Generated code for FOR-loops was wrong

lang/m2/comp/LLlex.c

@@ -123,7 +123,7 @@ GetString(upto)
 		}
 		*p++ = ch;
 		if (p - str->s_str == len)	{
-			str->s_str = Srealloc(str->s_str,
+			str->s_str = Realloc(str->s_str,
 				(unsigned int) len + RSTRSIZE);
 			p = str->s_str + len;
 			len += RSTRSIZE;

lang/m2/comp/code.c

@@ -1001,6 +1001,7 @@ CodeDAddress(nd)
 
 	register struct desig *designator = new_desig();
 
+	ChkForFOR(nd);
 	CodeDesig(nd, designator);
 	CodeAddress(designator);
 	free_desig(designator);
@@ -1015,6 +1016,7 @@ CodeDStore(nd)
 
 	register struct desig *designator = new_desig();
 
+	ChkForFOR(nd);
 	CodeDesig(nd, designator);
 	CodeStore(designator, nd->nd_type);
 	free_desig(designator);

lang/m2/comp/def.H

@@ -113,6 +113,7 @@ struct def	{		/* list of definitions for a name */
 #define D_BUSY		0x80	/* set if busy reading this definition module */
 #define D_FOREIGN	0x100	/* set for foreign language modules */
 #define D_ADDRGIVEN	0x200	/* set if address given for variable */
+#define D_FORLOOP	0x400	/* set if busy in for-loop */
 	struct type *df_type;
 	union {
 		struct module df_module;

lang/m2/comp/desig.c

@@ -30,6 +30,7 @@
 #include	"scope.h"
 #include	"desig.h"
 #include	"node.h"
+#include	"warning.h"
 
 extern int	proclevel;
 
@@ -165,6 +166,21 @@ CodeValue(ds, tp)
 	ds->dsg_kind = DSG_LOADED;
 }
 
+ChkForFOR(nd)
+	struct node *nd;
+{
+	if (nd->nd_class == Def) {
+		register struct def *df = nd->nd_def;
+
+		if (df->df_flags & D_FORLOOP) {
+			node_warning(nd,
+				     W_ORDINARY,
+				     "assignment to FOR-loop control variable");
+			df->df_flags &= ~D_FORLOOP;
+		}
+	}
+}
+
 CodeStore(ds, tp)
 	register struct desig *ds;
 	register struct type *tp;
@@ -175,6 +191,7 @@ CodeStore(ds, tp)
 	struct desig save;
 
 	save = *ds;
+
 	switch(ds->dsg_kind) {
 	case DSG_FIXED:
 		if (DoStore(ds, tp->tp_size)) break;
@@ -233,6 +250,7 @@ CodeMove(rhs, left, rtp)
 		generated.
 	*/
 
+	ChkForFOR(left);
 	switch(rhs->dsg_kind) {
 	case DSG_LOADED:
 		CodeDesig(left, lhs);

lang/m2/comp/walk.c

@@ -482,42 +482,66 @@ WalkStat(nd, exit_label)
 			label l1 = ++text_label;
 			label l2 = ++text_label;
 			int uns = 0;
+			arith stepsize;
 
-			good_forvar = DoForInit(nd, left);
+			good_forvar = DoForInit(nd);
+			if ((stepsize = left->nd_INT) == 0) {
+			    node_warning(left,
+					 W_ORDINARY,
+					 "zero stepsize in FOR loop");
+			}
+			if (stepsize < 0) {
+				stepsize = -stepsize;
+			}
 			fnd = left->nd_right;
 			if (good_forvar) {
-				uns = BaseType(nd->nd_type)->tp_fund != T_INTEGER;
-				if (fnd->nd_class != Value) {
-					/* Upperbound not constant.
-					   The expression may only be evaluated
-					   once, so generate a temporary for it
-					*/
-					CodePExpr(fnd);
-					tmp = NewInt();
-					C_stl(tmp);
-				}
-				C_df_ilb(l1);
+				uns = BaseType(nd->nd_type)->tp_fund !=
+						T_INTEGER;
 				C_dup(int_size);
-				if (tmp) C_lol(tmp); else C_loc(fnd->nd_INT);
+				CodePExpr(fnd);
+				tmp = NewInt();
+				C_stl(tmp);
+				C_lol(tmp);
 				if (uns) C_cmu(int_size);
 				else C_cmi(int_size);
-				if (left->nd_INT > 0) {
+				if (left->nd_INT >= 0) {
 					C_zgt(l2);
+					CodeDStore(nd);
+					C_lol(tmp);
+					CodePExpr(nd);
 				}
-				else	C_zlt(l2);
-				CodeDStore(nd);
+				else {
+					C_zlt(l2);
+					CodeDStore(nd);
+					CodePExpr(nd);
+					C_lol(tmp);
+				}
+				C_sbu(int_size);
+				if (stepsize) {
+					C_loc(stepsize);
+					C_dvu(int_size);
+					C_loc((arith) 1);
+					C_adu(int_size);
+				}
+				nd->nd_def->df_flags |= D_FORLOOP;
+				C_df_ilb(l1);
 			}
 			WalkNode(right, exit_label);
-			if (good_forvar) {	
-				CodePExpr(nd);
+			nd->nd_def->df_flags &= ~D_FORLOOP;
+			if (stepsize && good_forvar) {	
+				C_loc((arith) 1);
+				C_sbu(int_size);
+				C_dup(int_size);
+				C_zeq(l2);
 				C_loc(left->nd_INT);
-				if (uns) C_adu(int_size);
-				else C_adi(int_size);
-				C_bra(l1);
-				C_df_ilb(l2);
-				C_asp(int_size);
+				CodePExpr(nd);
+				C_adu(int_size);
+				CodeDStore(nd);
 			}
-			if (tmp) FreeInt(tmp);
+			C_bra(l1);
+			C_df_ilb(l2);
+			C_asp(int_size);
+			FreeInt(tmp);
 #ifdef DEBUG
 			nd->nd_left = left;
 			nd->nd_right = right;
@@ -642,9 +666,10 @@ WalkDesignator(nd, ds)
 	return 1;
 }
 
-DoForInit(nd, left)
-	register struct node *nd, *left;
+DoForInit(nd)
+	register struct node *nd;
 {
+	register struct node *left = nd->nd_left;
 	register struct def *df;
 	struct type *tpl, *tpr;