[generators] Perform state dispatch in loop header.

src/interpreter/control-flow-builders.h

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_INTERPRETER_CONTROL_FLOW_BUILDERS_H_
 #define V8_INTERPRETER_CONTROL_FLOW_BUILDERS_H_
 
 #include "src/interpreter/bytecode-array-builder.h"
 
 #include "src/zone-containers.h"
@@ skipping 64 matching lines @@
 
  private:
   BytecodeLabel block_end_;
 };
 
 
 // A class to help with co-ordinating break and continue statements with
 // their loop.
 class LoopBuilder final : public BreakableControlFlowBuilder {
  public:
-  explicit LoopBuilder(BytecodeArrayBuilder* builder)
+  explicit LoopBuilder(BytecodeArrayBuilder* builder, int yield_count)
       : BreakableControlFlowBuilder(builder),
+        yield_count(yield_count),
         continue_sites_(builder->zone()) {}
   ~LoopBuilder();
 
   void LoopHeader();
   void Condition() { builder()->Bind(&condition_); }
   void Next() { builder()->Bind(&next_); }
-  void JumpToHeader() { builder()->Jump(&loop_header_); }
-  void JumpToHeaderIfTrue() { builder()->JumpIfTrue(&loop_header_); }
+  void JumpToHeader();
+  void JumpToHeaderIfTrue() {
+    BytecodeLabel no_jump;
+    builder()->JumpIfFalse(&no_jump);
+    JumpToHeader();
+    builder()->Bind(&no_jump);
+  }
   void EndLoop();
 
   // This method is called when visiting continue statements in the AST.
   // Inserts a jump to a unbound label that is patched when the corresponding
   // SetContinueTarget is called.
   void Continue() { EmitJump(&continue_sites_); }
   void ContinueIfTrue() { EmitJumpIfTrue(&continue_sites_); }
   void ContinueIfUndefined() { EmitJumpIfUndefined(&continue_sites_); }
   void ContinueIfNull() { EmitJumpIfNull(&continue_sites_); }
 
+  // Number of yields inside the loop.
+  const int yield_count;
+
  private:
   void SetContinueTarget(const BytecodeLabel& continue_target);
 
   BytecodeLabel loop_header_;
   BytecodeLabel condition_;
   BytecodeLabel next_;
   BytecodeLabel loop_end_;
 
   // Unbound labels that identify jumps for continue statements in the code.
   ZoneVector<BytecodeLabel> continue_sites_;
@@ skipping 74 matching lines @@
   // this finally block will be caught. Note that such a prediction depends on
   // whether this try-finally is nested inside a surrounding try-catch.
   bool will_catch_;
 };
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_INTERPRETER_CONTROL_FLOW_BUILDERS_H_