[turbofan] Further fixing ES6 tail call elimination in Turbofan.

src/compiler/arm/code-generator-arm.cc

Index: src/compiler/arm/code-generator-arm.cc
diff --git a/src/compiler/arm/code-generator-arm.cc b/src/compiler/arm/code-generator-arm.cc
index 5c94ccf7c3b2d07bb6ce1b379cf99d14135080db..a0b0f8efe0af8fff786a7a3b9be76f8c25ccc497 100644
--- a/src/compiler/arm/code-generator-arm.cc
+++ b/src/compiler/arm/code-generator-arm.cc
@@ -405,6 +405,30 @@ void CodeGenerator::AssemblePrepareTailCall(int stack_param_delta) {
   frame_access_state()->SetFrameAccessToSP();
 }
 
+void CodeGenerator::AssemblePopArgumentsAdaptorFrame(Register args_reg,
+                                                     Register scratch1,
+                                                     Register scratch2,
+                                                     Register scratch3) {
+  DCHECK(!AreAliased(args_reg, scratch1, scratch2, scratch3));
+  Label done;
+
+  // Check if current frame is an arguments adaptor frame.
+  __ ldr(scratch1, MemOperand(fp, StandardFrameConstants::kContextOffset));
+  __ cmp(scratch1, Operand(Smi::FromInt(StackFrame::ARGUMENTS_ADAPTOR)));
+  __ b(ne, &done);
+
+  // Load arguments count from current arguments adaptor frame (note, it
+  // does not include receiver).
+  Register caller_args_count_reg = scratch1;
+  __ ldr(caller_args_count_reg,
+         MemOperand(fp, ArgumentsAdaptorFrameConstants::kLengthOffset));
+  __ SmiUntag(caller_args_count_reg);
+
+  ParameterCount callee_args_count(args_reg);
+  __ PrepareForTailCall(callee_args_count, caller_args_count_reg, scratch2,
+                        scratch3);
+  __ bind(&done);
+}
 
 // Assembles an instruction after register allocation, producing machine code.
 void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
@@ -428,6 +452,24 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
       frame_access_state()->ClearSPDelta();
       break;
     }
+    case kArchTailCallCodeObjectFromJSFunction: {

[Michael Starzinger, 2016/03/07 21:47:32]

suggestion: I would slightly prefer the common code to be shared, to make sure
it stays in sync. I was thinking about the following pattern ...

case kArchTailCallCodeObjectFromJSFunction:
case kArchTailCallCodeObject: {
  [...]
  if (opcode == kArchTailCallCodeObjectFromJSFunction) {
    AssemblePopArgumentsAdaptorFrame(...);
  }
  [...]
  break;
}

But I am not an expert on the backends and would be fine either way. So if
Benedikt suggested to implement it like this, then that's fine with me and we
can leave it as it is, just wanted to have it mentioned.

[Igor Sheludko, 2016/03/07 23:19:23]

Good idea! Done.

+      int stack_param_delta = i.InputInt32(instr->InputCount() - 1);
+      AssembleDeconstructActivationRecord(stack_param_delta);
+      AssemblePopArgumentsAdaptorFrame(kJavaScriptCallArgCountRegister,
+                                       i.TempRegister(0), i.TempRegister(1),
+                                       i.TempRegister(2));
+      if (instr->InputAt(0)->IsImmediate()) {
+        __ Jump(Handle<Code>::cast(i.InputHeapObject(0)),
+                RelocInfo::CODE_TARGET);
+      } else {
+        __ add(ip, i.InputRegister(0),
+               Operand(Code::kHeaderSize - kHeapObjectTag));
+        __ Jump(ip);
+      }
+      DCHECK_EQ(LeaveCC, i.OutputSBit());
+      frame_access_state()->ClearSPDelta();
+      break;
+    }
     case kArchTailCallCodeObject: {
       int stack_param_delta = i.InputInt32(instr->InputCount() - 1);
       AssembleDeconstructActivationRecord(stack_param_delta);
@@ -459,6 +501,25 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
       frame_access_state()->ClearSPDelta();
       break;
     }
+    case kArchTailCallJSFunctionFromJSFunction: {
+      Register func = i.InputRegister(0);
+      if (FLAG_debug_code) {
+        // Check the function's context matches the context argument.
+        __ ldr(kScratchReg, FieldMemOperand(func, JSFunction::kContextOffset));
+        __ cmp(cp, kScratchReg);
+        __ Assert(eq, kWrongFunctionContext);
+      }
+      int stack_param_delta = i.InputInt32(instr->InputCount() - 1);
+      AssembleDeconstructActivationRecord(stack_param_delta);
+      AssemblePopArgumentsAdaptorFrame(kJavaScriptCallArgCountRegister,
+                                       i.TempRegister(0), i.TempRegister(1),
+                                       i.TempRegister(2));
+      __ ldr(ip, FieldMemOperand(func, JSFunction::kCodeEntryOffset));
+      __ Jump(ip);
+      DCHECK_EQ(LeaveCC, i.OutputSBit());
+      frame_access_state()->ClearSPDelta();
+      break;
+    }
     case kArchTailCallJSFunction: {
       Register func = i.InputRegister(0);
       if (FLAG_debug_code) {