[turbofan] Support variable size argument popping in TF-generated functions

src/compiler/instruction-selector.cc

 // Copyright 2014 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.
 
 #include "src/compiler/instruction-selector.h"
 
 #include <limits>
 
 #include "src/base/adapters.h"
 #include "src/compiler/instruction-selector-impl.h"
@@ skipping 1871 matching lines @@
   call_instr->MarkAsCall();
 }
 
 
 void InstructionSelector::VisitTailCall(Node* node) {
   OperandGenerator g(this);
   CallDescriptor const* descriptor = CallDescriptorOf(node->op());
   DCHECK_NE(0, descriptor->flags() & CallDescriptor::kSupportsTailCalls);
 
   CallDescriptor* caller = linkage()->GetIncomingDescriptor();
-  if (caller->CanTailCall(node)) {
-    const CallDescriptor* callee = CallDescriptorOf(node->op());
-    int stack_param_delta = callee->GetStackParameterDelta(caller);
-    CallBuffer buffer(zone(), descriptor, nullptr);
+  DCHECK(caller->CanTailCall(node));
+  const CallDescriptor* callee = CallDescriptorOf(node->op());
+  int stack_param_delta = callee->GetStackParameterDelta(caller);
+  CallBuffer buffer(zone(), descriptor, nullptr);
 
-    // Compute InstructionOperands for inputs and outputs.
-    CallBufferFlags flags(kCallCodeImmediate | kCallTail);
-    if (IsTailCallAddressImmediate()) {
-      flags |= kCallAddressImmediate;
+  // Compute InstructionOperands for inputs and outputs.
+  CallBufferFlags flags(kCallCodeImmediate | kCallTail);
+  if (IsTailCallAddressImmediate()) {
+    flags |= kCallAddressImmediate;
     }

[Michael Starzinger, 2016/10/28 14:12:14]

nit: Indentation of the rest of the function off, please re-indent.

[danno, 2016/10/31 10:06:39]

Done.

     InitializeCallBuffer(node, &buffer, flags, stack_param_delta);
 
     // Select the appropriate opcode based on the call type.
     InstructionCode opcode;
     InstructionOperandVector temps(zone());
     if (linkage()->GetIncomingDescriptor()->IsJSFunctionCall()) {
       switch (descriptor->kind()) {
         case CallDescriptor::kCallCodeObject:
           opcode = kArchTailCallCodeObjectFromJSFunction;
           break;
@@ skipping 30 matching lines @@
 
     int first_unused_stack_slot =
         (V8_TARGET_ARCH_STORES_RETURN_ADDRESS_ON_STACK ? 1 : 0) +
         stack_param_delta;
     buffer.instruction_args.push_back(g.TempImmediate(first_unused_stack_slot));
 
     // Emit the tailcall instruction.
     Emit(opcode, 0, nullptr, buffer.instruction_args.size(),
          &buffer.instruction_args.front(), temps.size(),
          temps.empty() ? nullptr : &temps.front());
-  } else {
-    FrameStateDescriptor* frame_state_descriptor =
-        descriptor->NeedsFrameState()
-            ? GetFrameStateDescriptor(
-                  node->InputAt(static_cast<int>(descriptor->InputCount())))
-            : nullptr;
-
-    CallBuffer buffer(zone(), descriptor, frame_state_descriptor);
-
-    // Compute InstructionOperands for inputs and outputs.
-    CallBufferFlags flags = kCallCodeImmediate;
-    if (IsTailCallAddressImmediate()) {
-      flags |= kCallAddressImmediate;
-    }
-    InitializeCallBuffer(node, &buffer, flags);
-
-    EmitPrepareArguments(&(buffer.pushed_nodes), descriptor, node);
-
-    // Select the appropriate opcode based on the call type.
-    InstructionCode opcode;
-    switch (descriptor->kind()) {
-      case CallDescriptor::kCallCodeObject:
-        opcode = kArchCallCodeObject;
-        break;
-      case CallDescriptor::kCallJSFunction:
-        opcode = kArchCallJSFunction;
-        break;
-      default:
-        UNREACHABLE();
-        return;
-    }
-    opcode |= MiscField::encode(descriptor->flags());
-
-    // Emit the call instruction.
-    size_t output_count = buffer.outputs.size();
-    auto* outputs = &buffer.outputs.front();
-    Instruction* call_instr =
-        Emit(opcode, output_count, outputs, buffer.instruction_args.size(),
-             &buffer.instruction_args.front());
-    if (instruction_selection_failed()) return;
-    call_instr->MarkAsCall();
-    Emit(kArchRet, 0, nullptr, output_count, outputs);
-  }
 }
 
 
 void InstructionSelector::VisitGoto(BasicBlock* target) {
   // jump to the next block.
   OperandGenerator g(this);
   Emit(kArchJmp, g.NoOutput(), g.Label(target));
 }
 
-
 void InstructionSelector::VisitReturn(Node* ret) {
   OperandGenerator g(this);
-  if (linkage()->GetIncomingDescriptor()->ReturnCount() == 0) {
-    Emit(kArchRet, g.NoOutput());
-  } else {
-    const int ret_count = ret->op()->ValueInputCount();
-    auto value_locations = zone()->NewArray<InstructionOperand>(ret_count);
-    for (int i = 0; i < ret_count; ++i) {
-      value_locations[i] =
-          g.UseLocation(ret->InputAt(i), linkage()->GetReturnLocation(i));
-    }
-    Emit(kArchRet, 0, nullptr, ret_count, value_locations);
+  const int ret_count = linkage()->GetIncomingDescriptor()->ReturnCount() == 0

[Michael Starzinger, 2016/10/28 14:12:14]

nit: s/ret_count/input_count/ because the semantics of that value changed.

[danno, 2016/10/31 10:06:39]

Done.

+                            ? 1
+                            : ret->op()->ValueInputCount();
+  DCHECK_GE(ret_count, 1);
+  auto value_locations = zone()->NewArray<InstructionOperand>(ret_count);
+  Node* pop_count = ret->InputAt(0);
+  value_locations[0] = pop_count->opcode() == IrOpcode::kInt32Constant

[Michael Starzinger, 2016/10/28 14:12:14]

nit: Can we use g.CanBeImmediate here?

[danno, 2016/10/31 10:06:39]

Unfortunately, no. IFAICT, CanBeImmediate is platform-specific. It certainly
would be possible to turn it into a virtual method that's available in the
InstructionSelector superclass and override it in the subclasses, but should I
do that for this CL?

[Michael Starzinger, 2016/10/31 10:23:19]

Acknowledged. Nah, I thought it would be "an easy" change. I am fine with
keeping it as it is.

+                           ? g.UseImmediate(pop_count)
+                           : g.UseRegister(pop_count);
+  for (int i = 1; i < ret_count; ++i) {
+    value_locations[i] =
+        g.UseLocation(ret->InputAt(i), linkage()->GetReturnLocation(i - 1));
   }
+  Emit(kArchRet, 0, nullptr, ret_count, value_locations);
 }
 
 Instruction* InstructionSelector::EmitDeoptimize(
     InstructionCode opcode, InstructionOperand output, InstructionOperand a,
     InstructionOperand b, DeoptimizeReason reason, Node* frame_state) {
   size_t output_count = output.IsInvalid() ? 0 : 1;
   InstructionOperand inputs[] = {a, b};
   size_t input_count = arraysize(inputs);
   return EmitDeoptimize(opcode, output_count, &output, input_count, inputs,
                         reason, frame_state);
@@ skipping 107 matching lines @@
   return new (instruction_zone()) FrameStateDescriptor(
       instruction_zone(), state_info.type(), state_info.bailout_id(),
       state_info.state_combine(), parameters, locals, stack,
       state_info.shared_info(), outer_state);
 }
 
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8