some small fixes

[fw/sdcc] / src / SDCCast.c

diff --git a/src/SDCCast.c b/src/SDCCast.c
index 26f59d09957b9cb66d39ae3c9e8ed3a8456d7620..15f59285a84add354e7611937d698e1eadc1f75c 100644 (file)
--- a/src/SDCCast.c
+++ b/src/SDCCast.c
@@ -50,6 +50,7 @@ int noAlloc = 0;
 symbol *currFunc;
 static ast *createIval (ast *, sym_link *, initList *, ast *);
 static ast *createIvalCharPtr (ast *, sym_link *, ast *);
+static ast *optimizeCompare (ast *);
 ast *optimizeRRCRLC (ast *);
 ast *optimizeGetHbit (ast *);
 ast *backPatchLabels (ast *, symbol *, symbol *);
@@ -1146,6 +1147,66 @@ processBlockVars (ast * tree, int *stack, int action)
   return tree;
 }
 
+/*-------------------------------------------------------------*/
+/* constExprTree - returns TRUE if this tree is a constant     */
+/*                 expression                                  */
+/*-------------------------------------------------------------*/
+bool constExprTree (ast *cexpr) {
+
+  if (!cexpr) {
+    return TRUE;
+  }
+
+  cexpr = decorateType (resolveSymbols (cexpr));
+  
+  switch (cexpr->type) 
+    {
+    case EX_VALUE:
+      if (IS_AST_LIT_VALUE(cexpr)) {
+       // this is a literal
+       return TRUE;
+      }
+      if (IS_AST_SYM_VALUE(cexpr) && IS_FUNC(AST_SYMBOL(cexpr)->type)) {
+       // a function's address will never change
+       return TRUE;
+      }
+      if (IS_AST_SYM_VALUE(cexpr) && 
+         IN_CODESPACE(SPEC_OCLS(AST_SYMBOL(cexpr)->etype))) {
+       // a symbol in code space will never change
+       // This is only for the 'char *s="hallo"' case and will have to leave
+       return TRUE;
+      }
+      return FALSE;
+    case EX_LINK:
+      werror (E_INTERNAL_ERROR, __FILE__, __LINE__,
+             "unexpected link in expression tree\n");
+      return FALSE;
+    case EX_OP:
+      if (cexpr->opval.op==ARRAYINIT) {
+       fprintf (stderr, "skipping arrayinit\n");
+       // this is a list of literals
+       return TRUE;
+      }
+      if (cexpr->opval.op=='=') {
+       return constExprTree(cexpr->right);
+      }
+      if (cexpr->opval.op==CAST) {
+       // jwk: cast ignored, maybe we should throw a warning here
+       return constExprTree(cexpr->right);
+      }
+      if (cexpr->opval.op=='&') { 
+       return TRUE;
+      }
+      if (cexpr->opval.op==CALL || cexpr->opval.op==PCALL) {
+       return FALSE;
+      }
+      if (constExprTree(cexpr->left) && constExprTree(cexpr->right)) {
+       return TRUE;
+      }
+    }
+  return FALSE;
+}  
+    
 /*-----------------------------------------------------------------*/
 /* constExprValue - returns the value of a constant expression     */
 /*                  or NULL if it is not a constant expression     */
@@ -3904,7 +3965,7 @@ tryNext2:
 /*-----------------------------------------------------------------*/
 /* optimizeCompare - otimizes compares for bit variables     */
 /*-----------------------------------------------------------------*/
-ast *
+static ast *
 optimizeCompare (ast * root)
 {
   ast *optExpr = NULL;