Reapply "Allow LetCont to bind multiple continuations."

tests/compiler/dart2js/backend_dart/opt_redundant_phi_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';
 
 // The 'read in loop' IR tests the most basic case of redundant phi removal
 // and represents the following source code:
 //
 // void main() {
 //   int j = 42;
 //   for (int i = 0; i < 2; i++) {
 //     print(j.toString());
 //   }
 // }
 
 String READ_IN_LOOP_IN = """
 (FunctionDefinition main () return ()
   (LetPrim (v0 (Constant (Int 42)))
     (LetPrim (v1 (Constant (Int 0)))
-      (LetCont* (k0 (v2 v3)
-          (LetCont (k1 ()
-              (LetPrim (v4 (Constant (Null)))
-                (InvokeContinuation return (v4))))
-            (LetCont (k2 ()
-                (LetCont (k3 (v5)
-                    (LetCont (k4 (v6)
-                        (LetPrim (v7 (Constant (Int 1)))
-                          (LetCont (k5 (v8)
-                              (InvokeContinuation* k0 (v2 v8)))
-                            (InvokeMethod v3 + (v7) k5))))
-                      (InvokeStatic print (v5) k4)))
-                  (InvokeMethod v2 toString () k3)))
-              (LetPrim (v9 (Constant (Int 2)))
-                (LetCont (k6 (v10)
-                    (Branch (IsTrue v10) k2 k1))
-                  (InvokeMethod v3 < (v9) k6))))))
+      (LetCont
+          ((rec k0 (v2 v3)
+             (LetCont
+                 ((k1 ()
+                    (LetPrim (v4 (Constant (Null)))
+                      (InvokeContinuation return (v4))))
+                  (k2 ()
+                    (LetCont
+                        ((k3 (v5)
+                           (LetCont
+                               ((k4 (v6)
+                                  (LetPrim (v7 (Constant (Int 1)))
+                                    (LetCont
+                                        ((k5 (v8)
+                                           (InvokeContinuation* k0 (v2 v8))))
+                                      (InvokeMethod v3 + (v7) k5)))))
+                             (InvokeStatic print (v5) k4))))
+                      (InvokeMethod v2 toString () k3))))
+               (LetPrim (v9 (Constant (Int 2)))
+                 (LetCont
+                     ((k6 (v10)
+                        (Branch (IsTrue v10) k2 k1)))
+                   (InvokeMethod v3 < (v9) k6))))))
         (InvokeContinuation k0 (v0 v1))))))
 """;
 
 String READ_IN_LOOP_OUT = """
 (FunctionDefinition main () return ()
   (LetPrim (v0 (Constant (Int 42)))
     (LetPrim (v1 (Constant (Int 0)))
-      (LetCont* (k0 (v2)
-          (LetCont (k1 ()
-              (LetPrim (v3 (Constant (Null)))
-                (InvokeContinuation return (v3))))
-            (LetCont (k2 ()
-                (LetCont (k3 (v4)
-                    (LetCont (k4 (v5)
-                        (LetPrim (v6 (Constant (Int 1)))
-                          (LetCont (k5 (v7)
-                              (InvokeContinuation* k0 (v7)))
-                            (InvokeMethod v2 + (v6) k5))))
-                      (InvokeStatic print (v4) k4)))
-                  (InvokeMethod v0 toString () k3)))
-              (LetPrim (v8 (Constant (Int 2)))
-                (LetCont (k6 (v9)
-                    (Branch (IsTrue v9) k2 k1))
-                  (InvokeMethod v2 < (v8) k6))))))
+      (LetCont
+          ((rec k0 (v2)
+             (LetCont
+                 ((k1 ()
+                    (LetPrim (v3 (Constant (Null)))
+                      (InvokeContinuation return (v3))))
+                  (k2 ()
+                    (LetCont
+                        ((k3 (v4)
+                           (LetCont
+                               ((k4 (v5)
+                                  (LetPrim (v6 (Constant (Int 1)))
+                                    (LetCont
+                                        ((k5 (v7)
+                                           (InvokeContinuation* k0 (v7))))
+                                      (InvokeMethod v2 + (v6) k5)))))
+                             (InvokeStatic print (v4) k4))))
+                      (InvokeMethod v0 toString () k3))))
+               (LetPrim (v8 (Constant (Int 2)))
+                 (LetCont
+                     ((k6 (v9)
+                        (Branch (IsTrue v9) k2 k1)))
+                   (InvokeMethod v2 < (v8) k6))))))
         (InvokeContinuation k0 (v1))))))
 """;
 
 // The 'inner loop' IR represents the following source code:
 //
 // void main() {
 //   int j = 42;
 //   for (int i = 0; i < 2; i++) {
 //     for (int k = 0; k < 2; k++) {
 //       print(i.toString());
 //     }
 //   }
 //   print(j.toString());
 // }
 //
 // This test case ensures that iterative optimization works: first, v8 and v9
 // are removed from k5, and only then can k0 be optimized as well.
 
 const String INNER_LOOP_IN = """
 (FunctionDefinition main () return ()
   (LetPrim (v0 (Constant (Int 42)))
     (LetPrim (v1 (Constant (Int 0)))
-      (LetCont* (k0 (v2 v3)
-          (LetCont (k1 ()
-              (LetCont (k2 (v4)
-                  (LetCont (k3 (v5)
-                      (LetPrim (v6 (Constant (Null)))
-                        (InvokeContinuation return (v6))))
-                    (InvokeStatic print (v4) k3)))
-                (InvokeMethod v2 toString () k2)))
-            (LetCont (k4 ()
-                (LetPrim (v7 (Constant (Int 0)))
-                  (LetCont* (k5 (v8 v9 v10)
-                      (LetCont (k6 ()
-                          (LetPrim (v11 (Constant (Int 1)))
-                            (LetCont (k7 (v12)
-                                (InvokeContinuation* k0 (v8 v12)))
-                              (InvokeMethod v9 + (v11) k7))))
-                        (LetCont (k8 ()
-                            (LetCont (k9 (v13)
-                                (LetCont (k10 (v14)
-                                    (LetPrim (v15 (Constant (Int 1)))
-                                      (LetCont (k11 (v16)
-                                          (InvokeContinuation* k5 (v8 v9 v16)))
-                                        (InvokeMethod v10 + (v15) k11))))
-                                  (InvokeStatic print (v13) k10)))
-                              (InvokeMethod v9 toString () k9)))
-                          (LetPrim (v17 (Constant (Int 2)))
-                            (LetCont (k12 (v18)
-                                (Branch (IsTrue v18) k8 k6))
-                              (InvokeMethod v10 < (v17) k12))))))
-                    (InvokeContinuation k5 (v2 v3 v7)))))
-              (LetPrim (v19 (Constant (Int 2)))
-                (LetCont (k13 (v20)
-                    (Branch (IsTrue v20) k4 k1))
-                  (InvokeMethod v3 < (v19) k13))))))
+      (LetCont
+          ((rec k0 (v2 v3)
+             (LetCont
+                 ((k1 ()
+                    (LetCont
+                        ((k2 (v4)
+                           (LetCont
+                               ((k3 (v5)
+                                  (LetPrim (v6 (Constant (Null)))
+                                    (InvokeContinuation return (v6)))))
+                             (InvokeStatic print (v4) k3))))
+                      (InvokeMethod v2 toString () k2)))
+                  (k4 ()
+                    (LetPrim (v7 (Constant (Int 0)))
+                      (LetCont
+                          ((rec k5 (v8 v9 v10)
+                             (LetCont
+                                 ((k6 ()
+                                    (LetPrim (v11 (Constant (Int 1)))
+                                      (LetCont
+                                          ((k7 (v12)
+                                             (InvokeContinuation* k0 (v8 v12))))
+                                        (InvokeMethod v9 + (v11) k7))))
+                                  (k8 ()
+                                    (LetCont
+                                        ((k9 (v13)
+                                           (LetCont
+                                               ((k10 (v14)
+                                                  (LetPrim (v15 (Constant (Int 1)))
+                                                    (LetCont
+                                                        ((k11 (v16)
+                                                           (InvokeContinuation* k5 (v8 v9 v16))))
+                                                      (InvokeMethod v10 + (v15) k11)))))
+                                             (InvokeStatic print (v13) k10))))
+                                      (InvokeMethod v9 toString () k9))))
+                               (LetPrim (v17 (Constant (Int 2)))
+                                 (LetCont
+                                     ((k12 (v18)
+                                        (Branch (IsTrue v18) k8 k6)))
+                                   (InvokeMethod v10 < (v17) k12))))))
+                        (InvokeContinuation k5 (v2 v3 v7))))))
+               (LetPrim (v19 (Constant (Int 2)))
+                 (LetCont
+                     ((k13 (v20)
+                        (Branch (IsTrue v20) k4 k1)))
+                   (InvokeMethod v3 < (v19) k13))))))
         (InvokeContinuation k0 (v0 v1))))))
 """;
 
 const String INNER_LOOP_OUT = """
 (FunctionDefinition main () return ()
   (LetPrim (v0 (Constant (Int 42)))
     (LetPrim (v1 (Constant (Int 0)))
-      (LetCont* (k0 (v2)
-          (LetCont (k1 ()
-              (LetCont (k2 (v3)
-                  (LetCont (k3 (v4)
-                      (LetPrim (v5 (Constant (Null)))
-                        (InvokeContinuation return (v5))))
-                    (InvokeStatic print (v3) k3)))
-                (InvokeMethod v0 toString () k2)))
-            (LetCont (k4 ()
-                (LetPrim (v6 (Constant (Int 0)))
-                  (LetCont* (k5 (v7)
-                      (LetCont (k6 ()
-                          (LetPrim (v8 (Constant (Int 1)))
-                            (LetCont (k7 (v9)
-                                (InvokeContinuation* k0 (v9)))
-                              (InvokeMethod v2 + (v8) k7))))
-                        (LetCont (k8 ()
-                            (LetCont (k9 (v10)
-                                (LetCont (k10 (v11)
-                                    (LetPrim (v12 (Constant (Int 1)))
-                                      (LetCont (k11 (v13)
-                                          (InvokeContinuation* k5 (v13)))
-                                        (InvokeMethod v7 + (v12) k11))))
-                                  (InvokeStatic print (v10) k10)))
-                              (InvokeMethod v2 toString () k9)))
-                          (LetPrim (v14 (Constant (Int 2)))
-                            (LetCont (k12 (v15)
-                                (Branch (IsTrue v15) k8 k6))
-                              (InvokeMethod v7 < (v14) k12))))))
-                    (InvokeContinuation k5 (v6)))))
-              (LetPrim (v16 (Constant (Int 2)))
-                (LetCont (k13 (v17)
-                    (Branch (IsTrue v17) k4 k1))
-                  (InvokeMethod v2 < (v16) k13))))))
+      (LetCont
+          ((rec k0 (v2)
+             (LetCont
+                 ((k1 ()
+                    (LetCont
+                        ((k2 (v3)
+                           (LetCont
+                               ((k3 (v4)
+                                  (LetPrim (v5 (Constant (Null)))
+                                    (InvokeContinuation return (v5)))))
+                             (InvokeStatic print (v3) k3))))
+                      (InvokeMethod v0 toString () k2)))
+                  (k4 ()
+                    (LetPrim (v6 (Constant (Int 0)))
+                      (LetCont
+                          ((rec k5 (v7)
+                             (LetCont
+                                 ((k6 ()
+                                    (LetPrim (v8 (Constant (Int 1)))
+                                      (LetCont
+                                          ((k7 (v9)
+                                             (InvokeContinuation* k0 (v9))))
+                                        (InvokeMethod v2 + (v8) k7))))
+                                  (k8 ()
+                                    (LetCont
+                                        ((k9 (v10)
+                                           (LetCont
+                                               ((k10 (v11)
+                                                  (LetPrim (v12 (Constant (Int 1)))
+                                                    (LetCont
+                                                        ((k11 (v13)
+                                                           (InvokeContinuation* k5 (v13))))
+                                                      (InvokeMethod v7 + (v12) k11)))))
+                                             (InvokeStatic print (v10) k10))))
+                                      (InvokeMethod v2 toString () k9))))
+                               (LetPrim (v14 (Constant (Int 2)))
+                                 (LetCont
+                                     ((k12 (v15)
+                                        (Branch (IsTrue v15) k8 k6)))
+                                   (InvokeMethod v7 < (v14) k12))))))
+                        (InvokeContinuation k5 (v6))))))
+               (LetPrim (v16 (Constant (Int 2)))
+                 (LetCont
+                     ((k13 (v17)
+                        (Branch (IsTrue v17) k4 k1)))
+                   (InvokeMethod v2 < (v16) k13))))))
         (InvokeContinuation k0 (v1))))))
 """;
 
 // There are no redundant phis in the 'basic loop' IR, and this test ensures
 // simply that the optimization does not alter the IR. It represents the
 // following program:
 //
 // void main() {
 //   for (int i = 0; i < 2; i++) {
 //     print(i.toString());
 //   }
 // }
 
 String BASIC_LOOP_IN = """
 (FunctionDefinition main () return ()
   (LetPrim (v0 (Constant (Int 0)))
-    (LetCont* (k0 (v1)
-        (LetCont (k1 ()
-            (LetPrim (v2 (Constant (Null)))
-              (InvokeContinuation return (v2))))
-          (LetCont (k2 ()
-              (LetCont (k3 (v3)
-                  (LetCont (k4 (v4)
-                      (LetPrim (v5 (Constant (Int 1)))
-                        (LetCont (k5 (v6)
-                            (InvokeContinuation* k0 (v6)))
-                          (InvokeMethod v1 + (v5) k5))))
-                    (InvokeStatic print (v3) k4)))
-                (InvokeMethod v1 toString () k3)))
+    (LetCont
+       ((rec k0 (v1)
+          (LetCont
+              ((k1 ()
+                 (LetPrim (v2 (Constant (Null)))
+                   (InvokeContinuation return (v2))))
+               (k2 ()
+                 (LetCont
+                     ((k3 (v3)
+                        (LetCont
+                            ((k4 (v4)
+                               (LetPrim (v5 (Constant (Int 1)))
+                                 (LetCont
+                                     ((k5 (v6)
+                                        (InvokeContinuation* k0 (v6))))
+                                   (InvokeMethod v1 + (v5) k5)))))
+                          (InvokeStatic print (v3) k4))))
+                   (InvokeMethod v1 toString () k3))))
             (LetPrim (v7 (Constant (Int 2)))
-              (LetCont (k6 (v8)
-                  (Branch (IsTrue v8) k2 k1))
+              (LetCont
+                  ((k6 (v8)
+                     (Branch (IsTrue v8) k2 k1)))
                 (InvokeMethod v1 < (v7) k6))))))
       (InvokeContinuation k0 (v0)))))
 """;
 
 String BASIC_LOOP_OUT = BASIC_LOOP_IN;
 
 // Ensures that proper scoping is preserved, i.e. that the optimized
 // continuation body does reference out of scope primitives.
 // IR written by hand since this case is currently not being generated.
 
 String SCOPING_IN = """
 (FunctionDefinition main () return ()
-  (LetCont (k0 (v1)
-      (InvokeStatic print (v1) return))
+  (LetCont
+      ((k0 (v1)
+         (InvokeStatic print (v1) return)))
     (LetPrim (v0 (Constant (Int 0)))
       (LetPrim (v2 (Constant (Null)))
         (InvokeContinuation k0 (v0))))))
 """;
 
 String SCOPING_OUT = """
 (FunctionDefinition main () return ()
   (LetPrim (v0 (Constant (Int 0)))
-    (LetCont (k0 ()
-        (InvokeStatic print (v0) return))
+    (LetCont
+        ((k0 ()
+           (InvokeStatic print (v0) return)))
       (LetPrim (v1 (Constant (Null)))
         (InvokeContinuation k0 ())))))
 """;
 
 // Ensures that continuations which are never invoked are not optimized.
 // IR written by hand.
 
 String NEVER_INVOKED_IN = """
 (FunctionDefinition main () return ()
   (LetPrim (v0 (Constant (Int 0)))
-    (LetCont (k0 (v1)
-        (InvokeStatic print (v1) return))
+    (LetCont
+        ((k0 (v1)
+           (InvokeStatic print (v1) return)))
       (InvokeContinuation return (v0)))))
 """;
 
 String NEVER_INVOKED_OUT = NEVER_INVOKED_IN;
 
 /// Normalizes whitespace by replacing all whitespace sequences by a single
 /// space and trimming leading and trailing whitespace.
 String normalizeSExpr(String input) {
   return input.replaceAll(new RegExp(r'[ \n\t]+'), ' ').trim();
 }
@@ skipping 14 matching lines @@
   Expect.equals(expected, actual, "Actual:\n$actual");
 }
 
 void main() {
   testRedundantPhi(READ_IN_LOOP_IN, READ_IN_LOOP_OUT);
   testRedundantPhi(INNER_LOOP_IN, INNER_LOOP_OUT);
   testRedundantPhi(BASIC_LOOP_IN, BASIC_LOOP_OUT);
   testRedundantPhi(SCOPING_IN, SCOPING_OUT);
   testRedundantPhi(NEVER_INVOKED_IN, NEVER_INVOKED_OUT);
 }