backward inference

mcode.cm

@@ -52,6 +52,7 @@ var mcode = function(ast) {
   var s_cur_line = 0
   var s_cur_col = 0
   var s_filename = null
+  var s_has_disruption = false
 
   // Shared closure vars for binop helpers (avoids >4 param functions)
   var _bp_dest = 0
@@ -78,7 +79,8 @@ var mcode = function(ast) {
       function_nr: s_function_nr,
       intrinsic_cache: s_intrinsic_cache,
       cur_line: s_cur_line,
-      cur_col: s_cur_col
+      cur_col: s_cur_col,
+      has_disruption: s_has_disruption
     }
   }
 
@@ -99,6 +101,7 @@ var mcode = function(ast) {
     s_intrinsic_cache = saved.intrinsic_cache
     s_cur_line = saved.cur_line
     s_cur_col = saved.cur_col
+    s_has_disruption = saved.has_disruption
   }
 
   // Slot allocation
@@ -2230,6 +2233,7 @@ var mcode = function(ast) {
     var guard_t = 0
     var guard_err = null
     var guard_done = null
+    var last_instr = null
 
     if (stmt == null) {
       return null
@@ -2436,6 +2440,13 @@ var mcode = function(ast) {
       expr = stmt.expression
       if (expr != null) {
         slot = gen_expr(expr, -1)
+        // Mark tail calls: rename last invoke to tail_invoke
+        if (stmt.tail == true && !s_has_disruption) {
+          last_instr = s_instructions[length(s_instructions) - 1]
+          if (is_array(last_instr) && last_instr[0] == "invoke") {
+            last_instr[0] = "tail_invoke"
+          }
+        }
         emit_1("return", slot)
       } else {
         null_slot = alloc_slot()
@@ -2618,6 +2629,7 @@ var mcode = function(ast) {
     s_label_map = {}
 
     s_is_arrow = is_arrow
+    s_has_disruption = disrupt_clause != null && is_array(disrupt_clause)
 
     s_function_nr = fn_nr_node != null ? fn_nr_node : 0
 
@@ -2726,6 +2738,7 @@ var mcode = function(ast) {
 
     // Compile disruption clause
     if (disrupt_clause != null && is_array(disrupt_clause)) {
+      emit_label(gen_label("disruption"))
       disruption_start = length(s_instructions)
       _i = 0
       while (_i < length(disrupt_clause)) {