unused local variable detection

tools/qfcc/include/qfcc.h

@@ -290,6 +290,10 @@ typedef struct def_s {
 	int				initialized;// 1 when a declaration included "= immediate"
 	statref_t		*refs;		// for relocations
 
+	int				used;			// unused local detection
+	string_t		file;			// source file
+	int				line;			// source line
+
 	int				users;			// ref counted temps
 	struct expr_s	*expr;			// temp expr using this def
 
@@ -464,7 +468,7 @@ void PR_FreeLocation (def_t *def);
 def_t *PR_GetTempDef (type_t *type, def_t *scope);
 void PR_FreeTempDefs ();
 void PR_ResetTempDefs ();
-void PR_FlushScope (def_t *scope);
+void PR_FlushScope (def_t *scope, int force_used);
 
 void PR_PrintDefs (void);
 void PR_PrintFunction (def_t *def);

tools/qfcc/source/emit.c

@@ -50,12 +50,18 @@ emit_statement (int sline, opcode_t *op, def_t *var_a, def_t *var_b, def_t *var_
 		statement->c = var_c->ofs;
 		ret = var_c;
 	}
-	if (var_a)
+	if (var_a) {
 		var_a->users--;
-	if (var_b)
+		var_a->used = 1;
+	}
+	if (var_b) {
 		var_b->users--;
-	if (var_c)
+		var_a->used = 1;
+	}
+	if (var_c) {
 		var_c->users--;
+		var_a->used = 1;
+	}
 	PR_AddStatementRef (var_a, statement, 0);
 	PR_AddStatementRef (var_b, statement, 1);
 	PR_AddStatementRef (var_c, statement, 2);

tools/qfcc/source/pr_def.c

@@ -91,14 +91,19 @@ PR_GetDef (type_t *type, const char *name, def_t *scope, int *allocate)
 		.origin can be accessed as .origin_x, .origin_y, and .origin_z
 	*/
 	if (type->type == ev_vector) {
+		def_t      *d;
+
 		sprintf (element, "%s_x", name);
-		PR_GetDef (&type_float, element, scope, allocate);
+		d = PR_GetDef (&type_float, element, scope, allocate);
+		d->used = 1;
 
 		sprintf (element, "%s_y", name);
-		PR_GetDef (&type_float, element, scope, allocate);
+		d = PR_GetDef (&type_float, element, scope, allocate);
+		d->used = 1;
 
 		sprintf (element, "%s_z", name);
-		PR_GetDef (&type_float, element, scope, allocate);
+		d = PR_GetDef (&type_float, element, scope, allocate);
+		d->used = 1;
 	} else {
 		*allocate += type_size[type->type];
 	}
@@ -107,14 +112,19 @@ PR_GetDef (type_t *type, const char *name, def_t *scope, int *allocate)
 		*(int *) &pr_globals[def->ofs] = pr.size_fields;
 
 		if (type->aux_type->type == ev_vector) {
+			def_t      *d;
+
 			sprintf (element, "%s_x", name);
-			PR_GetDef (&type_floatfield, element, scope, allocate);
+			d = PR_GetDef (&type_floatfield, element, scope, allocate);
+			d->used = 1;	// always `used'
 
 			sprintf (element, "%s_y", name);
-			PR_GetDef (&type_floatfield, element, scope, allocate);
+			d = PR_GetDef (&type_floatfield, element, scope, allocate);
+			d->used = 1;	// always `used'
 
 			sprintf (element, "%s_z", name);
-			PR_GetDef (&type_floatfield, element, scope, allocate);
+			d = PR_GetDef (&type_floatfield, element, scope, allocate);
+			d->used = 1;	// always `used'
 		} else {
 			pr.size_fields += type_size[type->aux_type->type];
 		}
@@ -145,6 +155,9 @@ PR_NewDef (type_t *type, const char *name, def_t *scope)
 
 	def->scope = scope;
 
+	def->file = s_file;
+	def->line = pr_source_line;
+
 	return def;
 }
 
@@ -246,12 +259,19 @@ PR_ResetTempDefs (void)
 }
 
 void
-PR_FlushScope (def_t *scope)
+PR_FlushScope (def_t *scope, int force_used)
 {
 	def_t *def;
 
 	for (def = scope->scope_next; def; def = def->scope_next) {
-		if (def->name)
+		if (def->name) {
+			if (!force_used && !def->used) {
+				expr_t     e;
+				e.line = def->line;
+				e.file = def->file;
+				warning (&e, "variable %s unused", def->name);
+			}
 			Hash_Del (defs_by_name, def->name);
+		}
 	}
 }

tools/qfcc/source/qc-parse.y

@@ -143,7 +143,7 @@ maybe_func
 		}
 	  param_list
 		{
-			PR_FlushScope (&param_scope);
+			PR_FlushScope (&param_scope, 1);
 			current_type = $<scope>2.type;
 			param_scope.scope_next = $<scope>2.pscope;
 			pr_scope = $<scope>2.scope;
@@ -580,6 +580,7 @@ build_scope (function_t *f, def_t *func)
 		f->parm_ofs[i] = def->ofs;
 		if (i > 0 && f->parm_ofs[i] < f->parm_ofs[i - 1])
 			Error ("bad parm order");
+		def->used = 1;	// don't warn for unused params
 	}
 }
 
@@ -660,7 +661,7 @@ emit_function (function_t *f, expr_t *e)
 		e = e->next;
 	}
 	emit_statement (pr_source_line, op_done, 0, 0, 0);
-	PR_FlushScope (pr_scope);
+	PR_FlushScope (pr_scope, 0);
 	pr_scope = 0;
 	PR_ResetTempDefs ();