76e67e2f97
string table in the object file that (currently) holds all identifiers from the import, export and debug info sections. The plan is to put all strings into this table, so we have them in a central place and don't waste memory. Apart from that, the indices are unique, so comparing strings should be a lot easier than before (as soon as the programs take advantage of this fact, which is currently not the case). git-svn-id: svn://svn.cc65.org/cc65/trunk@2169 b7a2c559-68d2-44c3-8de9-860c34a00d81
559 lines
14 KiB
C
559 lines
14 KiB
C
/*****************************************************************************/
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/* */
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/* expr.c */
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/* */
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/* Expression evaluation for the ld65 linker */
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/* */
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/* */
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/* */
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/* (C) 1998-2000 Ullrich von Bassewitz */
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/* Wacholderweg 14 */
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/* D-70597 Stuttgart */
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/* EMail: uz@musoftware.de */
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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 "check.h"
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#include "exprdefs.h"
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#include "xmalloc.h"
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/* ld65 */
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#include "global.h"
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#include "error.h"
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#include "fileio.h"
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#include "segments.h"
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#include "expr.h"
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/*****************************************************************************/
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/* Helpers */
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/*****************************************************************************/
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static ExprNode* NewExprNode (ObjData* O)
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/* Create a new expression node */
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{
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/* Allocate fresh memory */
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ExprNode* N = xmalloc (sizeof (ExprNode));
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N->Op = EXPR_NULL;
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N->Left = 0;
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N->Right = 0;
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N->Obj = O;
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N->V.Val = 0;
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return N;
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}
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static void FreeExprNode (ExprNode* E)
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/* Free a node */
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{
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/* Free the memory */
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xfree (E);
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}
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/*****************************************************************************/
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/* Code */
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/*****************************************************************************/
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void FreeExpr (ExprNode* Root)
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/* Free the expression, Root is pointing to. */
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{
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if (Root) {
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FreeExpr (Root->Left);
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FreeExpr (Root->Right);
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FreeExprNode (Root);
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}
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}
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int IsConstExpr (ExprNode* Root)
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/* Return true if the given expression is a constant expression, that is, one
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* with no references to external symbols.
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*/
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{
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int Const;
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Export* E;
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if (EXPR_IS_LEAF (Root->Op)) {
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switch (Root->Op) {
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case EXPR_LITERAL:
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return 1;
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case EXPR_SYMBOL:
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/* Get the referenced export */
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E = GetExprExport (Root);
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/* If this export has a mark set, we've already encountered it.
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* This means that the export is used to define it's own value,
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* which in turn means, that we have a circular reference.
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*/
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if (ExportHasMark (E)) {
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Error ("Circular reference for symbol `%s', %s(%lu)",
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E->Name, GetSourceFileName (E->Obj, E->Pos.Name),
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E->Pos.Line);
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Const = 0;
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} else {
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MarkExport (E);
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Const = IsConstExport (E);
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UnmarkExport (E);
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}
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return Const;
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default:
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return 0;
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}
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} else if (EXPR_IS_UNARY (Root->Op)) {
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return IsConstExpr (Root->Left);
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} else {
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/* We must handle shortcut boolean expressions here */
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switch (Root->Op) {
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case EXPR_BAND:
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if (IsConstExpr (Root->Left)) {
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/* lhs is const, if it is zero, don't eval right */
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if (GetExprVal (Root->Left) == 0) {
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return 1;
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} else {
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return IsConstExpr (Root->Right);
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}
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} else {
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/* lhs not const --> tree not const */
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return 0;
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}
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break;
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case EXPR_BOR:
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if (IsConstExpr (Root->Left)) {
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/* lhs is const, if it is not zero, don't eval right */
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if (GetExprVal (Root->Left) != 0) {
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return 1;
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} else {
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return IsConstExpr (Root->Right);
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}
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} else {
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/* lhs not const --> tree not const */
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return 0;
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}
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break;
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default:
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/* All others are handled normal */
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return IsConstExpr (Root->Left) && IsConstExpr (Root->Right);
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}
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}
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}
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Import* GetExprImport (ExprNode* Expr)
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/* Get the import data structure for a symbol expression node */
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{
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/* Check that this is really a symbol */
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PRECONDITION (Expr->Op == EXPR_SYMBOL);
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/* Return the import */
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return Expr->Obj->Imports [Expr->V.ImpNum];
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}
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Export* GetExprExport (ExprNode* Expr)
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/* Get the exported symbol for a symbol expression node */
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{
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/* Check that this is really a symbol */
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PRECONDITION (Expr->Op == EXPR_SYMBOL);
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/* Return the export */
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return Expr->Obj->Imports [Expr->V.ImpNum]->V.Exp;
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}
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Section* GetExprSection (ExprNode* Expr)
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/* Get the segment for a section expression node */
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{
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/* Check that this is really a section node */
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PRECONDITION (Expr->Op == EXPR_SECTION);
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/* If we have an object file, get the section from it, otherwise
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* (internally generated expressions), get the section from the
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* section pointer.
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*/
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if (Expr->Obj) {
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/* Return the export */
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return Expr->Obj->Sections [Expr->V.SegNum];
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} else {
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return Expr->V.Sec;
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}
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}
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long GetExprVal (ExprNode* Expr)
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/* Get the value of a constant expression */
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{
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long Right, Left, Val;
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Section* S;
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Export* E;
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switch (Expr->Op) {
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case EXPR_LITERAL:
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return Expr->V.Val;
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case EXPR_SYMBOL:
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/* Get the referenced export */
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E = GetExprExport (Expr);
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/* If this export has a mark set, we've already encountered it.
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* This means that the export is used to define it's own value,
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* which in turn means, that we have a circular reference.
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*/
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if (ExportHasMark (E)) {
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CircularRefError (E);
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Val = 0;
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} else {
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MarkExport (E);
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Val = GetExportVal (E);
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UnmarkExport (E);
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}
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return Val;
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case EXPR_SECTION:
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S = GetExprSection (Expr);
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return S->Offs + S->Seg->PC;
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case EXPR_SEGMENT:
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return Expr->V.Seg->PC;
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case EXPR_MEMAREA:
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return Expr->V.Mem->Start;
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case EXPR_PLUS:
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return GetExprVal (Expr->Left) + GetExprVal (Expr->Right);
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case EXPR_MINUS:
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return GetExprVal (Expr->Left) - GetExprVal (Expr->Right);
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case EXPR_MUL:
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return GetExprVal (Expr->Left) * GetExprVal (Expr->Right);
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case EXPR_DIV:
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Left = GetExprVal (Expr->Left);
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Right = GetExprVal (Expr->Right);
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if (Right == 0) {
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Error ("Division by zero");
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}
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return Left / Right;
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case EXPR_MOD:
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Left = GetExprVal (Expr->Left);
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Right = GetExprVal (Expr->Right);
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if (Right == 0) {
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Error ("Modulo operation with zero");
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}
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return Left % Right;
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case EXPR_OR:
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return GetExprVal (Expr->Left) | GetExprVal (Expr->Right);
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case EXPR_XOR:
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return GetExprVal (Expr->Left) ^ GetExprVal (Expr->Right);
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case EXPR_AND:
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return GetExprVal (Expr->Left) & GetExprVal (Expr->Right);
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case EXPR_SHL:
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return GetExprVal (Expr->Left) << GetExprVal (Expr->Right);
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case EXPR_SHR:
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return GetExprVal (Expr->Left) >> GetExprVal (Expr->Right);
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case EXPR_EQ:
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return (GetExprVal (Expr->Left) == GetExprVal (Expr->Right));
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case EXPR_NE:
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return (GetExprVal (Expr->Left) != GetExprVal (Expr->Right));
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case EXPR_LT:
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return (GetExprVal (Expr->Left) < GetExprVal (Expr->Right));
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case EXPR_GT:
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return (GetExprVal (Expr->Left) > GetExprVal (Expr->Right));
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case EXPR_LE:
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return (GetExprVal (Expr->Left) <= GetExprVal (Expr->Right));
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case EXPR_GE:
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return (GetExprVal (Expr->Left) >= GetExprVal (Expr->Right));
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case EXPR_UNARY_MINUS:
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return -GetExprVal (Expr->Left);
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case EXPR_NOT:
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return ~GetExprVal (Expr->Left);
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case EXPR_BYTE0:
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return GetExprVal (Expr->Left) & 0xFF;
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case EXPR_BYTE1:
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return (GetExprVal (Expr->Left) >> 8) & 0xFF;
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case EXPR_BYTE2:
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return (GetExprVal (Expr->Left) >> 16) & 0xFF;
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case EXPR_BYTE3:
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return (GetExprVal (Expr->Left) >> 24) & 0xFF;
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case EXPR_SWAP:
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Left = GetExprVal (Expr->Left);
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return ((Left >> 8) & 0x00FF) | ((Left << 8) & 0xFF00);
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case EXPR_BAND:
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return GetExprVal (Expr->Left) && GetExprVal (Expr->Right);
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case EXPR_BOR:
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return GetExprVal (Expr->Left) || GetExprVal (Expr->Right);
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case EXPR_BXOR:
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return (GetExprVal (Expr->Left) != 0) ^ (GetExprVal (Expr->Right) != 0);
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case EXPR_BNOT:
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return !GetExprVal (Expr->Left);
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default:
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Internal ("Unknown expression Op type: %u", Expr->Op);
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/* NOTREACHED */
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return 0;
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}
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}
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ExprNode* LiteralExpr (long Val, ObjData* O)
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/* Return an expression tree that encodes the given literal value */
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{
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ExprNode* Expr = NewExprNode (O);
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Expr->Op = EXPR_LITERAL;
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Expr->V.Val = Val;
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return Expr;
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}
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ExprNode* MemoryExpr (Memory* Mem, long Offs, ObjData* O)
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/* Return an expression tree that encodes an offset into a memory area */
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{
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ExprNode* Root;
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ExprNode* Expr = NewExprNode (O);
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Expr->Op = EXPR_MEMAREA;
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Expr->V.Mem = Mem;
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if (Offs != 0) {
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Root = NewExprNode (O);
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Root->Op = EXPR_PLUS;
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Root->Left = Expr;
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Root->Right = LiteralExpr (Offs, O);
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} else {
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Root = Expr;
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}
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return Root;
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}
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ExprNode* SegmentExpr (Segment* Seg, long Offs, ObjData* O)
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/* Return an expression tree that encodes an offset into a segment */
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{
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ExprNode* Root;
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ExprNode* Expr = NewExprNode (O);
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Expr->Op = EXPR_SEGMENT;
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Expr->V.Seg = Seg;
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if (Offs != 0) {
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Root = NewExprNode (O);
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Root->Op = EXPR_PLUS;
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Root->Left = Expr;
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Root->Right = LiteralExpr (Offs, O);
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} else {
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Root = Expr;
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}
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return Root;
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}
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ExprNode* SectionExpr (Section* Sec, long Offs, ObjData* O)
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/* Return an expression tree that encodes an offset into a section */
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{
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ExprNode* Root;
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ExprNode* Expr = NewExprNode (O);
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Expr->Op = EXPR_SECTION;
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Expr->V.Sec = Sec;
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if (Offs != 0) {
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Root = NewExprNode (O);
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Root->Op = EXPR_PLUS;
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Root->Left = Expr;
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Root->Right = LiteralExpr (Offs, O);
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} else {
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Root = Expr;
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}
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return Root;
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}
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ExprNode* ReadExpr (FILE* F, ObjData* O)
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/* Read an expression from the given file */
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{
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ExprNode* Expr;
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/* Read the node tag and handle NULL nodes */
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unsigned char Op = Read8 (F);
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if (Op == EXPR_NULL) {
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return 0;
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}
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/* Create a new node */
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Expr = NewExprNode (O);
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Expr->Op = Op;
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/* Check the tag and handle the different expression types */
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if (EXPR_IS_LEAF (Op)) {
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switch (Op) {
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case EXPR_LITERAL:
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Expr->V.Val = Read32Signed (F);
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break;
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case EXPR_SYMBOL:
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/* Read the import number */
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Expr->V.ImpNum = ReadVar (F);
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break;
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case EXPR_SECTION:
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/* Read the segment number */
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Expr->V.SegNum = Read8 (F);
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break;
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default:
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Error ("Invalid expression op: %02X", Op);
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}
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} else {
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/* Not a leaf node */
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Expr->Left = ReadExpr (F, O);
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Expr->Right = ReadExpr (F, O);
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}
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/* Return the tree */
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return Expr;
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}
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int EqualExpr (ExprNode* E1, ExprNode* E2)
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/* Check if two expressions are identical. */
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{
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/* If one pointer is NULL, both must be NULL */
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if ((E1 == 0) ^ (E2 == 0)) {
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return 0;
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}
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if (E1 == 0) {
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return 1;
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}
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/* Both pointers not NULL, check OP */
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if (E1->Op != E2->Op) {
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return 0;
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}
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/* OPs are identical, check data for leafs, or subtrees */
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switch (E1->Op) {
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case EXPR_LITERAL:
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/* Value must be identical */
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return (E1->V.Val == E2->V.Val);
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case EXPR_SYMBOL:
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/* Import number must be identical */
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return (E1->V.ImpNum == E2->V.ImpNum);
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case EXPR_SECTION:
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/* Section must be identical */
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return (GetExprSection (E1) == GetExprSection (E2));
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case EXPR_SEGMENT:
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/* Segment must be identical */
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return (E1->V.Seg == E2->V.Seg);
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case EXPR_MEMAREA:
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/* Memory area must be identical */
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return (E1->V.Mem == E2->V.Mem );
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default:
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/* Not a leaf node */
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return EqualExpr (E1->Left, E2->Left) && EqualExpr (E1->Right, E2->Right);
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}
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}
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