newer version

lang/m2/comp/walk.c

@@ -16,11 +16,14 @@ static char *RcsId = "$Header$";
 #include	"main.h"
 #include	"LLlex.h"
 #include	"node.h"
+#include	"Lpars.h"
 
 #include	"debug.h"
 
 extern arith	align();
 static int	prclev = 0;
+static label	instructionlabel = 0;
+static label	datalabel = 0;
 
 WalkModule(module)
 	register struct def *module;
@@ -33,10 +36,12 @@ WalkModule(module)
 
 	scope = CurrentScope;
 	CurrentScope = module->mod_scope;
+
 	if (!prclev && module->mod_number) {
 		/* This module is a local module, but not within a
 		   procedure. Generate code to allocate storage for its
-		   variables
+		   variables. This is done by generating a "bss",
+		   with label "_<modulenumber><modulename>".
 		*/
 		arith size = align(CurrentScope->sc_off, word_size);
 
@@ -69,7 +74,7 @@ WalkModule(module)
 	CurrentScope->sc_off = 0;
 	C_pro_narg(CurrentScope->sc_name);
 	MkCalls(CurrentScope->sc_def);
-	WalkNode(module->mod_body);
+	WalkNode(module->mod_body, (label) 0);
 	C_end(align(-CurrentScope->sc_off, word_size));
 
 	CurrentScope = scope;
@@ -91,12 +96,13 @@ WalkProcedure(procedure)
 
 	/* Generate code for this procedure
 	*/
-	C_pro_narg(procedure->prc_name);
+	C_pro_narg(CurrentScope->sc_name);
 	/* generate calls to initialization routines of modules defined within
 	   this procedure
 	*/
+	instructionlabel = 1;
 	MkCalls(CurrentScope->sc_def);
-	WalkNode(procedure->prc_body);
+	WalkNode(procedure->prc_body, (label) 0);
 	C_end(align(-CurrentScope->sc_off, word_size));
 	CurrentScope = scope;
 	prclev--;
@@ -126,17 +132,151 @@ MkCalls(df)
 	while (df) {
 		if (df->df_kind == D_MODULE) {
 			C_lxl((arith) 0);
-			C_cal(df->df_scope->sc_name);
+			C_cal(df->mod_scope->sc_name);
 		}
 		df = df->df_nextinscope;
 	}
 }
 
-WalkNode(nd)
-	struct node *nd;
+WalkNode(nd, lab)
+	register struct node *nd;
+	label lab;
 {
 	/*	Node "nd" represents either a statement or a statement list.
-		Generate code for it.
+		Walk through it.
+		"lab" represents the label that must be jumped to on
+		encountering an EXIT statement.
+	*/
+	
+	while (nd->nd_class == Link) {	 /* statement list */
+		WalkStat(nd->nd_left, lab);
+		nd = nd->nd_right;
+	}
+
+	WalkStat(nd, lab);
+}
+
+WalkStat(nd, lab)
+	register struct node *nd;
+	label lab;
+{
+	/*	Walk through a statement, generating code for it.
+		"lab" represents the label that must be jumped to on
+		encountering an EXIT statement.
+	*/
+	register struct node *left = nd->nd_left;
+	register struct node *right = nd->nd_right;
+
+	if (nd->nd_class == Call) {
+		/* ??? */
+		return;
+	}
+
+	assert(nd->nd_class == Stat);
+
+	switch(nd->nd_symb) {
+	case BECOMES:
+		/* ??? */
+		break;
+
+	case IF:
+		{	label l1, l2;
+
+			l1 = instructionlabel++;
+			l2 = instructionlabel++;
+			ExpectBool(left);
+			assert(right->nd_symb == THEN);
+			C_zeq(l1);
+			WalkNode(right->nd_left, lab);
+
+			if (right->nd_right) {	/* ELSE part */
+				C_bra(l2);
+				C_df_ilb(l1);
+				WalkNode(right->nd_right, lab);
+				C_df_ilb(l2);
+			}
+			else	C_df_ilb(l1);
+			break;
+		}
+
+	case CASE:
+		/* ??? */
+		break;
+
+	case WHILE:
+		{	label l1, l2;
+
+			l1 = instructionlabel++;
+			l2 = instructionlabel++;
+			C_df_ilb(l1);
+			ExpectBool(left);
+			C_zeq(l2);
+			WalkNode(right, lab);
+			C_bra(l1);
+			C_df_ilb(l2);
+			break;
+		}
+
+	case REPEAT:
+		{	label l1;
+
+			l1 = instructionlabel++;
+			C_df_ilb(l1);
+			WalkNode(left, lab);
+			ExpectBool(right);
+			C_zeq(l1);
+			break;
+		}
+
+	case LOOP:
+		{	label l1, l2;
+
+			l1 = instructionlabel++;
+			l2 = instructionlabel++;
+			C_df_ilb(l1);
+			WalkNode(left, l2);
+			C_bra(l1);
+			C_df_ilb(l2);
+			break;
+		}
+
+	case FOR:
+		/* ??? */
+		break;
+
+	case WITH:
+		/* ??? */
+		break;
+
+	case EXIT:
+		assert(lab != 0);
+
+		C_bra(lab);
+		break;
+
+	case RETURN:
+		/* ??? */
+		break;
+
+	default:
+		assert(0);
+	}
+}
+
+ExpectBool(nd)
+	struct node *nd;
+{
+	/*	"nd" must indicate a boolean expression. Check this and
+		generate code to evaluate the expression.
+	*/
+
+	chk_expr(nd);
+
+	if (nd->nd_type != bool_type) {
+		node_error(nd, "boolean expression expected");
+	}
+
+	/* generate code
 	*/
 	/* ??? */
 }