Expr->IVal != 0) {
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Warning ("Converting integer to pointer without a cast");
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}
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} else {
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Error ("Incompatible types");
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}
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} else {
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/* Invalid automatic conversion */
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Error ("Incompatible types");
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}
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/* Do the actual conversion */
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DoConversion (Expr, NewType);
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}
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void TypeCast (ExprDesc* Expr)
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/* Handle an explicit cast. */
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{
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Type NewType[MAXTYPELEN];
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/* Skip the left paren */
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NextToken ();
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/* Read the type */
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ParseType (NewType);
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/* Closing paren */
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ConsumeRParen ();
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/* Read the expression we have to cast */
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hie10 (Expr);
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/* Convert functions and arrays to "pointer to" object */
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Expr->Type = PtrConversion (Expr->Type);
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/* Convert the value. */
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DoConversion (Expr, NewType);
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}
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