Revert "Allow LetCont to bind multiple continuations."

tests/compiler/dart2js/backend_dart/opt_shrinking_test.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'sexpr_unstringifier.dart';
 import "package:expect/expect.dart";
 import 'package:compiler/src/cps_ir/cps_ir_nodes.dart';
 import 'package:compiler/src/cps_ir/cps_ir_nodes_sexpr.dart';
 import 'package:compiler/src/cps_ir/optimizers.dart';
 
@@ skipping 26 matching lines @@
 //  int main() {
 //    int i = 42;
 //    int j = i + 1;
 //    return 0;
 //  }
 
 String ITERATIVE_DEAD_VAL1_IN = """
 (FunctionDefinition main () return ()
   (LetPrim (v0 (Constant (Int 42)))
     (LetPrim (v1 (Constant (Int 1)))
-      (LetCont ((k0 (v2)
-                  (LetPrim (v3 (Constant (Int 0)))
-                    (InvokeContinuation return (v3)))))
+      (LetCont (k0 (v2)
+          (LetPrim (v3 (Constant (Int 0)))
+            (InvokeContinuation return (v3))))
         (InvokeMethod v0 + (v1) k0)))))
 """;
 String ITERATIVE_DEAD_VAL1_OUT = ITERATIVE_DEAD_VAL1_IN;
 
 // Iterative dead-val. IR written by hand.
 
 String ITERATIVE_DEAD_VAL2_IN = """
 (FunctionDefinition main () return ()
   (LetPrim (v0 (Constant (Int 42)))
     (LetPrim (v1
         (CreateFunction
           (FunctionDefinition f (i) return ()
             (InvokeContinuation return (v0)))))
       (LetPrim (v2 (Constant (Int 0)))
         (InvokeContinuation return (v2))))))
 """;
 String ITERATIVE_DEAD_VAL2_OUT = """
 (FunctionDefinition main () return ()
   (LetPrim (v0 (Constant (Int 0)))
     (InvokeContinuation return (v0))))
 """;
 
 // Basic dead-cont: letcont k x = L in K -> K (k not free in K).
 // IR written by hand.
 
 String DEAD_CONT_IN = """
 (FunctionDefinition main () return ()
   (LetPrim (v4 (Constant (Int 0)))
-    (LetCont ((k0 (v0)
-                (InvokeConstructor List () return)))
-      (LetCont ((k1 (v1)
-                  (LetCont ((k2 (v2)
-                              (LetPrim (v3 (Constant (Int 0)))
-                                (InvokeContinuation return (v3)))))
-                    (InvokeStatic print (v4) k2))))
+    (LetCont (k0 (v0)
+        (InvokeConstructor List () return))
+      (LetCont (k1 (v1)
+          (LetCont (k2 (v2)
+              (LetPrim (v3 (Constant (Int 0)))
+                (InvokeContinuation return (v3))))
+            (InvokeStatic print (v4) k2)))
         (InvokeStatic print (v4) k1)))))
 """;
 String DEAD_CONT_OUT = """
 (FunctionDefinition main () return ()
   (LetPrim (v0 (Constant (Int 0)))
-    (LetCont ((k0 (v1)
-                (LetCont ((k1 (v2)
-                            (LetPrim (v3 (Constant (Int 0)))
-                              (InvokeContinuation return (v3)))))
-                  (InvokeStatic print (v0) k1))))
+    (LetCont (k0 (v1)
+        (LetCont (k1 (v2)
+            (LetPrim (v3 (Constant (Int 0)))
+              (InvokeContinuation return (v3))))
+          (InvokeStatic print (v0) k1)))
       (InvokeStatic print (v0) k0))))
 """;
 
 // Iterative dead-cont. IR written by hand.
 
 String ITERATIVE_DEAD_CONT_IN = """
 (FunctionDefinition main () return ()
   (LetPrim (v4 (Constant (Int 0)))
-    (LetCont ((k0 (v0)
-                (InvokeConstructor List () return)))
-      (LetCont ((k3 (v5)
-                  (InvokeContinuation k0 (v5))))
-        (LetCont ((k1 (v1)
-                    (LetCont ((k2 (v2)
-                                (LetPrim (v3 (Constant (Int 0)))
-                                  (InvokeContinuation return (v3)))))
-                      (InvokeStatic print (v4) k2))))
-          (InvokeStatic print (v4) k1))))))
+    (LetCont (k0 (v0)
+      (InvokeConstructor List () return))
+    (LetCont (k3 (v5)
+      (InvokeContinuation k0 (v5)))
+    (LetCont (k1 (v1)
+      (LetCont (k2 (v2)
+        (LetPrim (v3 (Constant (Int 0)))
+          (InvokeContinuation return (v3))))
+      (InvokeStatic print (v4) k2)))
+    (InvokeStatic print (v4) k1))))))
 """;
 String ITERATIVE_DEAD_CONT_OUT = """
 (FunctionDefinition main () return ()
   (LetPrim (v0 (Constant (Int 0)))
-    (LetCont ((k0 (v1)
-                (LetCont ((k1 (v2)
-                            (LetPrim (v3 (Constant (Int 0)))
-                              (InvokeContinuation return (v3)))))
-                  (InvokeStatic print (v0) k1))))
+    (LetCont (k0 (v1)
+        (LetCont (k1 (v2)
+            (LetPrim (v3 (Constant (Int 0)))
+              (InvokeContinuation return (v3))))
+          (InvokeStatic print (v0) k1)))
       (InvokeStatic print (v0) k0))))
 """;
 
 // Beta-cont-lin: letcont k x = K in C[k y] -> C[K[y/x]] (k not free in C).
 // IR written by hand.
 
 String BETA_CONT_LIN_IN = """
 (FunctionDefinition main () return ()
-  (LetCont ((k0 (v0)
-              (LetCont ((k1 (v1)
-                          (LetCont ((k2 (v2)
-                                      (LetPrim (v3 (Constant (Int 0)))
-                                        (InvokeContinuation return (v3)))))
-                            (InvokeStatic print (v0) k2))))
-                (InvokeStatic print (v0) k1))))
+  (LetCont (k0 (v0)
+      (LetCont (k1 (v1)
+          (LetCont (k2 (v2)
+              (LetPrim (v3 (Constant (Int 0)))
+                (InvokeContinuation return (v3))))
+            (InvokeStatic print (v0) k2)))
+        (InvokeStatic print (v0) k1)))
     (LetPrim (v4 (Constant (Int 0)))
       (InvokeContinuation k0 (v4)))))
 """;
 String BETA_CONT_LIN_OUT = """
 (FunctionDefinition main () return ()
   (LetPrim (v0 (Constant (Int 0)))
-    (LetCont ((k0 (v1)
-                (LetCont ((k1 (v2)
-                            (LetPrim (v3 (Constant (Int 0)))
-                              (InvokeContinuation return (v3)))))
-                  (InvokeStatic print (v0) k1))))
+    (LetCont (k0 (v1)
+        (LetCont (k1 (v2)
+            (LetPrim (v3 (Constant (Int 0)))
+              (InvokeContinuation return (v3))))
+          (InvokeStatic print (v0) k1)))
       (InvokeStatic print (v0) k0))))
 """;
 
 // Beta-cont-lin with recursive continuation. IR written by hand.
 
 String RECURSIVE_BETA_CONT_LIN_IN = """
 (FunctionDefinition main () return ()
-  (LetCont ((rec k0 (v0)
-              (InvokeContinuation* k0 (v0))))
+  (LetCont* (k0 (v0)
+      (InvokeContinuation* k0 (v0)))
     (LetPrim (v1 (Constant (Int 0)))
       (InvokeContinuation k0 (v1)))))
 """;
 String RECURSIVE_BETA_CONT_LIN_OUT = RECURSIVE_BETA_CONT_LIN_IN;
 
 // Beta-cont-lin used inside body. IR written by hand.
 
 String USED_BETA_CONT_LIN_IN = """
 (FunctionDefinition main () return ()
   (LetPrim (v0 (Constant (Int 0)))
-    (LetCont ((k0 (v1)
-                (LetCont ((k1 (v2)
-                            (LetCont ((k2 (v3)
-                                        (LetPrim (v4 (Constant (Int 0)))
-                                          (InvokeContinuation return (v4)))))
-                              (InvokeStatic print (v1) k2))))
-                  (InvokeStatic print (v1) k1))))
+    (LetCont (k0 (v1)
+        (LetCont (k1 (v2)
+            (LetCont (k2 (v3)
+                (LetPrim (v4 (Constant (Int 0)))
+                  (InvokeContinuation return (v4))))
+              (InvokeStatic print (v1) k2)))
+          (InvokeStatic print (v1) k1)))
       (LetPrim (v5
-                 (CreateFunction
-                   (FunctionDefinition f () return ()
-                     (InvokeContinuation return (v1)))))
+          (CreateFunction
+            (FunctionDefinition f () return ()
+              (InvokeContinuation return (v1)))))
         (InvokeContinuation k0 (v0))))))
 """;
 String USED_BETA_CONT_LIN_OUT = """
 (FunctionDefinition main () return ()
   (LetPrim (v0 (Constant (Int 0)))
-    (LetCont ((k0 (v1)
-                (LetCont ((k1 (v2)
-                            (LetPrim (v3 (Constant (Int 0)))
-                              (InvokeContinuation return (v3)))))
-                  (InvokeStatic print (v0) k1))))
+    (LetCont (k0 (v1)
+        (LetCont (k1 (v2)
+            (LetPrim (v3 (Constant (Int 0)))
+              (InvokeContinuation return (v3))))
+          (InvokeStatic print (v0) k1)))
       (InvokeStatic print (v0) k0))))
 """;
 
 // Eta-cont: letcont k x = j x in K -> K[j/k].
 // IR written by hand.
 
 String ETA_CONT_IN = """
 (FunctionDefinition main () return ()
   (LetPrim (v3 (Constant (Int 0)))
-    (LetCont ((rec k1 (v1)
-                (InvokeContinuation return (v3))))
-      (LetCont ((k0 (v0)
-                  (InvokeContinuation k1 (v0))))
+    (LetCont* (k1 (v1)
+        (InvokeContinuation return (v3)))
+      (LetCont (k0 (v0)
+          (InvokeContinuation k1 (v0)))
         (LetPrim (v4
-                   (CreateFunction
-                     (FunctionDefinition f () return ()
-                       (InvokeContinuation k1 (v3)))))
+            (CreateFunction
+              (FunctionDefinition f () return ()
+                (InvokeContinuation k1 (v3)))))
           (InvokeContinuation k0 (v3)))))))
 """;
 String ETA_CONT_OUT = """
 (FunctionDefinition main () return ()
   (LetPrim (v0 (Constant (Int 0)))
-    (LetCont ((k0 (v1)
-                (InvokeContinuation return (v0))))
+    (LetCont (k0 (v1)
+        (InvokeContinuation return (v0)))
       (InvokeContinuation k0 (v0)))))
 """;
 
 // Beta-fun-lin and eta-fun might not apply to us, since
 // a. in (InvokeMethod v0 call k0), v0 might carry state, and
 // b. there is no way to generate static nested functions that we could
 //    use InvokeStatic on.
 
 /// Normalizes whitespace by replacing all whitespace sequences by a single
 /// space and trimming leading and trailing whitespace.
@@ skipping 21 matching lines @@
   testShrinkingReducer(DEAD_VAL_IN, DEAD_VAL_OUT);
   testShrinkingReducer(ITERATIVE_DEAD_VAL1_IN, ITERATIVE_DEAD_VAL1_OUT);
   testShrinkingReducer(ITERATIVE_DEAD_VAL2_IN, ITERATIVE_DEAD_VAL2_OUT);
   testShrinkingReducer(DEAD_CONT_IN, DEAD_CONT_OUT);
   testShrinkingReducer(ITERATIVE_DEAD_CONT_IN, ITERATIVE_DEAD_CONT_OUT);
   testShrinkingReducer(BETA_CONT_LIN_IN, BETA_CONT_LIN_OUT);
   testShrinkingReducer(RECURSIVE_BETA_CONT_LIN_IN, RECURSIVE_BETA_CONT_LIN_OUT);
   testShrinkingReducer(USED_BETA_CONT_LIN_IN, USED_BETA_CONT_LIN_OUT);
   testShrinkingReducer(ETA_CONT_IN, ETA_CONT_OUT);
 }