[generators] Decouple generator resume from fullcodegen.

src/arm/builtins-arm.cc

Index: src/arm/builtins-arm.cc
diff --git a/src/arm/builtins-arm.cc b/src/arm/builtins-arm.cc
index 1fffcb67e596dd76147c9b4808358b491c90722e..feb12319f84619b281d7d8f0a0d4e85519e2d63f 100644
--- a/src/arm/builtins-arm.cc
+++ b/src/arm/builtins-arm.cc
@@ -704,6 +704,116 @@ void Builtins::Generate_JSBuiltinsConstructStubForDerived(
   Generate_JSConstructStubHelper(masm, false, false, true);
 }
 
+// static
+void Builtins::Generate_ResumeGeneratorTrampoline(MacroAssembler* masm) {
+  // ----------- S t a t e -------------
+  //  -- r0 : the value to pass to the generator
+  //  -- r1 : the JSGeneratorObject to resume
+  //  -- r2 : the resume mode (tagged)
+  //  -- lr : return address
+  // -----------------------------------
+  __ AssertGeneratorObject(r1);
+
+  // Store input value into generator object.
+  __ str(r0, FieldMemOperand(r1, JSGeneratorObject::kInputOffset));
+  __ RecordWriteField(r1, JSGeneratorObject::kInputOffset, r0, r3,
+                      kLRHasNotBeenSaved, kDontSaveFPRegs);
+
+  // Load suspended function and context.
+  __ ldr(cp, FieldMemOperand(r1, JSGeneratorObject::kContextOffset));
+  __ ldr(r4, FieldMemOperand(r1, JSGeneratorObject::kFunctionOffset));
+
+  // Flood function if we are stepping.
+  Label skip_flooding;
+  ExternalReference step_in_enabled =
+      ExternalReference::debug_step_in_enabled_address(masm->isolate());
+  __ mov(ip, Operand(step_in_enabled));
+  __ ldrb(ip, MemOperand(ip));
+  __ cmp(ip, Operand(0));
+  __ b(eq, &skip_flooding);
+  {
+    FrameAndConstantPoolScope scope(masm, StackFrame::INTERNAL);
+    __ Push(r1, r2, r4);
+    __ CallRuntime(Runtime::kDebugPrepareStepInIfStepping);
+    __ Pop(r1, r2);
+    __ ldr(r4, FieldMemOperand(r1, JSGeneratorObject::kFunctionOffset));
+  }
+  __ bind(&skip_flooding);
+
+  // Push receiver.
+  __ ldr(ip, FieldMemOperand(r1, JSGeneratorObject::kReceiverOffset));
+  __ Push(ip);
+
+  // ----------- S t a t e -------------
+  //  -- r1    : the JSGeneratorObject to resume
+  //  -- r2    : the resume mode (tagged)
+  //  -- r4    : generator function
+  //  -- cp    : generator context
+  //  -- lr    : return address
+  //  -- sp[0] : generator receiver
+  // -----------------------------------
+
+  // Push holes for arguments to generator function. Since the parser forced
+  // context allocation for any variables in generators, the actual argument
+  // values have already been copied into the context and these dummy values
+  // will never be used.
+  __ ldr(r3, FieldMemOperand(r4, JSFunction::kSharedFunctionInfoOffset));
+  __ ldr(r3,
+         FieldMemOperand(r3, SharedFunctionInfo::kFormalParameterCountOffset));
+  {
+    Label done_loop, loop;
+    __ bind(&loop);
+    __ sub(r3, r3, Operand(Smi::FromInt(1)), SetCC);
+    __ b(mi, &done_loop);
+    __ PushRoot(Heap::kTheHoleValueRootIndex);
+    __ b(&loop);
+    __ bind(&done_loop);
+  }
+
+  // Enter a new JavaScript frame, and initialize its slots as they were when
+  // the generator was suspended.
+  DCHECK(!FLAG_enable_embedded_constant_pool);
+  FrameScope scope(masm, StackFrame::MANUAL);
+  __ Push(lr, fp);
+  __ Move(fp, sp);
+  __ Push(cp, r4);
+
+  // Restore the operand stack.
+  __ ldr(r0, FieldMemOperand(r1, JSGeneratorObject::kOperandStackOffset));
+  __ ldr(r3, FieldMemOperand(r0, FixedArray::kLengthOffset));
+  __ add(r0, r0, Operand(FixedArray::kHeaderSize - kHeapObjectTag));
+  __ add(r3, r0, Operand(r3, LSL, kPointerSizeLog2 - 1));
+  {
+    Label done_loop, loop;
+    __ bind(&loop);
+    __ cmp(r0, r3);
+    __ b(eq, &done_loop);
+    __ ldr(ip, MemOperand(r0, kPointerSize, PostIndex));
+    __ Push(ip);
+    __ b(&loop);
+    __ bind(&done_loop);
+  }
+
+  // Push resume mode (consumed in continuation).
+  __ Push(r2);
+
+  // Reset operand stack so we don't leak.
+  __ LoadRoot(ip, Heap::kEmptyFixedArrayRootIndex);
+  __ str(ip, FieldMemOperand(r1, JSGeneratorObject::kOperandStackOffset));
+
+  // Restore value.
+  __ ldr(r0, FieldMemOperand(r1, JSGeneratorObject::kInputOffset));
+
+  // Resume the generator function at the continuation.
+  __ ldr(r3, FieldMemOperand(r4, JSFunction::kSharedFunctionInfoOffset));
+  __ ldr(r3, FieldMemOperand(r3, SharedFunctionInfo::kCodeOffset));
+  __ add(r3, r3, Operand(Code::kHeaderSize - kHeapObjectTag));
+  __ ldr(r2, FieldMemOperand(r1, JSGeneratorObject::kContinuationOffset));
+  __ add(r3, r3, Operand(r2, ASR, 1));
+  __ mov(r2, Operand(Smi::FromInt(JSGeneratorObject::kGeneratorExecuting)));
+  __ str(r2, FieldMemOperand(r1, JSGeneratorObject::kContinuationOffset));
+  __ Jump(r3);
+}
 
 void Builtins::Generate_ConstructedNonConstructable(MacroAssembler* masm) {
   FrameScope scope(masm, StackFrame::INTERNAL);