[generators] Store the resume mode in the generator object.

src/x64/builtins-x64.cc

 // Copyright 2012 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.
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/code-factory.h"
 #include "src/codegen.h"
 #include "src/deoptimizer.h"
 #include "src/full-codegen/full-codegen.h"
@@ skipping 461 matching lines @@
   //  -- rdx    : the resume mode (tagged)
   //  -- rsp[0] : return address
   // -----------------------------------
   __ AssertGeneratorObject(rbx);
 
   // Store input value into generator object.
   __ movp(FieldOperand(rbx, JSGeneratorObject::kInputOffset), rax);
   __ RecordWriteField(rbx, JSGeneratorObject::kInputOffset, rax, rcx,
                       kDontSaveFPRegs);
 
+  // Store resume mode into generator object.
+  __ movp(FieldOperand(rbx, JSGeneratorObject::kResumeModeOffset), rdx);
+  __ RecordWriteField(rbx, JSGeneratorObject::kResumeModeOffset, rdx, rcx,

[Benedikt Meurer, 2016/04/08 10:20:14]

You don't need a write barrier, the resume mode is always a Smi.

+                      kDontSaveFPRegs);
+
   // Load suspended function and context.
   __ movp(rsi, FieldOperand(rbx, JSGeneratorObject::kContextOffset));
   __ movp(rdi, FieldOperand(rbx, JSGeneratorObject::kFunctionOffset));
 
   // Flood function if we are stepping.
   Label skip_flooding;
   ExternalReference step_in_enabled =
       ExternalReference::debug_step_in_enabled_address(masm->isolate());
   Operand step_in_enabled_operand = masm->ExternalOperand(step_in_enabled);
   __ cmpb(step_in_enabled_operand, Immediate(0));
@@ skipping 60 matching lines @@
     __ bind(&loop);
     __ cmpl(rcx, rax);
     __ j(equal, &done_loop, Label::kNear);
     __ Push(
         FieldOperand(rsi, rcx, times_pointer_size, FixedArray::kHeaderSize));
     __ addl(rcx, Immediate(1));
     __ jmp(&loop);
     __ bind(&done_loop);
   }
 
-  // Push resume mode (consumed in continuation).
-  __ Push(rdx);
-
   // Reset operand stack so we don't leak.
   __ LoadRoot(FieldOperand(rbx, JSGeneratorObject::kOperandStackOffset),
               Heap::kEmptyFixedArrayRootIndex);
 
-  // Restore context and value.
+  // Restore context.
   __ movp(rsi, FieldOperand(rbx, JSGeneratorObject::kContextOffset));
-  __ movp(rax, FieldOperand(rbx, JSGeneratorObject::kInputOffset));
 
   // Resume the generator function at the continuation.
   __ movp(rdx, FieldOperand(rdi, JSFunction::kSharedFunctionInfoOffset));
   __ movp(rdx, FieldOperand(rdx, SharedFunctionInfo::kCodeOffset));
   __ SmiToInteger64(rcx,
                     FieldOperand(rbx, JSGeneratorObject::kContinuationOffset));
   __ leap(rdx, FieldOperand(rdx, rcx, times_1, Code::kHeaderSize));
   __ Move(FieldOperand(rbx, JSGeneratorObject::kContinuationOffset),
           Smi::FromInt(JSGeneratorObject::kGeneratorExecuting));
+  __ movp(rax, rbx);  // Continuation expects generator object in rax.
   __ jmp(rdx);
 }
 
 // Generate code for entering a JS function with the interpreter.
 // On entry to the function the receiver and arguments have been pushed on the
 // stack left to right.  The actual argument count matches the formal parameter
 // count expected by the function.
 //
 // The live registers are:
 //   o rdi: the JS function object being called
@@ skipping 2200 matching lines @@
   __ ret(0);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64